# Slaughtered Pig - What do do with this one...



## pleximaster

I got this project a 1967 Marshall Major 200 Pig that is totally slaughtered by Tommy Folkesson. I don't know what state it was in before but there are not many things "right" in this one. Any suggestions what to do with it?

best plexi


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## Micky

Kill it before it reproduces...


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## Clammy

Man... an ACTUAL "Pig"... those are so rare. It's a REAL crime what has been done to that amp.  I wouldn't even know where to begin...  Best of luck!

Cheers!


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## shooto

yes!...a REAL "PIG"!!!....I. WANT. THAT. SO. BAD.


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## Joshabr1

Makes me want to hunt up this Tommy guy and give him a good lashing mate.


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## Joshabr1

That said it looks like u have a great platform to rebuild it. Partridges are original I imagine? Never seen a pig in person. Not a ton of em over here in the states.


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## Codyjohns

What a bummer, such a great amp head. 

I'd bring it back to stock but the only problem is, where do you find a 200 watt partridge output transformer......

Maybe track this Tommy guy down and find out where the original OT is.


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## pleximaster

I believe that the mains transformer is an original even though it is flipped. I actually have another partridge 200watt MT from a Carlsbro PA. The output transformer can be found in old PA amps. 

I´ll guess I better stripp it clean have a new tag board made with NOS components. I have read somewhere that they only made these in 67 and only one batch of 50 amps so I guess it deserves to be restored. 

One one with period correct parts for this amp, please pm me. Anyone have any extra "PIG" front and back plexi panels laying around? 

plexi


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## shooto

Vintagekiki put up a schematic of the PIG in another PIG thread ...if you need it


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## pleximaster

Thanks 
I found it!

plexi


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## johan.b

I would contact marshall, see what documentation they may have left in their archives and just start over.
j


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## metromutt

At least he hasn't turned the chassis into swiss cheese like the rest of his mods.

I'd get that restored back as best as you can. There aren't many about and most have been messed with.

clothretainer

Amp Archives/Marshall/200 Watt Heads/1967 Marshall 200 - The Pig/67 1967 Marshall 200 - The Pig/5d77_1

https://www.facebook.com/media/set/?set=a.237813823010427.1073741829.235151569943319&type=3

http://www15.ocn.ne.jp/~dp70tool/dawkamps2.html


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## Joshabr1

Why in the hell would he turn the pt upside down? Who is this guy anyway?


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## keennay

He's been referenced in the past as the 'Swedish amp butcher.'

I wasn't convinced until this thread.


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## Joshabr1

Wonder how many amazing amps he has destroyed?


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## 66SuperTremolo

I've seen pics of some of his work on Vintage Plexi's.......not a pretty sight.

Turning Classic Marshalls worth $$$$$$$ into an abortion worth -------


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## CaptainZero

But can he give a tattoo?


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## pleximaster

I have actually been able to track down all parts needed, transformers board caps and resistors! For the panel I reproduced the pig "Marshall 200" logo using my PA 200 head. The Marshall Major logo returned to the back panel. 

All parts have not arrived yet and the the rebuild process... But hey Ill get a screening PIG!!!


Plexi


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## neikeel

pleximaster said:


> I have actually been able to track down all parts needed, transformers board caps and resistors! For the panel I reproduced the pig "Marshall 200" logo using my PA 200 head. The Marshall Major logo returned to the back panel.
> 
> All parts have not arrived yet and the the rebuild process... But hey Ill get a screening PIG!!!
> 
> 
> Plexi



I look forward to seeing it and hearing it


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## pleximaster

the pig Marshall 200 logo in place

plexi


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## allwheelz

Thank Jebus it fell into your hands!!!! Pleximaster saves the day...now to track down Tommy and smack his fingers....NO! BAD TOMMY!!!


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## dreyn77

NO wait!
I've ordered the parts for you.  

what's our role here?




As we look at this sad and sorry amp, we must take time to reflect on people of the past who thought they knew what they were doing and thought they needed to go above and beyond. 
essentially they were better than marshall. people of giant ego and would attack anything that came their way. 


nothing's changed. the guy who says leave it stock, gets attacked today in 2015.  
but once it's in stock form you'll just go out and buy the JVM.


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## dreyn77

break appart a perfectly good PA amp to remake this thing that lead a good life and died? 

RIP PA amp.  

If you limit (and you are) your perspective you won't notice the whole lot is going back to the soil.
when we all leave the soil will show some signs people were here for a short while. 

mucking around with amps. 

this damaged amp stuff should NEVER have happened in the first place. 
but that's people for you. they don't think about the amp in the future. they use almighty EGO and stuff up the amp.


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## pleximaster

Just to clear up things!

Of cause I didn't cut up my Marshall 200 PA!!!! It is as rare a the Pig! It´s even rarer as it is Kitchen-Marshall logod especially for a music store/rental service in Leeds UK called Kitchen. They had two 200 watts made!!!! 





The thing I did with the plexipanel was I took a picture of the Marshall 200 logo of the PA amp, printed it on a sheet of plexi mirror wise, spray painted it gold, clear coated it, cut it to fit the pig amp and the aged it to match the remaining part of the front panel. The Marshall Major logo part from the back panel that had been cut and put on from was removed and returned to its former location on the back of the amp!






Best plexi


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## Vostre Roy

Wow, very neat, looks like the original ahaha

The more I look for information on the PIG, the more I realise how rare these are and how much I want one now. I'm sure you'll do a better job that what that guy did. Hard to do worse lol

I'll follow that thread for sure. Thanks for sharing that horror story!

Btw, I'd like yo know if the schematic that was found in the other thread is legit, since you are working on the actual amp, could you share with us if it is the case?


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## pleximaster

http://www.marshallforum.com/lets-talk-vintage/40968-schematics-60s-marshall-200-watt-pig.html

Look in this thread! 

Best regards plexi


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## Vostre Roy

pleximaster said:


> http://www.marshallforum.com/lets-talk-vintage/40968-schematics-60s-marshall-200-watt-pig.html
> 
> Look in this thread!
> 
> Best regards plexi



Yes I'm aware of that schematic, but Vintagekiki (who draw it) has stated on another board that he made that schematic by looking at various pictures of gut shots of those amps, he didn't had one in front of him and was asking for other people to verify his work agains't an actual amp:

Here's the board: Vintage Amps Bulletin Board &bull; View topic - Marshall 200 a.k.a. the Pig schematics

And the quote that made me doubtful:



Vintagekiki said:


> Who owns Marshall 200 a.k.a. The Pig will probably find some minor disagreements amplifier vs. schematics. The reason lies in the relatively low-resolution images, so the same could not be accurately read off the value of the components
> 
> I would be immensely grateful, to tell me the differences amplifier vs. schematics, and also help me, so measured dc voltages on electrolytes (points 1 - 5 in the schematics), measured alternating voltages on to power transformer, detailed photograph wiring transformers, boards of power supply, and output tubes on the side of the components inside the chassis.



Cheers man and thanks for the information you give, so little is available


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## danfrank

pleximaster said:


> Just to clear up things!
> 
> Of cause I didn't cut up my Marshall 200 PA!!!! It is as rare a the Pig! It´s even rarer as it is Kitchen-Marshall logod especially for a music store/rental service in Leeds UK called Kitchen. They had two 200 watts made!!!!
> 
> 
> 
> 
> 
> The thing I did with the plexipanel was I took a picture of the Marshall 200 logo of the PA amp, printed it on a sheet of plexi mirror wise, spray painted it gold, clear coated it, cut it to fit the pig amp and the aged it to match the remaining part of the front panel. The Marshall Major logo part from the back panel that had been cut and put on from was removed and returned to its former location on the back of the amp!
> 
> 
> 
> 
> 
> 
> Best plexi



You were clear in your original post. Do you live in England; close to Blechley? Marshall has a PIG in their factory "Museum"; maybe you could swing by and have a look, if they'd permit you to? Tell them your story about how you received the amp you're putting back together and they may well help you out.
The "Vintagekiki" schematic is probably 90% correct.
The B+ voltage should be around 720 volts and the screen supply should be around 410 volts.
Good luck and please pass on any info you may find.
By the way, great work on making the label.
Thanks, Daniel

P.S. If that Kitchen-Marshall is yours, it's guts will be very similar to the 3 knobbed "Pig", after the first preamp inputs for the 4 input jacks... IE. The circuit should be the same except for the first triode sections that the 4 inputs feed into. The coupling caps to the output tubes may be a different value also, but those are minor details that are easily worked around. If you can take hi-res pictures of the guts of the Kitchen-Marshall PA, I can write out a schematic.


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## pleximaster

I am located in Sweden....

But I did as you suggested and send Marshall an email asking if they have schematics and if they could help me out with pictures. I know it is a long shot but since it is such a rare amp they might take some gut shots. ...

There are variations on all these known amps my Kitchen marshall PA differed from a similar amp a french guy had on plexi palace forum and both our amps differ from the Vintagekiki schematics. 


Best plexi


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## Swede

But how does it sound?.... Look wise it might be butchered but he's a pretty reputable amp guy in Sweden. He's modded for quite a few players.


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## pleximaster

It starts to oscillate as you turn it up and some other issues with the bias. So it really needs an overhaul and I don´t want to do it for this setup. Rather fixing this with the original design.

Best plexi


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## danfrank

Whoever modified this amp, their work is very sloppy. It's not a surprise that the amp oscillates. i'm not pro or con concerning amp modifications, but the work should be done correctly and neatly; it's good engineering practice which will result in a dependable, working amplifier.
Daniel


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## metromutt

What made him move the OT and the choke on chassis, the one's I've seen on the web all have the usual trannys to one side layout. Would the moving or rotation of them cause the oscillation?


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## pleximaster

I guess the move of the transformers were done to balance the amp when carrying it. Bet replacing the choke with just resistors is effecting the amp to sound more modern then vintage...

plexi


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## Swede

Tommy Folkesson | Give your amp a new heart!


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## danfrank

pleximaster said:


> It starts to oscillate as you turn it up and some other issues with the bias. So it really needs an overhaul and I don´t want to do it for this setup. Rather fixing this with the original design.
> 
> Best plexi


 
Disconnect the negative feedback of the amplifier and see if that stops the oscillation. The problem with these super high gain amps is that they are marginally stable the way their circuits are built/modified. Add to that any phase shift that may be introduced within the negative feedback loop and the amplifier becomes a full time or part time oscillator.
There is minimal difference between a circuit that amplifies and a circuit that oscillates.
Daniel


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## pleximaster

It is stripped now and I am filling the swiss cheese chassis. I filled the hole in the back panel and replaced the ecc83 valve holders, input jack, tone controls, mains and impedance switches with NOS parts.














plexi


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## danfrank

Hi again,
Nice work you are doing. How did you fill in the holes in the chassis? I see that you sanded the chassis down afterwards to smooth the surface. What did you use for filling material?
Did you measure B+ voltage before disassembly? B+ should be around 720 volts. I would recommend using ceramic octal sockets instead of the plastic/phenolic sockets that are on the amp. Arcing becomes a problem in these sockets, especially when the B+ is over 500 volts. High quality ceramic sockets will help with arcing problems.


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## pleximaster

The b voltage did not go over 600...

I use phenolic as its time period correct, Ill look at voltage when the new (old) transformers are in place.

For filling materal I used plastic padding liquid aluminum. It will be polished as will. From underneath I will a a thin alu plate to strengthen it all and make it look good.

best plexi


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## Grogshla

wow looks like it needs new everything!
Best of luck with it tho mate even if its for the rarity. Not sure 200w is all that useable but awesome amp none the less.


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## pleximaster

Yes it is a total rebuilt! The reason I am doing this is that these are so extremely rare only 50 were ever made. The difficulty is that they varied a lot when it came to components, layout, and transformers. I have seen two in the flesh, so to speak, and pictures of 10 others, none were 100% the same! So I don´t know how this will end up! 

best plexi


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## psychodave

Cool thread. Keep posting pictures of the restoration. Cheers and good luck.


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## LedZeppelinFan

I love Majors! Congratulations on owning one!


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## Ace Major

This 100 watt PA from Belgium also looks pretty beat up...

Marshall 1970 PA dagnall transfo Modded Folkesson - Te koop | 2dehands.be


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## pleximaster

Old Partridge transformers! The pig was the only marshall ever featuring these!

plexi


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## Codyjohns

Great job on the restoration so far !! 

Can't wait to hear this beast !!


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## danfrank

pleximaster said:


> Old Partridge transformers! The pig was the only marshall ever featuring these!
> 
> plexi



Hi again,
Could you possibly do some measurements on the output transformer? If you could, place the voltage from the filament winding through the primary of the output transformer and then measure the voltage coming out of the 16 ohm secondary tap, and then report back with the voltages measured? I would like to know the voltage going into the entire primary of the output transformer, to 3 decimal places, and also the voltage coming out of the 16 ohm tap, to 3 decimal places. This way, I can get the turns ratio of the transformer and figure out the transformer's primary impedance. I would really appreciate it, if it's not too much trouble.
Thanks, Daniel


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## pleximaster

New Pig board... Filtering boards to come... 

plexi


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## Viking62

Wow! great score get it to the ER quick..!
If you're in Sydney take it to Dave Peach or Terry (Engadine)
Errrrrr thanks for your input Dreyn as always..


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## Vostre Roy

Just for the sake of not having to go back to the previous page to compare before/after, I'm reposting this here. Holy upgrade, Batman!


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## danfrank

pleximaster said:


> New Pig board... Filtering boards to come...
> 
> plexi



You do really nice work. What schematic did you use?


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## neikeel

danfrank said:


> You do really nice work. What schematic did you use?


 
Yes, looks very nice

Were the old boards not salvageable?


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## dreyn77

there's always somebody who fires off the question before they bother to think should the question be asked. ? 

looks like it's getting into shape now. 
I have 2 concerns. 
lopsided carrying of the amp cause all iron is on one side. 
the closeness of the big iron. voltage jump across gaps. 

It would be great if you can get hold of a special camera and film the voltage arching into the atmosphere with this amp running. then put it on youtube.  
looks good. total rebuild.


