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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
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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