START/STOP FUNCTION UNSTABLE
If you notice that the start stop switch has no effect or only works
sometimes, there are important things to check before replacing chips.
Always check that power supplies are working properly IC101 Pin 20 is 20V and
IC201 Pin 10 is 9.4V
- Voltmeter, one lead on ground, one lead on IC201 pin 19 . With power
on. voltmeter should read 7V and 0V when switch is held down.
- Power on, press start and give platter a push. if it starts
rotating, stop and make the following measurements. Voltmeter, one lead on
ground, check voltage on IC 101 pins 2, 1, and 24. These should be 1.8V stop,
If any one of these are way off, turn power off and measure
resistance from left side of R101 to IC101 pins 2, 1 and 24. you should read 22
ohm for each. If any one reads open circuit, the motor coil assembly is
- Voltmeter one lead on ground, one lead on IC101 pin 22. 0.2V stop,
3-5V start. Also check on IC201 pin 21. If this is wrong IC201 defective.
- If good this far, IC101 is likely defective
Naturally, you should have service skills before tackling a job like
Return To Service Tips Page