Spindle only spins in reverse (1988 Triac)

[Matt]

Hi All

I have a old 1988 Triac pnc3. My problem is the spindle will only spin in reverse!

You select forwards, give it a speed and enter. Then relay 3 (spindle reverse) energises, followed by the relay on the spindle control board, and the spindle starts to turn, in reverse!

It will now only spin in reverse although I have had it spinning forward.

Its the North east electronics board with the Brown & Prestal spindle control. 3 Phase motor.

Does anyone have any experience of the problem or any suggestions?

[Denford Admin]

Not sure of the electronics here, but I'm guessing faulty relay contacts if its all worked OK before and nothing else has changed.

The spindle drive will possibly have a single input for CW/CCW select.
The reverse relay will pull this input up or down to (5/24??? Volts DC or Ground??) - it could be that the function of this relay is actually NOT reverse when energised

Check for faulty or broken wire to the spindle drive or a dirty contact on the reverse relay - if the relay can be "made" by pushing a little button, then do an ohms test across the contact going to the drive.

Can you pull the relay out and try it again ?

[Mr Magoo]

Have you had the spindle motor disconnected recently?

It could be just that the spindle motor wires have got crossed over. Try swapping two of the phases at the motor.

This will definatly make it run the other way which will at least get you going.

[Matt]

I have fixed it!!

It turned out to be a very temperamental relay after all.

Thanks for the suggestions.