Turntable speed problem

It all depends on the type of deck. Direct Drive models are more complex as the motor has it's own control circuit where any part can go wrong producing a slower speed.

Belt drive ones are easier to diagnose. The belt being a bit weak can cause it. If you need to replace it make a note of how it fits.
Oil and dirt, grease can cause problems on both types of deck. Grease can build up and cause it to slow up. Sometimes it might need Oil and Grease to be applied!!

There are speed pre-sets, but if the speed slowing is on all speeds then avoid touching them. On belt drive decks a bad motor can cause problems. But it is not common unless the deck is old.
A good test is the movement of the platter by hand. If it feels hard to push it around by hand, or stops very quickly after a good push by hand, then there is something causing drag.

It depends which type of turntable it is. If a belt one then change the belt, make certain you make a note of how the belt fits before removing it.

Direct drive turntables are more difficult. As it could be any number of faulty parts that cause it.
A build up of grease or dirt in any type of deck can slow the speed down.

A faulty motor on both types of deck will also cause it.

All decks have a speed adjuster. Sometimes hidden underneath the turntable, often covered with a sticky label. Some even have two one for 45 and the other for 33. If they are not there they can be found inside it. Sometimes on the power board. Trace the wires from the motor to find it. On some decks it's on the motor itself.

You do have to be careful if the deck is a direct drive model. The speed on these is controlled by a whole variety of devices, any which can cause it to speed up when faulty. But even on a belt driven deck, the power supply to the motor can be to much, caused by a faulty power supply.

If it is one of those turntables with the speed pre-sets on the underside, yes it is tricky to do. What I do is get one of those chairs where the seat pops out just leaving the frame. I mount the deck on the chair and thus having access to the pre-set while the deck plays. The only other way is to do it one small turn a time, turning it over then back to play while testing each time. But it's a very slow method!! If you haven't go a chair with a seat that removes, you could try constructing something out of boxes or something, which would be quicker than the other method.

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HI,
After long years of use the electrolytic capacitors in the circuitry will get slightly change its value. If so it can affect the speed of the turntable. Its better to replace all the electrolytic capacitors in the turntable's electronic circuit board. It will not coast a lot for all the capacitors. Will only come around $3 or $4. .
OK

If it's a belt driven deck it needs a new belt.

If I can understand you right, the turntable is running fast. I don't think you need a new motor, generally the deck will run slow if the motor is knackered (or not at all). What you need to do is remove the platter, you will find a horseshoe bracket holding it on at the spindle (it may be covered up so you wil have to remove the cover part often a silver disc). The most likely cause will be the rubber idler tyre being worn damaged etc or out of place. There could be grease dirt or something else causing the problem.

Check for grease on the platter or anywhere in the mechanism. Sometimes somebody has messed around with the speed preset, there might be two. You could try adjusting them. Sometimes they are found on the underside of the turntable, covered up, or they will be on the PC board of the deck.

Fader has to be ether cleaned or replaced if cleaning did not work.

you need to replace the Pitch controls. I'm presuming it is a sliding pitch control. Use the Red start stop lights that reflect on the rotating wheel. put the pitch in center 0. does one row of the dots on the wheel stay completely still.now just turn it up op down a bit until it starts to move the dots slightly. now watch the dots now while there moving. Do they fluctuate they should be smoothe. do this on both decks to find out which one is fluctuating.