Hi. I have post war diesel engine on a frame, and want to test the motor.
How do I bypass the E-Unit, and simply connect the positive and negative transformer leads to the motor itself?
Thanks.
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I see no wires running from the e-unit to the motor in your picture. That makes testing easier.
I assume you have a pair of test leads connected to a power source.
1 Take a jumper wire and connect one brush holder to the metal tab between the brush holders (this is the field tab)
2 attach one test lead to the other brush holder.
3 attach the other test lead to the metal solder tab on the side or the motor, or simply touch it to the metal side of the motor.
The motor should run.
Exchange the wires going to the brush holder, and the motor should run in the opposite direction.
Thanks C.W. That worked perfectly. Now I will try to figure out how to reconnect the E-Unit to the motor without the horn relay.
I see two black wires coming off of one side connection of the E-Unit, and three wires bundled together (green, blue, yellow) coming from the underside of the E-Unit.
If the wiring has not been changed, its Green to the field tab in the middle, blue to one brush holder, and yellow to the other.
There should be a short black wire from the contact plate on the side of the e-unit to the terminal that does not act as a switch contact. It may be hidden.
If the black wires are attached to that side terminal, they go to either the collector shoe or the lamp sockets.
How did you make out?
Good information. One thing I might add is checking the armature face for buildup. I just check on one I have, and the face was really black. I had checked it the same way you described but it arced and would not run the motor. Checking brushes and armature face are essential for the motor to run smoothly. Good discussion.
