Short when loose motor wire re soldered

[philsandy]

Further to my recent query re. Bachmann 4MT keeper plate wiring.

I have had this loco running very smoothly for a while when it suddenly became very erratic, this was down bad electrical contact somewhere, and not mechanical.

 

Whilst investigating, the red wire from the motor terminal came away from the keeper plate, (how unusual !!)When I re soldered it, the motor would not work, and there was a short somewhere.

I un soldered the red wire and put a crocodile clip from the DC controller on it, and held the other croc clip from the controller on the black wire/soldered terminal on the keeper, and the motor ran, as soon as the croc clip holding the red wire made contact with the pick up strip where it is supposed to be soldered, it shorts.

 

This is an usual wiring arrangement, ie. the black and red wires from the motor going to the same pick up strip, but apparently there is another strip underneath, so although both wires appear to be soldered to the same strip, there is one strip on top of another and they are somehow insulated from each other. 

The photo below shows the wires in their original state, ie,. before the red wire came loose.

I am completely baffled as to why this is now shorting.

 

[uax6]

I would say that the insulation on the black wire (presuming that goes through the first contact strip) is damaged, possibly when you re soldered the red wire. Can you re-route the wires so that they don't pass through both sets of contacts?

 

Andy G