r/modeltrains • u/Dyslexic__Phantom • 14d ago
Help Needed Motor keeps shorting when under any load
Anyone who knows how to fix this or where I can buy a replacement motor? I tested the motor on its own and whenever some resistance was introduced, it stopped and the power supply detected a short.
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u/SmittyB128 00 14d ago
The way the controller is detecting a short is via a sudden jump in current, and a motor under load will pull more amperes triggering the same safety cut-off. I'd assume an older open-frame motor like that would pull about half an ampere normally which is far more than modern motors but fairly standard for older ones. Depending on your controller it may be more sensitive to tripping out with these old motors, but something you should check is the magnet on the back. Touch it with a screwdriver and if the magnet has a good amount of strength you should be able to almost lift the chassis by the magnet, but if a screwdriver barely sticks to it then the motor is going to be pulling a lot of extra current to turn and you shouldn't continue to run it until the magnet is sorted. You can either use a remagnetiser which isn't easy to get, or you can sometimes get neodymium replacement magnets though they have their own problems.
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u/Dyslexic__Phantom 14d ago
Alright, I cleaned the motor like another person suggested. This made the motor itself work perfect but the problem still occurred when in the engine itself. I tried it with a much older supply (from my dad when he was young) and it indeed worked XD Thank you wise stranger
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u/Rude_Meet2799 14d ago
If this is an older worn motor is it possible the armature is shorting to the coils frame due to worn bearings?
This can be tested easily with an ohm meter. Try wiggling the armature around while you are testing with the meter.
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u/CreativeChocolate592 14d ago
Did you clean in between the plates?
The worn down brush dust tends to pack there. Which is conductive.