So last week the Pioneer SX-1010 coming in for replacement of it power supply arrived. Upon inspection and removal of the old power supply board an all to familiar smell of burnt component was noticeable. After removing the suspect board and installing the newly rebuilt one I began bringing the receiver up slowly on the variac. I am so glad I started at 20v because that smell started coming from my newly rebuilt board and magic smoke!!!
The 10ohm resistor that sits in series between a regulator trans and pin 14 which provides 56v to the amp boards was fried. Immediately I check the board that was removed from the unit and the same resistor was cooked. Desoldered both wires from pin 14 which go to pin 4 on the amp boards, I attached them one at a time and attempted a start up again. Left side amp board no problem, right side one not so much.
This evening the outputs were pulled from the right side and both amp boards were hooked back up to pin 14 on the power supply. The unit powers up now and I am beginning to point my fingers at the outputs. They diode test ok but diode testing does not always tell the whole story. This project although has become a bit more complicated will be even more rewarding when finished.