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Help! Need Info on Sansui Receiver

C

Chris F.

Jan 1, 1970
0
Made the mistake of selling a Sansui (model AU-2900) receiver on Ebay
without properly testing it for operation. Fortunately, I noticed the
problem (severe distortion) before billing the buyer, so no harm has been
done.
I had received the unit from another shop, the output and preamp
transistors were all messed up and it took some effort to get them back in
order. Or so I thought. At this point I can't find anything else wrong, and
I'm stuck until I can find a schematic (or at least, a detailed parts list).
If anyone out there has one, I would be extremely grateful if you could
E-mail it to me. (if over 200k, please send it to chrisatsnowfortzone.com
(change "at" to @ ))
Kind of hard to explain the problem, but I'll try; only the loud sounds
seem to come through and they're very distorted. There are two A798 (NTE 43,
dual PNP) transistors in the preamp; injecting a signal to one of the
collectors yields perfect sound at the speakers. However, injecting it to
one of the bases (as the amp is designed) yields the same distorted results.
Sound improves if I increase the bias voltage to the common emitters of the
A798's, but not enough to consider satisfactory (also makes the transistors
overheat). At this point I would guess the output / preamp transistors to be
in the wrong order, or perhaps the wrong parts are installed, and this is
where I need the schematic.
Any help would be greatly appreciated.
 
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