Sansui 5000A low level static

[jdg123]

Some time back I got a Sansui 5000A in trade...it had one blown channel. I thought I might part it out...

I opened it up and wow, you really have to admire the 5000a build quality. I fell in love, so much so that I went all out and cleaned every single solder joint and recapped every electrolytic after replacing the output transistors. I redid the transistors on the F-6013 board. I tried to give it the love it warrants. It really sings now...but...

There is this low level "static" kind of noise I can't trace. It is on all mode selections and does not get louder with the music. I'm (only) guessing it is noisy diodes but I'm really not qualified to even make a guess. How about you? ;-)


If you don't care to venture a guess how about a fact. If I go in and change out the diodes on the F-1042 "diode stack" board and maybe F-1041 "protector" boards...what diode should I use?

 

[slimecity]

Does the noise happen on just one, or both channels?

If just one, and it doesnt change with volume - then I would assume (if all switches pots etc have been properly cleaned) that this could be a failing small signal transistor in the power amp section (as the noise doesnt change with the volume control).

If the noise is in both channels however, again assuming all your controls switches etc are clean, I woud be looking at testing transistors in the power supply.

 

[jdg123]

Nail on the head slimecity! I replaced two 2sc458 on the 1041 protector board (with KSC1845) and it is much quieter now.

THANKS!

 

[slimecity]

I replaced two 2sc458 on the 1041 protector board (with KSC1845) and it is much quieter now

Good stuff - I should have said if you have any 458's replace them outright!

 

[jdg123]

I see a couple in the phono section, yikes! And one in the muting circuit...ironic. I'll eradicate them.

It is a lovely receiver. Nothing sounds quite like it. Did someone say it was "single ended, cap coupled"? I know about the cap coupling. I can't identify and have never heard of a single ended transistor amp...