Direct-drive, Hall-effect motor has slow start-up

Thread Starter

13hm13

Joined Jun 1, 2023
67
What is it?
CD spindle motor from a 1987 Technics SL-P120 CD player.

ISSUE:
Slow startup. Sometimes, a gentle nudge by finger is required to commence rotation. Some CDs spin slowly at first, and may take up to 10 sec to spin up. Then, all is normal. Can't really pin point at pattern.

QUERY:
What's the culprit?
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SOME ATTEMPTS AT REPAIR:
I did replace the three BP 47uF electro caps (the origs from 1987 tested fine wrt to ESR and loss) as well as carefully and lightly lube bearing surfaces. I also cleaned, with dry q-tip, many surfaces. Replaced some eletro caps in the mains PSU section on main PCB. (The orig electros tested fine with very low ESR and low loss).

After all that ... not much difference in solving issue.

I wonder if the permanent magnet rotor has not weakened since 1987 ????

These are actual pictures, I took myself, of the motor in question.



above: Bottom of PCB motor.



above: PCB stator and other components of Hall-effect DD motor.




above: Perm. magnet rotor.; shaft on spindle.
 
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