Re: PM 3520 motor control
Response To:
Re: PM 3520 motor control ()

John K Jordan
If the VFD has failed you should either see nothing or an error message on the small screen. If it looks normal it is likely something in the low-voltage control circuit. (I think it's 10v on the 3520) Doc Green has a wiring diagram and trouble shooting info on his web site.

Troubleshooting a switch is a matter of checking it's continuity.

If by continuity testing the switch turns out to be faulty you might be able to fix it. I had one quit on a Jet 1642 which I think is the same.

I disassembled the switch (don't drop and lose a tiny steel ball bearing) and found that dust had somehow gotten inside. I cleaned it out and lubed with dielectric grease. Before installing I wrapped the switch in plastic wrap to try to seal it from dust. It's worked fine since then, over 15 years.

The contacts on my switch were fine but I've fixed switches on other equipment by cleaning and polishing the contacts, again lubricating with a very light film of dielectric grease.

As long as some internal part is not broken most switches can be fixed. Those assembled with rivets instead of screws will need to have the rivets drilled to get them apart.


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