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Ground loop related to VPI SDS/motor at 45 rpm?

I'm having a problem with a ground loop that appears to be associated with the VPI SDS/motor that is present only when running at 45 rpm (not 33 1/3). Has anyone else experienced this? Did you solve it?
128x128ctlphd
philb7777
401 posts
 
If you haven't oiled your motor in a while, it might be time. Although I never had a hum or noise through my speakers, when I owed an Aries 3 the motor would hum ar 45rpm audibly when I placed my ears around 12 inches away from the motor. I fixed it by tightening the black plastic pully on the motor with an Allen wrench and oiled the motor with a couple of drops of VPI motor oil.
ctlphd's avatar
ctlphd OP
42 posts
 
I already tried the VPI motor oil. You just put a drop on the top of the spindle, right? I don't see where you tighten the black plastic pulley.
philb7777
401 posts
 
On the side of the pulley below where the belt attaches, on the side of the shaft you should see two small openings 180 degrees from each other. A small Allen wrench fits into both. Make re they are snug. It's how the plastic pulley is removed from the motor and gets loose over time.
ctlphd's avatar
ctlphd OP
42 posts
 
Is it on the black piece where the belt attaches? I don't see any small openings. There are two groves, either for the belt to fit in, and a flange just below them. The whole piece clamps down somehow on the motor's axle, but I don't wee any allen screws holding it on.
I also did some testing with my SDS. I changed the voltage from 102 to 96 and 108, and both of these voltages actually made the noise much worse.
philb7777
401 posts
 
If you have a stand-alone motor the are on the plastic flange that covers the motor's metal axle below the pulley.

Plug your motor into the wall outlet and remove he SDS from the system. If you have a pulley that has two different places to put the belt on (33 and 45). Try them both. If no noise, this probably isolates it to the SDS.

Unplug the SDS. Then plug it back in again and try the motor controlled by the SDS again. See if noise comes back.

If you have tried all these things including proper motor lubrication, then it may be time to call VPI and talk with Mike. If you have to call, make sure you have written a list of everything you have tried so it will help him quickly eliminate etiologies and treatments.

Good luck. It sucks when something goes haywire.
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