Just replaced the reversing E unit on my Marx 999 locomotive, and now instead of just going in reverse, it just sits there and hums. I then bench tested it, and smoke started coming from the armature! So what did I do wrong? I'm sure all the wires are connected correctly, and I did test the new (used) E unit before I installed it to make sure it worked correctly. So is my motor fried?
Replies sorted oldest to newest
Sounds like when you wired the new reversing unit you got a short somewhere or your new reversing unit already had a short in it. First thing to do is pull the commutator and check to see if it has a burnt winding.
Couldn't find one, but that is definitely where the smoke was coming from. Would a new commutator revive my engine? and perhaps I should try a new E unit?
How do you test a commutator on a Marx 999 engine for a short? And if there is one, would it be feasible to replace the commutator without risk of the new one shorting out?
you can test the commutator with o ohm meter check from each set of commutator copper plate to ground you should not get any reading !infinity no ohm reading at all if you get like 0 ohms or 2 ohm, etc. you burn out the armature winding and shorted it to ground! if the is the case you fried your armature winding for Sure. other wise you probably wired the E unit incorrectly which in turn is burning out your armature. what was the original problem?
let us know so we can help you!
i dont know if you understand how reversing unit work's but the E unit reverses the field winding in relation to the armature or what you call the commutator, that is the only way to reverse a AC motor reversing field coil in relation to armature winding !
do you understand
I repaired an AC American flyer for some one on the forum and the reversing unit was wired incorrectly and almost burn up the field and armature winding!
if your not sure what you are doing you should have someone that knows to do it for you otherwise it can cost you a lot of unnecessary money which originally started out to be a simple repair!
sincerely hope this helps you understand
Alan
p.s. you may have wired the E unit backwards which caused the e unit to power the winding incorrectly!
Originally the loco would only go in reverse. It had been sitting a long time. I bought a used E unit on line which had been tested by a reputable seller. There are only 4 wires to install, and I can't see how I could have wired it wrong except I might have crossed the 2 wires that go to the magnet part of the motor. Would that cause the problem? The armature seems to test fine, as I got no type of + readings. The E unit still toggles back and forth as it should.
Access to this requires an OGR Forum Supporting Membership
