[sdiy] Very OT: direct drive turntable troubles...

[Trevor Page]

Hi all,

Sorry for being OT - suggest that any replies are off-list. I'm a bit stuck with a problem I have with a direct-drive turntable and there may be someone on this list who knows a thing or two about turntables and can help me!

It's a Toshiba turntable. Massive motor on the underside (why do they stick washing machine motors on these things anway? :-). Problem is - the motor just seems to take ages to get to the correct speed (well a few seconds) and if you even touch it very, *very* slightly - it will slow, and needs a small time to get to speed again. Seems that there are no gears inside (like with some DD turntables) because you can effortlessly stop the platter or even spin it in the opposite direction while the motor is running. Seems that the motor does not have the torque it should have. 

Another odd thing is the strobe lamp on the side. This lamp actually dims when the platter is speeding up and then instantly brightens when the platter has reached the correct speed. The stroble lamp therefore instantly dims slightly when you touch the platter lightly. This even occurs when I touch the record that has been placed upon a slipmat. 

Both the strobe lamp and motor are AC driven from a mains transformer inside. Seems that when the motor is spinning up, it draws excess current from the transformer resulting in the voltage drop that causes the strobe lamp to dim. This doesn't seem right: maybe the transformer is a dud? Where should I go from here?

The deck is totally usable if you just want to play records - but no good for mixing, which is what I'm using it for. 

Could the speed control circuit be to blame at all here? 

Many thanks in advance for any help on this matter!

~ Trev




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