Lionel TMCC UP Dash-9 - 6-18286 #9717 Flywheel Magnet Ring Broken

Hi Forum,

I need some assistance with my UP Dash 9. I read all the posts with what to do if you have a loco with a broken magnet ring and I chose option with the can motor replacement from Lionel Parts.

I replaced the can motor with the new magnet ring, R&R with a soldering iron the two wires (Yellow an Blue) and the electrolytic capacitor, R&R connector.  

Here is where the trouble starts for me; The loco powers up, sounds function and when I increase the speed knob on the CAB2, the engine revs high but the loco will not move however, with the engine cover removed I can see ever so slightly that the loco with small jerking intervals moves but barely. When I placed my fingers over the flywheel I can feel the jerking motion but no real response. I rechecked my soldering and verified the connector was plugged in all the way. The motor is not binding with finger rotation and I lift the loco off the track to feel resistance and there is none. Same for the rear can motor assembly. No stress or resistance felt from the wheel gearing assembly.

So I started to probe visually for obvious things and I can see on the driver controller board that is mounted near the front Can Motor has a bubbled electrolytic capacitor on the top of that part. (I will try to furnish a picture)

So for the forum; Do the symptoms point to a bad driver board even before mentioning the blistered capacitor?  Does anyone have any ideas for the next troubleshooting steps to rule out?  Any help is greatly appreciated.



Original Post

You as an electrical engineer know that when something doesn't work after maintenance has been performed, greater than 90% of the time it was something that was touched.  So in this case, I wonder if the new motor is bad, the new cap is bad, or the soldering is bad.   Some things to consider:

Did you confirm the polarity on the cap?

What about applying voltage directly to the yellow and blue motor terminals to validate the motor turns?

Have you check continuity between the board solder terminals and the driver board terminals?

Hi Steims,

Thank you for your response.

That is the reason I am posting here to get the experienced train tech's to help me and others with the troubleshooting and the necessary repair steps whenever we encounter issues such as this issue posted to determine the root cause. Also, this loco was purchased from a pawn shop as-is so i don't have history nor seen this loco operate fully so I am tackling it blindly.

I haven't ruled out a bad motor nor a bad board yet - My soldering on the wires to the board thru-hole connections are good, the original cap soldered on the motor is measured and good and the polarity verified prior to my installation back onto the new motor. No change in performance after verifying the steps.

My second step to troubleshooting will be to power up both DC motors with an external DC Power Supply. Is there anything I need to worry about prior to applying power besides removing the original harness connector?





The six pin molex connector at the motor driver board have been problematic.  Remove and replace and consider wiggling it. 

The motor driver board for this loco is for Mabuchi motors.  Confirm your replacement motor is  a Mabuchi and not a Pittman. 

If you disconnect the harness for the motor you can safely drive the motor with your DC power supply. 

The motors and board are still available from Lionel - so, the replacement motor should be the correct one. I assume you were replacing the rear motor.


Is this what you purchased and /or received?

Have you tried an engine reset?

When you test the motors - check the rotation - are both motors jerking? perhaps the color code isn't the same polarity on the replacement motor and they are opposing one another.

A photo of the board would help - a bulging cap may indicate another problem. Here's the replacement part photo - the creases in the top are for bulging safety when they begin to fail





Arctic Railroad


Photos (2)

Rotate flywheel and make sure it is not binding, on both trucks.  Make sure motors are phased correctly, one turning in rev while other is going in fwd.  As mentioned check all your connections.  If the motor driver is good, at least one motor would try to turn.  So DCDS is a culprit, but did it have the same symptoms before you replaced the motor?  What did it do with a broken ring?  G

MTH Authorized Service Center

Authorized ERR Dealer

Lionel Independent Repair Tech

Virginia Train Collectors Member

Thank you guys (Steim/Moonman/Cjack/GGG) for all responding -

So Steim - That is a good information that i will note and check today. I will be sure and see if the DC motor that I received is in fact the Mabuchi brand and not a Pitman. If i cannot tell, I will take a picture of it but in the meantime, here is the picture of the DC motor that i removed. I will be sure to check the black molex connector for possible bad solder joints or broken connection terminations to the PC board of the DCDS.