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## neikeel

dreyn77 said:


> there's always somebody who fires off the question before they bother to think should the question be asked. ? .



I will restrain myself with not answering you with the venom you deserve....

To my eye the board looks salvageable but maybe I am missing something, perhaps Pleximaster can answer


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## pleximaster

dreyn77 I do like a good ironic humour but sometime I don´t get you and I almost feel like you´re trying to be offensive. But hey, it might be me and a language issue since I have Swedish as my mother tongue, not English. So bare with me ok! 

Location of the Iron is based on their original position one can have concern about their position I am aware of that but wanted it to be as close as possible.

Neikeel If you look closely at the before picture you can see that it is a black plastic board not original to the amp. It is actually made of two sheets of plastic from a lid of a cookie jar!  So it had to go. Only a few components were old, but their leads were cut too short to use. The board is made of old paxoline that I bought from a great supplier in Greece. They make very nice amp boards and have great stock of vintage components.

best plexi


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## neikeel

pleximaster said:


> Location of the Iron is based on their original position one can have concern about their position I am aware of that but wanted it to be as close as possible.
> 
> Neikeel If you look closely at the before picture you can see that it is a black plastic board not original to the amp. It is actually made of two sheets of plastic from a lid of a cookie jar!  So it had to go.


 
Ah I see, I must look more closely. The long view in the pics looked a bit like a really dirty 69/70 dark fibre board. The components look like they were thrown at the board before.
The new one is a transformation. Presume you will be using new ceramic sockets for the KT88s to avoid the light show Dreyn was speculating about. BTW what KT88s are you going to use a good matched quad of GECs must be a fortune now?


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## strato2009

That's incredibly cool amp. Can't wait to hear it on youtube!


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## pleximaster

I am having a bit of problem with this one and the Marshall 200 PA Major I have. To make the power stage stable I am having a guy installing individual bias pots for each KT88.

plexi


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## danfrank

pleximaster said:


> I am having a bit of problem with this one and the Marshall 200 PA Major I have. To make the power stage stable I am having a guy installing individual bias pots for each KT88.
> 
> plexi



I put a 1k5 ohm on each pin 5 of the 4 output tubes. I dont know why the original pig only had 2 of these resistors on the amp. I thought that was strange. I haven't had instability problems. My B+ is 705 volts and screen voltage is 410 volts working into a 2k5 primary impedance output transformer. Pretty much what 4 KT88s want to see as a load.
I thought about using the 4 separate bias pots with 4 0.1caps but decided to try it with each output tube having its own 1k5 resistor at pin 5 of the tube first. The 1k5 resistor has to be as close as possible to pin 5 of each output tube to avoid instability issues.
Resistor going to bias supply cant be more than 100k either. 100K is on the border. I thought about going with a 68k but the 12AX7 is such a wimpy tube I decided against it. Output tube bias is stable on my amp.
Also make sure that output transformer is in correct phasing with output section because of negative feedback tap. There is no getting that wrong though because if it is, the noise will chase you out of the house.


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## pleximaster

danfrank said:


> I put a 1k5 ohm on each pin 5 of the 4 output tubes. I dont know why the original pig only had 2 of these resistors on the amp. I thought that was strange. I haven't had instability problems. My B+ is 640 volts and screen voltage is 358 volts working into a 2k5 primary impedance output transformer. Pretty much what 4 KT88s want to see as a load.
> I thought about using the 4 separate bias pots with 4 0.1caps but decided to try it with each output tube having its own 1k5 resistor at pin 5 of the tube first. The 1k5 resistor has to be as close as possible to pin 5 of each output tube to avoid instability issues.
> Resistor going to bias supply cant be more than 100k either. 100K is on the border. I thought about going with a 68k but thec12AX7 is such a wimpy tube i decided against it. Output tube bias is stable on my amp.
> Also make sure that output transformer is in correct phasing with output section because of negetive feedback tap. There is no getting that wrong though because if it is, the noise will chase you out of the house.



Dan 
Do you have the 1967 Marshall 200 Major Model (Pig and Pig PA) or the later model introduced in 1968 with regular Prec, Bass, Middle, Treble, Vol 1 and Vol 2? they are quite different...

best plexi


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## danfrank

Hi Plexi,
I cloned the original Marshall 200 schematic with NO screen taps on the output transformer. See the end of this thread:

http://www.marshallforum.com/lets-talk-vintage/40968-schematics-60s-marshall-200-watt-pig.html

Typically, instability in the output stage of a push-pull parallel amp comes from two sources... 
Parasitic oscillations that are picked up from the control grid (pin 5) of the output tube. The 1K5 resistor takes care of this but one resistor needs to be on each output tube's grid. I don't know why the original Marshall 200 only has 1 of these resistors on each tube pair in the output stage; very strange from a design standpoint.
The other place is too high of a resistance value in the bias circuit of a fixed bias amplifier. If the amp has too high of a bias circuit resistance, the output tubes will start acting "with a mind of their own" and not hold the correct bias. This will cause instability.
By the way, I am using the Reissue Gold Lion KT88 tubes in the amp I built. I am not a big fan of new production tubes but these new Gold Lion KT88s are very well made. 

You stated that you are having instability issues with your amp... What is the amp doing? Is it oscillating? Is the bias drifting?


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## Muziekschuur

I own a dutch amp called a Multitone (Myagra) M200 deluxe. It's A dutch amp and from the maker where Dolf Koch learnd his trade (hence his Koch Multitone amps). It's a 8x El34 amp. And it is LOUD. There is a lot of maintenance involved. And allthough I do have all the tools I am not really a tech guy. So I'm silent here and hope to learn. Thank you for all the details and everyones reminder to be safe. These are high voltage amps and it would be great nobody does get hurt maintaining these amps. 

Yesterday I heard an Universal Audio emulated Marshall Lead amplifier. And it is just not the same. These old amps still hold their magic. And the fact that they are saved and maintained is just way cool. Ah well. I would be silent... Would I not? Did I mention my Dynacord BA300? 225 watts out of 4 EL34's at 800 volts? Eh... silent...


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## pleximaster

The new boards...

plexi


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## danfrank

Beautiful work!
One more thing can be done for output stage stability... Put more capacitance on the Screen grid supply of the output tubes. On my clone amp, I have over 100uf capacitance on the screen supply; much more than the 16uf on the screen supply that the PIG schematic shows. Take a look at the attached pictures; where the PIG schematic shows a 16uf capacitor I placed a 100uf capacitor. I also put a small 10uf capacitor very close to each pair of 1K 5 watt resistors that go to each output tube's screen grid (pin 4). More capacitance means a "stiffer" (less sag) screen supply. In a pentode or Beam tube output stage, a well regulated (high capacitance) screen supply is very important for proper operation. 

There is a drawback to adding too much capacitance to the screen supply though. Add too much capacitance and the amplifier will start sounding more like a Hi-Fi amp instead of a guitar amp; so the key is to add capacitance so the output stage is stable, but not too much so the amp doesn't sound good with a guitar.

Daniel


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## Namkrad

Wow, great work fixing it back to life 
Will follow this with interest


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## pleximaster

Gonna mount the boards in the pig tomorrow...

plexi


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## danfrank

Hi Plexi,
What is the status of this rebuild? I am super interested in hearing a YouTube clip of this amp once it's finished. Keep up the great work.


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## pleximaster

I haven´t done much on the pig, I´d like some help from a friend of mine (I don´t have a working scope right now) on this one I got respect for the 4xKT88 and their voltage...

plexi


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## pleximaster

Work in progress... slowly...





See if I can get the transformers connected next week... I fear those monsters!!! 

plexi


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## danfrank

Can't wait to find out the final results of your project!
One more thing that I wanted to add... I remember you stating that you had instability issues with your "PIG" amps. Even though it isn't on the original "PIG" schematics, placing a 47pf capacitor across the plate leads of the PI, like the Superlead schematics have, should tame down a lot of the ultrasonic / parasitic trash that may be present in the signal. The 47pf cap will null any of this before it gets to the power tubes.


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## pleximaster

I´ll try that!

Thanks!

Best plexi


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## Gries Amps

Any updates? Thanks.


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## pleximaster

I am having a problem with a cut in the output transformer outer layer, it needs to have a few of the outer layers to be unwound... so there is a setback in progress...

plexi


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## Gries Amps

Thanks. I'm not very familiar with the "Pig" and I'm looking forward to hearing about your successful restoration.


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## danfrank

pleximaster said:


> I am having a problem with a cut in the output transformer outer layer, it needs to have a few of the outer layers to be unwound... so there is a setback in progress...
> 
> plexi




Hi Plexi,
Do you have access to an old Carlsbro 200 watt P.A.?
From what I understand, it uses the original Partridge 200 watt output transformer that the Marshall 200 uses.


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## ricksconnected

why are these call a pig or thee pig?


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## neikeel

ricksconnected said:


> why are these call a pig or thee pig?


 
These are the first Marshall 200w Majors, only made in 1967. They had an active EQ and only three knobs on the front. My understanding (someone please correct me if I am wrong) is because the control panel looked short and stubby like a pigs face with little piggy eyes! 

I do not know who coined the phrase, there is a section on it in the Doyle HOM book.


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## ricksconnected

thanks neikeel.


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## Harlequin tusk

What an awesome project, bringing a classic back to life! Go all out!


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## ricksconnected

Harlequin tusk said:


> What an awesome project, bringing a classic back to life! Go all out!




why not right.


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## strato2009

Any progess on this one? Really interested to see how it ends up


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## pleximaster

Me too!!!! 

I am still waiting for the tranny to have the outer winding fixed.... 

plexi


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## pleximaster

Only a minor update!





plexi


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## neikeel

pleximaster said:


> Only a minor update!
> 
> 
> 
> 
> 
> plexi



Looks like a pretty 'Major' update to me


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## danfrank

Damn! I need to move to Europe...


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## pleximaster

neikeel said:


> Looks like a pretty 'Major' update to me


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## danfrank

Hi,
I picked up a couple of transformers for a 200 watt amp; I think they came from a Sound City 200 Plus amplifier. The choke was made by Partridge but the transformers were made by a British company called Electro-Voice. Not the same company that makes the speakers. These transformers are wound to the same specs as the Partridge transformers; Sound City switched to the EV transformers sometime around 1975-1976. I don't know if this was because Partridges were no longer being made or if the EV units were much less expensive for Sound City to source. I think Hiwatt used EV transformers also, later on.
Anyway, the OT's primary impedance is around 2300 ohms Center Tapped. The secondary has 4, 8, 16 ohm out plus 100 volt out for sound distribution. Each secondary tap has 2 wires per tap. IE. the 4 ohm tap has 2 green wires that need to be joined, the 8 ohm tap has 2 yellow wires that need to be joined, etc.
The PT has input voltages of 115, 220 and 240 volts. There are 4 secondaries: a 6.3 volt filament winding, a bias winding of 38 volts, and 2 HV windings: one is 300 volts and the other is 220 volts AC. This will give B+ voltages of 420 volts and 720 volts (the 2 HV windings are rectified and then "stacked" on top of each other.)
I think I will build another "PIG" with these.

By the way Pleximaster... Did you ever get the output transformer fixed on your 200 watter?


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## pleximaster

Thanks for pushing me Frank! 

I´ll see if I can visit my friend who has the transformer now and se if we can fix it. He is a good friend but the kind that not always delivers unless your are standing next to him padding his shoulder ....   

I must get this one up and running!

Best plexi


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## tomsvintage

Pleximaster ~ Beautiful restoration !! Congratulations !! I'll bet it will sound glorious when you are finished. Best, Tom


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## strato2009

pleximaster said:


> I must get this one up and running!
> 
> Best plexi




Yes, and we must hear it being played by you or Johan!!


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## pleximaster

Fixed the output transformer myself this morning. I went up a 5.00 o'clock before the family woke up and started with the transformer. There was a cut in the paper and the wire if one of the primaries were cut. It kind of scary to use a scalpel near the wires to do the bypass operation... it was´t the neatest surgery but it worked! The OT is up and running again!

Materials some solder, super glue, wax paper and a wire...
























[URL=http://s139.photobucket.com/user/pleximaster/media/IMG_8551_zpsw5sg8csj.jpg.html]





[/URL]




plexi


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## strato2009

Really nice work


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## sinner 13

CaptainZero said:


> But can he give a tattoo?



And where's the Cup holder?


----------



## tschrama

The " Swedish swish chees amp butcher" .. 

What a lovely callsign... LMAO


----------



## pleximaster

danfrank said:


> Hi again,
> Could you possibly do some measurements on the output transformer? If you could, place the voltage from the filament winding through the primary of the output transformer and then measure the voltage coming out of the 16 ohm secondary tap, and then report back with the voltages measured? I would like to know the voltage going into the entire primary of the output transformer, to 3 decimal places, and also the voltage coming out of the 16 ohm tap, to 3 decimal places. This way, I can get the turns ratio of the transformer and figure out the transformer's primary impedance. I would really appreciate it, if it's not too much trouble.
> Thanks, Daniel



Now I might be able to to this! 

plexi

Edit:
Look at this thread: http://www.marshallforum.com/showthread.php?t=40968 Ampbuilder wrote:

"Hi everyone. I own one of the first 'Pigs' made. Its still in excellent condition but needs a new output transformer. I have got the circuit drawing somewhere which I will draw up on CAD. The circuit is quite different to the 'Majors'. A brief description ;-
two ECC83, one ECC82, and four KT88. The power circuit is quite traditional (NOT an ultralinear type). HT volts is 750VDC ( ouch ). Screen grids are 550vDC from four grid resistors. HT is generated from center tapped transformer through three diodes in series from each tap. Smoothing caps are four 33uf 450V wired as two parallel pairs in series. Screen grid is from a seperate supply with two smoothing caps in series. The transformers are made using grain oriented continuously wound strip C cores. These cores I believe was made by a company called Seddon and Bramall in Sheffield UK. Who wound the transformers Ime not sure. The output transformer primary was 550 0 550 turns of 25swg (british wire guage). These were split into smallergroups and interspaced to achieve a better balance. Output winding was 150 turns for 15 ohm and 75 turns for 8 ohms. Guage Ime not sure I guess 20SWG. On full output into 15 ohms I once measured 235V AC . Hope this is of interest. I will post full circuit when done as it appears ime the only one whos got it. It had one problem the output NFB was fed into the ECC82 phse splitter and there was some crossover distortion. I notice later versions take the feedback to an earlier stage to have more effect."


