Tripping Sansui

[burntfingers]

Sansui Model SV 2918.
Works fine for a while.
Then goes on tripping and auto tuning, impossible to stop with remote or locals.
Customer doesn't want to spend a lot.
I replaced caps in power supply, to no avail.
I suspect the M/processor.
Must I give up?

[PlainBill]

Re: Tripping Sansui

Sansui Model SV 2918.
Works fine for a while.
Then goes on tripping and auto tuning, impossible to stop with remote or locals.
Customer doesn't want to spend a lot.
I replaced caps in power supply, to no avail.
I suspect the M/processor.
Must I give up?

Service manual.

I'd check the voltage regulators on the main board.

PlainBill

[burntfingers]

Re: Tripping Sansui

Thanks for the diagram. Appreciated.
Set goes erratic; works fine for sometime, but suddenly starts tripping and then stops but keeps repeating auto tuning through the three bands, impossible to stop until switched off.
I checked for dry joints carefully. None found.
No caps looking bad or too hot.
Power supply is a simple one.
The customer told me the set had this problem some six months ago, and has been working fine for all that time until now.
I don't want to spend much time with such nasty intermittent faults.
It could be a stock fault on this model, do you think?

[PlainBill]

Re: Tripping Sansui

Thanks for the diagram. Appreciated.
Set goes erratic; works fine for sometime, but suddenly starts tripping and then stops but keeps repeating auto tuning through the three bands, impossible to stop until switched off.
I checked for dry joints carefully. None found.
No caps looking bad or too hot.
Power supply is a simple one.
The customer told me the set had this problem some six months ago, and has been working fine for all that time until now.
I don't want to spend much time with such nasty intermittent faults.
It could be a stock fault on this model, do you think?

This REALLY sounds like a bad solder joint somewhere; a common problem with lead-free solder.

PlainBill

[burntfingers]

Re: Tripping Sansui

Maybe.
I will check it once again, but shaking the PCB causes no interference or any alteration - I've tried that trick already a couple of times.
I was going to waste a full can of quick freeze on some areas, but I decided not.
Since the customer is not keen on repairing it - no money - I will not spend much more time on it.
But I get very frustrated no to be able to find the culprit!