View Full Version : How to adjust speed on PL-12D TT?


mrGrosvenor
03-26-2005, 12:13 PM
Hi,

I just changed the belt on my Pioneer PL12 D turntable, now I noticed that the platter speed is a little too fast.. the belt was ordered for this model so it should be the right lenght...

I just played an old Tina Turner record (not my favourite music) and she sounded about 10 years younger :D

Can I do anything to adjust the speed? What could be wrong...? the speed is stabile just a little too fast.

Will be thankful for any advices.

regards/Grosvenor

Celt
03-26-2005, 12:34 PM
If it uses a DC motor, there should be a trim pot to regulate the speed mounted in the motor (look for a small hole on the bottom of the motor) or nearby on a pcb. You'll need a strobe disc and a neon lamp to make sure you have it right. The trim pots on the motors can be tricky. A small adjustment can affect the speed to a great degree. So expect some trial and error.

Nat
03-26-2005, 07:43 PM
I had a PL 12D lo these many years ago, and if I remember correctly, there is nothing much you can do about the speed. I don't think its a DC motor because I don't remember any circuitry associated with the motor, only a cap to get rid of turn on transients. I think you may have to simply wait until the belt loosens a bit, but using a dust bug might help, as might raising tracking force up a bit. Otherwise, remember that everyone ages -- wait a bit and Tina Turner will be her real age.

mrGrosvenor
03-27-2005, 02:15 AM
Hi,

Thanks for answers,

Yeah I looked inside and didnt find anything where I could adjust the speed, think its not possible on this model and motor...I probably just have to give it some time and play a lot of records :banana:


regards/Grosvenor

radiolee
03-28-2005, 01:39 AM
Make sure there's no crud on the motor pulley like old belt material.

Lee

Celt
03-28-2005, 08:48 AM
It's also possible if it's an AC non-synchronous motor that the speed is being affected by the voltage feed to your house. :scratch2:

danj
03-29-2005, 01:14 AM
The PL12D uses an AC-synchronous motor that is unaffected by normal voltage fluctuations. It also uses a tapered drive pulley. I suspect that the belt you've purchased is not the correct belt. It may be a bit wider that the belt it replaced which may make it not ride on the correct part of the motor pulley.

Belt width is important when the turntable uses a tapered pulley. It is unimportant only when the turntable uses a straight (non-tapered) pulley (seldom seen on an AC motor but common with DC motors) or if the platter speed is servo controlled, in which case the motor would not be a synchronous motor. A belt too narrow may make a platter run a bit slow. A belt too wide may make it run a bit fast.

A too tight belt would likely make the platter run a bit slow, if it affects speed. A too tight belt is bad for the motor bearings and can play hell with a suspended table such as a Thorens, AR, or Linn.

One more thing: make sure the motor mounts are true and even and that the motor pulley is vertical (parallel) to the platter bearing. Being out of line could make a platter run fast or slow, depending on the direction and degree of the misalignment.

However, a missized belt IS the most likely culprit. :thmbsp: