I’m new and need help. Using Kato Unitrack (HO) running 3 Atlas locomotives with DCC and sound (all purchased within the last 18 months). Layout was working fine until I installed a reversing loop. Bought an MRC reversing module, and believe I connected it in accord with the directions. First trip with a loco and it traversed the loop just fine. On the return trip, it stopped and shorted out the DCC. Tried it with another loco and it shorted out again. Tried another loco and it worked fine. Tried the 3rd loco and it too went fine. Operations seemed to go fine until today. Now every loco shorts out in the reversing loop. It always happens at the same spot; where I have installed one of the pairs of insulated track connectors.
Put a locomotive on the reverse loop and turn the headlight on. Then, take a paper clip, small piece of wire or a pair of alligator clips and “jumper” across the insulators on each of the rails, one at a time. Watch the headlight as you do this.
It should stay on all the time, or perhaps flash briefly and then come back on. This tells you that the auto-reverser is working and is wired correctly. If the light stays out as long as you’ve got a jumper over one of the insulators, it’s most likely a wiring problem.
On the other hand, if this simple test works but the engine still shorts when running, you may have one of those wheel-gauge problems.
Also, what happens if you go through the loop the other way?
I don’t know what wheel gauge would have anything to do with it.
Most problems with reversing loops are either caused by a misplaced set of feeder wires or improperly gapped rails so that the reversing loop is completely isolated electronically from the rest of the layout.
A third problem is a properly wired and gapped reversing section that is not long enough to accomodate the longest train on the layout. This problem is less likely unless your train includes lighted passenger cars or lighted cabooses. However, even an unlighted train can cause shorts due to metal wheels if the reversing section is too short.
If your reversing section is longer than your longest train, then check your rail gaps to be certain that your reversing section is completely isolated from the rest of your layout. If it is, then the problem is most likely with your feeder wires. The only set of feeders to the input side of your auto-reverse unit should come from the main bus wires. No feeders from the main bus should connect to any rails inside the reversing section. Conversely, no feeder wires from the reversing section should be connected to the main bus wires. All feeder wires within the reversing section should connect to the output side of the auto-reverse unit.
If all of the above problems are eliminated, then the problem is the auto-reverse unit. In that case, it would either be defective or else it would need to be adjusted to the proper setting for your overall system.
As I re-read your initial post, the shorts were intermittent at first, but now the shorts are constant, The shorts always occur at the same spot where you have installed insulated track joiners.
Are these shorts dead shorts that shut down the DCC system or does the engine stop or pause and then continue?
What if you just run the engine through the affected area instead of the entire train?
If you are running an entire train, not just an engine, through the reversing loop, does the engine make it completely through the reversing loop before the short occurs?
Tell us more if you can. Can you include a drawing or photo of the reversing loop or at least describe the affected area in more detail?