----------



## danfrank

pleximaster said:


> Now I might be able to to this!
> 
> plexi
> 
> Edit:
> Look at this thread: http://www.marshallforum.com/showthread.php?t=40968 Ampbuilder wrote:
> 
> "Hi everyone. I own one of the first 'Pigs' made. Its still in excellent condition but needs a new output transformer. I have got the circuit drawing somewhere which I will draw up on CAD. The circuit is quite different to the 'Majors'. A brief description ;-
> two ECC83, one ECC82, and four KT88. The power circuit is quite traditional (NOT an ultralinear type). HT volts is 750VDC ( ouch ). Screen grids are 550vDC from four grid resistors. HT is generated from center tapped transformer through three diodes in series from each tap. Smoothing caps are four 33uf 450V wired as two parallel pairs in series. Screen grid is from a seperate supply with two smoothing caps in series. The transformers are made using grain oriented continuously wound strip C cores. These cores I believe was made by a company called Seddon and Bramall in Sheffield UK. Who wound the transformers Ime not sure. The output transformer primary was 550 0 550 turns of 25swg (british wire guage). These were split into smallergroups and interspaced to achieve a better balance. Output winding was 150 turns for 15 ohm and 75 turns for 8 ohms. Guage Ime not sure I guess 20SWG. On full output into 15 ohms I once measured 235V AC . Hope this is of interest. I will post full circuit when done as it appears ime the only one whos got it. It had one problem the output NFB was fed into the ECC82 phse splitter and there was some crossover distortion. I notice later versions take the feedback to an earlier stage to have more effect."




Hi again... Very nice work with the transformer! It looks like the transformer was dropped onto something sharp sometime during it's life.
The above quote has some discrepancies in it. The screen voltages are going to be somewhere between 400-450 volts. 720-750 volts looks correct for plate B+ voltage, depending on what the wall voltage going into the power transformer is. 235 volts @ the 15 ohm winding is not going to happen. This equates to over 3000 watts. These Marshall 200 amps are powerful, but not THAT powerful. I do believe the turns on the primary being 550-0-550, considering the resistance of the whole primary being around 33 ohms, that sounds about right. His secondary turns are off though. On transformers like this, there are usually more than one secondary winding, and they are usually connected in parallel. The 15 ohm secondary on his transformer has more like 2 sections of 75 turns each. He added the turns, mistakenly. 75 turns on the 15 ohm secondary tap will give the correct impedance for the primary of 2300 ohms.
My transformer measures 33.8 ohms DC resistance across the whole primary winding. Each half of the primary is very well balanced with the other half of the primary. I measured about 0.2 ohm difference between primary halves. These are extremely well balanced windings.


----------



## pleximaster

You are much more knowledgeable about this stuff. You will have to guide me through the process as I have the amp up and running to get the measurements you want.

The injury on the transformer looks as if someone tucked in the cower cord and connector in a non gentle way. The paper is rather thin and no metal bell plates to protect them. The transformer a Partridge TH1499 is one of the transformer versions found on Pigs but this one came from a heavily gigged Carlsbro PA amp. These are the durable versions the other ones look like these and are probably Partridge too, but they seldom survive the PIG design. These pics below are not mine but I borrowed them from the net. 








My The Pig PA has the same MT as the one above and the TH1499 OT. My three knobs, the Pig, has Partridge TH1499 OT and TH1498 MT from donor amp. Chokes are all over the place and hard to tell if they are original or not. Seen Drakes, Partridge and RS. Never seen an unmolested The Pig ever not even a picture. To use them you should be a tech and keep checking them often so no parts fail. There are extreme currents in these so there are a lot of stress on the components. This is another reason (apart from the market wants low wattage amps) that Marshall will never release these amps, at least not it the original state.









The story i´ve heard is that the rounded partridge transformer were older units not longer produced that marshall got a good surplus price on, in some chases the story is told that they got them for free, I don´t know. However when they ran out and the amps started to return to the shop with broken trannies whey had to get the very expensive new ones. This was one of the reasons they redesigned the 200 into the Major and started using Drakes and Dagnall transformers instead. The Partridge transformer are quite different from the Drakes and Dagnalls.

plexi


----------



## danfrank

pleximaster said:


> You are much more knowledgeable about this stuff. You will have to guide me through the process as I have the amp up and running to get the measurements you want.
> 
> The story i´ve heard is that the rounded partridge transformer were older units not longer produced that marshall got a good surplus price on, in some chases the story is told that they got them for free, I don´t know. However when they ran out and the amps started to return to the shop with broken trannies whey had to get the very expensive new ones. This was one of the reasons they redesigned the 200 into the Major and started using Drakes and Dagnall transformers instead. The Partridge transformer are quite different from the Drakes and Dagnalls.
> 
> plexi



Sure, let me know, and I will help you any way I can.

The Marshall 200, Carlsbro PA 200, Hiwatt DR203, Sound City 200+ all had very similar output sections in their amplifiers. The power and output transformers are all very similar in these amplifiers.
As far as quality, Partridge transformers were some of the best, physically they were very well built and the engineering that went into them was some of the best. Partridges were very high quality units, much better than the Dagnall or Drake transformers. The easiest way to tell what is a Partridge transformer, besides them having the yellow sticker, is that all Partridge transformers have a thick amber coating of transformer varnish on them. This varnish was applied to give the transformer higher voltage resistance and to make the transformer somewhat weatherproof, especially in high humidity climates.
The rounded Partridge transformers use "C" cores for the magnetic component of the transformer. "C" cores are much more efficient at holding the magnetic field inside the transformer with less losses. Typically, only the best quality transformers use "C" cores, as they were more expensive to manufacture.


----------



## pleximaster

I know that Partridge are considered the top notch in transformers however the design of the Pig and the way especially guitarists used them made the amps fail and often damaged the transformers even though they were of great quality. The transformers are often ok in PA amps but not in lead amps... tells you something about guitarists...

Turning up a pig till "ten" with unmatched tubes and without biasing and then put a fuzz pedal in front of the amp, certainly could make the amp tube arch and cause the "smoke on the water" effect...  bringing down any transformer.

Thank you about the info on "C" cores, you learn something new everyday!

plexi


----------



## pleximaster

Ok... more or less done... never built one of these before (few have) and have no referens. It´s not like a KTM45 or a Super lead... I am a bit terrified to firing it up. I have used the schematics made by "Vintagekiki" but I don't know if there are any errors in there. To me the bias wiring looks quite interesting compared to other marshalls but this one have its own power tap. Choke placement?

And the voltage of 750V to OT! 

Do I dare... don´t want to blow any transformers now... and the only KT88s I have at home now are original vintage GEC... I have some 6550 I could use in a startup.
All suggestions for a pre-check soft startup are welcome! 












plexi


----------



## danfrank

Yes! Now is the moment... Great work! The Vintagekiki schematic is good, you will get a working amplifier. Just double-check your work to make sure that what you assembled is the same as the Vintagekiki schematic.
Are your filter capacitors new stock? Do you have a variac? With NO tubes in the amplifier, plug the amp into the variac and slowly bring up the voltages. Do this with NO tubes in the amp. Get the variac up to house voltage (220v or 240v?) and start taking voltage measurements.
The voltages I give you will be referenced to the Vintagekiki schematic:
#5--- 705v
#4--- 410v
#3--- At least -60 volts. My amp takes -53 volts bias with the RI Gold Lion KT88s
#2--- 350v
#1--- 305v

These will vary depending on the amplifier +/- 20%. These are the voltages measured on my amp, properly biased, ready to play. The B+ going to the OT on my amp is only 705 volts not 750v, so adjust as needed.
Good luck!

EDIT: Use the 240v primary tap on your PT.


----------



## danfrank

One more thing... And this is IMPORTANT!
Work with one hand in your pocket. This will prevent you from accidentally getting voltage through your heart. I've been shocked with 500vdc in my 20s and it hurt like hell and my heart beat weird for 15-20 minutes. 750v through the heart will probably kill. Be careful.


----------



## danfrank

Oh! I forgot...
Choke placement is correct on the Vintagekiki schematic. 
Anchor your boards to the amp with standoffs... Loose boards are asking for trouble.


----------



## danfrank

I just saw your wiring and I have a question...
Correct me if I'm wrong but why do you have 5K6 resistors going from pin 5 of each power tube to ground? Or are the 4 lugs isolated from the chassis? Either way, those 4 resistors should not be there.
I see the 2K7 resistors going from pin 5 of one power tube to pin 5 of the other power tube in the pair; this is OK. 2K7 is similar to 1K5.
If you need a more negative bias voltage (more bias) change the 150k resistor before the bias diode. Put in a smaller value resistor.


----------



## pleximaster

Thanks a lot Frank! I appreciate it!

Boards have anchor standoffs! I just haven´t fasten the bolts yet as I am checking the wiring. I haven´t put HT fuse in the circuitry as well as I am uncertain were it will go. The on/off switch is the original one and is a dual switch. Should I wire the second half of the switch to the filter board or is that unnecessary as it will turn on at the same time.

5K6 resistors going from pin 5 of each power tube to ground? 

The wiring around the power tube sockets have a few remnants of the old wiing of this amp. Please advice me here. I posted this on the "Work bench"

http://www.marshallforum.com/showthread.php?t=88810

I guess I should have posted it here...

These are close ups of the tube socket wiring 







best regard plexi


----------



## danfrank

Good morning to you, Plexi.
Remove the 4 5K6 resistors. Not only will this affect bias voltage, it will greatly reduce signal voltage going to the power tubes, so your power output will suffer.


----------



## pleximaster

Thanks Dan!

Does the rest of the power tube socket wiring look ok to you? I never done KT88s before but I guess they are similar to the EL34 and KT66 wiring?

best plexi


----------



## danfrank

There should be 2 fuses. One for the plate B+ (750v) and the other fuse for the screen/preamp supply (450V). Both fuses are placed after the filter capacitors of each supply. Both fuses should be fast or non time delay fuses. Take a look at the picture.
As for the standby switch, I don't know what to tell you as your power transformer secondary has more voltage than what the switch is rated for. It will be a hard solution for this amp. For now I would just wire the power switch as a mains switch that turns power on and off to the primary of the PT.


----------



## danfrank

pleximaster said:


> Thanks Dan!
> 
> Does the rest of the power tube socket wiring look ok to you? I never done KT88s before but I guess they are similar to the EL34 and KT66 wiring?
> 
> best plexi



The rest of the power tube socket wiring looks good. Pins 1 & 8 go to ground, pins 2 & 7 filament power, pin 5 signal in and bias voltage, pin 4 & 6 resistor for screen. Yes, KT88 same as EL34 and KT66.

Why did you select 1K8 for screen resistors? This will provide a bigger safety margin for tubes but power output will be a little less. The voltage that goes to the screen is what determines the power gain of the output tube.


----------



## pleximaster

Yes I have used the 1.8K for screens to save a bit on the tubes and don´t mind loose a bit on power on a 200 watt amp 

About the fuses, I have 250V in the wall and 1 amp and 0.5 amp seems a bit low...I have 2 amp mains and 1 amp in most my 100watters. 

- Your the man - Dan! 

plexi


----------



## pleximaster

On most amps you have the mains fuse to common primary. Why not here? Or do you mean I should add a third fuse as often found in Scandinavian export amps. 500mA fuse before the choke 

In the Carlsbro 200 watt the HT fuse is before the capacitors


"I would just wire the power switch as a mains switch that turns power on and off to the primary of the PT."
That´s how it is wired now...

best plexi


----------



## danfrank

Hi Plexi,
Sorry, I was not clear about my answer about the fuses. There will be 3 fuses total in your amp. 
First one will be the mains fuse which you will place before the mains switch that goes to the primary of the PT. This will be a slow-blo or time delay fuse. For 220-240v mains, it should be a 4 amp fuse.
Second fuse will be for the 750v B+; place it between the filter capacitors and the connection of the output transformer. This one should be a fast fuse rated at 1-1.5 amps. 1 amp fuse will be safer. Look at above picture from last night.
Third fuse will be for the 450v screen/preamp B+; place it between the filter capacitors and "in" wire of choke. Again, look at picture from last night for placement in the circuit. It should be a 250-500ma fast fuse. I use 500ma here because 250ma will sometimes burn when I turn the amp on. Either way, if there is a power tube short, this fuse along with the other HV fuse will save your amp.

I guess I should explain something before I get too far along... My main concern when building/restoring amplifiers is reliability and safety. Sometimes I deviate from the original schematics on fuse placement and other safety features. In the HV supplies I like to use fast or non-time delay fuses because they offer a greater margin of safety. You CAN place the HV fuses BEFORE the filter capacitors, like Marshall does, but then you will have to use time delay or Slow fuses because fast fuses will burn when the filter capacitors first charge up when you turn the amp on. Slow fuses do not offer as much protection in the HV supply. If something goes wrong with a tube, you want the fuse to burn immediately.


----------



## pleximaster

Thanks for the clearup! This was my initial instinct to place the Mains Fuse and the HT Fuse. However, I did my PhD in neuroscience - experimental brain research and not engineering!  So I am really grateful that you help me out! 

I´ll put in a third fuse at the choke!

plexi


----------



## pleximaster

This is how i wired it now; The two outside fuse holders are traditional Marshalls setup, one on the common mains primary and the other on the "HT" before filter caps.

I added two more fuses inside as you suggested one in line with the choke and one after the caps. Overkill?

plexi


----------



## danfrank

pleximaster said:


> This is how i wired it now; The two outside fuse holders are traditional Marshalls setup, one on the common mains primary and the other on the "HT" before filter caps.
> 
> I added two more fuses inside as you suggested one in line with the choke and one after the caps. Overkill?
> 
> plexi



The extra fuses will not harm anything. The "HT" fuse before the filter caps may have to be a time delay fuse so it can withstand the charge-up of the filter caps at power on. The 2 fuses on the inside need to be fast or non-time delay fuses.


