Help with sx 1050 after new outputs installed

You could have a mod move this to the Pioneer forum! Sometimes specific repairs to these old units have already been explored, and may help get to the solution a bit faster?

As for me, although I have not opened my 1050 yet, I read all these threads and continue to learn! That box of parts from Mouser is just waiting patiently for me to have enough bench space!

I have ohmed out quite everything I could think of. Between all pins on amp board, between all pins on transistors to semi and I cannot find a short.

I'm thinking this will only show itself when the relay is closed. Do you have any idea what pins I should put a set of jumpers on to simulate a closed relay?

BTW I have tested with both outputs plugged in and unplugged. Also ohmed between plug terminals.

Edited: added this crop of the schematic, showing the power amp and protection.



Ok, so your output transistors are not shorted, at least without power on them. A short in any of the drivers will activate the protection, please check the transistors marked with a green dot.

The relay is visible, I think it's wired to pin 4 and pin 17 (L and R channel signal output), and then to the speakers selector. Edited, schematic confirmed this

Anyway, the relay just connect both parts of the circuit, so if you have a short in one side, you can measure with the multimeter at both sides of the relay.

If you want, by-pass the relay, but with the unit UNPLUGGED, just as a passive test. Don't by-pass a protection circuit with the unit powered ON.

Also, check the power supply for a short. BE SURE THE LARGE CAPACITORS DON'T HAVE VOLTAGE ACROSS THEM, and then, measure resistance from + to - terminals. If you read a short, or very low resistance, post your results. Try to isolate the fail, if you can, disconnect boards from the power supply until the short is gone.

Please , try to detail what connector you disconnected when the dim bulb tested OK.