WaynerN
Addicted Member
Once the motor is running, the vibration is gone. I think that to a lesser or greater degree, this happens to all split phase synchronous motors, not just to the AR (Heydon) motor (in the off position). Of course weird problems are hard to diagnose, so you have to eliminate the easy to blame sources first, like the contacts from headshell to arm, grounds and things like that. When those fail to be the cause, you have to get even weirder with ideas of what could be the cause.
I've had several instances where people were trying to eliminate hum, only to find out its source was mechanical by nature. Another good test that I just thought of would be to put a record on the table, not turning it on and set the stylus somewhere in the clean-out groove. Turn the volume up and see if you hear hum. If so, lift the stylus off the record and see if the hum seems to go away for the most part. This will pretty much prove that there are mechanics making their way to the platter (and maybe tonearm).
Wayner
I've had several instances where people were trying to eliminate hum, only to find out its source was mechanical by nature. Another good test that I just thought of would be to put a record on the table, not turning it on and set the stylus somewhere in the clean-out groove. Turn the volume up and see if you hear hum. If so, lift the stylus off the record and see if the hum seems to go away for the most part. This will pretty much prove that there are mechanics making their way to the platter (and maybe tonearm).
Wayner