[ctw]

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

Cal

[Don Pearce[_3_]]

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

Could be almost anything. Does it have connectors on the back that
allow you to plug in, say, a CD player? If so try and see if the
problem is still there. If it is, it is certainly the amplifier to
blame. You will need a schematic to get any deeper than that.

d

[chuck]

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

[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

[Mark Zacharias]

"Phread" wrote in message
...
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


These also had problems with bad (solder) feedthrough connections on the
Dolby switch board.

Mark Z.