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View Full Version : PM3520B fwd/rev switch issue


Ricc Havens
05-20-2024, 4:05 PM
My fwd/rev switch is acting up. Runs in forward but not reverse. I have unplugged and let the VFD reset but still n reverse. Right now I am assuming it's an issue with the toggle switch and not the VFD. I have done forum searches and google searches and not having any luck. Searches come up with results on the red on/off switch and the potentiometer. Even the old Mustard Monster forums that were converted to documents on Doc Green's site only speak of the pot and on/off switch or the VFD. Nothing about the fwd/rev swtich.

Even a google search for 3520b replacement forward reverse switch comes up primarily with results for the option remote on/off switch. Anyone have any suggestions on a replacement switch?

Thanks!
Sam Force
05-20-2024, 5:52 PM
It is just a simple switch, I believe they are called double throw center off. Any electrical supply house should have one or you could even buy one at AutoZone or any automotive store like Napa. 520183

This is the basic wiring involved for my PM
Richard Coers
05-20-2024, 8:16 PM
Lathe switches filling with sawdust is a super common problem. Secondly, the manufacturers use cheap switches.
Ricc Havens
05-21-2024, 8:53 AM
It is just a simple switch, I believe they are called double throw center off. Any electrical supply house should have one or you could even buy one at AutoZone or any automotive store like Napa. 520183

This is the basic wiring involved for my PM

Sam -- Thanks! I may do that. But would prefer the switch it came with. The fwd/rev switch is not a three position switch with a center off position. From what I have found out it's a SPDT with only on/on switch positions - no center off. I know it's just me being picky but it's what I am used to on the lathe - just flipping it back and forth. Adding the center off stop would be an annoyance (a minor one but annoying) :)

Richard -- I should have mentioned in my post. I did blow it out an used spray contact cleaner with no success. yes, I agree that it may be a cheap switch. That's why I was looking to see if anyone had other options.
Sam Force
05-21-2024, 9:23 AM
Ricc, you are correct, my bad the center off switch is from another project I was working on. The diagram I posted earlier is correct for the PM forward-reverse switch