A 1/2(?) horsepower 2-brush DC motor was having bearing issues so I disassembled it and replaced the ball bearings, turned down the commutator on a lathe, and installed new original equipment brushes. A good clean-up was done as there was much grease and carbon dust inside.
Now when I apple power it just growls. If I turn it by hand with power applied it will turn 1 or 2 revolutions then stop. Before disassembly the motor ran as expected.
The field and armature are separately terminated at the outside of the motor and wired to a motor speed control PCB.
The commutator segments are well-separated. I put an ohm meter on the brush terminals and turned the motor slowly. I see 10 ohms across the armature with each commutator position (each brush contacts 3 segments). The field measures
1000 ohms. I thought that a bit high, so I found where the 2 separate field windings are connected (in series) and measured each winding separately: each is approximately 500 ohms.There is no mechanical reason the motor should not spin at speed. By hand, it turns freely and there is no interference between the armature and field laminations(?).
The motor is rated at 180 volts DC, 1.5 amps. There are 2 separate field windings (wired in series) and the commutator has 36 segments.
I've had this motor apart several times but still can't find a reason it's not operating like it should.
Any suggestions would be greatly appreciated (and the sooner the better ;-) ).
Thanks, Dave