Sx3700

Dearslayer

Dearslayer

Super Member
Picked this unit up this morning after work for $10.00. Wasn’t sure how many issues it had and it powered up at the guys place ( and what a disgusting place it was ). I went there because he had advertised a Marantz 2250B the day before for a decent price but I was late to that party. Anyway the 3700 is really dirty and has some rust. I removed the bottom cover when I got home and I swear some critter must have been laying roots there with the amount of crud and fluffy nesting material. Placed the unit on the DBT and the bulb dimmed but the relay is not clicking. Seems like all the displays are functional ( note : haven’t had time to really check anything as I’m on night shift and had to leave for work early) but no sound at all on any input. Dead silent. So when I do have time to get to it where might be the best place to start ? I assume checking for proper voltages etc? I’ve only ever restored ( Recapped) one other Pioneer SX950 before with the help from the awesome folks on this forum so I’m not well versed on my own. I hope to get some hand holding on how to proceed to bring this thing back to life if possible. I only bought it becuause of the price and because I might want to tinker with it just to see if I can make it work proper. Note in one of the photos below that there are two red wires on the PSB that look to be cut. Is this normal from the factory?
 

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I'm currently at work but just managed to download the SM and it looks like you are correct.
 

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Measure the DC voltage at test points 36,37,38 and 39. With your black test lead fastened to the metal chassis (ground)

Just checking for a possible shorted output transistor.
 
I may have to take some time to clean this first as I can't even see the numbers on any of the boards. I assume those test points may be buried on the bottom PCB and some disassembly may be involved to gain access ?
 

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I agree but this one needs lots of TLC and isn't in the greatest of shape however with some time and patience I hope I can make it look better than what it currently is.
 
IIRC those NSA units (Non switching amps) are really sensitive to DBT's and won't kick in the relay. If the DBT with a 75W bulb dims down (shorts test) then plug it in to the wall, junk speakers connected, Volume all the way down, and power it up. It may come on for you if there's nothing really wrong with it.
 
larryderouin said:
IIRC those NSA units (Non switching amps) are really sensitive to DBT's and won't kick in the relay. If the DBT with a 75W bulb dims down (shorts test) then plug it in to the wall, junk speakers connected, Volume all the way down, and power it up. It may come on for you if there's nothing really wrong with it.
Click to expand...


Thanks.... I’ll try that later tonight. Moving my GF’s son and the weather really sucks. Of course it would on moving day right.
 
Visual check of the PS trace side solder connections.
Some of those regular connections get hot an crusty.
PS voltages would be nice to see.
 
avionic said:
Measure the DC voltage at test points 36,37,38 and 39. With your black test lead fastened to the metal chassis (ground)

Just checking for a possible shorted output transistor.
Click to expand...

Checked the DCV on the bottom of the board ( it will be a bugger to disassemble to get at the test points from the top ) and I got a 0 reading at all 4 test points.
 
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