OKHIKER posted:Forest posted:Did you test the armature with a ohm meter. Check the resistance between the three plates . All readings should be the same. Then check between the commutator plates and the armature shaft. You should not get any reading there. If it is shorted you will get a very low ohm reading as low as Zero. If these readings check out Clean out the grooves between the armature plates with a toothpick and some alcohol. You should have already done this but didn't mention it. If there is too much gunk between the plates it will short and smoke when you try to run it.
Forest
Bear with me here as I am no electrician. Anyway, I initially cleaned out all of the grooves between the commutator segments. They weren't clogged to begin with. I also polished up the commutator to a bright shine. I did the transformer test with two leads and got a good deal of sparking when testing the shaft against the commutator plates. This would indicate a problem. When testing the plates against one another I got the sparking which is normal. According to what I've read the shaft and commutator plate sparking would indicate that the armature is shorted against the shaft. Anyhow, I'm not positive as to how to use the multimeter for this test. I know I have to set the OHM meter to its lowest scale. Do I do this test with or without power to the loco? In any event without power to the loco the reading between the shaft and all of the commutator plates is one. The readings between the commutator plates are all one except one plate reads 1.7. Am I doing this correctly or should I just bag it? Like I said I'm no electrician.
Looks like you tested right the armature coils are shorted to the frame. Remove and replace. Do you have a replacement armature? Little point in doing disassembly if you don't have the parts to repair. (Ohmeter test is done without power, just as you did)
