F-G Servo Control

Discussion in 'The Projects Forum' started by dhoneycutt, Mar 24, 2013.

  1. dhoneycutt

    Thread Starter New Member

    Jan 1, 2011
    9
    0
    Hello,
    I have a Technics SL-D303 turntable that has a problem. Hoping that you might be able to give me a bit of advice. The turntable has very low torque, will hold constant speed if you help the turntable get moving, but it just does not have the power to pull up the speed. I have checked everything in the drive circuit and found nothing defective. The control IC gets really hot. Any thoughts?
    Thank you,
    David
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    (Assuming it is a DC motor) it could be a faulty DC motor or faulty controller IC.

    How many wires come from the motor? Just 2, or does it have an "end cap" with 4 wires coming from the end cap (ie does the motor have a speed sensor or is it just a 2-wire DC motor?).

    I used to replace a lot of DC turntable motors, and with "very low torque" as the symptom it was usually the motor, not the driver.
     
  3. dhoneycutt

    Thread Starter New Member

    Jan 1, 2011
    9
    0
    Thanks for the info... How did you diagnose the motor to be defective? My motor is of course a flat pancake motor with 4-wires to the stator windings, 4-wires to the Hall Effect sensors, and 2-wires to the FG feedback.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    For DC motors I connect a DC variable power supply and check the torque. :)

    In your case if it is a flatpack 3 phase pancake motor, it is very unlikely the motor is faulty, they only have a few turns per winding and run very cool. The hall sensors are also quite reliable, and a failed hall sensor would not generally make the driver IC run hot.

    Since you mentioned originally the driver IC was "getting really hot" then it looks likely the IC is toast. ;)
     
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