On my railroad, I run DC two cab common wiring. I have not had any issues using this method. I figured someday I would run into a short somewhere. Well, that day has come perhaps. Today, I went out to my train building & 1/2 of the layout won’t run correctly. When I last ran trains a few days ago, everything was fine. Though I only use one cab at this time ( both are hooked up ) neither cab will operate correctly when I try on the 1/2 that’s goofy. It’s like I have to flip certain other toggles to make engines on another block work… but on the cab that I’m not even using. To give an example… I run on cab 2. but if I flip a block over to cab one, cab 2 throttle will still operate. Changing direction is a new thrill as well. If I don’t flip toggles, it’s like there’s no power to move anything other than a crawl now & then. The direction control on the throttle does not change direction, I have to flip toggles to get that to happen. Perhaps this isn’t that great of a description, but by any chance has anyone else run into this oddball situation. The building is heated where the recent fridgid weather shouldn’t be an issue, not that it should be I suppose. It’s as if someone came in & changed some wiring ( which didn’t happen of course ) unless you count gremlins…lol. It’s even possible for two different engines on two different blocks using the same cab to go in opposite directions as well.
Hmmm interesting problem. Usually problems are due to bad electrical joints – bad soldering – coming undone. that can be very difficult to detect without redoing all soldered joints!
One possibility is that a toggle switch has gone bad. Another is that a minute piece of metal is bridging a gap between sections? Such as a freight car truck with metal wheels? remove every piece of equipment from the layout.
If the building is heated, is it sometimes not heated - that is, have there been recent temperature changes that might have pulled a connection apart or pushed a gap together?
Dave Nelson
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I would look first for a short in the track between one block and another by inspecting all the insulated joints. Look for contact or contamination between the rail ends.
Next I would look for a short in the switch that controls which cab provides power to the block. Also the cables leading to it, if you have bundled the cables together from both cabs.
Try completely disconnecting the low voltage output of one cab at the cab. If the block operates OK, then that would support the idea of a short in the above-mentioned switch. Re-connect that cab and try it with the other cab disconnected.
Disconnect the block from the above-mentioned switch, disconnect the low voltage output of a cab completely, and connect that cab directly to the block. If the block operates OK with this direct connection, then the problem is likely in the wiring or the switch. If not, then there is probably a problem somewhere in the track.
Good luck. Let us know how it comes out.
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Man o man… I hope it’s not in the toggles themselves…lol. I don’t understand how I can get 'em to go in different directions on the same current, though they’re quite sluggish when it happens.
If you have power-routing turnouts, you must have insulating gaps. Part of my layout had gaps cut in the rails. The temperature dropped in my basement and some of the gaps closed up to the point where the rail ends touched and shorted. I spread the rails and inserted some styrene to keep them apart.
Jim
IT almost sounds like you have a short circuit where BOTH controllers are trying to power the same sections of track at the same time. If the directions don’t match, the train will run slowly or not at all. The voltage “drop” will be high somewhere and may overheat the controller.
If you have an ammeter check the current draw. Otherwise, disconnect blocks (remove wire) and use clip leads to test one block at a time with a single pack. Check that disconnected blocks do NOT have power too. This may be tricky to troubleshoot.
Tada !! I found the short today… if it was indeed a short. My layout is a point to point, & the way things were acting was driving me nuts. Why a certain toggle that had nothing to do with where the problem was,& can have an effect on things we’ll never know I suppose, but as I was running engines ( & trying to figure out why they were running in the manner that they were ) I found that the negative rail was acting up in the rail joiner right where the other 1/2 of the layout was ok. All I had to do was solder that joiner & life is good again. There’s a lesson to be learned here when 1st laying track. The thought of having to mess with all those toggles really scared me…lol.
I just saw this thread. It was not a short. I was going to suggest an incomplete common rail. It is sort of like trailer wiring - never try to work on it unless it is hooked onto the vehicle as the hitch is often the common ground. When the common wire is broken, the electricity will feed back funny through any other circuit it can find. On a trailer this means turn lights through the brake lights etc. On a model railroad this means through any other locomotive on the track, through the second power pack, through the accessories, etc.
TZ:
Your mention of brake lights reminds me of a Dodge Diplomat I once had. If you shut off the engine, but placed the wipers in ON, the turn signal lever in either direction, and turned on the 4-way flashers, current would take a weird path back through the turn signals and the wipers would jerk across the windshield in time with the flashers. It was amusing, and it wasn’t just my Diplomat - another one I had did the same thing.
And people laugh when I gap both rails and solder ALL joiners, including at the turnouts. They don’t laugh when they have to go chasing connectivity problems on their own layout.
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Hah! Congratulations. I didn’t think of that one, even though I have had the experience with tail lights, brake lights, and turn signals on old cars.
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And it was the exact same tempo as “Only You” by The Platters.
http://www.youtube.com/watch?v=ZEe4zMBQlaQ
Dave Nelson