Wacky VFD controller on PM 3520
Hal Taylor
The short story - I blew out the controller with air, and it's been working fine since.
The long story - I had put this question to WC before with no solutions. About perhaps a year ago I plugged in my 3520a and pulled the switch on and immediately the speed maxed out even though the speed controller was turned "down". Luckily, at the time, what was mounted on the lathe stayed on. Had it been a big, unbalanced piece - disaster. After unplugging then replugging with the switch off, the controller read about 1700. I punched the reset a number of times, and the controller finally "reset" to 000. I then began to check the controller readout before pulling the switch on. This has happened a number of times since. A few days ago - same thing, but this time, no matter what I did to the controller - punching all the buttons numerous times, unplugging, repeating punching the reset, etc., no resolution. Readout was about 1700 - no error codes. (I figured I would need to replace the VFD for the second time.). Finally, in desperation I removed the controller front and blew out the insides. Some dust did blow out. Result - been working fine so far. I have not seen this problem addressed before, but for what it's worth, blowing out the controller on a malfunctioning one may solve the problem.
