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Old 17th September 2003, 05:45 AM   #1
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Join Date: Oct 2001
Location: New Zealand
Question Speed control woes

I've recently acquired a Kenwood KD500 direct drive turntable. Unfortunately, it doesn't always turn the platter at a constant 33.3 RPM - so I get some major wow. The speed adjustment knobs are very fiddly, ie a tiny movement of them can (sometimes) produce a large change in rotation speed. HAving said this, the TT will usually hold a constant speed for a whole side of an LP.

Are the speed control circuits in these turntables particularly difficult to overhaul/fix?? Any help would be appreciated, as I know virtually nothing about these sort of circuits. My electronic tool kit really only consists of a multimeter and a soldering iron.

Cheers,
Joseph
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Old 17th September 2003, 05:53 AM   #2
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Join Date: Jan 2003
Location: piedmont
question for those who know, from one who doesn't: is this one of the reasons audiophiles seem to prefer belt-drive over direct-drive?

a thought which may help your tt: maybe your platter would benefit from some added mass, especially at the perimeter. seems to me the flywheel effect would tend to dampen speed variations. just a guess, anyway - not speaking from experience.

/andrew
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Old 17th September 2003, 06:03 AM   #3
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Hi Andrew,
Thanks for your suggestion, but the changes in speed are fairly large - too large for increased rotational inertia to obliterate.

I think the biggest advantage with belt drive is that less vibration is transferred from the motor to the turntable platter. Although good motors run very quietly, the pick-up cartridge is fundamentally designed to amplify vibrations.

I suppose that the sort of problem I'm having is just as likely to occur in belt-drives as it is in direct-drives.

Cheers,
Joseph.
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Old 17th September 2003, 06:40 AM   #4
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controls are dirty....first try and clean then replace if its a no go...basic dc servo circuit....no big deal
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