----------



## pleximaster

Thanks for all your help Dan! Better to be safe than sorry... I was once saved by a Residual-current device when working renovating our old house, some previous owner had made some non standard electric "improvements" lucky we had installed the RCD a few weeks before... 

Besides I had the holes from the unneeded resistors that I could use to mount the fuse holders, and this amp is not a "virgin" by any means so I don´t mind stepping outside originality when it comes to safety.

I will try to fire the thing up on Sunday! My oldest daughter turns 10 years tomorrow and there will be some celebration tomorrow as well as on Friday and a Saturday! I don´t know if I will survive Saturday as she will have 12 of her friends for a sleep over party! My Good! 

I´ll keep you posted on my progress with the amp as soon something happens!


----------



## danfrank

Ok! I need to move to Scandinavia so I can have a 3 day birthday celebration! 
If you have any other questions, don't hesitate to ask. I can't wait to see the "pig" video on Johan's YouTube page.
One more thing... Place a strip of vinyl electrical tape under each of the 2 inside fuse holders, between the chassis and fuse holder. I don't think it will arc from fuse holder to chassis but the tape won't hurt anything, and it's an extra safety precaution.
I hope your family has a great birthday celebration.
Daniel


----------



## pleximaster

Thanks for the tip!

If you can make it you´re welcome to join the celebrations! Where are you at Dan?

It is cool that this amp project is starting to come to a closing. I was offered this amp for some time and I passed on it several times due to the state it was in. I even consider building in a 1 watt JMP1 head into it just for fun. But this is really great to have tried to make it back to something it was suppose to be once. It will never be an unmolested amp and a collectors piece but it still hold it part in the Marshall history. The more I´ve investigated in these amps I realised how very rare they are. Many of the big dealers never even seen one less owed or sold one. I have not even found a single picture of an unmodified or repaired Marshall 200. The maximum number of amps were 50, thats how many front plates were ordered according to the ledgers, however that does´t meen they made 50 of them. probably 20-30. 

I am a bit scared of the voltage in these ones but it will be upp and running and it will be my coolest amp in the collection. Big, heavy, loud and "useless" amp for the modern guitarist! 

plexi


----------



## danfrank

Ha Ha! Thank you for the invitation but I live far far away. I was making a joke that in your country you all do a grand job in celebrating birthdays. Where I am, I am lucky if I get a stale piece of cake for my birthday! Ha Ha!


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## pleximaster

Actually I got an hour to look at "the pig". Turned it on without valves. Heaters fine but no B+. I either made a stupid misstake or something is broken... 

plexi


----------



## danfrank

Hi Plexi,
I'm crossing my fingers.
Hmmm... I don't know if I like the new layout on this forum. It looks like there are more options now (good) but it means I will have to relearn it (bad). And I was a "senior" member but with the new format, I've been demoted...


----------



## pleximaster

Oh, their is no CT and no buried ground so I have to creat an virtual ground... Duh....


----------



## pleximaster

You are senior to me Sir! 

plexi


----------



## pleximaster

I have the Partridge TH1498 Mains transformer and it has four secondary linings. The heaters 3,15 - 0 - 3,15, 0 - 40V (bias), 300v - 0V and 220 - 0 V

I´ll try to create virtual ground on the 300 and 220 windings by using two pair of 100K resistors 1 watters going to ground. What do you think about that! 

By the way! Party night numer 2 is over Just need to clean up!  

plexi


----------



## danfrank

NO! No virtual ground! That will be a disaster. Give me a few minutes and I'll post a picture of what to do.


----------



## danfrank

Try to rewire the rectifiers (diodes) like in the attached picture



Make sure the 0-300volt winding is the "Bottom" of the two windings.

Here is a link to a sound city 200+ amp which is connected the same way. Let me know if this makes sense to you.

http://soundcitysite.com/soundcity200plus.pdf

After you get your amp up and running I will give you a picture of how to make more efficient use of the filter capacitors in the amp. But as the above picture looks, your amp will run as it should.


----------



## pleximaster

Shouldn´t the 300V go like this on the Hiwatt 200 amp? Or did I miss interpret you message?

Thanks plexi


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## pleximaster

I wired it just the picture you made, 720 V!!! 

Now time for the last birthday party!

Best Lenny


----------



## danfrank

Hi,
The Hiwatt version is good also but I don't understand your question. Where do you see a difference between my picture and the Hiwatt picture?
The important thing is that the 300 volt winding, after going through the diode bridge, is the one tied to ground. If you have the other winding on the "bottom" you will still get 720 volts but the screen/preamp supply will only be at 300 volts. Make sure the screen/preamp supply (where the choke is connected) measures around 420 volts. If the 2 supply voltages are correct (420v and 720v), great job!
Now test your bias supply and find out what the voltage range is when you adjust the voltage potentiometer. Your KT88s will need somewhere between -52 to -55 volts to bias correctly.
In fact, if the bias winding on your power transformer is 0 - 40 volts, you may want to wire your bias supply like the Hiwatt diagram. What you want is the bias supply to output between -48 to -58 volts.


----------



## pleximaster

I misread the Hiwatt version at first. I followed your pic. 

Right now we have 15 kids running around (and its a sleep over party) so I don´t mess around with an amp with 720volts. 

But I am excited to start!!!!

I really appreciate the time you spend on this. Its great to get the voltage so I know it I am on the right track! 

Best regards

plexi


----------



## danfrank

Have a great party.


----------



## pleximaster

The voltages I give you will be referenced to the Vintagekiki schematic:
#5--- 705v
#4--- 410v
#3--- At least -60 volts. My amp takes -53 volts bias with the RI Gold Lion KT88s
#2--- 350v
#1--- 305v

______________________________________

I am measuring voltages now, I get 720 on 5, 415 on 4, - 30 on 3 and 415 on 2 and 1 as well, have 3 voltages on the exactly the same voltage of 415 seem very fishy!!! ...

plexi


----------



## danfrank

All Your voltages are good. The tubes are not in the amp so there is no load in order to drop the voltages. When you put the tubes in the amp, the voltages on 1 and 2 will drop to appropriate values.
The problem seems to be your bias voltage. It is too low, but this I expected. Try to rewire your bias supply like the Hiwatt diagram and you will get correct bias voltages. The added bonus of the Way Hiwatt did their bias supply is that with 2 bias potentiometers, you will get more accurate bias settings, even if the 4 KT88s are not well matched.
By the way... How did the party go? Is your house still in one piece?


----------



## pleximaster

I was thinking of using this bias circuitry... It from Marshall and was used in two PA the pig Ive seen

The party went well but I got migraine today 

plexi


----------



## pleximaster

But two bias pots... thats good! I have to see how I can make it look good on the board.... 

best plexi


----------



## pleximaster

Dan 
Could you help me out with how the two 10K bias variable resistors the hook up to the Vintage Kiki schematics?

Thanks plexi


----------



## danfrank

Hi again,
The problem with the Marshall 1978 schematic is that it will not work; Marshall made a mistake on that schematic because the bias supply is not connected to ground so if done that way you would have no bias voltage. 
The key to making a good bias supply is that you want the bias adjustment to be as negative as possible because the power transformer that you are using only makes just enough voltage to bias the tube correctly; there is no voltage to spare. With 0 - 40 volt winding of transformer, after the diode the most negative voltage you will see is -56 volts; so your bias adjustment will have to be at the most negative end of this voltage... IE. -56 to -46 volts adjustment.
That is why I recommend using the bias drawing on the Hiwatt amp schematic you uploaded here. It will do what you need.
When you build the bias supply, ignore the "Vintagekiki" schematic. Take all the bias supply components off of your board and rebuild like the Hiwatt bias supply. Look at my attached pictures. Where the 2 100K resistors attach to test point #3, you want to separate them at this point. They remain separated, not connected together. Each of these 2 100K resistors will attach to the wiper (middle leg) of the bias potentiometers. Let me know if this is understandable.


----------



## pleximaster

Edit!!! i had bad luck thinking    

best Lenny


----------



## danfrank

Edit: Problem solved? 
Here is a better picture to follow:


----------



## pleximaster

fixed the circuitry now (kids asleep) I get can get -52V to -42V is that ok do you think? Could I put in tubes in the bad boy?

plexi


----------



## danfrank

Take a look at the new picture I just posted (post #139) and see if your amp is connected this way. -52v will bias your tubes a little on the hot side. How much hotter, I don't know.
Can you tell me what the resistance value is between pin 3 of KT88s #1&2 and the CT of the output transformer?
What is the resistance value between pin 3 of KT88s #3&4 and the CT of output transformer?

TAKE THESE MEASUREMENTS WITH FILTER CAPACITORS DRAINED - NO VOLTAGE. Zero voltage. Important.


----------



## pleximaster

pin 3 and ct KT88 1 = 17 ohm
pin 3 and ct KT88 2 = 17 ohm
pin 3 and ct KT88 3 = 20 ohm
pin 3 and ct KT88 4 = 20 ohm

pin 4 and ct KT88 1 = 27k
pin 4 and ct KT88 2 = 27k
pin 4 and ct KT88 3 = 27k
pin 4 and ct KT88 4 = 27k


----------



## danfrank

pin 3 and ct KT88 1&2 = 17 ohm

pin 3 and ct KT88 3&4 = 20 ohm

Mark each KT88 tube with a marker (Sharpie) "A", "B", "C", "D". You want to keep each tube clearly marked to which one it is.
Connect amplifier to speaker or other type of load.
Turn all three pots (treble, bass, volume) on front of amp to "0" or low position
Adjust bias pots for most negative voltage.
Install preamp tubes
Install KT88 "A" in output tube socket position 2 & KT88 "B" in output tube socket position 3 in the amplifier. Leave the other 2 KT88s out of the amplifier. You are going to do this to see how each tube biases to get the tubes matched as closely as possible.
If amplifier makes super loud noise, turn off amp and reverse OT leads to output tube sockets.
Take a DC voltage reading between Pin 3 of KT88 "A" and CT of OT. What is the voltage measurement?
Take a DC voltage reading between Pin 3 of KT88 "B" and CT of OT. What is the voltage measurement?
Now measure from CT of OT to ground. See if it is still at 720 volts with tubes installed.


----------



## pleximaster

Thanks a lot Dan!

i´ll better do this in the morning half past one in the night here!

Good night!
best regards plexi


----------



## danfrank

OK. The rest of the testing will be sort of long and tedious. 
I kind of feel that I am taking over your project. 
I am more than happy to help, just ask if you need help.


----------



## pleximaster

Hi Dan!
I have no problem what so ever for you "taking over" my project! I just want this amp up and running. So grateful for people like you and Neil and others giving their time and knowledge to disposal! Thanks guys!

Both girls are ill today! (No kidding after 3 days of celebration! They got some bad cold from the kids visiting so I and "working" at home today and the pig got in between  !

I put in preamp tubes and 2 power tubes. The dual bias is great I can monitor both with my probe and they adjust well. I get a nice thump sound when changing switching between the probes (have a quad probe) so the OT and power stage are making sound!

Next problem!!!  

No input from the preamp stage! 

plexi


----------



## pleximaster

Do you have voltage measurements for V1, V2 and V3? I guess they are not the same as on SL or JTM, those I know... 

best

found the problem, cable bad from me jerking around with the board


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## pleximaster




----------



## pleximaster

It has a lot more gain than I expected! This is two power tubes (TAD) I have a quad of GEC but I´ll wait installing them. Preamptubes are just modern marshalls That I pulled of some amps. Settings are Treble volume 10 Bass volume and Master Volume 4

As you can see one tube is red plating after some playing. I need to be able to adjust bias more.

plexi


----------



## pleximaster

Dan
What do you think of this one? Would it work here? It is a voltage doubler but I don´t quite get it. 

best plexi


----------



## pleximaster




----------



## pleximaster

I changed tube/valves and now the bias is ok and no red plating its on the edge but on the right side! (So far...  )

















played around a bit more


plexi


----------



## danfrank

Hi Plexi,
Yes, I think your KT88s are using too much current. To be safe I think you will need a voltage doubler in your bias circuit. Here is a picture and let me know if it is clear to you:


After implementing this into your amplifier find out how the bias adjustment works, see if it is within the -50volts to -60volts range. If it is NOT in that range, you can change the values of the two 22K resistors; make them less or more in value in order to get the bias adjustment into range. But remember, if you change one 22K resistor for a higher value, you need to change the other 22K resistor to a lesser value.

EDIT:>>>> Whatever values you use, those two resistors need to add up to 45K to 55K in value. <<<<


----------



## danfrank

Are your GEC KT88s well matched? I see you have a bias adjustment tool... Those are so nice! They make adjusting bias so much easier and accurate.


----------



## pleximaster

Thanks Dan! 
The picture is clear but I might be soft in the head but from where do I get the -100v, -110v from. I have the 300V winding and the 220v winding and the 40 v bias

Best plexi


----------



## danfrank

Ooops! Take another look at the picture... I only drew one winding on that picture, the 0 - 40volt bias winding. Is the rest of the drawing clear to you?


----------



## pleximaster

Yes they are matched Got 10 old ones and ended up with these, very closely matched. In the clip however I am using just a pair of matched TAD tubes just to get it up running incase I do something stupid.


----------



## danfrank

This is fun! I really enjoy watching you get this together into a running amplifier.

Great job, Plexi!


----------



## pleximaster

You mean the 100 -110 is just a measuring point? I thought it was a wiring coming in with -110v! My bad! 

plexi


----------



## pleximaster

I just add an extra diod, a resistor and a capacitor accordingly!

When its done I have my friend Johan Segeborn do a demo! 

plexi


----------



## danfrank

Yes, at that test point you will get somewhere between -100 to -110 volts.


----------



## danfrank

" I just add an extra diod, a resistor and a capacitor accordingly!

When its done I have my friend Johan Segeborn do a demo!

plexi"

Yes. Just make sure that the diodes and capacitors are in the correct polarity.

I can't wait to hear what Johan does with this amp! Tell him to make the clip long and loud!


