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Need a DOLBY NR selector switch for a SANSUI QRX 9001

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rawmacias

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Jun 2, 2012
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378
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Hello, I am in need of a "working" DOLBY NR selector switch. I hope someone can help on this. I was told the quad ability runs through this switch . Unfortunately , I purchased one only to find when installed , it too did not work. That was a waste of a lot of money and time.
 
Hello, I am in need of a "working" DOLBY NR selector switch. I hope someone can help on this. I was told the quad ability runs through this switch . Unfortunately , I purchased one only to find when installed , it too did not work. That was a waste of a lot of money and time.

Can you describe the exact symptoms you are experiencing?
 
I bought the unit with only the two front channels working. I took the unit to a repair shop . The shop owner said the Dolby NR switch was bad and that the front and back channels ran through the switch. So I went online and found a switch that was supposed to be in working order. The shop owner installed the switch and found that it too was not working right. He could only get the two front channels to work. He said that he might be able to bypass the switch and make it a quad only receiver. Thus I need a working switch . I already owe a lot of man hours and still back to square one.
 
Wow. One in a million? There are other much more likely things to cause that, and to see two switches seem to cause the same symptom seems improbable. I know you have no suspicion of the servicer, but having been there, I can't help but wonder if he flexed the dolby assembly and heard the channels pop back in. I thought I had a bad switch in a 9090 before I knew about through-board connection problems. I did have one bad switch in a 9090 but it was a current-carrying terminal that supplied power to dial lamps only when tuner was selected.

Switches of all types do go bad if they've seen a lot of use though. I've just never used a dolby switch, just leave it off, except to work it around when I operate all switches looking for noisy contacts. Maybe that's the problem, it is a switch that rarely gets used so any oxidation never gets scraped off. You did work all the switches to see if there was any sign of life from the rear channels, right? I think there's also a separate protection relay for Front and Rear but I'd have to dig through a schematic.

I'm interested to hear the outcome.

-john
 
My immediate thought was those through-board connections. Those are notorious for causing problems.

Did anybody test either of the switches? Shouldn't be difficult to if they're on the bench. Either you have good connectivity or you don't. It at least eliminates (or confirms) that as being the culprit.
 
I just had a look at the user manual & schematic on https://www.hifiengine.com/manual_library/sansui/qrx-9001.shtml

It has Dolby FM, OFF, Play & record for the Dolby switch. So I'm assuming in OFF it didn't work.

If it was simply the switch it would work in another position, so turn the Sansui to the FM tuner, select the Dolby FM mode on the switch, and put it into a Quad mode and something ought to come out of all 4 channels, even if its noise. If nothing comes out of the rear channels its more likely its something else.
 
Yeah , I have a lot of faith in the shop owner knowing what he is doing. I have done business with him for the last twenty years . And he restores and collects vintage Sansui equipt . So I am sure he would know about needing to check connections due to age. What I really need is a switch that has been tested and found to be in good order.
 
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