Randall RG100ESXP sparks and LEDs don't work

[PRNDL]

This Randall RG100 has problems with the LEDs on both the front panel and in the foot switch. They would work sometimes if you jiggled the connector cord to the foot switch.

It turns out to be a problem with the -40 volt cap (50V/6000µF) that is connected to the bridge diode. It has black burn marks between the leads. With the amp on, the -40V rail measured in millivolts, but went to -43 after a little while.

I took the cap out and it tested fine with the resistance/charging method, so I put it back in and turned on the amp, which caused a big spark near the bridge and cap.

The -40VDC rail feeds the output transistors and the LEDs.

I suspect the output transistors have shorted and are drawing too much current, and plan on removing them for testing this morning.

Any ideas/suggestions?

Is there a modern replacement for the 2N6254 power transistors?
(Mouser doesn't list any).

Thanks!!

[PRNDL]

Fixed a wiring mistake

It turns out the owner swapped a ground wire with one of the LED driver wires, which was shorting 40 volts to ground.

A simple fix.

The original foot switch now works fine most of the time. Every now and then it acts funny, but jiggling the connector sets it right. From what I've read, these connectors have issues.

There is a new replacement switch made specifically for this amp that I went ahead and re-wired based on the original, but it doesn't want to work. I think the old connector likes the old connector on the original, and if I replace the connector on the amp, the original won't work, but this new foot switch will. Who knows. I left it up to the owner.

Although there wasn't time to respond, I appreciate being able to post on this forum and know that knowledgeable people will usually respond with tips.

Thanks!