----------



## pleximaster

I just learned that this bias problem is often found in the Hiwatt 200 amps which have same/similar transformers - making them go hot and break down...


----------



## danfrank

I agree. If the tubes are red-plating that means the metal inside the tube is getting red hot. This will make the tube fail, which then takes out the OT then the power transformer burns up.
The fuses in your amp will help prevent this if one of the tubes go bad; you have implemented good safety measures into your amplifier.


----------



## pleximaster

danfrank said:


> " *New* I just add an extra diod, a resistor and a capacitor accordingly!
> 
> When its done I have my friend Johan Segeborn do a demo!
> 
> plexi"
> 
> Yes. Just make sure that the diodes and capacitors are in the correct polarity.
> 
> I can't wait to hear what Johan does with this amp! Tell him to make the clip long and loud!





I told you that without you and the vintagekiki schematic this amp would not have been restored, he´d like to interview you in that clip! 

the polarity of diods and caps is alway the trick 

best plexi


----------



## danfrank

OK. Sounds fun!

Is there any way that after all is finished that you can revise the "Vintagekiki" schematic to make it more accurate? That would be a great service. I will try to email "Vintagekiki" and let him know about this post and all the work that you have done to this amp. I think he will be very interested in this.


----------



## pleximaster

Great! I have tried to contact him but I haven´t got his email. Love to have him on as well

Sure I can make my version of the schematic, but there are a few different versions of the original ones, which makes it interesting. Different transformers, components different sizes of chassis (my is the short chassis) and variations in the circuitry


plexi


----------



## pleximaster

I think I got spare part to build another one, except box, chassis and panels... I have got two extra mains transformer one partridge and one electro voice, two partridge chokes, and two replica output transformers. 

I have a the Pig PA 200 as well that has not been up and running and been away at a friend for 4 years now. I will take that back and fix it up as well. It would have been easier to have had that amp close by during this project but I have learned more this way. The PA have a different MT that is right according to the Vintagekiki schematics


----------



## danfrank

I just emailed "Vintagekiki". I found his email address on another forum. I posted a link in the email that will direct him to this thread.

Yes! Next is to get your PIG P.A. working! If you have any questions or need help with that PIG P.A., feel free to ask. It's a great feeling knowing I have something to offer that helps another person out.


----------



## pleximaster

Here is the pa 200 inside...



Thanks for your offer on helping out I will probably "use" your knowledge here!


----------



## danfrank

This is not urgent, but when you have time, can you do some measurements of the 200 guitar amplifier for me?
1) What are the chassis dimensions?
2) How thick is the lamination stack of the Power transformer and output transformer?
3) What is the value of the choke? I see "150ma" in a picture but how many "henries" is the choke?
4) How wide and tall is the front cutout in the wood cabinet?
5) Pictures of the completed amplifier, inside and out.

A lot of the filter capacitors in your amplifier can be rearranged to make more efficient use of them. Depending on how much capacitance you want in each amplifier stage, you may be able to eliminate some of the capacitors.



The way my picture is drawn, the total effective capacitance of the first filter stage for the 720volt supply is 32uf.


----------



## pleximaster

Ill get them for you but I did´t get so much sleep last night so I am off to bed, the choke is 10 hendry, so is the partridge one in the PA 200. 

Thanks for the MT picture with caps!


----------



## danfrank

OK. Have a good night and it's great that the amp is up and running. Talk to you soon.


----------



## vintagekiki

Dear colleagues

Advance to apologize for my posts if someone do not understand.
Do not blame me, the reason is my modest knowledge of foreign languages, so I'm forced to use in communicating https://translate.google.com/ .

As for the professional work of my posts, there is no problem, because behind me is 30 years of engineering work in the field of electronics and telecommunications, as well as in the field of musical electronics. In musical electronics my experience consists from servicing, restoration rebuild damaged amplifier to amplifier modifications.

*Marshall aka The Pig*

Schematics _Marshall 200 a.k.a. The Pig_ is drawn on the basis of various photos from internet photos of type Look "Under the Hood"
I was not able to see detailed photographs intact (clean) amplifier, because it were mainly amplifiers that have survived over the years a variety of intervention and customization.

Links that I used when creating schematics are listed here
http://www.marshallforum.com/index.php?threads/schematics-for-a-60s-marshall-200-watt-pig.40968/#post-1405857

In all photos, power transformer is not shown in detail, so if not a problem, please photographed in detail connecting wires from the secondary mains transformer that I could draw a complete schematics.
I would be immensely grateful if someone would measure all AC voltage on the secondary power transformer. _Marshall 200 a.k.a. The Pig_ used two models of the power transformer: _Partridge TH1498_ or _7032-6_.

From image http://www.rig-talk.com/forum/download/file.php?id=11908 to be concluded that the negative end of all electrolytic capacitor are connected in one point, which indicates that there are two independent sources of high voltage using the full wave rectifier circuit consists of two diodes (not bridge rectifier)

Electrolytic capacitor in the anode supply (+700 V) are modest value (32uF), so that the amplifier at very loud playing, quickly achieves to natural crunch, because drop voltage +700V (insufficient filtration).
By replacing the electrolytic capacitor on the value to 100uF and more, we get "tough" rectifier and amplifier is very clean with loud playing (does not come quickly to a voltage drop).

As for setting the operating mode of the output tubes, the bias is not adjusted to a certain value (-Ug1), bias is set to the cathode current 15 - 25mA per tube.

Due to the lower voltage Ug2 (+450V) output tubes submitted to a high +Ua (+700 V).
It is understood that the output tubes must be increased dissipation (6550 / KT88), and must be matched to within 5 to 10%
A similar configuration of the power amp was used in Dynacord amplifiers (Eminent II, Favorit II)

The difference between the _Marshall 200 a.k.a. The Pig_ and the others Marshall amps is in the concept of tone control. _Marshall 200 a.k.a. The Pig_ uses advanced version Paraphase Tone Control described in Radiotron Designers Handbook, 4th Ed. - Paraphase Tone Control p. 665

Sorry for the possible grammatical irregularities, translation is the machine https://translate.google.com


----------



## pleximaster

Great to have you on this thread! Without your schematics this amplifier would never have been rebuilt! Thank you so much Vintagekiki! I will be happy to provide voltage readings and colour codes of the TH1498 transformer. 

The amp sound great now and I love the crunch the low filtering provides. I am using 22uF and 32uF capacitors in this built.

I have another The Pig a PA model that i´ll be restoring soon, see posture above. That one have a different (but original) mains transformer (Dual core Partridge)

Thanks for joining the thread!

Best regards
plexi


----------



## vintagekiki

For a better understanding of the structure of power supply will try to help.
Both High voltage using the full wave rectifier circuit, does not use the bridge rectifier.
All electrolytic capacitor (for + 700V and 450V for +) are connected in one point to chassis, in other words, there is no "floor" supply.


----------



## pleximaster

Specs Partridge Mains Power transformer TH1498





Voltage readings taken when hooked up at my place (Should be 230-240V in the wall socket but...)








Primaries 
White or grey Shield
Red 234 V (240-250V)
Yellow 212V (220-230V)
Orange 190V (200-210V)
Green 102 (110-120V)


Secondaries (measured to ground)
Black thick heater 6,3V
Green or purple CT
Black thick heater 6,3V

Orange 1 (to ground) 0V (Between 37V)
Orange 2 37V

Black 128V (Between 226V)
Yellow 128V 

Green 175V (Between 297V)
Red 151V


----------



## pleximaster

Chassis dimensions 
(This is for the short Pig Chassis)

Height




Inner width 







Outer width







deapth


----------



## pleximaster

Cabinet dimensions!


----------



## pleximaster

Cabinet dimensions 2


----------



## pleximaster

Hi Dan, Vintagekiki and all

Ill post some final gutshots of the amp when I dressed it up! i`ll shorten some wires and fasten balts and make it look a little tidy! 

AND DO YOU KNOW WHAT JUST HAPPEN A FEW MOMENTS AGO!!!!?

I got an email last night due to this thread on the forum. There is another molested Pig amp three knobs that I have been offered to buy. And I just got a confirmation that we have a deal.!!!

It is in almost as sad state as mine was, but has original boards with some components, Changed MT but original TH1999 OT. I seems as if we can have both a "PA the Pig" thread and a new "Slathered Pig" thread! I really excited! I am starting a Pig farm!

plexi


----------



## danfrank

Hi Plexi,
Wow! That is great news about the other amp.
Thank you so much for taking the measurements; It helps me very much as I will have to have a cabinet made for my amplifier. The "PIG" cabinet is the exact same size as the Marshall Major cabinet but the Major has a bigger cutout in the front.
Just to verify: The front cutout on your cabinet is 2.375 inches X 11.25 inches? That is what it looked like in your picture.

One more question... Is the cabinet made with .625 inch thick plywood? Is the front panel of the cabinet the same thickness as the other 4 sides?

You can give me the measurements in centimeters if that is easier for you.

Thanks again for posting the measurements Plexi, it has helped me a lot.


----------



## pleximaster

I am a metric guy, inches are so strange and they are not the same in all countries... meter centimeters and millimeters please... 

cut out in millimeter mm
60mm high and 292mm width (look at my thumbnail)

sides 15mm 
front 12mm
back 9mm
plywood

plexi


----------



## pleximaster

Some other info I got from www.chambonino.com

_*Partridge output transformer TH1499 has a plate-to-plate load of 2,250 ohms*_.

_*Partridge power transformer TH1498 has a 8 amp heater winding, *_*the main HT windings are rated at 650 m/a *
t_*he bias winding is 300 m/a *_


----------



## danfrank

I like that website, it is very informative. He builds some really crazy amplifiers!
The TH1498 Partridge PT is a beast! 650ma for the HV windings is insane. In fact, you could add another 2 output tubes (6 total) and the 650ma HV windings would have no problem providing power. The 8 amp heater winding is small though. They should have made it with a 10-12 amp heater winding. The VA rating of the TH1498 transformer is somewhere around 600-750 watts. It is a BIG transformer!


----------



## vintagekiki

pleximaster said:


> Some other info I got from www.chambonino.com
> 
> _*Partridge output transformer TH1499 has a plate-to-plate load of 2,250 ohms.*_


 

https://web.archive.org/web/2005021...tar_Transformers/Hiwatt/Partridge_TH1499.html

Partridge transformer TH1499


----------



## strato2009

pleximaster said:


> I seems as if we can have both a "PA the Pig" thread and a new "Slathered Pig" thread! I really excited! I am starting a Pig farm!
> 
> plexi



Genetically modified power pigs!


----------



## pleximaster

Dan ...
Johan was here yesterday and played the "Piggelin"! (Piggelin is a well known ice-cream in Sweden and is very small so that name got stuck to this little amp  )

He´ll do a one sound clip and one "documentary" on how this restauration when along. He finds it vey interesting in how this project came along and how it evolved to become in international project retrotronicst (Greece) on eBay that help out with parts and boards, Vintagekiki and his fantastic work on the schematics and how you first encourage me to continue when I was stuck and then all input with the power stage and so on. Especially as these amps are so incredibly rare. Only 9-10 amps are known to still be out there today and not one is in original state. So this project is not only about restoring an amp but also resting a lost "sound".

"Vintagekiki" where are you located?

plexi


----------



## vintagekiki

pleximaster said:


> "Vintagekiki" where are you located?


Yugoslavia/ Beograd


----------



## pleximaster

Thanks Vintagekiki!


----------



## strato2009

Definately a piece of marshall history, I'm sure it will sound as stock as possible. Now we just have to wait until metro or someone makes a "PIG KIT" so we can all copy the tone of these amps.

Can't wait to hear it in all settings, all mic configurations and with different guitars.


----------



## pleximaster

Here is a first sound clip Johan made! He will do a documentary clip (with a lot of input from this thread and all you guys that helped out!)

best plexi


----------



## Codyjohns

pleximaster said:


> Here is a first sound clip Johan made! He will do a documentary clip (with a lot of input from this thread and all you guys that helped out!)
> 
> best plexi




Love the video, just awesome. 
I'm going to post this video in the Major thread.


----------



## danfrank

Hi Plexi & Johan,
What a nice surprise when I woke up this morning! What a great video clip! Love the sound; great breakup when the volume is turned up.
Mine has only been played with single coils (Strat) so that may be part of the reason why mine sounds cleaner than your amp. IIRC, humbuckers have a considerably higher voltage output. The humbuckers definitely match up nice to your amplifier.

Plexi, what did you finally use for the filter capacitance in the power supply? Did you modify it, or did you leave it as you originally had it wired? This plays in to the sound/breakup of the amp. However it is, it sounds good.

Thanks again for posting this clip.


----------



## pleximaster

Thanks a lot Dan! means a lot to me coming from you! I didn´t change a cap! 

This is how it looks under the hood in the video. (Only two GEC are used)






























7.jpg.html]




[/URL]


----------



## danfrank

Hi Plexi,
Thank you for the hi-resolution pictures.


----------



## strato2009

Really great vid and pics. the amp looks almost like it's straigt from the factory, congrats and thanks from a marshall fan!


----------



## pleximaster

Hi vintagekiki and Dan and others! 

At a Swedish forum some amp gurus are discussing the schematics. They suggest that the signals from respective treble and Bass side should be in phase opposition scince that on the treble side takes out the signal on the cathode and passes to the pot . 

Any thoughts on this?

