Professor Motor Controller issue

[Zcarfan]

I have a question regarding my Professor Motor controller.
This is one of the base model home use controllers, I bought it used so it ma just be junk but want to see if I can fix it.

When Connected the car immediately runs at full speed. When the trigger is pulled the car will stop at some point in the sweep of the contacts, usually just as presser is applied. I have cleaned the contact surfaces and reassembled, that did not help it it.
This is a three wire controller, and I did hook it up right. I have used other controllers and they work fine with same or other cars, so it's the controller.
My track is Positive polarity, could this controller be set for negative?

Any ideas gang? or is this for the junk pile?
thanks.

[Zcarfan]

weird, I don't see tis on the main forum thread.

[mattb]

Mike that sounds like you have the wrong polarity for your track wiring. The electronic controllers are polarity sensitive. Commercial track wiring is positive polarity. Most home tracks unless re-wired are negative polarity. I think one of my racin buddies bought a used one from ebay and it was negative polarity. When hooked up at the commercial track it did exactly as your is doing. He didn't know there was a difference. It's not cost efficient to buy the new parts to change on over.

[SlotCat]

Great info thanks!

[jaws]

I have both Positive and Negative polarity Professor Motor controllers. When I looked at your pictures, it matches my Negative polarity controller. In the second picture, look at where the transistor is connected, to the "N" connection. This type of controller would be used with the "manufacturers" connection track. These are wired for Negative polarity.

Jim W

[Zcarfan]

I see that N, OK, well this is good info gang. I appreciate the info. anyone want to by a Negative Polarity controller?

[jaws]

If you keep trying to use it on the wrong polarity track, by trying to just reverse the black and red wires, Don't. You will take out, burn up, the main power transister. Ask me how I know, someone tried it, not me. I was able to get a new transistor from Professor Motor and the controller lived to see another race. I had a "P" or a "N" marked on each controller, so I could tell what track is was to be used on.

[SlotCat]

Great info, thanks!

[Zcarfan]

I definitely will not modify the controller, maybe just list it here or on eBay as a negative polarity controller.

[mattb]

Those are great controllers for guys with plastic tracks that haven't been converted to commercial track wiring.

[Zcarfan]

I 'm plastic track but I converted to Commercial track power. This was the first time I ran into a negative polarity controller.

[4424ever]

Put a polarity reversing switch in it cheap and easy I have 2 this way and NEVER had a problem

[War Eagle River]

Not sure if it’ll work on your controller? But a quick phone call to PM will tell you.
Link to reverse polarity switch.

https://www.professormotor.com/product-p/pmtr2036.htm

[Zcarfan]

I will check into that, thank you.

[Fast Co.]

Yep. Definitely sounds like you've got a negative polarity controller there.

[waaytoomuchintothis]

I have been doing business with Andy (Prof Motor), for a long time, practically from the very beginning of his business. I have had to call to get things explained to me, to get advice for installing things, and once for a repair to send to them. Always 100%, always friendly, and I even look forward to talking to the nice lady family member who answers the phone. I have to treasure anyone who's older than I am at this point! Call them. Make friends.

[mattb]

Does the polarity switch work on all of these controllers? Any instructions?

Andy's wife and son (Oliver) are pretty much the whole business now. Those 2 are pretty much the whole company.

[RichD]

For a start all set type plastic tracks with the exception of Policar come wired for negative polarity. Most commercial raceways and club type tracks as well as Policar tracks are wired for positive polarity. The difference is the direction that electricity will go through the controller. If you use a resistor based controller polarity is not an issue, but electronic controllers are almost always polarity sensitive. The older Professor Motor controllers used diodes and some of those had a switch to change the polarity. The newer Professor Motor controllers are transistorized and I do not recall ever seeing a model that was dual polarity. Some of the Difalco controllers have a dual polarity feature, there is no switch, you have to change a couple of wires.
Some electronic controllers only work with tracks that are wired for brakes. If a controller will work without a brake connection, but does not match the polarity of your track, there is a partial fix. Leave the red brake wire disconnected and swap the black and white wires, the controller will work normally, except that there will be no brakes.

[jaws]

So true, since I had two tracks in my basement, one Positive polarity and one Negative polarity, I did buy the Difalco Neo controller .I could use on either track by changing one wire.

[RichD]

It is fairly easy to change track polarity if you are not using the plug in wiring that comes with sets. Just reverse the two wires at the power supply and switch the two wires that connect to the track rails. My local commercial raceway had three tracks and one of those was the opposite polarity from the other two. I raced on an HO track that had some positive lanes and some negative lanes. I was using a Cidex Omni controller that works either way without having to do anything, but the one guy with an old Professor Motor diode controller was having problems.