IM Tunnel motor up and quit- any troubleshooting suggestions?

[squirrelhunter]

I have an IM tunnel motor that has generally run well for me, although I have only run it occasionally. The other day I pulled it out to run it a bit and it wouldn't move at all. The lights would come on, but that's it. Pulled off the shell, and everything looked ok, nothing out of place or missing. I'm at a loss as to what to do or what is wrong.

I haven't run it nearly enough to burn up the motor- does anyone have any suggestions for anything I should try to do to test it or fix it?

[peteski]

I'm not familiar with that specific model but general advice for troubleshooting is to divide the problematic devices into separate parts and troubleshoot each one separately.

Is it DC or DCC?

If DCC, take the decoder out of the equation and troubleshoot the loco as a  DC model.

If DC (and headlights work), did you verify that there is a positive contact between the motor contact strips and the light board?  First try moving the motor armature by hand - does it spen freely in both directions? If yes, remove the motor and test if it works by itself. Either power it with a throttle or even with a 9V battery.

That should pretty much pinpoint where the problem is.

[nkalanaga]

As Peteski said, turning the armature by hand is the first step.  If it won't turn manually, something is jammed, and further electrical testing may damage the motor.  You might be able to move the armature a little due to gear play, before it jams, in which case it's probably the drive train, not the motor, and should be treated as not turning.

On DC you may not have to take the motor out to test it.  If you can reach both brush covers, touch your test leads to them.  If the motor doesn't at least try to turn, there's your problem.  At that point I'd suspect either a bad brush, which shouldn't be hard to replace, or the motor is burned out.   

If the motor can't be turned, or doesn't turn freely for several revolutions, remove the trucks. 

Try turning the main gear on each truck.  if the trucks turn freely, retry the motor manually, and if it turns, electrically.  If it still doesn't turn, either the motor or one of the worm shafts is jammed.  At that point you'll probably have to take the frame apart. 

If everything turns with the trucks out, and the motor runs, it may have been a truck installed wrong, or in your case, bumped out of position.  Put one truck back on and retry the motor.  If it still runs, put the other truck on, and retry.  If the motor is good, and the trucks are properly seated, it should now run.

[squirrelhunter]

Thanks for the suggestions guys! It is a DC only SD40T-2 and the headlights do work. But with power applied the motor will not turn.

I did try moving the motor armature by hand and it turns and so does the worm gear. The gears on the trucks don't seem to be moving when I do this though.

The light board appears to be solidly touching the frame at the 4 points where there is copper touching the bits of frame that hold the board down.

I will try to test the motor using nkalanaga's method this weekend and report back.

[jagged ben]

My guess would be that the problem lies where the motor tabs contact the lightboard.  A little twist out of place or a little bit of corrosion can easily break the connection on these locomotives.

I case you don't know, you are looking for the two spots in the middle of the lightboard above where the metal strip comes up one side of the motor.  It's the same design as Atlas locomotives.

[peteski]

Hmmm... you would have to rotate the motor armature several full revolutions to be able to notice the wheels move (slightly).  The gear ratio is pretty high.

[PROPULDUDE]

Does it pass the smell test?  Is the armature discolored?

[nkalanaga]

Again, I agree with Peteski.  You'll have to turn the motor a long time to make the wheels move much.  That's why it's easier to take the trucks off to see if they turn.  But if the motor makes a full revolution by hand, you know it and the worms aren't jammed, so I'd think the motor was probably good.

Jagged Ben:  Thank you.  I don't have one of these handy, so have no idea what the inside looks like, other than a "typical" split frame mechanism.  Knowing where to put the wires is a big help!

[phil55]

I have a Bachmann GP 7 with DCC doing the same thing . Will try these tips to see if I can get it to run.

[johnh35]

I second the motor contact/lightboard connection suggestion. If it was running fine when you last ran it, I seriously doubt that the motor has failed. The motor/lightboard connection has always been less than perfect.

[ristooch]

If, after you've determined that you have good contact between motor and light board, you might want to try this on for size:
1. Disassemble the locomotive frame and pull out the motor and its cradle. Remove carefully.

2. Touch a 9V battery to the motor (hopefully you have a 9V battery holder laying around). If the motor rotates, great. Repeat this several times in both directions to ensure the motor has not developed a "flat spot," which might be a winding defect and pretty much means "new motor." Based on my no-too-scientific survey, Atlas, Kato, and other brand motors can be substituted, but this entails pulling off the flywheels and pressing onto new motor.

3. Turn the top spur gear on each truck with your fingertip to see if they are binding. Again, do this in both directions several times. If you have a bind, disassemble/clean/lube the truck. You might want to take the opportunity to check and re-gauge the wheels. I like to put a drop of Conducta Lube in the "sups" into which the wheel pointy things sit once the truck is assembled.

4. Reassemble the trucks. If you start stressing and the parts aren't going back together, R-E-L-A-X. Put everything down and walk away for a while. Hard to do but often provides good results.

5. Re-check light-board to motor contact.

Hopefully my explanation will give you some help. good luck with your trouble shooting.

[peteski]

If, after you've determined that you have good contact between motor and light board, you might want to try this on for size:
1. Disassemble the locomotive frame and pull out the motor and its cradle. Remove carefully.

2. Touch a 9V battery to the motor (hopefully you have a 9V battery holder laying around). If the motor rotates, great. Repeat this several times in both directions to ensure the motor has not developed a "flat spot," which might be a winding defect and pretty much means "new motor." Based on my no-too-scientific survey, Atlas, Kato, and other brand motors can be substituted, but this entails pulling off the flywheels and pressing onto new motor.

3. Turn the top spur gear on each truck with your fingertip to see if they are binding. Again, do this in both directions several times. If you have a bind, disassemble/clean/lube the truck. You might want to take the opportunity to check and re-gauge the wheels. I like to put a drop of Conducta Lube in the "sups" into which the wheel pointy things sit once the truck is assembled.

4. Reassemble the trucks. If you start stressing and the parts aren't going back together, R-E-L-A-X. Put everything down and walk away for a while. Hard to do but often provides good results.

5. Re-check light-board to motor contact.

Hopefully my explanation will give you some help. good luck with your trouble shooting.

Excellent compilation of the previous posts with some more info sprinkled in. 

[nkalanaga]

If you do have a bind in the trucks, a magnifier and a toothbrush are very handy.  Often the problem is a TINY piece of dirt, usually ballast, between the teeth of one gear.  The magnifier can help you see it, and scrubbing the gears with a wet toothbrush, with or without soap, can remove even the pieces you can't see.  Be sure to relube lightly after scrubbing everything.  Don't use toothpaste, as it's slightly abrasive, and delrin gears don't need to be roughened.

[squirrelhunter]

Thanks for all the help everyone! I haven't been able to do anything on it since earlier this week, and with the holiday upon us, I probably won't get to my trains again until the middle of next week. But I'll try the suggestions about checking the light board and pull the mechanism apart to see if I have a bind in the trucks, and keep y'all posted on the results.

[nkalanaga]

Good luck, and enjoy your holidays.