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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
noromance's avatar
noromance
9,769 posts
 
Use a micro screwdriver and turn *very* gently. This is not an engine.
mjcmt's avatar
mjcmt
710 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
23 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.
rff000 OP
23 posts
 
Since writing that two years ago I got my TD 203 turntable back from the shop long ago. It was still a little off so I gave it another try, turning the screws as gently as I could. The main problem was that each tiny turn made a relatively big change in the RPM, but I eventually got it as close as I could and I left it alone since then. If it had an easier adjustment I'd check it and readjust often, but now I don't want to even try since it's working OK and my warranty is long over. Not a bad sounding TT. I wish my digital sounded as good. Luckily I live near a used vinyl shop with very good selections on the one dollar table.
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