QRX-7001 Demodulator board W. T. actual F?

tabpat

Member
I am working on my Sansui QRX-7001. One of the issues that its had for longer than I've owned it (around 20 years) is the CD-4 demodulator has never worked. The phono stage is OK, but it's never properly demodulated CD-4 albums. I can't remember if the light comes on or not, but it's been a dud. Anyway, I opened it up and quickly discovered that someone has been all through this thing. The capacitors are not original and they are of no-name quality. The soldering was horrific. But, there is an addition on the back of a transistor ( that coincides with where TR603 is marked on the other side) with a capacitor and three resistors - one of which has what looks to be a diode strapped across it. On the component side, there is a transistor that has two legs going through and the third leg is soldered onto a resistor (R610). There is no reference to this transistor being there in the schematic. I can't imagine it coming from the factory like this...but I also can't imagine the numb-nuts that did the capacitor replacement being smart enough to attempt a new circuit design. Anyone got a photo of theirs or any ideas???
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Looks like your board is a different version than mine. The traces are laid out differently, but seem to have all the same components. That appears to require yours to have C-606 on the underside. Plus mine has TR-04 where yours has it labeled TR-03. Yours (apparently) has TR-04 on the underside. I don't have a clear readable schematic. I wish I did because this 7001 I have had been butchered up too.
 
Please post the serial number for the database. Click on the link in my signature block.

- Pete
 
I'd have to get it back out but I'll try to get it. Oddly enough, the demodulator started working once it was all put back together and I gave up on it. "Working" is a loose term, however. It's terrible and slips in and out of CD-4 mode at the drop of a pin. It partly be a shielding issue as that's the only thing that changed - i.e. the metal cover...
 
Do you have a good clear schematic? If you do would it be possible for me to get a copy of it? The scan I have is not readable. I would really appreciate it.
 
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