Sansui 7070

[Minejahmouth]

Hey guys new to this forum. I'm looking for some help to try and fix my beloved sansui 7070. The bugger just plumb stopped working one day. I used to turn it on then like 7 seconds later the sound would kick on. Now when I turn it on it doesn't click and theres no sound to any speakers anymore.

I'm wanting to make a go to replacing the components that failed but I'm not sure where to look. I'm a electrician so I know my way around a meter. I can also solder ok.

I've read about some 180 ohm resistors could be my problem on one of the boards. I really know nothing about small electronics but I know I'm capable enough to make readings under instruction.

Please help me get this unit working again. As far as I know everything besides a couple burned out lights works nothing changed just no pop then sound only silence.

Thanks in advance

 

[mbz]

You can start replacing parts you or someone else thinks have failed or you can adopt a more systematic approach and
try and diagnose... sorry been a long day. No relay click indicates the amp in either in protect mode or there is a failure
in the protect circuit. First step would be to check for excessive Vdc at power amp outputs or protect relay. Will download service
manual and get some test points...

 

[avionic]

Welcome aboard...

 

[mbz]

Measure Vdc at Pin 37 on main board, repeat for pin 50. Alternatively you can measure at R21, repeat for R22.
Should be less than 100mV (ideally less than 20mV).

 

[mbz]

I've read about some 180 ohm resistors could be my problem on one of the boards

Yes, those resistors on the power amp are problematic, check them out/replace. I've got the 5050, same issue with the R's. Nice
amp, like to move up the food chain a bit...

 

[Kevin D]

Welcome!