Technics 1200 speed warble at -0-, ideas?

[JonnyPaycheck]

Hello folks,

Recently my oldest 1200 - I bought it new perhaps 17 years ago - has started to have an issue whereby the speed/pitch "slips" while it's playing at -0- (regular speed). At 33 with the pitch set at -0- the strobe dots don't stay put - every 20 seconds or so the dot "slips" and there's an audible slow-down to the music. The problem seems less present at different speeds and at 45...

Is it the quartz locking speed circuit (I've read this elsewhere)? We've popped the unit open and cleaned it, but not much change (it sounded a little better for an hour or two). I've also tried a different platter, with no change.

Any help is appreciated.
Thanks- Jonny

[bozakdla]

There are two trim pots for pitch adjustment. One is under the pitch control circuit board (remove bottom cover) and is for adjusting the pitch slider to 0% at center. Set pitch control to 0, and adjust trim pot to 2.7kOhm.
Second trim pot is under the platter (remove black plastic cover), on drive circuit board. You'll see next to the motor two pots. The metal type, right side of motor, is the brake adjustment. The (usually) blue pot in the near upper right corner is pitch gain adjustment. You can place back the platter and adjust the trim through the hole. You set the pitch slider for 6, are the 6% dots pitching too slow or too fast? Turn off power and with screwdriver back in it and inch the pitch gain potentiometer forward if the dots were pitching slow or backward if they were pitching fast.

You might need a new pitch slider or the motor needs few drops of motor oil.

You can download the service manual from vinyl engine

[tommy1000]

The electrolytic capacitor in the power suppy has probebly dried out and needs to be replaced. I remember it uses only one and it is labeled less than 1000uF.