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Need help! Thorens TD 125 MK1 speed problem

V

Vinylyte

New Member
I recently upgraded/ replaced all caps on the board, recalibrated speed pots, and cleaned and polished speed switch gold contacts. Before I did this, all speeds worked and were steady though I had to adjust 45 every time I used it, there was always slow start up and occasionally 33 wouldn’t start at all until shifting the speed switch a few times.

Now 33 works flawlessly, 45 is waaaaay slow and rumbles. 16 is also slow. My settings are 8V at 45, 5V at 33, and 3.2 at 16. I think “0” pot is seeing too much voltage. It’s overloaded on MV. Also, the speed switch arcs a little when going to 45. When going to 16, the motor stops for a split second, then engages.

I did swap power cables to a neutral/positive two prong plug. It’s a generic from Lowe’s so it has a ground prong, but not a third prong. So one wide prong and one skinny.
 
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If mine ever quits I guess it will be a SL 1300G or a SL 1200 GAE for me depending on what the state of my entertainment savings fund. Plus, where I can get the best deal. If I had the room I would get another VPI, but space is at a premium. A Clear Audio Ovation with the TT5 arm would be my preferred choice. But we are talking tons of money for that choice.
 
Sometimes the speed board/switch contacts need a good cleaning - and sometimes the potentiometers need to be replaced even though they may seem to be operating ok. Othertimes it will be a random resistor.

It would be a good idea to trace the 45 line and replace everything in that circuit as it seems to be misbehaving but maybe start with the potentiometers as calibrating new ones is always a bit nicer anyway.
 
I’ll check all the values for the resistors powered off and see if some are out of whack. I wish someone had a kit that replaced everything, not just caps. It’s a pain to hunt all the individual pieces down. I’d be fine with paying extra for someone else to do that part of the work.

How do I check if the pots are in spec? They each have around 20ish volts to them and allow adjustments to their respective allowances. At 45rpm, the blue and black motor wires are very unsteady. Voltage bounces all over the place and transfers that to the motor as vibration. It spins, but erratically.

I’m not sure I could get the switch any cleaner than it currently is.
 
twiiii said:
If mine ever quits I guess it will be a SL 1300G or a SL 1200 GAE for me depending on what the state of my entertainment savings fund. Plus, where I can get the best deal. If I had the room I would get another VPI, but space is at a premium. A Clear Audio Ovation with the TT5 arm would be my preferred choice. But we are talking tons of money for that choice.
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I picked up the Thorens about 13 years ago at an estate sale for $45. It didn’t work so I replaced the belt. Then I had perfection for about 12 3/4 years. I love this thing. I’ve completely rebuilt the tone arm (SME 3009 improved) and changed the oil about 12 times for the shaft. Until the switch issues arrived, and I recapped it, I never had a single issue. I wish now I would have just cleaned it and left it alone.
 
To check the potentiometers you pull them out and check them with the voltmeter. I forget which pins but one set of pins will give you the current value respective of the wiper and one will give you the range.

Digikey and Mouser are great places for the potentiometers - just make sure you get the right size phyisically (which is escaping me at the moment)
 
I forgot to say I bought one of the first the first TD 125's to come to Texas back in the early 70;s or maybe late 60's. She runs great today. I use her with a Rabco Liner arm, after starting with a Grado, and 4 different SME's. three 9 inch and a 12 inch. I lubricate her once a year and clean all the switches once a year. Belts last between 3 and 5 years. "C" Battery for the Rabco arm two to three years.
 
They’re really very wonderful tables. I couldn’t believe the step up in quality over a 160 and understood what top of the line vintage was like when I first worked on the 125.
 
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