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Turntable speed slow with quartz lock

I have an 30 year old Harman Kardon T-60 turntable that runs slow (according to strobe) while in quartz lock mode. I would chalk it up to a bad unit except my friend's unit does exactly the same thing. The coincidence is too great for me to ignore. Any ideas on how 2 units that use a quartz referenced oscillator could both run slow. I have recapped the power supply on mine with no effect.
heyraz

Showing 2 responses by kirkus

kirkus
502 posts
 
Two questions - what strobe are you using for reference, and how slow are they running?
kirkus
502 posts
 
If it's like i.e. the Micro DD decks, the built-in strobe is sync'd to the mains frequency, whereas the internal oscillator is not. So if it's by a very small amount, and you're using a mains-frequency strobe . . . It could be the mains that's ever so slightly off, not the turntable.

But if it's way off, then probably the TT is indeed at fault. Crystals do indeed drift with age, and sometimes surrounding circuit components can affect their accuracy as well.
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