Sansui QS-800 Volume Control

[Wagonmaster_91]

The volume control on one of my Sansui QS-800s has gone bad (mechanically) and locked up. Potentiometers can do that when they get old. The control is a bit unique as it is 4 potentiometers (one for each channel) ganged one behind the other on one pole. Anyone out there know where I can find a replacement or have a dead QS-800, QS-800A or QS-500 they would be willing to part out? (I am sure the same control is also used in the Sansui QS-800A and more common QS-500 models.)

 

[Doug G.]

What happens if you flood it with spray cleaner/lube?

Doug

 

[DuncanS]

The volume control on one of my Sansui QS-800s has gone bad (mechanically) and locked up. Potentiometers can do that when they get old. The control is a bit unique as it is 4 potentiometers (one for each channel) ganged one behind the other on one pole. Anyone out there know where I can find a replacement or have a dead QS-800, QS-800A or QS-500 they would be willing to part out? (I am sure the same control is also used in the Sansui QS-800A and more common QS-500 models.)

I don't know if you can get the value or size you want, you do need to select the 'right' resistance taper see http://www.alps.com/prod/info/E/PDF/Potentiometer/TAPER.PDF and https://en.wikipedia.org/wiki/Potentiometer

So you'll need to check with the manufacturer which of their tapers matches the log taper used on most volume controls, there appears to be no standard.

ALPS do a Quad-ganged potentiometer for Pro Audio kit http://www.alps.com/prod/info/E/HTML/Potentiometer/RotaryPotentiometers/RK501/RK50114A0001.html

ALPHA do a Quad ganged unit http://www.alphapotentiometers.net/html/8mm_pot_4.html

 

[Circular Vibes]

If the above advice doesn't pan out, most pots are disassembleable. If you are mechanically inclined, have the time and space, and can not find an alternative, you might try disassembly with digital photos to remember how to reassemble, and to post here. You may be able to find spare elements and put them in the old shells.

 

[Wagonmaster_91]

Doug, one or more of the pots has an obvious mechanical problem that cleaner can't fix. It started scraping and then finally locked up. Thanks anyway.

DuncanS, thanks for the info. I'll check that website. I believe that quad ganged unit in your last link is only a single channel control but uses 4 resisters (or taps along one resister) to achieve its process and that is what they are calling "quad".

CV, I may do that. Pots aren't that complicated, but from the feel of it I think there is permanent damage to at least one of the pots. If it is not the resister ring, I might be able to use parts from another pot. Thanks.

 

[bigbillquad]

Hi. Wagonmaster_91
Having part`s trouble I thought of a person that might be able to help if things don't turn out right for you, he is a QQ member or was or still is & He Restore`s Sansui Units he might be able to supply the parts or give some ideas to get you going, his name is ( Jim Showker Email-qrxrestore.com or his Web site - www.qrxrestore.com ).
Bill...

Doug, one or more of the pots has an obvious mechanical problem that cleaner can't fix. It started scraping and then finally locked up. Thanks anyway.

DuncanS, thanks for the info. I'll check that website. I believe that quad ganged unit in your last link is only a single channel control but uses 4 resisters (or taps along one resister) to achieve its process and that is what they are calling "quad".

CV, I may do that. Pots aren't that complicated, but from the feel of it I think there is permanent damage to at least one of the pots. If it is not the resister ring, I might be able to use parts from another pot. Thanks.

 

[Doug G.]

OK, the only reason I suggested flooding the pots is because, sometimes, the shaft/bushings can get so dried out or the old lube can get so stiff that they freeze and won't turn. Applying control cleaner/lube liberally, will often free them back up.

Doug

 

[Bonzodog]

OK, the only reason I suggested flooding the pots is because, sometimes, the shaft/bushings can get so dried out or the old lube can get so stiff that they freeze and won't turn. Applying control cleaner/lube liberally, will often free them back up.

Doug

Agree totally.

That usually works
.
But sometimes at work we have to remove the pot and soak it in denatured alcohol. Loosens up the dried out lube so we can apply fresh lube and bring a 70 year pot back to life.

This is on rare professional recording equipment. Langevin, Fairchild, Lang, etc.

 

[Bonzodog]

Also, more than once, we have had knobs that, over time, with people pushing on them while turning, have been driven into the front panel.

The friction between the knob and the panel stops them from turning.

People think the part is broken, but just re-positioning the knob fixes the problem.

 

[surteess]

look on Ebay - there are quite a few "Quad parts" for sale -

http://www.ebay.com/itm/PIONEER-QA-...hash=item2577e52a0a:m:mSoGRwZuA3IdELQwplCx0MQ