[Volphin]

Hi Guys,

I've got a beautiful Legacy NYC J3A, #1922051. I just pulled her out to run her for the first time since new. She went around the layout a few times, then when crossing a switch she just went dead, and tripped the circuit breaker. I took her to my test track hooked to a CW 80, and she just dead shorts out. I popped the hood looking for anything obvious (pinched wires etc) and found nothing. I inspected the board for any burned out components and didn't find any. Maybe the motor failed??? Any assistance would be appreciated! Thanks!

 

[gunrunnerjohn]

Start at the trucks, I'd be checking wiring and pickups first. Measure the resistance between the wheels and center roller.

 

[Volphin]

Thanks for the help John. With my meter set to 2000K, I get a reading of 1310 from each pickup to each driver and truck. I've inspected the wiring from the pickups to their soldered pigtail, then up to the connector on the board. There is no chafing, loose pins or connector. The driveline feels a little rough as I roll her manually though. Do you think the board is toast?

 

[Norton]

Unplug the connectors here and see if you still have a short.

Pete

 

[Millstonemike]

Thanks for the help John. With my meter set to 2000K, I get a reading of 1310 from each pickup to each driver and truck. I've inspected the wiring from the pickups to their soldered pigtail, then up to the connector on the board. There is no chafing, loose pins or connector. The driveline feels a little rough as I roll her manually though. Do you think the board is toast?

1310 is not a short if it's truly 1.3K ohms. That's likely reading the electronics impedance. Try connecting the transformer wires directly to the loco (wheels and pickup roller). Perhaps the short occurs when the engine is place on the track - a physical malady causing the short. Or, once the electronis "wake up" and try to power up other parts of the loco (lights, motor, etc.) it encounters the short. Then Norton's suggestion would be warranted.

 

[Lehigh74]

I had a similar problem with a Railking decapod recently. Started up fine and idled. Dead short at soon as I rotated the control thumb wheel. At the suggestion of GRJ, I checked for continuity between motor leads and frame. Should not be any continuity.

I checked between motor leads and wheels a few times and got between .2 Mohms and 6 Mohms. I figured that was as good as no continuity, but I guess not. I fiddled with the motor leads to look for shorts and to physically separate them from potential shorts. That solved the problem. It now works fine. Continuity check came up as OL (lazy eight ohms). Looking at the wires, there were a few spots where one of the leads was tight up against another wire or the motor, but no signs of missing insulation.

 

[Volphin]

1310 is not a short if it's truly 1.3K ohms. That's likely reading the electronics impedance. Try connecting the transformer wires directly to the loco (wheels and pickup roller). Perhaps the short occurs when the engine is place on the track - a physical malady causing the short. Or, once the electronis "wake up" and try to power up other parts of the loco (lights, motor, etc.) it encounters the short. Then Norton's suggestion would be warranted.

Tried this with her on her side. Still a short on all pickups & grounds. It's not a roller sticking up.

 

[Volphin]

Unplug the connectors here and see if you still have a short.

View attachment 596663


Pete

Pete, short is absent when connector is unplugged. This confirms rollers and axles are proper. I'm leaning toward board or motor. You would think with an immediate short, it would have obvious damage, but I don't see any...

 

[Norton]

You can check the motor but the motor is not connected directly to the tracks, rather a bunch of circuitry. The same connector that connects the RCMC to the track also connects the motor to the RCMC.
Those Canon motors do have a history of failing though And taking the RCMC out when they do. I think Harmonyards caught his just before it blew up.

Pete

 

[gunrunnerjohn]

A shorted motor normally wouldn't show up at the pickups, sounds more like the board. However, a bad motor can take out the RCMC, I've had a parade of bad Canon motors in Lionel's large steam, and a few have smoke the RCMC board!

 

[Volphin]

A shorted motor normally wouldn't show up at the pickups, sounds more like the board. However, a bad motor can take out the RCMC, I've had a parade of bad Canon motors in Lionel's large steam, and a few have smoke the RCMC board!

How have these motors failed? I was going to unsolder it and test it with a DC transformer...

 

[Jetguy]

How have these motors failed? I was going to unsolder it and test it with a DC transformer...

I documented that analysis and teardown. Pittman motors, a history lesson please
Potentially one way was the brushes touch this large metal washer pressed on the motor shaft causing a short to frame.

the other noted "weakness" is the brush end bell specifically how the brush arms are mounted and constrained and the small tabs or posts can snap off.
It's the combination of the two weaknesses that a stray brush moving around can then short to the shaft via the washer and thus frame ground that is specific to these motors.

 

[Jetguy]

Again, in a nutshell, the 2 things that stand out about the Canon motor is this metal pressed on washer, that likely is there to sling oil to prevent brush and commutator oil contamination from the endbell bushing. On other brands- that washer is plastic and also prevents the brush from touching the metal bushing.
That "flaw" coupled with an especially brittle endbell plastic material and very weak and failure prone brush guide plastic molded posts that can snap off internally. This can allow the brush arm to shift and move position.

 

[gunrunnerjohn]

Don't be fooled if the Canon motor momentarily seems normal, that's bit me as well!

 

[Volphin]

Thanks John. Lionel doesn't list a replacement motor online. Any suggestions?

 

[Norton]

Thanks John. Lionel doesn't list a replacement motor online. Any suggestions?

You can use a 56mm Pittman. Lionel has those but if the motor has indeed shorted you will likely need another RCMC. Some of us replace the motor as soon as the engine arrives.

Pete
member of warranty voiders anonymous

 

[gunrunnerjohn]

I've rescued a couple of RCMC boards after the motor shorted, but some overheat so much that they destroy the PCB, those are toast.

 

[Volphin]

You can use a 56mm Pittman. Lionel has those but if the motor has indeed shorted you will likely need another RCMC. Some of us replace the motor as soon as the engine arrives.

Pete
member of warranty voiders anonymous

What part number should I use for the 56mm Pittman motor?

 

[Norton]

What part number should I use for the 56mm Pittman motor?

This will work. Pretty sure its the same one used in the TMCC engines. Shaft diameter is the same as is the bolt pattern but I think these use 6-32 flathead screws. Hardware store item if you don’t have any handy.

Pete

 

[Volphin]

This will work. Pretty sure its the same one used in the TMCC engines. Shaft diameter is the same as is the bolt pattern but I think these use 6-32 flathead screws. Hardware store item if you don’t have any handy.

Pete

Thanks Pete