I got a SPEC-4 to repair and recap from a guy in North Carolina, it had quit working with crackle pop and some magic smoke. Upon receiving it and checking it out, I found almost every transistor on the right amp board was either shorted, open or both! Four resistors had also fried, two of them had melted.
Some before photos, I will add to these soon.
Right amp board, you can see the burned out resistors from browned heat wraps over them.
Left amp board
Left amp board
Right amp board
I had to customize the boards a little to fit the new relay in, the old relay is a small MY2 style relay that is no longer obtainable, so I had to get a regular MY2 relay which is larger and fit it in. The photos below are of the right amp board.
I first checked the fit and drilled some new holes using a 1/16" bit, I was a little off on the last two on the far right, they should have been even with the others
Soldering it in, I scraped some the green coating off of the trace around where the new holes were so the solder would stick and soldered it in. The output wire that goes to the speaker terminal needs to be moved from pin 12 to pin 13, also needed are two jumpers, one, the green wire, jumps the 48VDC for the relay over to the new relay position and two, the bare wire jumper connects pin 13 to pin 12 so the meter drive circuit (pin 10) works, as pin 10 is directly connected to pin 12 but not pin 13.
And it's all together again!