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Turtnables - Direct Drive
Speed stability problems
Question:©Technics SL-D2 - Direct drive turntable with front panel speed control adjustment potentiometer: "The speed of my SL-D3 is all over the place. do you repair them? can I since i'm pretty handy?"
Answer: Yes, I can repair, even if the problem is complicated. If you want to do it yourself here quick instructions meant to convey the concept, but please: all at your own risk only! Nor do I guarantee that it will work for you, nor that you may not destroy the turtnable in the process, to "unrepairable", if not skilled or experienced enough to perform this type of electronics work. And to mention: Should you wish to ship the turtnable in for repair after having worked on it yourself, then likely a repair will be considerably more, if I have to repair / undo other problems that did not exist before starting to work on it.
Any work to be performd only when the unit is unplugged form power - danger of electrocution - exposed wiring. Remove the rubber mat form the patter, then the platter itself by pulling it up with a sudden jolt to release. Careful with the tone arm: secure it, remove head shell, etc. Then turn the entire unit upside down to remove the bottom panel. Pay attention to which spring goes into which of the feet, so that the original springs are back at their original position when putting the unit back together.
One bottom panel open you will see: There are electronics boards, the motor and part of the mechancs that make one assembly.The whole assembly is fastened with about 10 screws, that all will have to come out, so that the assebly can be lited out and turned over (leave all wiring undisturbed), The parts to work on are at the under side.
Possibly take photos before starting to disaseble, and at every step, so that there is a record on how to put it back together after the work was performed. The work to be performed: The switch that selects the speeds and the speed adjustment potentiometer need to be restored with quality contact cleaner. To gain access to the potentiometer: remove the black thumbwheel by unscrewing the tiny screw that holds it in place, also lift out the brown insutalor washer from the potentiometer shaft, so that the potentiometer will be open. Carefully spray quality contact cleaner (suitable for potentiomers!) into the inside of the potentiometer and speed selector switch (if not available: WD-40 may do). Careful not to get contact cleaner into other parts of the turntable as this may upset the lubrication that may be present there. Then: operate both the switch and potentiometer quite a few times to work the contact cleaner into it (power off at all times until the unit is put together again!). That type of work has fixed contact issues that were existant in the poterntiometer and switch that likely caused speed related iregulary problems, as experienced with most direct drive turtnables of that age.
When all properly put together again and working again, set the front panel speed adjustment potentiometer to it's exact center position and leave it there. Carefully calibrate the speed pre-set trimmers (labled with 33 and 45 on the electronics board - some D2/D3 allow acess form the top - underneath the platter) with a screw driver for accurate speed for each: 33 + 45. This calibration is usually perofrmed after the turtnable was continuously running for at least 15-20minutes, so that all circuitry stabilized.
Anyhting else that still may not be working will need expert electronics repair.
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