Music Hall mmf-7 spins faster


I have a Music Hall mmf-7 turntable (EAR 834P phono preamp) and it spins faster than normal. I bought a new motor and a new belt from Roy Hall, but it didn't change a thing. I borrowed my friends' motor (he has an mmf-7.1): no change... I even bought a Pro-Ject Speed Box (on Roy Hall's advice): it still spins faster. My cartridge is a Sumiko Blackbird. I really don't know what much else to do: any ideas? Did someone run into this problem?

I am desperate.
lrmellon
One more additional bit of information. The multi-meter reads 18 volts at the motor's power adapter output.

Question: is there any kind of belt inside the motor that might be causing the problem (because it's dilated or something)?. It's definitely not the AC voltage.

Still desperate.
Lrmellon -- Are you reading the 18 volts while the motor is connected and running (in which case it is probably much too high), or when the motor is not connected to the power adapter or is not running (in which case it might be ok, and the best way to tell is to compare the measurement with your friend's table, under the same conditions)?

Re your second question, I have no knowledge of what might be inside the motor assembly, but my guess would be "no."

Regards,
-- Al
Thanks, Al.

I have that reading when the power adapter is connected, but with the motor not running. I have the same with the mmf-7.1.

I don't get what's wrong; there must be a rational explanation (and a solution), I'm sure.
Just grasping at straws here, but have you at any point taken your complete turntable to another location, such as your friend's house, and tried it there? Although it would seem unlikely, perhaps there is something grossly wrong with your ac power, either the frequency being too high, or unusually large amounts of harmonic distortion. If, as I suspect, the turntable's rotational speed is synchronized to the power line frequency, perhaps that could be the explanation.

Also, you've undoubtedly checked this, but just to be sure, could there be an accumulation of some sort of detritus around the rim of the small pulley, that would in effect increase its diameter?

Regards,
-- Al
As a matter of fact, I did: no change.

The small pulley is clean, the larger one too (as I have tried to correct that speed problem with a Pro-Ject Speed Box II).

I am expecting another motor from Music Hall, but at this rate, I doubt that will change a thing. We'll see...