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Why will my PM3520B only work in reverse?

D

David Valencia

Joined
Apr 23, 2010
Messages
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Location
Minneapolis, MN
I was sanding on my PM3520B, using both forward and reverse, and the forward direction stopped working. Reverse still works fine. Anyone have an idea as to why?
 
First thing I'd check its to see that the switch is actually working. It's a simple SPDT switch that should be easy to replace if necessary.
 
I would check for loose wires first. Make sure the machine is unplugged before touching any wiring.
 
I tried that and there are no loose wires. When it is in reverse the phase converter has a light on for reverse and run but when the switch is in the fwd position only the fwd light on the phase converter is on... It did this once before but started working again after I unplugged it for a minute. Maybe I will just have to wait until the service line for WMH tool opens on Monday.
 
Wondering if dust has either filled the switch or if the dust has burnt the one side of the switch up. Had that happen on my Jet in which I put a reversing switch on. Dust in the switch had arced enough that it burnt the leaf and pins in the switch.
 
David Valencia said:
I tried that and there are no loose wires. When it is in reverse the phase converter has a light on for reverse and run but when the switch is in the fwd position only the fwd light on the phase converter is on... It did this once before but started working again after I unplugged it for a minute. Maybe I will just have to wait until the service line for WMH tool opens on Monday.
Click to expand...

The marvel of the magic box. I agree with the call to the experts.

If your switch has made contact to command the converter to reverse (which it is apparently acknowledging), it's not the likely culprit. Not that you shouldn't clean it once in a while, but save some of that low pressure air to dust off the converter boards too. They work on low volts which are easily diverted by dirt. A natural-bristle brush should loosen anything packed, so it can be washed away.
 
It is the switch despite being nearly dust free and registering on he phase converter. I have to wiggle it a little and it will start working It's not ideal, but it allowed me to turn over the weekend:D A single call to PM and a new switch is on the way. Thanks for the suggestions!
 
Good news. I recall the bad old days when I used to trace schematics for hours before I learned the "shake and sniff" troubleshooting stage should precede the metering. The new surface-mount components are so small that they probably don't give off much of a smell, though.
 
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