My Lionel 623 Switcher stopped running and just started humming and kicked out the #91 circuit breaker. I took the motor apart and disassembled/cleaned the armature (i.e. cleaned the face, the thrust bearings and the thrust washers). I also replaced the brushes and greased the armature gear and the drive gear. After re-assembly, the switcher ran great for 2 days and then stopped again just like before. I repeated the cleaning procedure but the switcher still didn't run. I disconnected the motor from the e-unit and connected the motor directly to track power. The motor doesn't run all the time. When it does run, it will run in either direction at 7 volts. When I increase the voltage slowly up to 10-12 volts, the RPM of the motor does not increase and finally stops and hums. I have attached a video demonstrating this. Has anyone on the forum experienced this problem and knows what is causing the problem?
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Agree with Dan. Also check the commutator for a unsoldered wire. You might have a open comm. section.
Check the commutator segments for continuity among them, and shorts to the shaft.
Dan/Ed: I didn't see any unsoldered wire on the commutator. Before re-assembly, should the thrust bearings (2) be packed with grease for smoother/quieter running?
ADCX Rob: Using an Ohm Meter, the 3 commutator segments have continuity among them. Concerning shorts to the shaft, there is no continuity between the commutator segments and the shaft. Is this the way it should be?
Here's a video showing the resistance between segments A-B, A-C and B-C. In your opinion, are the resistances close enough? Also, there is no continuity between the shaft and the segments. If the resistances are close enough, what's the next step in our diagnosis?
It looks okay to me. I don’t think all the noise is electrical. Examine the shaft, bearings and thrust washer for damage and wear. Also check axial and radial movement of the armature shaft. There should be no perceptible radial movement (side to side). There should be a few thousands of axial play. Radial play indicates a bad bushing. Excessive axial play indicates bad or missing thrust washer(s).
Your first resistance check, A to B, shows zero resistance. The resistance should be about 1.7 ohms. Is the A to B slot shorted? Might be time to start looking for a replacement armature.
So based on your comments, I started to think about what could be causing the short between segments A-B. The first thing I thought about was the slot between A-B. I always clean the slots between the segments whenever I service any of my engines, but this time I really cleaned out the slot between A-B. Then checked the resistance between the segments again and found that the resistance between segments A-B now shows a reading of ~1 ohm, similar to segments A-C and B-C (refer to attached video). I placed the locomotive on my test track and it ran. I oiled the thrust bearings on the armature shaft and placed the locomotive on my platform. Now it runs great (refer to attached video). I never realized how important it was to keep the slots between the segments clean in order to maintain a smooth running locomotive. Thanks to Dan, Ed Horan, Rob and David Johnston for your extremely helpful comments.