Marshall voltage question

scottster

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Maybe this is the more appropriate place for this question-- I bought a new JVM215C from the UK that got here late last week and want to confirm that its working while I try to find the right step up transformer (I bought one with the right specs but wrong plug).

While I'm looking for the right one, can I plug a 220V amp into a 120V wall plug for a few seconds to make sure it fires up and can take a signal before I lose my return window?
 

scottster

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No, I wish it did. It looks like the legacy amps like the JCM800 2203 and 1987x still have them but not on this one
 

fitz

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I wouldn't do that.
I have no electrical basis for that advice, I'm an accountant.
Seems like it might have the potential to result in a substantial financial decline to the value of your investment.

Get the right plug, or see about getting the amp transformer rewired to 120v, or replaced, for a long-term solution.
 

Dr.Twang!

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Oops I see that now on the 410 schematic that each power transformer has separate part number and input voltage for region of export.
It would be worse to go in the other direction, but not sure using 120v that you will have enough volts out of the heater circuit to get tubes to work.
Can you discuss your dilemma with seller to give you some more time to verify proper operation?
 

chocol8

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You can wire up a 240 outlet in your house, or if you already have a dryer outlet or electric stove outlet, you can make a converter cable or pop a new end on the power cord.
 

scottster

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Thanks all for the info- here's a pic. I bought a Hammond 176C (plug on the left) and the Marshall UK plug is on the right
 

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Whatwhatringrang

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You know you could. Trouble Is that it will probably not be enough for the heaters to start working. Just wait it out till you get what you need. Or maybe a local tech around you could check real quick for you ? Or even exchange the variac for one with universal plug and operations? That way you don’t need that much more to worry about. With plugs and what have you.

I would also put a label on that particular amp so you do not forget. Like mentioned above would be bad the other way around 120 to 220/240.

On the 66/ early 67 100 old Marshall amps I use a step up transformer to 240-250. These according to what I have been told and read. Those early transformers are not quite wound in the fashion they would become. I will not derail the thread about all that.

I like slowly bring up the voltage to amps with old caps when starting . Anyhow I notice the quality of these step ups I can find are less than ideal. Anyhow not relevant to your problem amp going there… So anyhow

I would just wait till you get your adapter plug for the step up. It sucks to lug around a decent rated step up and a old American made variac everywhere though . Then again I don’t buy Marshalls for portable reasons or even convenience lol.

Make sure the stepup is rated at way more than the min required specs . I wish I could find American company that Makes nice step up transformers . I need to look or find a company that makes them.

I bought the most expensive brand Chinese one I could find. Very overrated in specs. Never any problems but not really happy with it either ,it does what it does. Mine is a lite fuze lt-5000 or something like that. Still not really quality stuff imo. Then again what do I know .

If anyone knows about a U.S.A made one send me a pm. Or even a good old Made in U.S.A or U.K. One. I can not find old U.S made step ups. Variacs not a problem but not step ups.

What I do not like about it you have a lot transformers next to each other. It can pickup stuff Like noise and what not depending how close they are .
 
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scottster

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You know you could. Trouble Is that it will probably not be enough for the heaters to start working. Just wait it out till you get what you need. Or maybe a local tech around you could check real quick for you ? Or even exchange the variac for one with universal plug and operations? That way you don’t need that much more to worry about. With plugs and what have you.

I would also put a label on that particular amp so you do not forget. Like mentioned above would be bad the other way around 120 to 220/240.

On the 66/ early 67 amps I use a step up transformer to 240-250. I like slowly bring up the voltage to amps with old caps when starting . Anyhow I notice the quality of these step ups I can find are less than ideal.

I would just wait till you get your adapter plug for the step up. It sucks to lug around a decent rated step up and a old American made variac everywhere though . Then again I don’t buy Marshalls for portable reasons or even convenience lol.

Make sure the stepup is rated at way more than the min required specs . I wish I could find American company that Makes nice step up transformers . I need to look or find a company that makes them.

I bought the most expensive brand Chinese one I could find. Very overrated in specs. Never any problems but not really happy with it either ,it does what it does. Mine is a lite fuze lt-5000 or something like that. Still not really quality stuff imo. Then again what do I know .

If anyone knows about a U.S.A made one send me a pm. Or even a good old Made in U.S.A or U.K. One. I can not find old U.S made step ups. Variacs not a problem but not step ups.

What I do not like about it you have a lot transformers next to each other. It can pickup stuff Like noise and what not depending how close they are .
Sounds like what may end up working for me may work for you?

