Sansui B2101 - Bias voltage gone crazy 10V++ and something missing on board.

Steven Sze

New Member
To owners of Sansui B2101,

I need your kind help to snap a clear photo of the bottom of board 4619(the one with the heatsink).. Im not sure why is one part of the circuit being cut.

About a year ago I bought this Sansui Pre and Power B/C 2101 for about $300. Thought I had a good deal, end up the power amp B2101 is faulty.. protection light stays on.. (long story short - buyer dissappears).

Opened up saw its has bèen recapped with the lousiest capacitor ever...some china crap. I spend another couple of hundred to buy new capacitors. Basically replaced all the capacitors except for the 4 big 10,000 uf ones.

After recapping still the same problem protection light on all the time. The Bias adjustment stays at about +- 10V! when in service manual stated it should be about +- 5mV!

I've no technical back ground so the most I can only do is recap. so I put it a side for almost a year..in between i sent to 2 techinican.. one doesnt want to do after checking and another took more than 3 months and did nothing. So I took back the amp chuck it in the storeroom.

Screenshot_20171001-235106.jpg
And Couple of months ago I took the amp out and I found out that 1 rectifier diode is missing from each board :/ i replace with 1N160 (is this ok?)

Screenshot_20171001-235047.jpg
Anyway I just realised that below the power amp board 4619 ( the one with the sink) one of the circuit was cut.. I need someone with same amp to help me to take a photo of the bottom.Also I need a full photo to see where the 3 wires from PSU goes onto the 4619.


I need to check to see if everything is in order before I can proceed to next step.

Please help.. tq
 
Repost this in the Sansui forum - you will get more help there.

Just to clarify - are you trying to adjust the bias, or the DC offset? Are you getting around 10V on the bias, or the DC offset?
 
if that diode is kd8 .it should be same as kd9 .
10v bias is a lot .. maybe an emitter resistor is open or high ohms
 
DSC04141.JPG This board seems to be a little different from yours. But the factory jumper wire is installed connecting the two traces.
 
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