2. analog
  3. 1243962141

Speed problems with Pro-Ject Debut III

Okay, I am new here, so be gentle. I have a problem: I recently moved to the US from Denmark, and brought my Debut III (purchased in Denmark) with me. I plugged in, and set it up, and noticed that the speed was much too slow. Aha, I thought, this is because in Denmark the mains voltage is 230 V, but in the US it is 120 V. So I bought a voltage transformer, and powered the turntable through that. It definitively helped, but now the records play slightly faster than they should. My questions are:

a) Why would this be? Could it be because the frequency is 50 Hz in Denmark and 60 Hz in the US?
b) Would buying a new power supply solve the problem?
c) If not, would buying a new motor solve the problem?
d) If not, would buying the speed box solve the problem?

An answer to any of these questions, or any other suggestion would be appreciated. Just don't tell me to buy a new turntable, because that's what I am trying to avoid. :-)
peterock
larryi
3,969 posts
 
Elizabeth is correct, the pulleys have a different diameter. The speed of an AC motor is determined by the frequency of the alternating current, not voltage. The converter only changes the 230v to 120v, but does not change the 50 hz to 60 hz frequency.
palasr
526 posts
 
I would agree, except the poster notes the speed was too slow when he first tried it - if anything, it should have been too fast, since a 50Hz pulley would have to be larger than a 60Hz pulley (given the differing line frequencies). He then states (after plugging into a transformer) that the deck ran too fast, which frankly makes no sense and leads me to believe something else is wrong in the power supply. Look at the specs on the website, the power supply output is 16VAC

As others have stated, contact Pro-ject.

-Richard
larryi
3,969 posts
 
The motor is, I believe, a 16v motor. So, it already has, built in, a means to step the 230v down. Just plugging it into a 120v socket would mean that the motor was probably receiving only half the voltage it needed, so it was running slow for that reason. The converter would have stepped the voltage back up, so that it would now run too fast because of the change in frequency coupled with the wrong sized pulley. A change in pulley is needed.
palasr
526 posts
 
I disagree - whether the motor runs at 16 volts or 160 volts, it's an AC motor (at least according to their website) - half the voltage isn't going to change anything - half the normal voltage might cause the motor to not start, but it's the FREQUENCY which determines how fast (or slow) an AC motor spins, not the voltage.

-Richard
larryi
3,969 posts
 
Palasr,

Yes, I am aware that it is a synchronous motor. I was trying to account for what the poster said. He is NOT using an outboard power supply for the motor, and I doubt that the built in circuitry regenerates AC and could be outputting the wrong frequency due to damage as you think might be the case. I would agree that if the built-in circuitry stepped the voltage down so low as to slow the motor down, the more likely event is that it would not turn at all, but, still I can't otherwise account for why the motor turned too slowly when first plugged in.

What happened at first, is somewhat irrelevant. The table is now running too fast, consistent with a change from 50Hz to 60Hz AC. The cheapest thing to try IS a change in pulley.
More to discover