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I fixed this, but not sure how.  Could it be the light thing?

DCS, ZW powered, been running this double tracked overhead layout for ten years.  Added two streetlamps and a lighted diner to track power three years ago. Been running the same MTH engines.  A month ago, my Conrail GP7 5605 began hesitating when it crossed a straight gargraves joint and the lamps and diner lights blinked. My MTH AMT Imperial 464 passenger consist crossed the same joint, no blinking of lamps or cars, no hesitation of the engine.  The layout is large enough to run two consists on both lines. No issues on the other line. So.....

After checking the track, transformer, wiring, TIU, engines, and cleaning the track I could find no apparent problems, other than the ground B side of the ZW was hot and the input on Fixed 1 was warm. Tried disconnecting the lamps and diner.  Problem got worse, the GP7 shutdown, always when one truck hit the other side of the track joint, and the other was on the same side. Got a new Conrail SD45, #6088, and hooked up my backup TIU. Entered all four engines on a test track. Nothing changed, the new SD45 stopped at the exact same place, and the fixed 1 input remained warm, the same ground on the ZW was hot. I'm aware that all the grounds on the ZW are connected.

Volt/Ohm meter showed no differences.  Put jumpers connecting the offending tracks, the center rail sparked.  Clearly a short somewhere.  Reconnected the lamps and diner wire to the track.  Jumpers had no spark. Engines ran normally.  Problem solved, BUT HOW?

How can three engines (the two Conrails, and I tried my NH F3 #6691) all cause a short, but the AMT Imperial not, on the same track?

100_0638

Jerry

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  • 100_0638: Very old pic of the GP7
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It wasn’t the engines, they wouldn’t have started up if they had a short inside of them. In your post, it sounds like you jumped around a lot trying this & that, so not really sure what caused the issue,…..Maybe it wasn’t a short as much as it could’ve been a bad connection up there causing an excessive amp draw??……perhaps one of the accessories is pulling too much current across the track ?

Pat

Thanks, Pat.

No, it's clearly not a short in the engines.  The engine trucks, on both sides of the track joint, are causing that.  Still don't get why the Imperial doesn't do the same thing.

Yes.  I agree something is causing an amp draw.  Re-connecting the three lamps has solved the issue, but the Fixed 1 port between the ZW and TIU gets pretty warm after 30 minutes of running time.  Since the layout is 7 1/2 inches from the ceiling, it's gonna be a chore to take down the 100 cars and re-check the wiring with little room to see.  I still don't get why the same wiring has functioned without issue for nearly ten years.

How serious is a warming TIU port?

Jerry

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