Moonman - The photo of the DC motor that you provided is the rear motor and I have replaced the front motor with the magnetic ring glued to the brass flywheel. BUT that is a great point to make - I did NOT reset the loco and that is a plan i will do today as well. thank you for that. For the color codes of the wires, I pretty much matched to what I removed via a picture that I took prior to disassembling - When I felt the jerking of the front motor flywheel and with the rear motor flywheel, they both were turning opposite as they should and so I verified that the wires are correctly phased.

GGG - that was my first indication when I felt the small jerks, possibly a binding but there is no binding. both motors are turning freely. As satted above, the symptoms were a short 1ft burst of motion and stop and continue until you basically turn the Red CAB2 remote knob to zero. But of coarse there was the problem when i noticed there was no magnetic ring around the flywheel and it was in 8 pieces. I tried to tape them together to further my curiosity and there loco still a lot of jerking which is the culprit with all of the NorthSouth breaks.  And both motors are reacting the same way with small incremental jerks. I will provide more photos.

Thanks -- Richard



Photos (2)


I had a chance yesterday to continue the troubleshooting on the 9717 DASH-9 with the broken Magnetic Ring. So after replacing the motor i posted the issues that I was experiencing. You all provided great "look for's" and I am proud to announce that the loco is alive.

But first it appears when I purchased this loco from a local pawn shop it had already been touched and tinkered through, i will explain in a moment. But first I took the advise from Steims in regards to the checking the Molex connector - Under a magnified lens it did in fact appear to have bad solder connections on the board. I just reflowed the connection with solder. I couldn't take a picture to show the before and after but it was obviously bad. Thanks Steim - Next i replaced the bubbled top capacitor on the DCDS Board with another 100uF - 50V. The original cap was a 100uF - 35V. 

After those fixes I put the loco on the track and just as some of you responded, the loco motor was rotating normally BUT in opposite directions. I did take a picture of the motor prior to tear down and I put the wires back the way I removed it BUT doing further inspections in noticed that the wire bundled in the wire nut connections blue and yellow appear odd. The 3 wires in each wire nut were soldered together - I have seen on other locos that they weren't but then again there was a mix of wires - One Wire nut had 2 yellows and 1 blue and the other had 2 blues and one yellow. I think you guys know where I am headed. I cut the bundle and tied the 3 yellows in one wire nut and the 3 blues in another - IT IS ALIVE!

Thank you all and the Forum for helping me find the little nuances that brought the loco to run once more - Now I can see I have lights that don't work but I don't need the forum for that - I will be posting another brain thinker issue with a Lionel ES44 Conrail 8098 with rear truck noise when you add a load - Stay Tuned!

Thanks again Steims/Moonman/Cjack/GGG/Carl -


Glad we could help and keep another locomotive going. 

These Dash-9s cab/marker/headlights have a contact block when you mount the cab to the frame.  The pad on the frame is stationary and the block in the cab can be rotated.  The contacts are actually springs (copper?).  Getting these aligned can be finicky.  Either 1 or both could have been inadvertently repositioned during the maintenance or actually bought with this problem.   I remember on an older U30C it took me a dozen tries to get this set correctly.  Here is a pic of the lighting pad I am talking about:



Photos (1)

Hi Steims --

That is exactly what I see with the cab cover removed - I noticed the Cab shell springs are not aligned and the stem where it seats into appear cracked. It looks like i will be using some model cement for the plastic pieces that have cracks and some hot glue for the wires that have came loose over time. Thanks for the helpful hints again.




Hi Richard,

Thank you for reporting the result. It helps others when searching for solutions.

You will find when working on Lionel engines that the wire colors can vary. Where it starts and where it ends is more important.

Good to see that you have skills - nice work repairing this engine.


Arctic Railroad

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