I'm working on a friend's 675 which he bought last week and has all sorts of issues. Correcting them one at a time, but ran into one I can't figure out. It didn't run well and I suspected it was old lube or an e-unit issue. I was planning to rebuild the e-unit today, but decided to bypass it and hardwire the motor to my test transformer to see if it's a motor issue. Clipped a transformer lead to one brush plate and the other to frame. The other brush to the field wire. It ran in forward. When I reversed the brush plate wires, it would not run in reverse. The motor buzzed loudly (not the e-unit, which was disconnected) and the wheels felt "locked". Only when the wires were connected in that arrangement, otherwise, the wheels turn freely in both directions. The springs and brushes are relatively new and the commutator is clean. Any ideas what is going on here?

Roger

Original Post

you have to revere the field coil in relation to the armature winding for it to reverse not switch the 2 ac wires you had connected!

certified MTH ASC tech and train repairs august 2019

repairs down to component level on all electronics

repair computers and reload windows 10 and windows 7

been in tv radio and all electronic repair since 1962

board repair also!

Alan,

Update on the 675. The replacement brush plate arrived this afternoon and I just installed it. Runs like a top! This had me baffled. I've never run into that issue and had tried everything I usually do to get it to run. The giveaway was the wobble I saw in the shaft when it was in (what was supposed to be) reverse and I could feel the magnets struggling to turn it. I put it under my high power illuminated magnifier (which BTW, is the best tool on my bench) and I saw the crack.  And a bit of a bonus......I was going to rebuild the e-unit to see if that helped, but held off until I found the actual source. Good thing I didn't. This one works and proved to be one of the rare dead silent e-units. So, all is good and my friend will be pleased

Roger

Alan Mancus posted:

you have to revere the field coil in relation to the armature winding for it to reverse not switch the 2 ac wires you had connected!

Not on that model. One side of the field is grounded.  He did it correctly.

Jon G TCA 95-41020

Independent Lionel Service Tech

MTH Service Technician at MTH

Add Reply

Post
OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
330-757-3020

www.ogaugerr.com
×
×
×
×
×