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Technics SL-220 speed slowly increases

Posted: 08 Oct 2019 14:31
by chiwahua
Hello VE fellows,

I have a Technics SL-220 (belt drive) that I have cleaned the 4 pots but doesn't seem to keep the speed.

I adjust it at 33.3 rpm and then it slowly increase. After 15 minutes the speed is 33.8 rpm.

Cleaning the pots was my go-to but I've done it and it still accelerates. I also applied sewing machine oil on the spindle bearing and on the motor bearing without benefits..

The belt is aged (and a too long, should be 23.6 but it is 24.5), and this is what I now suspect. I'll try a new one when I get it but maybe there's something else...

Thanks for your input.

Re: Technics SL-220 speed slowly increases

Posted: 08 Oct 2019 14:58
by lenjack
Did you clean the pots internally, from underneath? If not, that's what's needed, after the belt change. If you don't know how, let us know.

Re: Technics SL-220 speed slowly increases

Posted: 09 Oct 2019 13:16
by chiwahua
lenjack wrote:
08 Oct 2019 14:58
Did you clean the pots internally, from underneath? If not, that's what's needed, after the belt change. If you don't know how, let us know.
Well I sprayed inside the little openings a few times but I didn't split open the pots. The two that are controlled with knobs, I could find my way to open them but the two that you adjust with a tiny flat head screwdriver seem delicate...! These small ones don't seem serviceable to me..

One thing I could do would be to just replace the pots with the ones I could cannibalize from an SL-210. Maybe it's easier than a potentiometer open surgery. I don't know.