Lots of pictures of RM50 Repair

The following are pictures I took while working on my RM50. They include
swapping transformers and circuit boards. DON'T TRY THIS AT HOME UNLESS
YOU KNOW WHAT YOU'RE DOING! REALLY!

Nice pics--but what caused the meltdown?

Plate voltage connectors shorted to the PC board. Once you get a carbon trace from even a small spark, the rest is history. I changed the board eventually and the output transformer. The smaller trans is the newer one.
When I have time I'll check the board at the component level and do an AC
test of the tranny.

Too many wires.

Lotta pretty colors.

The patience of a saint......

Thanks for the compliment!

Ugh....

Nice work in there though. How did things come out?

It's all good.
Reason for the swap is that, until the Plate connections
finally shorted to the pc board, it was an intermittent problem.
I would get red plating on only the right hand output tube and, of course, checked the usual suspects, screen grid resistors, coupling caps, switched tubes, monitored voltages under load, etc.
I repaired the first board (milled out the carbonized area and filled with epoxy. I did check the dielectric specs. for the epoxy) put it back together
and no more shorts but still red plating if I pushed it hard.
I changed out the O.T. and power amp board, (the newer O.T. is smaller
with the same part number) because I only had a certain amount of time between gigs to fix it.
When I have time I will check the board down to the component level
and for the O.T. I have a Sprague TO-6 Capacitor/Transformer tester
with which I can actually verify the turns ratio and leakage with.
If I find anything off spec. I'll post it.

I know there are photos of the same thing happening to my RM50 on here somewhere....sucked mightily!

Which one is teh new tranny? want to compare it to mine....is it a Randall part?

JKD
I knew someone wanted to see the difference between the trannys.
The new one is the smaller one labeled made in Taiwan. The original has more laminations, probably the same turns ratio.
I'm really not certain there is anything wrong with the original tranny
but I had to get it fixed and didn't want to take it apart "yet again."
I don't take shortcuts just to get it working (no splices).
The trannys are in the photos, with and without the caps.

Forgot, It's a Randall part, the same part number.

Have you thought about upgrading to a Mercury transformer? since you can do all the work yourself, the cost will just be to buy the transformer itself. Good to see an MTS user with the technical know-how.

I've thought about Mercury Magnets but for the style I play, blues, R&B,
"classic" rock, I actually prefer an O.T. with a more "collapsible" magnetic
field. That's why I didn't mind the fact that the new replacement transformer
had a smaller core than the original one, even though it has the same part number. I had to swap the bell covers and fit spacers on the mounting brackets for the new O.T. to fit the chassis holes. I like the sound of a pushed output section and speakers. I still don't think it can be duplicated
by modeling or re-amping. I even like a room mike in addition to the speaker mike.