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Problem with Thorens TD-203 speed adjustment screws

My Thorens TD-203 was rotating around 2% too fast (33.9 RPM) a few months ago, so I tried to adjust the little adjustment screw on the bottom of the table. I wound up getting no speed change but apparently ruining the screw. I just brought it in to the store's service department because it's still under warranty and they said the potentiometer was broken and the motor has to be replaced. I saw some videos that showed the adjustment done "live"--with the platter rotating. I tried to adjust the screw with the power off and by tipping the table up. I later found some messages that said this adjustment is very tricky and breaking the potentiometer is common.

Is there any advice about this other than never attempt a speed adjustment? Do you have to do it in real time or can you turn the screw a little bit and measure RPM after that? I used an RPM app on my phone and that seemed to work OK.
rff000
rff000 OP
7 posts
 
Actually, they were very nice and said that they'd order a new factory motor and I would not have to pay. It would be covered under the warranty. I told them the truth that I really don't know if it was damaged to start with or if I caused it. I do know that the speed was not on specs originally, which was why I attempted the adjustment in the first place. My questions are about how I can avoid this issue in the future, once the warranty ends six months from now. Turning a screw should not be such a hassle. I've installed spark plugs in cars with no trouble and a turntable should be a lot easier!
noromance's avatar
noromance
1,780 posts
 
Use a micro screwdriver and turn *very* gently. This is not an engine.
mjcmt's avatar
mjcmt
479 posts
 
rff000 said "I used an RPM app on my phone and that seemed to work OK."

I never found the RPM app accurate. I’d get different readings depending how far I placed the phone from the plater spindle.
rff000 OP
7 posts
 
I read that the trick with those apps is to place an object around the spindle (like a roll of tape or plastic cup) and center the phone on that. When I did that I got a constant 33.9, but when I just laid it on the platter I was getting different speeds as it rotated. The 33.9 correlated with the mismatch in my digital recordings compared to the timings on record jackets. My digitals were always around 2% faster than the timings. I knew I needed a little less speed, but I didn’t know I’d mess up the screw and pot when I attempted the adjustment. Now it’s in the shop for a warranty replacement. Live and learn.
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