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Old 24th Nov 2018, 11:45 am   #3
Lucien Nunes
Rest in Peace
 
Join Date: Apr 2008
Location: London, UK.
Posts: 2,508
Default Re: Help Pls = Grundig TK64 Motor Not running

It is a long time since I had one of these, and the schematic in your post isn't clear enough to read, but to the best of my recollection the motor operation is quite conventional. It is a 'permanent split capacitor' type, where the capacitor is permanently in circuit to shift the phase of the current through one winding. I.e. the capacitor is a 'run' cap, not a 'start' cap.

A supply is taken from a tapping on the mains transformer primary via the relay contacts, into one winding of the motor ('left' lead). The other end of that winding returns to neutral ('right' lead). The third terminal is fed from one or the others via the capacitor, to provide a phase-shifted current through the second winding. Which side the capacitor connects to will depend on the specifics. On the TM schematic it looks like there are alternatives, depending on something (motor version, frequency etc). The capacitor value may also be dependent on frequency, e.g if there is a large cap and a small one, the frequency selector probably parallels them for 50Hz.

With the middle lead disconnected and the power off, I would test the resistance from left lead to right, and middle to right, to confirm that there are at least two circuits through the motor. That is not conclusive but if either is showing open circuit, there is definitely a winding fault. I would make sure that the transformer tap voltage (is it 120?) is reaching the two outer leads with the power on, and then briefly connect a substitute cap (value equal to larger original cap) from the middle lead to one of the outers. If it does not turn, try the other. If you can read and confirm the markings on the TM schematic outer leads that might help understand which of the outer leads is correct.

Note that as per your TK40 readings, the voltage at the capacitor winding can be in excess of supply voltage. For consistency, if you are taking voltage readings, it's convenient for them to be with respect to neutral / right lead. So the left lead will always be at the voltage present on the transformer tap / relay contacts, and the middle lead is the one of interest.
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