Short that is driving me NUTS!!!!!!!!!!!!!!!!!

[Fred Bear]

I had a derailment a few days ago on a 4 truck MTH Shay. It cooked the black and red wires together coming from the rollers. I did NOT have a quick blow fuse in place. I replaced all the wiring with the proper wire, but when I put the shell back on the body, it blows a fuse. I have a graveyard of blow fuses trying to fix this thing. It works great without the shell, but for the life of me, I cannot find the bare wire that is causing the short. I can plug in the tender and it's fine, but only without the shell. If I add the shell, it shorts out everytime. Does anyone have any ideas other than visually inspecting the wires? I've done that over and over and I cannot find the bare wire or the wire that is causing my problem. Thanks much, Jake

[chuck]

Continuity check on a multimeter could be usefull.  Most likely place to look for this is where the wires for the tether come together.  You might have an intermittent short on the board where the wires come together and the placement of the shell completes the circuit.

[raymans]

one trick I used to use on an intermittent short was to hook it up with an automatic circuit breaker, then you can watch what is going on more closely without having to worry about replacing fuses.

 

[Fred Bear]

It has to be contact from the shell somewhere, unless the wiring harness it getting squashed and pushed into something else. The problem is a person simply can't see into the darn thing needless to say as it's closed. This is making me bonkers, as with the shell lying next to the mai body, all functions on the DCS work perfectly. This is one tough cookie to crack! Jake

[otftch]

What I usually do at this point is to wrap the wire with electrical tape.try and slide a piece of tape under all the wires you can on the harness and then put a piece lover the top of the wire.Don't worry avbout wrapping  it,just lay it over the wire.This will keep the shell from contacting it.This might work.

                                                              Ed

[spikejones52002]

I trick I use to find and intermittent short.

Place a low voltage, low amperage light bulb in series with your power wire. Set your veriable power suppy to match the low voltage lamp.

Then start to slowly resemable your equiptment.

The lamp will light immediately when the problem occures.

The low current lamp will not let any wires burn up or fuses blow.

Then you can slowly undo and redo your movements to see where the problem occures.

[chuck]

Check the wiring harness very carefully.   Sometimes for the sake of appearance, they route the harness into "hidden compartments" and this may be where it's getting pinched.  The other likely culprit is the small "board" where the tether terminates on the loco side.  Check to see if there was an insulating piece of clear plastic that went over/under this terminus.  The pins taht the harness is soldered too could be protruding and maing contact with the shell.

[Fred Bear]

I taped everything over and under I could. I checked, rechecked, over checked, under checked and double checked all those, still no apparent problem area. Took the shell off, fired right up. Put the shell back on, pop goes the weasel on fuse # nine thousand, six hundred and fifty eight, or something like that. I cannot do the light bulb deal, as the wiring, cover, and trucks prohibit that, but thanks for the suggestion, most appreciated. Any other ideas anywhere? Thanks, Jake

[lionelsoni]

Put the lamp in series between the transformer and the track.

[Fred Bear]

I've tried to assemble the train on the track, it's about impossible. The lamps are not a problem, just the assembly. Jake

[PhilaKnight]

This happened to me but not on a toy train. On a old Harley Davidson I have. The thing would run when I had the ignition cover plate off but when I put it back on it would not start or shut off if running. I had the bike running with the lights off in the garage and started to put it back together while it was running with a small watt light so I could just see what I was doing. Here the wire to the points was bad. I spark would jump from the insulation of the wire to the cover causing the short. I had to replace the whole wire. You might have a bad piece of wire that you used to replace the ones that got burnt. Hope this helps 

[dwiemer]

I don't have this engine and certainly don't have the vast knowledge of Bob and a few others, but I have seen two issues that may be the culprits.  One: if the fastening of the shell somehow compresses the board down to make contact on the underside.  Two: perhaps the wiring in the jacket is compressed and crimped to a point that the shell causes the short.  In the second case, you may want to remove some of the jacket to see if the wires are in tact and then use heat shrink tubing to replace.  On the first scenario, you may try pressing down on the boards while the shell is off and see if that is happening. 

Good Luck,

dennis

[Fred Bear]

Thanks again for all the suggestions, if anyone has any other suggestions, please don't hesitate to write, Best Regards, Jake

[sir james I]

IF it's a metal shell? try plastic tape on the inside of the shell so the wires cannot touch the shell.

[Fred Bear]

Finally! I took the shell off with the power on, something I can not done for fear of blowing something else, or messing up with board. I saw some arcing around the trucks, pulled them off, and sure enough, when I rewired the trucks, I bent one of the little spade connectors down and it was touching the frame, happened to be the hot side.  When you rocked the shell back and forth, it would actually spin the motor while arcing the trucks.

      Anyway, it's fixed, and a big thank you to all the guys & gals if any gals, who sent stuff in. What a relief! Jake

[EIS2]

Congratulations.  I knew you would eventually solve the problem.  Persistance pays off almost 100% of the time.

Earl

[Fred Bear]

So true, I was about down to the last candle however! Jake

[raymans]

that's what can happen when you don't give up