Guys,
I have Baldor BC138 (BC139) drive problems, at least I think I do. The power LED is lit on this drive but the motor doesn't move. Just last week i had an incident where the motor took off at full speed for a few seconds but that problem went away. Now it doesn't turn at all that's why i am suspecting the drive and not the motor.
Go back to basics, is there a fuse on the output of the drive. If I'm not mistaken, these are the drives used on fractional motors with a DC output. I would say it's most likely there is an output fuse. heck the fuse and check for output voltage.
These simple checks will give you some answers.
Also, here's the troubleshooting guide for BC138 and BC139 drives
1. Motor does not run: AC input voltage not present at L1, L2 terminals. Verify correct wiring, Blown line fuse or tripped circuit breaker, Blown armature fuse or control
circuit fuse. Replace blown fuse with SL-40 or equivalent. If fuse blew due to miswiring, power bridge module may be defective.
2. Motor is not running. Power ON LED is illuminated: Check ENABLE or INHIBIT circuit for loose or disconnected wiring, Main speed pot is set to zero. (Re-adjust to desired speed), Main speed pot, speed reference signal input, or motor connections are open (Verify there are no loose or disconnected wires).
3. Motor hums or runs at very low speed (Motor slows when load is applied). CL LED is illuminated: Incorrect motor wiring (Verify correct wiring), Motor is overloaded (Check motor current with DC ammeter and reduce load), Motor may be defective (Check motor for shorts or grounds), Check brushes, Current Limit (CL) trimpot may not be set correctly (Re-adjust CL trimpot).
4. Motor runs at high speed and does not respond to main speed pot or speed reference signal: Check field wiring, if using tachometer feedback, check tachometer signal.
The Baldor operator's manual is pretty simple, not alot there.
Here's what they're showing for internal drive diagram:
(http://www.obsoleteindustrial.com/photos/baldor-bc138-bc139-drive.jpg)
Baldor BC138 BC139 Drive