# Professor Motor Electronic Controller Advice



## SDMedanic (Apr 21, 2011)

Over the weekend a PM electronic controller started to misbehave. Found this on line and it should resolve the problems as the issues are identical to the ones described here. 

http://www.slotcarouthouse.com/viewtopic.php?f=10&t=876


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## swamibob (Jan 20, 2009)

Steve;

I've never used a Professor Motor controller for HO racing. I just went from a resistor controller right up to a Bruce Theisen controller, because I race with him.  I was thinking about building one of yours, do you still give advice on the build process?

Tom


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## SDMedanic (Apr 21, 2011)

The PM advice was for a racer at the test and tune that had a PM that was acting up. Hopefully he found it and repaired his controller.


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## Ratwagon64 (Dec 23, 2011)

Steve, Was Joe having problems with his controller? I repaired 1 of them and he has a second 1 that I picked up. Might just need servicing. Pat


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## SDMedanic (Apr 21, 2011)

Pat

Joe was having problems. IMO the wiper contact gap between brake and first band is bridged. It happens with this type of controller. It needs to be cleaned. On my Ruddock I dug a hole between these two points with a cutoff disk to make the bridge almost impossible to form. It still will but it takes longer.


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## Ratwagon64 (Dec 23, 2011)

Steve, That is a problem with those controllers. I replaced the power transitor and added the brake pot on Joe's controller. I also cleaned it and used the PTFE synthetic grease. Pat


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## SDMedanic (Apr 21, 2011)

Now that I know what the problem is we might be able to do a better fix. We need to widen the gap between the brake band and the first power band. As I said I did that on my Ruddock with a cutoff disk. Once that is done we can get the brakes working again. Unfortunately, with any controller of that design cleaning the board is something that has to be done on a regular basis.


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## Ratwagon64 (Dec 23, 2011)

Steve. I did the work back in February. All the controller had was full on or off. I will look into opening the gap next time I see Joe. Also did you fill the gap with any insulating epoxy. I have some that we use on motors and generators. Pat


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## SDMedanic (Apr 21, 2011)

I did not fill the gap as the problem is grunge from the trigger bridging the gap. My best results were obtained when I made the gap as wide and as deep as possible.


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