Got a request for advice that I can't directly answer -

[R.G.]

I got this question in my email, and I'm not familiar enough with Marshall transformers to just pop an answer. I *think* it's OK, but I suspect that some of you and probably certainly you, Enzo, have some direct experience. The sender is clearly not a user here or he'd have posted here. I'll point him over here for the answer.

I was hoping you could help me with a transformer issue. I have a 100w Marshall head that needs a new OP transformer, but cannot find any info for the transformer. Can I use a JCM800 transformer, the both amps use 4 x el34's?

[J M Fahey]

Basically yes.
Impedance and power handling will match.
*Maybe* mounting does not.
jm2c

[Amp Kat]

Depends on which 100 watt amp he has as ^^^ mounting could be different. The JCM 900 Trannies were much smaller.

[Enzo]

100w quad-of-EL34 transformers ought to work in one another's place. I don't keep track of all the premutations of transformer and model compatibilities, I leave that to the amp fans. SO yes, it would work, the main issue would be does it fit the mounting, as was pointed out above.

[drewl]

What Marshall does he need it for?
He's asking if he can use a JCM800 OT, and yes probably, but some of the older 100w marshalls put out ALOT more than 100w, I've seen some scream at least 180watts, so he might want to find a vintage tranny or repro if it's an old Marshall.

And obviously something close in size/mounting.

[newtube]

Hello, thanks for the reply, I need the trans for a fairly new Marshall MA100H. Some wonderful mastermind swiped it out of my amp when the chassis was on my bench. Still haven't figured out who or better yet WHY?

[newtube]

R.G. Thank you so much for posting this to the forum, I'm glad I was able to get an answer from knowledgeable folks!

[Amp Kat]

Hello, thanks for the reply, I need the trans for a fairly new Marshall MA100H. Some wonderful mastermind swiped it out of my amp when the chassis was on my bench. Still haven't figured out who or better yet WHY?

This is what I was thinking which is why I said the JCM-900 tranny is much smaller and so is this one being it's a head there is no way they have one of those beefy JCM-800 Trannies in it and if I'm not mistaken the MA-100 and the JCM 2000's are different from the JCM 900's but they would all work circuit wise but mount up different. I would call Paul at Mercury Magnetics as he may have a cross for one or could tell you what to use. Extremely knowledgeable transformer guy.

IMO you are going to have to go through Korg to get this exact replica as it's to new of a model to just buy from a amp distributor like Antique or CE but someone like Enzo who I believe is a certified Marshall tech or someone else could likely get the tranny or maybe you have a Marshall account. They can also get schematics for it and from what I've heard this is a Vietnamese made amp and quite cheap so I'm sure that's what you wanted to hear.

[Alex R]

Marshall now supply the same replacement transformer for all the amps mentioned. It's supplied in Z-mount form but will sit down in X-mount with the old cover installed.

[Enzo]

Just so you know, KB, Korg is no longer the US distributor of Marshall. And when that relationship ended, I did not follow the Marshall line to the new distributor, I let it lapse, so i am no longer a Marshall repair station.

[Amp Kat]

Just so you know, KB, Korg is no longer the US distributor of Marshall. And when that relationship ended, I did not follow the Marshall line to the new distributor, I let it lapse, so i am no longer a Marshall repair station.

Thanks for that Enzo as I hadn't contacted them in awhile and am not one either and don't plan to be and good choice on your part as always

[Trimbert]

Hi fellas… I’m new here and pretty much new to tube amps. Definitely new to attempting to work on them , I have a Marshall ma100h yep the cheap one , it’s actually a nice sounding one I think .. I have no clean channel is one problem and the other one is no in and out ( leads ) coming out of the reverb tank .
Furthermore I can’t find a decent schematic for it .. I have th chassis pulled and right away I can see that there are 3 two pin and a three pin .. post with no plug going two them .. sorry about my terminology guys bear with me .. they are labeled con 17 and 18 do you guys have any idea what they are for .. con 7 is the other