Frankenstein Pioneer SX 737

rossm

AK Subscriber
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Halloween is coming up so how about a Frankenstein project ? I hope to make one good unit from the 2, plus will still need to build a case.

What’s the odds of finding 2 Pioneer SX 737’s at the dump ? I really felt sorry for the abused guys so I drug them home. Some folks might have passed but I like a challenge.

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Luckily both units passed the dim bulb test and the relay also clicked.

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What a trooper even in this state the lights are on and it wants to rock !!

The bottom unit, the one labeled A was much cleaner inside so I decided to go with that chassis.

Between the 2 I should have 1 set of nice knobs and switch’s
So far the score is

Receiver A
had broken tuner string
Bent function shaft
Bent record selector shaft
Bent power switch shaft
Bad fm mute switch
Bent power switch

Receiver B
Was filthy inside
Was missing speaker terminals
Bent volume shaft
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Receiver A is on the right
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I have the front off receiver B to harvest some switches.


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The front cleaned up pretty nice.

This with be my 1st pioneer of this vintage so I will likely be back to ask questions
Thanks for reading
 
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Bent shafts can be repaired. I've done many.

That face may also be repairable if handled with care. The glass/plastic is going to be the toughest part.
 
I would try lexan for the replacement glass. The original glass is hard to find and trying to have a glass shop drill three holes in new glass is virtually impossible.
 
Selector switch installed, was pretty happy I didn’t melt any insulation
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Pics of damaged switches, you think they can be repaired?
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Crap, just placed a mouser order and now I need 4.7 uf audio caps for the tone section

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Haven’t looked at schematic yet, I am assuming only the yellow caps are audio ?
 
The orange caps are usually low leakage types. Are any bipolar?
Thanks for the hint!
Did some searching here and found they’re indeed low leakage caps and not bipolar, the neg leg is marked. Found a post by markthefixer where he recommends the kl series, which I had in stock.
The old caps were way off spec almost double the 4.7uf. So I was able to recap and replace the transistors on the ctl amp board
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if your game to drill your own glass the chinese sell diamond drills cheap on ebay. if you have a drill press be more than happy to explain. the glass is 3mm thick dont toss the old one as with either lexan or glass it will be handy as a pattern. if its like a 939 theres a plastic bushing in the push button holes. it halves for removal its got some rubber glue holding it together. soak the bushed end in lacquer thinner for an hour or so it WONT eat the bushings but will soften the glue
 
Yeah, Good glass cutters are hard to find these days. When I was young (and day gigs harder to find) I worked in a Hardware store and learned to cut glass. Cutting holes in it can be done, but like restoring this stuff, it's an acquired skill. But they're out there. Just not easily found at a Home Despot or Lowe's.
 
"glass hole drills" on ebay a 15 piece set for 9 bucks and 1 $ shipping and they work really well. im sure there are higher quality available but how many holes do we need to drill in GLASS???
 
I got some diamond drill bits (more like a small hole saw) from Amazon and used my drill press. I watched some YT videos to see how it was done. I was able to start the hole okay, but it chipped out when it came through and I had the glass clamped tightly against a piece of wood. I tried starting the hole on one side and flipping the glass over to finish, but it chipped out even worse when the drill broke through. And I went slooooow.

Did I use the wrong kind of bit?
 
i had the same problem on a 939 glass. but all i had was a hand held drill. i chalked it up to a "no drill press" issue but that set used a plastic insert behind the knob and the ragged edge was covered by it.it very well could also be an issue with rpm as well as feed pressure or even a combination.. in your case it might be worth while to see if the bit runs true to the press table...just a thought mind you. if i had a lot of them to do and a drill press i might be tempted to experiment a bit.the cut glasses here were only 25 piso's each @ 50 cents.i bought 5.the first one i broke the next four were reasonable and i used the best one.since then i made one for a qx949 and that was EASY.the three hole configuration was the most difficult. but if it was easy i guess everyone would be doing it!.... and whats the fun in that?
 
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I think you want to get those tantalum caps (C1, C2, C23, C24) out of there too.
Hi cuda440,
Are you referring to the blue caps ? Good catch, I think they are electrolytic, they have + side marked
Need to update my order
Thanks
 
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