Best regards plexi


----------



## danfrank

Hi Plexi,
Yes, the treble and bass outputs are out of phase because the bass is a normal plate loaded output and the treble is a cathode follower. I thought this would cause problems because of the signals being out of phase but there is a reason for this.
Think of the bass and treble as 2 separate pre-amplifiers. The bass pre-amplifier only increases the signal of the bass frequencies, while the treble pre-amplifier only processes the treble frequencies. Since the treble pre-amp is a cathode follower, it does not increase the treble signal. Now both of these signals (bass and treble) are out of phase with each other. This does not matter because one only works with bass frequencies while the other only works with treble frequencies. There is some overlap in frequencies that BOTH pre-amplifiers work with (some middle frequencies) but because both signals are out of phase, these similar frequencies that both pre-amps work with, cancel each other out. So I am assuming that the output of the whole amplifier can be made to be very flat in frequency response.
If you notice, the bass pre-amp has a 22K resistor on its grid to ground. This reduces the signal going into this tube VERY much. This is done so the bass output matches the treble output which is a cathode follower and has a gain of only 0.9 or thereabouts. Less than unity gain for this stage.
So, all of the voltage gain of the "PIG" comes from the first input preamp tube, the tube after the bass and treble stages, and the phase inverter. Signal is effectively lowered at the bass and treble stages. The treble stage because it is a cathode follower and the bass stage because of the 22K resistor.
Maybe this picture helps with how the "PIG" amplifies signal. As the volume knob of the bass pre and/or treble pre is raised or lowered, not only does it change the volume but it also changes the amount of frequencies that are amplified.




Hopefully this is understandable... Maybe Vintagekiki can better explain.


----------



## pleximaster

Spoke to a guy on the phone yesterday and he used to own a Pig in the 80´s. He made a schematic of the amp he had before he sold it and he has compared it to the Vintagekiki schematic and they are more or less the same, however a few minor differences that he said was original. The 1k5 resistors going to pin 3 and 8 on V1 and V2 were all 820 ohms and the fist cathode resistor had a 500uF cathode capacitor, a bit similar to other marshalls. Wouldn't this increase gain a lot?

I have seen pictures of other pigs with a cathode capacitor but did´t know if they were original or not. Here is one with a 500uF capacitor, it has the 1k5 resistors though...

One more thing I forgot
He had a 2 Meg Master volyme pot, a 1 meg linear Treble volume pot and a 1 meg Log Bass Master volume pot. I wonder what the effect this will have on the blending of the different channels. 

I am starting to think that we have quite a few interesting variations in of the Pigs preamps.



PS Thanks Frank for the illustrative picture above! I´ll speak to Johan to set the date for our "Pig Gathering" 




plexi


----------



## danfrank

Hi Plexi,
That is a very interesting phone call you received. Can you ask him to email you a copy of the schematic that he drew of his amplifier, and you post it here? What was the history of the amplifier that he had? Did he know if it was modified at all before he received it? I would be very interested to see the schematic of the amp he had.
The 820 ohm cathode resistors would definitely increase the gain of each stage. The 500uf capacitor would increase gain even more.
I think the 1meg log potentiometers on each control are best for the "PIG" amplifier. These 3 controls are not configured as traditional tone controls, they are configured in the circuit as volume controls. I think using a linear potentiometer here would make the treble volume rise too much with just a little turn of the treble knob. Maybe you can try it out and see what the difference is.


----------



## Zagnut

I'm merely an observer for this kind of thread as the skill is way beyond my capability, but I would like to offer a HUGE thank you to Pleximaster and everyone who has generously donated their time and expertise to contribute to the rebuilding of these great amps. I love looking at the photos and reading the suggestions, (though most of it's over my head) while seeing the dedication to old Marshalls. Well done to all! Thanks again for letting me watch from the sidelines.


----------



## pleximaster

I will talk to him again and we will go through i point to point compare it to the vintage one. He says it a quick hand drawn thing he made fast so he means it y´would be hard for anyone else to read. I´ll make a computerised version after we compare and Ill sure post it here. He doesn´t have pictures of the amps inside (No smart phones back then)


----------



## pleximaster

I got a copy of Thomas´ hand drawing he made in the 80´s of the schematic of his PIG yesterday (Thanks Thomas!). Thomas and I will go though it together and make sure i got the values correct as its a little bit hard to read another persons handwriting some times.

The drawing is more of a component layout not a pure schematic. I will redraw it in the computer with all 3 boards shown individually, transformers, socket connections and pots, like the Metro Layouts. There are some jumpers underneath the boards I already see that are missing, but using the Vintagekiki schematics I am sure we can figure those out. I know some people prefer component layouts over schematics and we are missing a layout for the Pig! 

best plexi (Pig farmer)


----------



## danfrank

Hi Plexi,
Yes, component layouts are easier to understand. Hopefully this will get other people to build "PIG" amps for themselves!


----------



## pleximaster

Noooooooooooooooo!


I got the other Pig amp about a week ago. I thought I do a good documentary of the restoration of it using a good camera and not my phone. I am almost done and was up loading the pics to the computer and something was wrong! It says the memory card is bad and there are no pictures to be found! F@kc and all other bad words! Aaaaaaghh!

plexi


----------



## danfrank

Hi Pleximaster,
I am sorry to hear that; what a frustrating ordeal! If you put the card back in the camera, can you see the pictures?

Otherwise, how did the restoration of the second "PIG" turn out?


----------



## pleximaster

I havent fired it up but it looks like this now. I filled the holes for the extra filtering caps that seems to be common thing on these. Put in a new transformer, cleaned out the bord from various strange things and tried to keep all the parts that seemed to be old. It is a mix of the amps history the Vintagekiki schematics and the layout I for my hands on. This amp also had the 500uF cap as a first on the board. 

The layout on this is more true to the original than my last restoration.

plexi


----------



## tomsvintage

Great restoration job ! Congratulations !


----------



## pleximaster

First test run of this little animal! 



plexi


----------



## danfrank

Sounds very good! Is this one using the TH1498 and TH1499 transformers?
Did you use 1500 or 820 for the cathode resistors?
Does the 500uf capacitor change the sound of the amp much?
What do you think about the sound?
Great job Plexi! The cabinet, from what I can see, looks very clean also.


----------



## pleximaster

Thanks Dan

It has the same transformers as the other one, TH1498 and TH1499 transformers. It has what I believe are original resistors but a mix three 820 and one 1500 ohm! The 500uF makes it more Super Lead sounding. It is beefier, gainer and more 3D sounding and not as old school as the other one. I just got the amp up and running and I havn´t tested the two Pigs at the same time.

The cabinet is "clean" now, it was painted (thick paint all over) I think it saved the vinyl a bit. The plexi panels are taken of too as they were also more or less painted.

plexi


----------



## pleximaster

By the way Dan

What fuses value do you recommend for this amp. Right now I have 1A HT fuse 2,5A Mains and 1A to the output transformer primary 750V

plexi


----------



## Codyjohns

pleximaster said:


> First test run of this little animal!
> 
> 
> 
> plexi




Man, I love this amp. 
Sounds awesome, thanks for posting the clip.


----------



## pleximaster

Thanks Michael means a lot from "Mr Major"

On friday I am picking up my Marshall 200 PA amp that have been at my friend for 4 years now since I did´t dare messing with these monsters. I feel comfortable fixing it up now! Two "major" restorations of Pigs will make this one (It is in good shape compared to the way these other two were) will hopefully be rather "minor".

Have to find some more GEC KT88s (Anyone need a kidney)


plexi


----------



## danfrank

pleximaster said:


> By the way Dan
> 
> What fuses value do you recommend for this amp. Right now I have 1A HT fuse 2,5A Mains and 1A to the output transformer primary 750V
> 
> plexi



Hi again,
Yes, 1 amp fast for the HT and I would put in a 3 amp slow or time delay fuse for the Mains. 2.5 amp for the mains is right on the margin of what this amp consumes when volume is turned up loud. 3 amp mains fuse will give you good protection. If the 1 amp fast HT fuse burns out when you power amp on, then use a 1 amp slow or time delay fuse also. Leave 1 amp fast fuse for the OT primary.


----------



## pleximaster

Thanks Dan!

I´ll use your fuse suggestions! The amp came with a 10A Mains and the other one had a 13,5A no wonder the transformers needed to be replaced! 

Other differences between the two pigs the screen resistors are the original 1K 5 watt I think I put in 1,8k in the first one.

The filtering on the mains are in both amps F&T 47uF 500V instead of the original 32uF. However the preamp filters are 16uF in the later amp and 22uF in the first one.

Volume pots are 1meg log in the first one and 1 meg in treble and bass volyme and 2 meg master in this one (all logarithmic)

Transformers choke are the same. 

Been busy with this one but we still have the documentary clip to do, contact you soon

plexi


----------



## neikeel

Wow, all those pigs in one place, time to make bacon!
I missed that you had another on the way (thought you just had the PA)
Love the tone of the latest one - does that run the quad of GECs?


----------



## pleximaster

I got the option of buying this pig from a guy in Norway due to this thread, it had been dead for 20 years and he thought I be a good guy to fix it up. I looked worse then the first one on the outside, painted an all but it was actually much better inside, boards and a lot of original components, (the first one was not more than a shell actually). 

There are no GEC KT88s in this one as I just started it up a few hours ago. I have this pair of TAD that I use for upstarters since the GEC are so damn expensive. If something fails... For instance I had a bad NOS diod in the bias circuitry taking out one of the old yellow bias capacitors seen in the first picture. I replaced the diod with a modern one for now as well as the bias capacitor. Will probably replace them later with period correct ones later. The TAD valves/tubes sounds good though but are a "tad" brighter then GEC. Will put some GEC in it later when everything is settled. 

When I put all three knobs on 10 i sometimes get some oscillations coming and going. I´ll try shortening some cables before I do any thing else as I like the sound otherwise.

plexi


----------



## danfrank

pleximaster said:


> When I put all three knobs on 10 i sometimes get some oscillations coming and going. I´ll try shortening some cables before I do any thing else as I like the sound otherwise.
> 
> plexi



Check to make sure that the pots are "clean". IE the wiper of the pot makes good contact with the rest of the pot. Sometimes, the pot wiper will make intermittent contact and when the wiper "lifts" it causes the circuitry to oscillate. The pots you are using are old, clean them with Deoxit or other quality contact cleaner/lube. If the pots make good contact, I would suspect the 2 meg pot next; maybe change it to a 1 meg log?
What is funny about mine, is that when I turn the treble pot up about half way, I get a buzzing sound (mains hum) if I am not physically touching the amplifier chassis. When I turn all 3 controls up to "10", the amp is very quiet with no interference or hum noise. It is quiet until the guitar is played; then it is not so quiet anymore!


----------



## Codyjohns

pleximaster said:


> Thanks Michael means a lot from "Mr Major"
> 
> On friday I am picking up my Marshall 200 PA amp that have been at my friend for 4 years now since I did´t dare messing with these monsters. I feel comfortable fixing it up now! Two "major" restorations of Pigs will make this one (It is in good shape compared to the way these other two were) will hopefully be rather "minor".
> 
> Have to find some more GEC KT88s (Anyone need a kidney)
> 
> 
> plexi



I hope all goes well with your Marshall 200 PA. 
Much respect to you for restoring these jems, it's not an easy task. 
I've almost got my circuit restored, I just need three more Mustard caps and I'm done.
When I got this '68 Major a few years ago someone had replaced all the Mustard coupling caps with Orange drops so I'm slowly bring all the couplers back to its original state.
This is what it looks like so far.


----------



## pleximaster

Thats a cool amp Michael!

I don´t know why there are so many amps with Orange Drops even in Europe (They are made by sprague, right?) I got a bunch of them that a got from marshall amps I restored. 


Dan and others 
I got this crazy idea of building a "Mini-Pig" amp with the same preamp but only one KT88 tube. Any suggestions of the spec one would need for the transformers?

Best plexi


----------



## danfrank

You would need a B+ of around 400 volts for the KT88. Most single ended amps use cathode bias for the output tube, but you might be able to use fixed bias. For the output transformer, 3K - 3.5K primary impedance would be good for a single KT88. You could probably just take away the P.I. from the schematic and hook up the KT88 to 12AX7 V2B. Feedback connection might take some trial and error to get correct or you could use no feedback like old VOX amps.
This arrangement would output 10-15 watts power.

Another tube that would work well for single ended is the EL156. It's like a super EL34; 50 watt plate dissipation.

EDIT: Another nice thing about the EL156, is that it takes much less bias than the KT88, so the output of V2B on the "PIG" schematic would probably be more than enough to drive the EL156. Chinese EL156 tubes are good, if you buy then already tested. A lot of them come out of the factory bad but if you buy them from a good tube dealer that tests and matches tubes before selling them, they are a good tube.

Here is a good webpage on the EL156 but it is directed more about Hi-Fi. There is good technical information about the EL156 here:

http://attitube.com/tube-projects/amplifiers/el156-se/


----------



## strato2009

Pigs of valhalla


----------



## jerms

what a great thread!!!! now i want to build one!


----------



## pleximaster

As soon as I have the time I´ll fix a nice layout of the amp with various known variations so its easy to built! 

plexi


----------



## ScienceFriction

This is really amazing pleximaster! The Marshall Pig is my holy grail amp- excellent work bringing them all back to life and compiling such great data. I look forward to seeing your layout.


----------



## pleximaster

I just got back my 1967 Marshall 200 PA the Pig! I left it at a a friends in 4 years ago to fix up since I at the time were not sure I could do it. The process have been slow and not much have happened. And thanks to this thread I now feel comfortable to fix it up myself.

Thanks Dan, Vintagekiki and all you others that have helped out and/or cheer me up when things got a backlash.

best plexi


----------



## danfrank

Hi Plexi,
Thanks for the picture of your "PIG" PA. It looks like there are 3 25volt electrolytic capacitors on the middle circuit board. They each have a cathode resistor across them. Can you tell me what the vale of those 3 resistors are and the value of those 3 electrolytic capacitors?
Thanks,
Daniel


----------



## pleximaster

Hi Dan! They are all 1,5k resistors and 125uF 25V capacitors (They might be original, this amp has not been so much tampered with.)

I have had a bad blow out on one of the power tubes as one can see melted aluminum around, I guess this brought down the original TH1499 output transformer and replaced with a modern Major 200 OT. The Mains transformer is still intact and are the Partridge Dual core version. I have put in another TH1499 OT now from a doner Carlsbro PA. Fits perfect all mounting holes!

It had some increased filtering but it was put inside on the board so this time no extra chassi holes for cans (Only extra holes are for the OT mounting, rather small.)

Some mods were done to the bass and treble Masters but they were not affecting the board, most components were just mounted free round the pots, (I am installing old RS pots for the ones missing now. 1meg log for the masters and 100k for the preamp volumes.

