[Phread[_2_]]

chuck wrote:
On Thu, 27 Oct 2011 17:43:15 +0000, ctw
wrote:


Anyone out that advising me regarding repair a vintage sansui 9090db
receiver.
One channel has lower output (wattage) than the other.

Cal


Back in the day when I worked on these beauties, they came in with
intermittent tape monitor switches, low pass filter switches, mode
switches etc., etc.. I would spray Deoxit 5 into these switches and
work them. It might take care of the issue. If not , it is probably
caused by dried out electrolytics in the preamp / tone circuits. Chuck

+1

I fixed a 9090db a month or two ago. Both channels coming and going
and half the display out. Oxidized switch contacts and open caps, and a
shorted zener in a power supply feeding part of the display. IIRC there
were bad solder joints at the filament pins on the frequency display tube.
You'll have to improvise on the dial & display lamps if you don't want to
pay a fortune for them. The schematic is on the 'net if you look, and for
free if you look as hard as I did.

Note the 9090db has nothing in common with the 9090 which is an 8080
with a little higher rail voltage for a few more watts.

Equipment this old needs a full electrolytic cap job to be reliable for more
than the next month or two. Seriously. Plus, it will improve the sound. A
lot. Actually, a whole lot if you use good caps like 105 degree low Z caps
intended for switching power supply applications.

Good luck!

Fred