Marshall 6101 (combo) problem

siav

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I can’t post photos, too large for the forum’s policy.
Everything is nicely connected, no burnt signs or cable / board overheating
 

siav

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So I took it out, tested it > it was ok.
Put it back in test it > it's still ok

I don't get it....
 

ronald a aguiar

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Hello,

I haven't played with that amp for a while and I have a problem with it.
No sound at all... Everything is lighting up as they should, the fuses are ok.
I have tested the speaker (Celestion gold, 8 Ohm) with an other amp and it works properly.

Could you please suggest a test runthrough or a diagnostic plan?

Thanks a lot!
OK as I read the replies, there are a lot of well meaning people who don't have first hand experience with these amps- I do . I have owned 3 6101 ,models and one 6100. People who have responded with info that these are not simple amps are absolutely correct. One this about these is that there are not only external fuses but there are also mini ( micro?) fuses on the circuit board, that can only be accessed by pulling the chassis. I strongly recommend that you bring the amp to a tech who has experience with this model or at the very least a wide base of amp repair doing hybrid circuits. Great amp- good luck
 

Mike_LA

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Please make sure ALL OF THE SWITCHES in the back are set properly. Is the link switch in or out? I own 3 6101s. When not playing one for a while people forget to check alllllll of them. It happened to me once as well. If it is not that problem, in one amp i had an issue with the treble cutting out of ch 1. While looking at it on the bench i noticed flashing/sparking on the board at the connection of one of the spade connectors. A careful resoldering solved the issue.
Best of luck
 

siav

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OK as I read the replies, there are a lot of well meaning people who don't have first hand experience with these amps- I do . I have owned 3 6101 ,models and one 6100. People who have responded with info that these are not simple amps are absolutely correct. One this about these is that there are not only external fuses but there are also mini ( micro?) fuses on the circuit board, that can only be accessed by pulling the chassis. I strongly recommend that you bring the amp to a tech who has experience with this model or at the very least a wide base of amp repair doing hybrid circuits. Great amp- good luck
Thanks! I checked the internal fuses, they're all ok
 

Max Maxwell

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Hello,

I haven't played with that amp for a while and I have a problem with it.
No sound at all... Everything is lighting up as they should, the fuses are ok.
I have tested the speaker (Celestion gold, 8 Ohm) with an other amp and it works properly.

Could you please suggest a test runthrough or a diagnostic plan?

Thanks a lot!
Check the effects loop series/parallel button. I went through the same thing with mine. Drove my tech crazy. Don't know why, but if that button is pushed in it won't make a sound but it's still lit up like it's ready to rock. Hope this helps.
 

eenaoo

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The amp can be a pain in the ass. There are some ways to debug the amp, like mentioned here. Sample the singnal out from the effect loop, to check the preamp. Send a signal inn to the effect loop to check the power section etc. With an oscilloscope it all gets a lot easier, where you can check each stage. The amp is not that difficult to understand. However the PCB quality is crap. I replaced all the potentiometers and recapped mine. Even with proper desoldering and soldering equipment it was not easy not to prevent liftoff of the trances. I have the 6100LE version, maybe later versions have improved. I'm based in Norway but in the South.
 

Mrmadd

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You can get an app or program for your computer to shrink photo file sizes.

Pictures help
 

Rick Cruz

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Sorry... when the chassis was out, plugged in HP and guitar > sounds like a good amp.
When I put the chassis back in, with HP and guitar plugged, I get no sound (but everything lights up).
I haven't changed any tubes, just used electronic contact cleaner to fix the CH2 volume pot (which was fixed when I tested with the chassis out).
Perhaps a mounting screw is shorting something upon it entering into the chassis?...or a circuit board with an intermittent connection when it is flexed? Maybe try poking around with something non conductive (with one hand in pocket) while the chassis is out to try and duplicate the silence. Last year, I purchased a (non functioning) 6101LM, blue tolex, polished brass chassis, OEM EVM12L 8 ohm speaker. It had a "stake on" wire end attached to a high voltage rail that burned off. The insides of this beast is scary, but you already know that.
I hope you get it going. It sounds like you're close to finding the problem, because you've already gotten it to function properly .
 
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LOVETONE

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Hello,

I haven't played with that amp for a while and I have a problem with it.
No sound at all... Everything is lighting up as they should, the fuses are ok.
I have tested the speaker (Celestion gold, 8 Ohm) with an other amp and it works properly.

Could you please suggest a test runthrough or a diagnostic plan?

Thanks a lot!
Hi I would check the send / return jacks, put a guitar lead in the send and return if there is a faulty jack socket you should get normal output.
 

fitz288

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Hi I would check the send / return jacks, put a guitar lead in the send and return if there is a faulty jack socket you should get normal output.

read the thread - problem solved back on post #23...
 

fitz288

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I think I found the problem: there was a button next to the FX loop that was pressed on. with that on, I had no volume
Series/Parallel switch (button)?
1652713708932.png
In series, the effects knob on the front acts like another MV.
In parallel, the effects knob blends the loop with a non-loop signal.
1652713525218.png
(I run gate, EQ, chorus & reverb in the loop set to series - effects knob on front at 10)
 

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