Pioneer SX-780 overhaul

gonzothegreat

Super Member
After many delays and unforeseen schedule conflicts, the first of my SX-780s is on the bench.

It powers up and the output relays engage but the left channel is very weak. If I turn up the volume I can barely hear it and it scarcely moves the meters. Cosmetically, the wood case is in VG shape but the faceplate has a couple black pitted spots near the tuner knob.

I opened her up and the first thing I noticed was a thick coat of ancient flux coating the pcb. Since the first thing I check is for bad solder joints, I took her outside and washed the boards with flux remover (taking care that the runoff didn't dribble onto switches or the tuner section). Fortunately, the solder job was pretty clean aside from some marginal looking joints from the last tech's output module replacement job.

Next I took my small schematics and had them blown up at the local copy shop. I think I may have overdone it but I can always fold it up like a AAA Roadmap to show the relevant stage.

The next stage will be to track down the cause of the weak channel. Then its time to fire up the vacuum desoldering gun and start replacing caps.
 
Nothing to stain - the 780 has a vinyl-veneer finish. You can either recover with PE vinyl or go snazzy with real wood veneers...I'd love to see a 780 done in Sapele.

TP
 
B3Nut said:
Nothing to stain - the 780 has a vinyl-veneer finish. You can either recover with PE vinyl or go snazzy with real wood veneers...I'd love to see a 780 done in Sapele.

TP

I think someone did a "Oak Veneer" project not too long ago on a SX Series... looked real sharp... I'll see if I can find the link. :yes:

Here it is... Link...

Great job again Franksta !!! :thmbsp:
 
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