Hey guys
I have a HO Athearn GP-38 that is only picking up power from the front truck. I have taken apart and looked at everything and stll cant find the problem. There is still contact from the metal clip to the truck clip and nothing… I am so stumped to what the problem could be??? I hope somebody might be able to help me with this one.
thanks
Jeremy
Remove that long silvery metal clip and solder wire in its place. Those metal bars corrode or get bent and lose contact with the trucks. Get some flexible, multi-stranded wire of 22 gauge or so, and solder a wire between each truck and the clip that is on top of the motor.
Very carefully remove the clip from the top of the motor before you solder to it to prevent heat damage to the motor brushes. There is a coil spring under one end of the clip that holds the brush in place, so be careful that you don’t lose the spring.
radio shack has a flat blade connector that can be soldered or crimped on some wire that is the same size as those metal springs. cut the flat metal springs shorter and slide the connectors on which will make better contact to the motor.
Power path on the trucks depending on polarity is left wheel to bearing to left truck frame to clip to motor to frame to right truck frame to bearing to right wheel. Both trucks work the same way. The wiring recommendations are good practice anyway for Athearn and may cure your problem but I’d still check the path with a spare piece of wire. We’re assuming that the truck rolls properly so there is no junk in the gears.
Since the front truck is working you can eliminate the motor to frame and return to truck path.
One last thought. Are the wheels in gauge? It’s possible the wheel halves are out of gauge and are shorting in the spur gear. If set to NMRA specification there wont be a short in this area.
One problem I’ve had on an Athearn loco (a DD40A) which was very similar to this was a slightly bent truck pivot - the bit of metal that the frame rests on was bent resulting in poor contact (and a loco that rocked from side to side), easily fixed with some careful pliers work but took a while to figure out. Hope this is of help!
A MISNOMER.
(You indicated that ONE truck was not picking up power)
If any pair of wheels is picking up current, the MOTOR turns.
IF one TRUCKS’s wheels are not turning, and the other’s ARE, it’s a Mechanical problem.
Check your ‘U’ joint’s.
One odd problem that I had like tthis, I found that the pivot surface where the truck rides on the frame had paint on it. If there is paint, there is no contact. That surface needs to be clean.
Im thinking that could be the problem, Thanks Roger. What would be the best thing to take the paint off??
Jeremy