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QX949A SQ/Mode/Switches

GeezerB

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Picked up a QX949A that was worked over badly, an abandoned project. But it was practically free so I could not resist.
I worked through all of the shoddy repairs, broken traces, poor soldering, masking tape, and bad jumpers. It sounds really nice and got the scope working, which is a cool feature.
I was not getting phono or AUX on the SQ setting (though it did work on CD4) so I recapped that board to get rid of all of the troublesome little blue Sanyo caps and fix some bad soldering and jumpers.

Then I was able to confirm that I had a good clean signal coming into and out of the SQ board.

I was not able to understand the schematic and the path that the signal takes after that switch (S2).... looks like it goes to the mode switch. I cleaned that switch a couple times but same result. I don't know enough to chalk it up to a bad switch.

I've got a lot to learn and this quad unit wiring is challenging me greatly.
 
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Breakthrough... the bad channel on the SQ board. That post was poorly soldered by previous owner, touching it with the probe would make it behave and conduct, but left on its own in normal state, was not making connection. Reflowed and that is acting normally now.

Should have caught it first time around.
 
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