Atlas HO GP38

Model Railroader General Discussion (Model Railroader)
1

I am new to the forum and fairly new to the hobby. I have a couple of Atlas HO GP38’s with the dual-mode DCC decoders. I am running them on DC right now. One of them quit running today. I am getting voltage to the motor, I checked it on the buss bars on the motor. This makes me think the motor is bad. I have not checked resistance on the motor yet, what kind of resistance reading should I expect?

Thanks for you help and this forum. I have learned a lot just by reading the forum.

2

Although doubtful, You may want to check to see if the pin may have worked loose on the board that has it set to DC control.

3

I checked that and it was OK. I am getting track voltage to the board and on the motor itself.

Thanks

4

To eliminate the motor as the problem,remove the motor wires from the decoder and run power straight to the motor.There may be something on the decoder with an open circuit.You can do this with alligator clips or strips of wire.It is very rare for an Atlas motor to go bad.Dan

5

I would suspect the decoder has gone bad rather than the motor. As suggested by dancarm, bypass the decoder and see if the locomotive runs. If it does, you need to contact Atlas about a replacement decoder, which should be under warranty.

6

Just for giggles, you may want to swap the decoder of the defective unit with one from a good unit. This is let you know immediately where the problem lies.

As a side note, this is only the second time I have heard of a problem with an Atlas HO GP38. The other being a problem I had with a decoder board as somehow it managed to burn a hole in the two IC chips yet it still ran in DC mode! Atlas replaced the decoder at no charge. You may want to give them a call tomorrow.

7

Thanks, that’s a good idea. I will try that this afternoon. I already have alligator clips rigged on a set of leads where I was checking out some other loco’s for a friend. That’s what got me interested in the hobby, checking out a friend’s trains.

But would I be getting track voltage (14 vdc at full throttle) on the motor leads if the decorder was bad?

8

Yes, it’s possible that you could get 14 Volts DC but with too low an Amperage to turn the motor. Another thing to check before you do burn up the motor is to turn one of the flywheels by hand and insure that the mechanism has not locked up for some reason.

Although a very rare occurrence, you may indeed have a bad motor. In that case, I would definitely contact Atlas and get it replaced by them with a totally different engine under their warranty program.

9

Charles make a good point. You might have a piece of ballast or some other debris that may have worked its way into the gears of a truck preventing the gears from turning. It is unlikely but certainly possible.

BC

10

I had already checked to be sure the drive train was not locked up, but it did feel tight. I hooked the motor up directly isolated from the decorder. It did not run, I spun the flywheel and the motor started running but not near full speed. I will look at the gears next.

On another problem, what type grease is recomended for the gear box? I am working on one for someone else and they had sprayed WD-40 in the gearbox. Now it is all over the bottom of the loco. I am in the process of cleaning it up but need to know what type grease to put back.

Again, thanks for all the help. This is a great board.

11

Definately check the gears for a crack or debris.If you know how,pop off the worm covers and remove the worm and shaft and try the motor again.If it runs you have a bind in the mechanism. Also check for a loose brush or cap on the motor.As for the other locomotive,GET THE WD40 OUT OF THE GEARBOX.It will eventually eat the plastic.For lube I use Labelle grease and oil.Make sure they are plastic compatible and use sparingly.Hope this helps,Dan

12

Thanks, I will inspect the gears. I also thought about uncoupling the gearboxes from the motor (if it easy) and try it.

You are right about the WD40. And it is all over the underneath of the train. I guess it is all over his track also.

Thanks

13

No problem.Welcome to the forum and the hobby.Dan

14

Thanks for the welcome, this is one of the most active forums I have ever been involved with.

Turns out it was the motor. I took it out and hooked it up to the controller and it does not run. When I spin it, at one spot in the rotation I can feel the magnetic field kick in for a second. When I check the resistance it reads open, when I rotate it and hit the spot it will read resistance for a second. I am talking with Atlas now.

15

The Labelle grease that dancarm mentions is the 106 w/ teflon. You may have to disassemble the trucks to clean out all the WD-40, other than dishwashing detergent and a toothbrush, I don’t know of any other solvent that won’t harm the plastic. Good luck on the GP-38.
Bob K.