So my JCA2112rc decided to stop producing sound. Which is good for the people that do not want to listen to my s*** playing, but not so good for me. I was banging the chassis around quite a bit while I was changing speakers, so I attribute the problem to this.

So while this might not completely resolve the issue, I was dabbling in the idea of upgrading the trannies anyway. But I am a bit lost and I admit that I wasn't really getting anywhere through various Google searches.

What I need to know about is compatibility. Surely, one cannot put a transformer from a 120W tube amp onto that of a 20 watter, right? (Assuming that it would even fit).

I have a 50 watt tube amp that I do not use, but it works. It runs EL84s like the Jet City. Would the transformers from these amps be compatible with the Jet City? Or do I need some type of 20 watt transformers?

I apologize for my ignorance, but I literally know nothing. I would certainly appreciate the help, though.
You'd need a transformer designed for a 20 watt amp - a transformer won't have the right output to the speakers, if the input is too low. At lower-than-designed-for wattages, this will probably not damage anything but it won't sound good.

If it was the other way around (20 watt trafo in 50 watt amp) you'd blow something up.
Ceci n'est pas une signature.
From the title, I thought you were dating a younger, cuter transgendered person.

Go to the Mercury Magnetics website; not only do they have a wide variety of some of the best transFORMers in the business (not cheap, mind you), but they also have some really good advice and probably something specific for your amp. http://www.mercurymagnetics.com/

Here's something else.

Mercury Magnetics notes: "We're looking for transformers from Jet City amps so we can offer upgrade versions. Your original transformers may be working (or not working) when you send them in. Be the first... get the sweet deal. If you'd like to upgrade the tone of your amp, all you have to do first is contact us ( patrick@mercurymagnetics.com )."

In my experience, upgrading your transformers can change the sound of your amplifier. I have the MM kit installed in my EVJr (the kit plus installation was four times the cost of the original $99 amp <G>, but I have trouble getting near that head any more; seems like it's always out in one recording studio or another with "friends."