So last post was about the issues facing this Pioneer SX-1010 causing the 10 ohm series resistor on the power supply that feeds the amp boards being fried shut. With more inspection of the transistors and diodes on the amp boards a shorted driver was found on the right side amp board. Replaced the transistor and tried to power up again on variac. 60VAC relay pulls in, 90VAC relay trips and puts amp in protection.
After inspecting the power supply, high voltage rails were found. Even though the board was completely rebuilt with modern components, something was damaged from the shorted driver. After checking out of circuit all diodes and transistors a bad voltage regulator and two other transistors were found. C-E gaps were open, and allowed too much voltage through. Replaced and powered up slow again and successfully repaired.
This of course sums up quite a bit of time consuming diagnosing. I want to give a big thanks to the great Pioneer guys at AudioKarma.org as they were very helpful with the diagnostics of the receiver. Please also check out www.MattsVintageAudioRepair.blogspot.com . Matt did the original refurbishing of the 1010 and did an amazing job. Shame that shipping caused so much trouble.
Coming up I will be replacing the faceplate on the 1010 with one is excellent condition and reinstalling the knobs. Updates and pictures to come. Here is the rebuilt power supply installed before tidying up the wires around it.
Mike, you’re teasing me man, let me have it!