Technics SA-DX750 Receiver

If you check the DC voltages all around the Pwr Amp IC before/after and look for the cause of DC voltage on the speakers from some fault condition going in, you can debug further. You could also disconnect speakers and bypass the relay protection for more time to measure this.

So, you have the RLY pin on those thee IC's that you should look at. There's an overdet and powelimit as well, so maybe you should jot down all of the voltages on the three IC's before and after fail.

You need to check the voltage at the outputs BEFORE the protection relays, to see which (if any) is going faulty.

There's no point checking on the speaker outputs, as the relay disconnects them when faulty.

Click to expand...

You are right, check the output voltage when they are not enough voltage will make the circuit do not work

I have a friend who's uncle is gonna look at it in his spare time then I will do the repairs on it. Thanks for all the help.