Mister Disc/Soundburger spinning too fast

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yubm12
Posts: 4
Joined: 18 May 2018 23:33

Mister Disc/Soundburger spinning too fast

Post by yubm12 » 06 Aug 2018 00:57

Hey all hoping this is an easy fix. I have used Mister Disc and have been working on getting back into fighting form. When I got it, it was spinning too slow, so I replaced the belts and while I was trying to adjust the pots to dial it in, I realized one of them was broken. So I had to replace the pots. I did and now I can’t get it below 39rpm/48 rpm. I used Piher 5k pots recommended on this site. Any ideas why it’s still too fast?

Coffee Phil
vinyl addict
vinyl addict
United States of America
Posts: 5770
Joined: 20 Sep 2008 08:22
Location: California

Re: Mister Disc/Soundburger spinning too fast

Post by Coffee Phil » 06 Aug 2018 23:14

Hi Yubm12,

Since it was too slow and after replacing the belts it is now too fast, I suspect that a former owner changed the values of R401 and R404 in an attempt to speed it up.

The manual is here: https://www.vinylengine.com/library/aud ... rger.shtml

R401 is for 45 RPM and R404 is for 33 1/3 RPM. Larger values give higher speed. That may seem counter-intuitive as it is backwards from controllers which compare a tach signal to RC time constants. This controller requires no tach feedback but rather generates a negative resistance to partly cancel the winding resistance of the motor. It actually works better than you might expect.

Let us know what you find.

Phil

yubm12 wrote:Hey all hoping this is an easy fix. I have used Mister Disc and have been working on getting back into fighting form. When I got it, it was spinning too slow, so I replaced the belts and while I was trying to adjust the pots to dial it in, I realized one of them was broken. So I had to replace the pots. I did and now I can’t get it below 39rpm/48 rpm. I used Piher 5k pots recommended on this site. Any ideas why it’s still too fast?

Viabobinc
Posts: 1
Joined: 01 Sep 2018 03:09

Re: Mister Disc/Soundburger spinning too fast

Post by Viabobinc » 01 Sep 2018 04:12

Hi folks! First post. I am trying to repair one myself and have this same problem and in the diagram blowup I can't identify the screws for the tone adjustment. Prior owner must have fiddled them enough one night that they came out because they are definitely missing. I can't find a comparable screw either. Any recommendations?

If you really wanna scratch your head, like I am, I played a 33 single of Live and Let Die from Apple that includes an insert, and it played maybe at 32. Then a larger 12" LP must have been going 45. Only thing I can think of is the insert caused sufficient drag.

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