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Technics SL-1300 Speed Flying

J

Joolian

Member
I should really learn to leave things alone..

I bought this SL-1300 used a few years ago, non working (speed was lurching). I bought a recap kit which included all new transistors for the board, although it was my first soldering job and I was intimidated by soldering transistors so I only changed out the caps except one on the back that seemed, at the time, daunting to get to. That did the trick and it was running probably 95% perfect, but there was still a bit of W/F that I could notice in some sections of songs. Between my picky ears and seeing the bag of transistors sitting on my shelf I decided I should finish the job in the hopes that I could dial it in perfectly. The remaining new parts went in, buttoned it up and got the platter spinning, and it's going a million miles an hour. External and internal pots don't affect the speed, neither does speed switch. I took photos of the board before and after and can confirm that nothing is touching where it shouldn't and pinouts are all correct. I pulled every transistor again to test them just in case, and they were all fine so they're back in. Just a few minutes ago I checked VR3 and VR4 and now have them set to 51mV and ~1.3V respectively (VR4 voltage set off recommendation from another thread), but no luck. I also cleaned all the pots and the selector switch. Is there something obvious I'm missing? Many thanks in advance!
 
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Servo open loop. Probably one of the transistors is backwards or has a different pin out to the original.
 
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The top two photos are before, last two are after. I can confirm that all new transistors (2SC1845, 2SA1015, 2SA1013, 2SC2383) are all ECB pinout, except TIP41C which is BCE.
 
There's a couple of parts that jump out.

Do you still have continuity between these points:

1772219126370.png

And these:

1772219249750.png
 
J1mbo said:
There's a couple of parts that jump out.

Do you still have continuity between these points:

View attachment 3709310

And these:

View attachment 3709314
Click to expand...
Yes to the first picture, no to the second. That was a pad I had lifted (but not ripped) when I did the capacitors a few years back and it had still worked. I tried to reflow it this time but then remembered about the pad so I didn’t wanna bother it too much. I’m gonna go ahead and scrape away the trace a bit & get a wire on there and see where that gets us.
 
J1mbo said:
Nice, what app is that?
Click to expand...
It’s just called Turntable Speed on the App Store, but there’s a few that all do the same thing. I’ve used it to dial in speed on this and a Sony belt drive. I usually grab a roll of duct tape and put it in the middle of the platter so I can get my phone as centered as possible.
 
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