short circuit

Hi Phil!

Forgive the obvious question, but why do you have the E-unit on it's side? These are gravity sequenced and must be upright to operate correctly.

From what I can see, everything else looks OK.

get a ohm meter and check continuity from engine pickup roller to chassis or frame ground if you read a short it could be in brush ASSY or commutator wires touching frame from center roller many things! short would be 0 ohms or close to that number.  also you could check field coil to ground you could have burnt up windings in field coil or armature bad or even reverse relay coil burnt out shorted to ground !   

Alan

Here is the wiring diagram:

That loose black wire probably needs to be soldered back onto the e-unit tab where the other two black wires and single yellow wire is. I'm guessing that the yellow wire is a replacement of the red wire indicated on the diagram above.

Take a picture of the wiring, then completely disconnect the 'E' unit.

Wire up the motor directly to the rollers and ground according to the left-center diagram here, ''Wiring Diagram of Locomotives with No Reversing Mechanism''.

Power up the loco and it should run properly. Reverse the brush wiring and the loco should run in reverse. If it runs, you may have a bad 'E' unit. If it does not run, you need to check elsewhere.

Larry

@TrainLarry posted:

Take a picture of the wiring, then completely disconnect the 'E' unit.

Hi`, thanks for the kind responses, the E-unit is on it`s side because i was able to trace the disconnected wire to the rear truck, the E-unit was in the way, it`s been re-attatched but i still don`t where that front black wire goes, it`s the one i traced  to the rear truck,  i`ll give All of your suggestions a try,, again, thanks for your help, Phil

Take more pictures to show where the disconnected wire comes from.

Larry

@Love trains posted:

... i still don`t where that front black wire goes, it`s the one i traced  to the rear truck, ...

It's the wire from the coupler slide shoe to the coupler.

hI`, adcx rob,thank you so much for posting the diagram,  i soldered the wire to the tab on the  front coupler, and i`m still getting a short circuit, any other ideas would be greatly apriciated, thanks to you and every one who posted ideas, Phil

Check the wire from the roller pickups to the 'E' unit. The insulation has been known to go bad over the years, and the wire shorts out. Check that the wire is in good shape.

The 'E' unit can fail with a broken drum, and that can also cause a short circuit.

If this does not solve the issue, do as shown in the above Wiring  Diagram of Locomotives With No Reversing Mechanism, and remove all the wiring from the 'E' unit and wire the motor directly to the power lead and ground. That should get the loco running.

Larry

@Don Winslow posted:

Hi Phil!

Forgive the obvious question, but why do you have the E-unit on it's side? These are gravity sequenced and must be upright to operate correctly.

From what I can see, everything else looks OK.

For the record, some e-units were "spring loaded" and mounted horizontally, specifically those found in the "dual worm drive" 1946 versions of the 726 Berk and 671 Turbine. In the horizontal position, the piston was more likely to get dirty and quit working. I just had to work on one in a 1946 671 variation A.