Sansui AU-217 repair

[MiauwMaster]

did you replace the 5 pin transistors with matched pairs of transistors ?

I couldn't order matched pairs but I ordered a whole bunch of the KSA992's and matched them myself as closely as possible. I don't know how reliable my meter is though. I replaced both channels and left is working brilliantly, so I tend to trust my meter.

EDIT: they are within 3 of eachother, so I'd say that's close enough

 

[petehall347]

ok .best check resistor values that connect to those pairs .also feedback resistors if they look good .
maybe just check all resistors .
i check in circuit first comparing channel to channel ..power off of course . if any look wacky lift one leg and check again ..if ok i start to look into why the reading is way off .

 

[MiauwMaster]

DONE! So easy, one of the resistors had a bad solderjoint and wasn't connected. Both channels now reading around 10mV DC, which is quite acceptable. Now all I need to do is replace the Bias Current Adjustment pots as they're the horrible cheap white ones and they're going bad. Was thinking of ordering Bourns 3296W-1-501LF, but they seem quite big and there isn't a lot of space, so looking for something multi-turn but compact.

 

[Soundphile]

Good that you found the problem. The AU217 is a rather nice amp !!!

 

[MiauwMaster]

Really happy with the repair. Ordered the Bourns 3296W-1-501LF and ill just make them fit.

Thanks very much to all who helped and offered suggestions!

Next up; my Rotel RA-930BX

 

[MiauwMaster]

Damn thanks again to all! Replaced the crappy trimpots with the Bourns and after all the work and care the DC readings are as follows:

Left: +-3.5mV
Right: Between +1mV and -0.6mV

I'm a happy camper!

 

[petehall347]

well done .