I have a lot to do this week so I have to see when I have the time for "amping" 30 min here 20 there... Other wise I think this could be up and running soon. Cross my fingers! I mostly do some cosmetic stuff like having all old tube sockets, wire dressing and so on. But then there is always the bias issue... I might need you again Dan, would be nice with dual bias pots for this one too...

I got some 4 old GEC KT88s and 5 siemens ecc83s in this one!

Best plexi


----------



## danfrank

Thank you for the information.
Yes, this amp looks very clean inside.
The power supply looks like the one in the Vintagekiki schematic with 2 separate transformer windings, one for the HT plate supply, and another for the HT screen/preamp supply.
Let me know if I can be of help to you for the bias supply or anything else.
Thanks again for the information.


----------



## pleximaster




----------



## danfrank

I don't know if it is possible on your amplifier, but if you place the transformers on your amp like in the picture below, your amp will have less noise induced hum.


----------



## pleximaster

I know about the transformer interactions. However this is the original mounting holes and I could see the old TH1499 shadow on the chassis so this is how it was mounted originally. There is another dual core OT Partridge found in these but they have another mounting base so I am pretty sure this is the correct transformer for this amp. Here is an other one


----------



## pleximaster

By the way here is the other transformer setup (Note the long chassis on the three knob Pig, same as the PA version)


----------



## pleximaster

Interesting about the chokes, they are all over from RS 10 H, Partridge 10H Drake 3H 

I think the small 3H are out specs when pushing 200 watt, I think they are even ot of spec in a 100 watter on full tilt... The RS I think is good for 250mA


----------



## pleximaster

danfrank said:


> Thank you for the information.
> Yes, this amp looks very clean inside.
> The power supply looks like the one in the Vintagekiki schematic with 2 separate transformer windings, one for the HT plate supply, and another for the HT screen/preamp supply.
> Let me know if I can be of help to you for the bias supply or anything else.
> Thanks again for the information.



Yes it does have two separate transformer windings. The Vintagekiki shows a separate bias winding but this doesn´t have one it is taken from one of the other windings.

plexi


----------



## jc298607

Incredible work Plexi! I just stumbled on this thread while searching for a solution for my '69 SLP. Your Pig sounds absolutely fantastic and I look forward to hopefully being able to use your hard work to build a clone someday!


----------



## pleximaster

Thanks JC 298607!

I cleaned the PA 200 up a bit and its ready for tubes, Voltages seems ok... (Fingers crossed)


----------



## danfrank

Hi Plexi,
Did you figure out how to take the bias voltage from the HT winding? What are the secondary voltages of this mains transformer?


----------



## danfrank

pleximaster said:


> Interesting about the chokes, they are all over from RS 10 H, Partridge 10H Drake 3H
> 
> I think the small 3H are out specs when pushing 200 watt, I think they are even ot of spec in a 100 watter on full tilt... The RS I think is good for 250mA



3H is not much inductance; this will add to the harder sound of the later amps that have more power supply capacitance. 10H is much better for a "Plexi" style amp that has fairly low power supply capacitance.


----------



## danfrank

I would reinstall the resistors that go across the 720v HT capacitors. Ideally, 2-68K (136k total) resisters across each of the capacitors. These carbon resistors have a breakdown voltage rating of approximately 250volts each, that is why 2 should be used for each of the 720v HT capacitors. These resistors form a voltage divider so one capacitor does not receive more voltage that it can take at turn on of the amp. You can hide these resistors under the capacitors so they will not be seen.
The resistors have an added bonus of bleeding off the caps at power down of the amp.


----------



## pleximaster

The voltages from this transformer

2 x 508 V
2 x 347 V

This give a B + of 710 V (Rectified)
and 483 V (rectified) between choke, 10K/2watt and 16uF

The bias voltages is taken from one of the windings see pictures white wire. This wiring was intact. Look at this picture of a PIG it got the same transformer as mine and a white wire to the bias as well. 









Funny detail The first two boards have vintage slotted turrets the two other boards have push through turrets... they were made at different stations at the factory! 

plexi


----------



## pleximaster

The resistors were not aesthetical enough... 

Do they alter sag also? 

Another question the last 0,1uF cap with a 4k7 resistor what does this cap do to the circuitry? I don´t seem to get it can´t it go directly to ground?


----------



## danfrank

pleximaster said:


> The resistors were not aesthetical enough...
> 
> Do they alter sag also?
> 
> Another question the last 0,1uF cap with a 4k7 resistor what does this cap do to the circuitry? I don´t seem to get it can´t it go directly to ground?



The 4 68K resistors will consume 2.5ma from the power supply; I don't think this will alter sag. 2.5ma is such a small amount of current. At zero signal, the KT88s will consume 80-150ma total. At full power, the 4 KT88s will consume around 500ma from the 710v power supply; so 2.5ma is nothing in comparison. If you want even less drain from the power supply, you can use 4 100K resistors instead of the 68K resistors. 4 100K resistors will consume 1.8ma total.

For the 0,1uf cap, do you mean the one close to the phase inverter circuitry?


----------



## pleximaster

Yes near the phase inverter, I think there´s also only one 4K7 resistor in the circuitry 

The resistors on the electrolytes were not 68k they were 680k. I was thinking on putting 47k underneath but I wanted the amp to be as original as possibly before doing tweaks, I most often do so.

Thansk for you help Dan!

plexi


----------



## danfrank

Yes, originally they were 680K. The problem with only one resistor per cap is that the voltage across each cap is at the limit of each resistor's breakdown voltage.
That 0,1uf cap and 4K7 resistor by the P.I. is the "presence" circuit of the "PIG". If you change the 4K7 resistor to a 5K potentiometer, that would become the "presence" control like a 45-100 Super Amp has. And, yes, the end closest to the power tube sockets goes to ground.


----------



## pleximaster

That the 0,1/4k7 would influence the NF somehow. Then thesis a preset presence control with the precence set on 0, right?

plexi


----------



## danfrank

pleximaster said:


> That the 0,1/4k7 would influence the NF somehow. Then thesis a preset presence control with the precence set on 0, right?
> 
> plexi



According to the layout diagrams and how the 0.1uf cap is attached to the 5K pot on a 45-100, it would be like the presence control is on "10". On "10", the cap is all the way across the 5K pot.


----------



## pleximaster

I must have had bad luck thinking again about the presence thing...    I´ll check the schematics again.

I just got the PA Pig up and running, being a PA it doesnt gain as easily as the lead versions. It allows new options with the four channels and it acting a bit different from my other PA marshals have the 3 masters (Treble bass and volume) It sounds closer to my first PIG restoration with its fuzzier sound. I could really sound test it as 11 o'clock in the evening and my young daughters are sleeping right above the test room and 200 watt... its a bit loud. I´ll be away tomorrow, so perhaps friday afternoon I can make a sound clip.

Best regards plexi


----------



## danfrank

Great work! With the extra tubes in the PA amp, there is a lot of room for modification. Maybe 3 or 4 differently "voiced" channels. I'm not saying with your PIG PA because it is such a rare amp, but if somebody wanted to clone the circuit, there are many possibilities with this amplifier topology.
Amazing that you have 3 Marshall "PIGS" now. I doubt if anybody EVER owned 3 PIG amps at one time. You need to start a very LOUD power trio group. You, Johan and ?


----------



## pleximaster

Three little Pigs on the run... where are they? 





Here they are! 





They ore ot hunting tubes!





By the way Dan!

Thanks for urging me to put in an extra fuse for the B+. Yesterday one of the old 16uF worked well for an hours but then totally shortened. The Fuse pulverised but it save the newly installed TH1499 OT! You saved it!

best plexi


----------



## pleximaster

I have done som tube swapping and I feel this PA amp it almost as gain as the first restored pig, perhaps its the Capacitors over the 1,5K resistors that does it. 

As I often run this flat out I feel a need of a dual bias pot as the once we did the other pigs, Dan how would you suggest the making the circuitry? 

I also have experience overload in the preamptubes when jumping channels and I can´t seem why I have gone through the wiring and most of it is original and It look right? With all on ten it sounds glorious then it kills preamptubes and fuses... Voltage readings seems ok compared to the two other pigs (But you can't jump them)

plexi


----------



## danfrank

pleximaster said:


> As I often run this flat out I feel a need of a dual bias pot as the once we did the other pigs, Dan how would you suggest the making the circuitry?
> 
> I also have experience overload in the preamptubes when jumping channels and I can´t seem why I have gone through the wiring and most of it is original and It look right? With all on ten it sounds glorious then it kills preamptubes and fuses... Voltage readings seems ok compared to the two other pigs (But you can't jump them)
> 
> plexi



Here is a picture of how to wire the dual pot bias supply. The 47K - 300K resistor should be 2 watts to be safe. Basically, you want to start with a 300K pot or resistor and adjust it down until there is approximately -65 volts after the bias supply diode where it is connected to the 100uf/100volt capacitor.




For the tube overload and fuse burnout, I think a filter capacitor is bad and is drawing too much current. Feel all the power supply filter capacitors to see which one is warm or hot to the touch. Also, if there is a resistor before the bad capacitor, it will be unusually warm also. Also check power supply diodes. With the 7032-6 transformer, the diodes have to EACH be rated for at least 1000volts PIV. If not, they will break down connected to this transformer.


----------



## pleximaster

I have been all over the capacitors (Some times I get this tick sound for the amp, typically for cap problems) but Ill just replace them all since they are non original anyway (I have a set of unused RIFA 33uF 450 I´ll use instead, I guess 450V will be ok since they are in series) No one seems to get hot or short but I don´t really enjoy touching these in an amp like this with the high voltages inside.  PUFF! 

The original top hat diodes are 1S107 diodes rated at 800V and the other small once I can´t read. I´ll replace those, got some solar panel diodes at 1000V 10A, they will cope. Would you recommend to replace the 1S107 as well?

The bias circuitry is about the same as the once we did in the other two. If you look at the picture above you see the old bias wiring and it is very marshall like with two 10uF caps, 15k resistor and in this case 100k following the wire from the power board. Why will we need this big 100uF? (I am as you know not a that in to physics  ) Whats the effect of using higher capacitance in the bias circuitry, less current variations? 

Thanks!

best regards plexi


----------



## danfrank

Hi Plexi,
Yes, the way Marshall does it is good too. Basically, the bias pot is just acting as a voltage divider to get the correct bias voltage to the KT88s. On my picture, I just copied the Hiwatt bias schematic since they use 2 bias pots. The capacitor does not have to be 100uf.
I think the 1S107 diodes are rated for 1 amp. I would use the 1000 volt solar panel diodes here also. They are big for the job but will work. Ideally 1000 volt @ 3 amp diodes would be good. I would use 2 or 3 in series instead of 1 for each half winding in the Plate HT supply. This is because these diodes will "see" around 1500 volts PIV on this portion of the power supply. The TH1498 transformer is better suited in this amp because the HT plate voltage is obtained by "stacking" 2 lower voltage supplies onto each other to get the High B+ voltages. This way is much easier on the power supply components.
Be careful with the RIFA 450 volt capacitors on the screen supply; be sure to use them in series because with the 7032-6 transformer, you will get 470-480 volts for the screen supply, not 420 volts like with the TH1498 transformer.


----------



## pleximaster

Thanks Dan!

I´ll just order som 32uF 600V caps. I don´t want any failures here! 

Best regards Lenny


----------



## pleximaster

I put some old KT88 GEC in the Second pig today, it screams!



And here is a picture on how bacon is made...





plexi


----------



## tomsvintage

Nice !! I can hear it SiZzliNg !!


----------



## Codyjohns

pleximaster said:


> I put some old KT88 GEC in the Second pig today, it screams!
> 
> 
> 
> And here is a picture on how bacon is made...
> 
> 
> 
> 
> 
> plexi




Totally awesome!! 
Major Madness is running wild and I love it.


----------



## pleximaster

My dear friend Johan Segeborn made a documentary out of this 13 pages thread! 



plexi


----------



## BygoneTones

Enjoyed that. Great story, thanks for sharing.


----------



## Codyjohns

pleximaster said:


> My dear friend Johan Segeborn made a documentary out of this 13 pages thread!
> 
> 
> 
> plexi




Great Major documentary, I really enjoyed the video. 

I have you ever thought of getting a '68 Major with passive tone controls??
You'd be surprised how awesome they sound as well.


----------



## pleximaster

Yes I am sure I will when the right one comes along 

I am fascinated by the sound of your 6 knob marshall Major. I know you have a master but it does´t sound like only preamp gain. How loud do you run it?. The traditional Majors I´ve tried have also been hard to go into power amp distortion due to the Ultra Linear OT, is you UL tap disconnected and run like a regular OT or is it still UL?

plexi


----------



## Codyjohns

pleximaster said:


> Yes I am sure I will when the right one comes along
> 
> I am fascinated by the sound of your 6 knob marshall Major. I know you have a master but it does´t sound like only preamp gain. How loud do you run it?. The traditional Majors I´ve tried have also been hard to go into power amp distortion due to the Ultra Linear OT, is you UL tap disconnected and run like a regular OT or is it still UL?
> 
> plexi



They're getting harder to fine because most of them are modded and messed up. There's not many stock '68 Majors left in the world these days.
Most of the clips I've made are recorded at TV listening volume so I'm not getting any power tube gain and also it is still in it's stock Ultra Linear form which doesn't help increase the gain levels. All the gain is coming from the preamp and this video I made will help explain how.


----------



## danfrank

pleximaster said:


> PS Dan
> The Pig PA is running stable now, I had to change some diodes in the rectifier and added 600v Capacitors. I increased the filtering a little compared to the other pigs and this one had no ghosting at all (it does have a little less gain being a PA model, no channels bridged) I ran it flat out on all and jumped channels for two hours and everything sounded great and nothing got too hot.  Put in the Hiwatt dual bias pots in this one as well. It is much superior to the original marshall one, reliability and performance (it seems to deliver currents and voltage better when the amp is pushed real heard)
> 
> plexi



Hi again,
That is great! Hopefully you and Johan will find time to do a video on the PIG PA, and maybe a video on comparing all 3 PIG amps you have. That would be interesting to see and hear the similarities and differences.
I really like the way HiWatt does their bias supply also. It is a little different from the way Marshall does theirs but it is very stable for the output tubes.
By the way, when you tested the PIG PA, did you use all 4 KT88s or only 2? With 2 KT88s it's plenty loud!
One more thing... How much filter capacitance did you finally use in the PIG PA?