I bought a Hammond 176C step up 115v to 130v. It feels like a lead brick- very sturdy, nice construction, looks to be very high quality. It appears that the specs are good for a 50 watt Marshall to me but I'm a newby with this stuff. Here's the link to the specs- https://www.hammfg.com/electronics/transformers/line/176

Anyway, they have quite a few models in the 176 step up line with the difference being voltage capacity.

The "C" is rated at 300 volts and it looks like max draw on my amp is 175 watts so should this be ok?
 

Matthews Guitars

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That'd simulate a serious brownout condition. It wouldn't harm anything but it may not get the filaments hot enough to get any sound out of the amp.
 

Gene Ballzz

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@Matthews Guitars

Maybe I'm missing something here, but might it be appropriate here in the US, to simply wire up a 220VAC (actual 240-ish) outlet for use with British/EU intended amplifiers? Please explain why I am full of POO, if I am?
Just Advance Thankin'
Gene
 

chocol8

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Wiring up a 220/240 outlet would be what I would do. Actually, the first thing I would do is check if the PT has a 120 tap tucked inside the amp. Sometimes manufacturers get cheap with the switches and just hard wire a single voltage even though the transformer is multi voltage.
 

AtomicRob

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It won't hurt the amp or the tubes to power it with 120v but it probably (?) won't make any sound either if it's expecting 240v. I regularly bring up amps slowly on a variac and IIRC with a 120v amp it's not making much noise yet at half voltage. And that's with older amps that don't have solid-state circuitry like you'd have in a JVM215C for channel switching, fx loop, midi control, etc. None of that solid-state stuff will probably work on half voltage.
might it be appropriate here in the US, to simply wire up a 220VAC (actual 240-ish) outlet for use with British/EU intended amplifiers?
I'm not an electrician but I think the problem is that USA a 240v residential circuit is split into two 120V circuits using a grounded center-tap secondary, so each circuit is 120v from the center-tap neutral. UK 240 power grounds one end of the secondary, not the center tap, so the plug has one live wire that is 240v from neutral. In order to get 240v in the USA, you'd have to take the two live wires (red and black typically) and make one the "live" side in the UK plug, and the other the "neutral" side. But then your neutral is 120v away from ground, which is not the way it works in the UK and could maybe be unsafe or cause who knows what issues for equipment that is expecting neutral and ground to be at nearly the same potential.
 

Matthews Guitars

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Sure, you can wire up a 220/240 volt outlet, but I figured you were asking if you can kinda sorta test the amp at 120 volts. It would do no harm to attempt that, but it may not be enough voltage to get anything out of the amp.
 

chocol8

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Ground reference of the AC power shouldn't matter once it hits the transformer. If you have an existing outlet, you can cheaply and quickly change the end of the power cord and test the amp out before any return window issues. Long term, I would put an outlet in where the amp would live, rather than have to use it with a 1:2 step up all the time.
 

Whatwhatringrang

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Sounds like what may end up working for me may work for you?

I bought a Hammond 176C step up 115v to 130v. It feels like a lead brick- very sturdy, nice construction, looks to be very high quality. It appears that the specs are good for a 50 watt Marshall to me but I'm a newby with this stuff. Here's the link to the specs- https://www.hammfg.com/electronics/transformers/line/176

Anyway, they have quite a few models in the 176 step up line with the difference being voltage capacity.

The "C" is rated at 300 volts and it looks like max draw on my amp is 175 watts so should this be ok?
Just waking up so this probably will read horrible like all my posts lol. I am also not familiar with your amp model.

Well i got the right one . I have heard 5 to 10 times the draw for the amp. not right in front of my notes or amp backpanels for that right now. Using these with old 100 one at a time mine is rated for 5000 watts. Could run both outta the one. His one has universal plugs on the front that will work with 3 prong ,english, or European type.

No need for adapters on this and also the different switches in back for voltage. Using a big USA made variac that goes to 300VAC if you have more than 120 going into it .

If you are only using it in your house maybe have some one rewire possibly like mentioned above. Maybe even getting a good replacement of same type of transformer for your amp 120. Makes life easier.

The pics below would go step up plugged into (power strip conditioner/wall). Then plug big 300 vac variac into the step up . The guitar amp into the variac. I would not suggest in any ways this being ideal or practical. Some of these early ones operate a little different concerning the early 105-115 if they even have them. That is why I have and us this whopping crap. I need to look for a non Chinese higher quality step up /step down transformer.

I would say the other methods mention by some is the way to go here. Putting different correct 120 PT transformer in (having a tech whatever)probably maybe more affordable and better on the amp you are planning on doing this with. For many reasons maybe Marshall even would sell you one they use on the U.S model so your tech could put it in??
 

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