Sony SQD-2020 trying to fix!

[nubba111]

Hey everyone, and thanks in advance for any help!

Sony SQD-2020.
When in 2 channel stereo sounds fine
Sending stereo to the fronts and backs (2->4) sounds fine too!
However, going to SQ channels start acting very intermittent, sounds goes in and out... playing sq vinyl by the way (Miles Bitches Brew)

 

[quadsearcher]

Disclaimer: I don't have one of those and never saw inside. I don't know what might be the proper (only?) way to clean the switches.

Looking at a picture of it, my guess would be the System switches need to be cleaned. What does sound fine eliminates a bunch of stuff. Maybe the former owner only switched between 2 and 2->4. Switches are somewhat self cleaning and I often find the rarely-used switches to cause problems.

 

[nubba111]

Thanks for the suggestion... I had a similar thought. Just to make sure, I am hooking this up in an acceptable way, correct?

Turntable>preamp>sony sqd2020 in> sqd2020 front and rear outs > rca front and surround ins on a yamaha amp

as as side note, I also own a sony sqd-2050 and this set up seems to work fine with it (used PM test lp)

 

[Rich DM]

I've just acquired one of these from an eBay auction. The sound was generally poor particularly in SQ. I'd read that on the circuit board there are about 50 pins that connect one side to the other - its a 2 sided PCB. As advised by others I re-soldered all the pins. A google search for the 2020 and solder pins should help, here's an example https://www.quadraphonicquad.com/forums/index.php?threads/sony-sqd-2020.16811/ .
That did the trick, mostly, but with classical SQ LPs the rear channels do seem to have odd incidents of emphasis and de-emphasis. I have been doing further research and have come across a phenomenon know as logic 'pumping' where the logic decoder seems to be overcome by the complications of the music. Other SQ music sounds OK with the SQ setting. So no definitive diagnosis yet. The 2050, I think, has lower channel separation and thus not as aggressive logic circuits.
I'm going to re-solder again in case I missed one. Not sure how to clean the switches and pots as I can't see where to squirt any switch cleaner (isopropyl alcohol should do it - just don't smoke at the same time), as they all appear to be sealed.
I'm using a separate back amplifier.
Good luck. Let us now how you get on and if you come across any other solution.
Hope that helps.