----------



## JAC

Nice project amp!


----------



## pleximaster

Hi Dan and everyone else! Before I had my accident I apparently bought another amp. I have no memory of this what so ever, being almost a month at the hospital of which two of the totally sedated make stuff to you. But it seems I got another pig. Came today

Thanks to my neighbour Per for helping me getting inside as I am not to lift heavy stuff... 









plexi


----------



## Codyjohns

pleximaster said:


> Hi Dan and everyone else! Before I had my accident I apparently bought another amp. I have no memory of this what so ever, being almost a month at the hospital of which two of the totally sedated make stuff to you. But it seems I got another pig. Came today
> 
> Thanks to my neighbour Per for helping me getting inside as I am not to lift heavy stuff...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> plexi



Wow, That is the best collection of Majors I have ever seen!! 
Amazing my friend.


----------



## pleximaster

When I get better i´ll find a regular Marshall Major with the ultra linear Dagnall, I don´t have one! 

plexi


----------



## danfrank

That's a crazy collection you have there, Plexi. I am sure someone will offer you a Marshall Major sooner than later. I was reading somewhere that Marshall had more problems with the Dagnall transformers in the Major and that because of several problems with the output transformers blowing out, a US winder offered replacements, using thicker insulation so the OTs would have less problems with burning out. Here is the website:

http://meyer-repair.blogspot.com/2011/02/majestic-marshall-major.html

I don't know how much of the above is true, but it sounds reasonable.


----------



## Sir Don

Full credit to you Plexi!! Your tenacity and determination are admirable. I would have shelved the project long ago. Well done.


----------



## strato2009

Great photos, now we need more Johan's demo's!

Pleximaster, get well soon!


----------



## pleximaster

Joahn is visiting soon! 

Here is the inside. This has I think has the most accurate component layout. I had the MT that was broken replaced and recapped it and made the dual bias circuitry as the other one. Replace some other component they were later with correct specs and brand. Sounds very much like the other ones, which is a good thing. I think I got the pig sound!





plexi


----------



## danfrank

Hi Pleximaster!
How are you feeling? This is the 3rd lead PIG? It looks great; very clean work. Does this one have the TH1498 mains transformer?


----------



## pleximaster

I am feeling much bettet but there have been set backs and this Monday I had an acute ambulance ride again to the emergency...

It's hard to except that I can't do what I am used to. Everything is so slow... I can only concentrate for shorter periods of time...

Yes this is the third three knob pig amp 

This thread stirred up a few of them sitting dead in cupboards around. I thought I had passed on this one but the very day of my incident I had made a deal on it. I didn't remember it but I have the emails. So to my surprise it turned up with UPS a few days after my return from the hospital. Now I don't need any more!!!

Yes it has the same transformer I had a spare, I think I mentioned that before. 

I have used the same 600 v capacitor in the filtering as in the PA pig. 4x30uf+ 6x30uf on the filter board 
This works great for me, what filtering are you using?

Best Plexi


----------



## Marshallhead

Unreal... What a sight!


----------



## neikeel

Wonder what happens when you have a wall of those monsters at full tilt (cf Johan's wall of 100w stacks


----------



## danfrank

pleximaster said:


> I have used the same 600 v capacitor in the filtering as in the PA pig. 4x30uf+ 6x30uf on the filter board
> This works great for me, what filtering are you using?
> 
> Best Plexi



Hi again,
For the main 700 volt B+ I am using 4 X 32uf capacitor (total effective capacitance 32uf) and for the screen supply (first capacitor after the choke) is 30uf. Before I had 200uf on the main B+ and 100uf for the screen supply but it sounded too "sterile"; great for a bass amp but not good for guitar. Now with the lesser capacitance, it sounds much better for guitar. The filter caps seem to play a big role in the amp's sound.


----------



## pleximaster

danfrank said:


> Hi again,
> For the main 700 volt B+ I am using 4 X 32uf capacitor (total effective capacitance 32uf) and for the screen supply (first capacitor after the choke) is 30uf. Before I had 200uf on the main B+ and 100uf for the screen supply but it sounded too "sterile"; great for a bass amp but not good for guitar. Now with the lesser capacitance, it sounds much better for guitar. The filter caps seem to play a big role in the amp's sound.



Help me out here 700 volt B+ output point right

My old physics book are long gone... 

You are now using 4x32uF capacitors as stated in Vintage Kiki schematics and wired that way (2 in series x 2 parallel) giving a virtual 32uF capacitor as we don't care about the 1500V 0,05uF one

Then I use 6x30uF capacitors (2 inserts x 3 parallel) that you give me 15uF right? So I am actually have lower filtering than spec.

My Screen is then only 7,5uF by the choke right? It has the big large choke.

On the other two lead pigs I have the "right" number of caps but did´t use 32uF as stated in the schematics but 47uF. Giving me a virtual 47uF cap at B+ 

Still I hear less ghosting on the two ones with lower filter... and have good attack.

Am i messing up the physics class again?

plexi


----------



## danfrank

pleximaster said:


> Help me out here 700 volt B+ output point right



In your amp, where the OPT CT attaches to the filter caps. I have effective 32uf capacitance here. (4 X 32uf in series parallel)




pleximaster said:


> You are now using 4x32uF capacitors as stated in Vintage Kiki schematics and wired that way (2 in series x 2 parallel) giving a virtual 32uF capacitor as we don't care about the 1500V 0,05uF one



Yes. I have the choke attached to the "+" of the lower 2 X 32uf capacitors and the OT CT attached to the upper 2 X 32uf capacitors. Lower 2 X32uf caps "+" leads are attached to upper 2 X 32uf caps "-" leads. Each of the 2 power supplies (upper and lower) is under 500 volts so this works well with the TH1998 PT.



pleximaster said:


> Then I use 6x30uF capacitors (2 inserts x 3 parallel) that you give me 15uF right? So I am actually have lower filtering than spec.



6 X 30 in series parallel will give you 90uf / 2 = 45uf



pleximaster said:


> My Screen is then only 7,5uF by the choke right? It has the big large choke.



Your screen supply filtering should have 16-22uf after the choke.



pleximaster said:


> On the other two lead pigs I have the "right" number of caps but did´t use 32uF as stated in the schematics but 47uF. Giving me a virtual 47uF cap at B+
> 
> Still I hear less ghosting on the two ones with lower filter... and have good attack.
> 
> Am i messing up the physics class again?
> 
> plexi



47uf is good. Anywhere from 32uf - 47uf will be similar to what original PIG had.

If you can, please attach a drawing of how you configured your power supply filtering, diodes and transformer windings if you want me to verify your values.

On more thing... What value is the big grey capacitor across the 820ohm cathode resistor to the far right in the picture you posted above?


----------



## BlackSG91

That would make a great foosball table with added effects and a great score on tone! The loads of capacitors can make great defence and the electrolytic 
offense tubes can can great chances when when the capacitors begin to discharge their loads.

















*;>)/*


----------



## pleximaster

I hope I got the jumpers in place now on the pic!





plexi


----------



## danfrank

Hi Plexi,
It looks like you have 18uf total for the 720volt main B+ (Test point 5 on the Vintagekiki schematic). Remember that not only do you have the 6 X 30 capacitors in series parallel with this voltage, the amp also has the 4 X 30uf capacitors from the "lower" 420volt supply in series with the "upper" 6 X 30uf capacitors.
420volt capacitance BEFORE choke looks like 30uf, if the four caps in the center of the picture are 30uf each.
Then 22uf for test points 1 and 2? It looks like the 2 caps on the left of the picture are 22uf.


----------



## pleximaster

Thanks Dan!

I am not a tech guy Like you!

Good or bad you say?  All the caps on the wide filter board are 30uF 600V

If I were to use the the 2 x 30uf + 4 x 30uF as it was stock (32uF) what would the the total capacitance be at the various points?

best plexi


----------



## pleximaster

The stock caps on the small board is
2 x 22uF (Stock should have been 16uF, I wanted a bit higher value) and the big one in the Hiwatt dual bias circuit is 100uF so that ond doesnt count here. 

the metal cap on the side I use one 32uF as I did´t have a 22uF


----------



## danfrank

To get the capacitance similar to the original PIG, do away with the series parallel for each supply. You only needed to do this with the Kitchen Marshall PA PIG because the 750volt B+ is only done with one transformer winding, instead of 2 different windings "stacked" on top each other, like with the Lead 3 knob PIGS.
So, to get it like original PIG with the TH1498 transformer, use 2 X 30uf capacitors in parallel where the 4 X 30uf capacitors are AND where the 6 X 30uf capacitors are. This will give a virtual capacitance of 30uf for the 720volt B+ supply. If you want a little more capacitance (45uf total) use 3 30uf caps in each location instead of 2.
Take a look at the picture:


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## pleximaster

Thanks Dan!

Best Lenny


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## danfrank

If you want to get the filter capacitance like when the PIG originally came out in early 1967, I would use the 30uf metal cap for the PI. At this era of Marshall amps it seems like the Main B+ capacitance is 32uf, the screen supply is 16uf, the PI filtering is 32uf-50uf and the 2 preamp tubes filtering is 16uf. You may have less ghosting on Lead PIG #3 because you have 30uf filtering for the preamp tubes.
Because these early Marshalls used 16uf for the first 2 preamp tubes (and maybe the 16uf screen cap), I think this is where the "ghosting" happens. This is just a theory on my part.


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## danfrank

pleximaster said:


> Thanks Dan!
> 
> I am not a tech guy Like you!
> 
> Good or bad you say?
> 
> best plexi



It's good if you like the way it sounds. Only bad if it sounds bad.
If you have the time, play around with the different capacitance values for each area (test points 1, 2, 4 and 5) to see what sounds best.

I do have a question... What do you think sounds better? A capacitor across the 1st 820ohm cathode resistor or NO capacitor?


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## pleximaster

With capacitor!!!

On this one they are 1,5k and not 820 as in the PA and the First one.

The PA Pig also have 1,5k... sorry I am still soft in the head... 


Best plexi


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## pleximaster

I haven´t got around doing a layout of the pig but here are the my cleanest restoration/rebuilt with correct layout on the main board. The bias is the dual Hiwatt version which I recommend anyone that builds it. If someone wants to do a layout from these pictures I am happy to answer any questions! This is a lead version of the amp.

...and yes the box is recovered... thats why its so clean...


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## Codyjohns

pleximaster said:


> I haven´t got around doing a layout of the pig but here are the my cleanest restoration/rebuilt with correct layout on the main board. The bias is the dual Hiwatt version which I recommend anyone that builds it. If someone wants to do a layout from these pictures I am happy to answer any questions! This is a lead version of the amp.
> 
> ...and yes the box is recovered... thats why its so clean...



Best example of a '67 Major on the planet earth. 
Looks absolutely beautiful!!


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## roef

Thanks for all the great pics and all the great technical info! This is the best info about these amps I've ever seen. Early Marshalls were often underfiltered and often suffered from ghost notes if you crank them. The ghosting is created in the power amp, not the preamp, in my experience. The phase inverter will become unbalanced when you dime the amp. The negative feedback helps most of the time, but not when you really dime the amp


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## Allan

Hi everyone. First time posting but a long time follower of this forum.

Thank you *danfrank* and *Michael RT* for you insight into these amps.

*pleximaster*, a giant thank you for sharing all of this information that corrected my earlier research on this subject. I gathered information years ago but it fell short due to not owning a Pig.

I recently had a U.S. chassis maker produce a run of these chassis confirmed by your measurements. I was off a couple of inches in length but you straightened me out with your pictures.

The seller is on ebay as
zachmdhunter
and they have the chassis for sale as "Blank Major 'Pig' 200 Chassis for Project DIY". So it is an undrilled chassis. In the future I'll try to figure out the correct specs for the holes and see if they will produce them punched.

I bought two and they have five more for sale. Figured I'd share this with all of you after all of the info you have given me.

Thanks everyone.

-Allan


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## pleximaster

Posted in wrong thread... 

plexi


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## G the wildman

Can we hear it please.
G


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## pleximaster

The pig?


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## The_Nuge

Very cool pleximaster!


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## Flat5th

Swede said:


> But how does it sound?.... Look wise it might be butchered but he's a pretty reputable amp guy in Sweden. He's modded for quite a few players.


I'm not even a experienced tech,but I can see this amp was turned into a complete abortion.As someone else asked," who is this guy"? More importantly how did he ever get e reputation as a amp tech that ANYONE would trust their amp to ? However,what a great thread it turned into with tons of info. Nice work to all the techies who chimed in. And such creative responses to the disaster this amp was turned in to.


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## proxy

I am sure you'll know what to do with it ✌


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## pleximaster

proxy said:


> I am sure you'll know what to do with it ✌



Sure I do know what to do now... Over five years after this old thread stared and 7 restored Marshall "The Pig amp" restorations...

I have one that I just sourced the final parts for and need to attend... 

Best regards
plexi


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## proxy

pleximaster said:


> Sure I do know what to do now... Over five years after this old thread stared and 7 restored Marshall "The Pig amp" restorations...
> 
> I have one that I just sourced the final parts for and need to attend...
> 
> Best regards




Great
Get Johan to record nice video


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## pleximaster

This one last one I got. It need new caps that survive at least 600v each. The black capacitors does but the silver ones doesn't... Here I go with modern caps and not vintage...

Selectors and fuse holders were changed to modern ones and here it must be retuned to vintage ones or it will kill the sound!  Haha!

plexi


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## danfrank

Hi Plexi!
Another PIG... That's crazy. We should start calling you PlexiPigMaster.
Hope you're doing well.


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## pleximaster

I actually had this for some time but missed a few parts, also you now me it’s fun when you learn when you replete oneself it’s not as much fun... luckily my memory is so bad I have to relearn the pig wiring and start over... fun again!!!

best plexi


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