So the SX-636 restoration is complete. Power, EQ, main amp boards are all recapped with new electrolytics And new transistors. The output transistors were changed to modern ON brand semiconductors and nichicon premium caps throughout. Brought the receiver slowly up on a variac last night to break in the new caps and aligned the bias. I really like the classic Pioneer TO3 output trans mounting system to the heat sink. Very simple and no soldering of the transistor legs.
After warming up at 120v for about 30 minutes decided it was time for some listening and today we will do some actual bench testing. Fresh non broken in caps and it sounds great. That punchy pioneer sound I love.
This afternoon will hopefully do some probing with the scope and see where this received bench tests at. The manufactured rated it a 30wpc originally, but I feel it’s going to take a bit more to make this amp clip now.
Here’s a few pics of the main amp board before and after.
