Hi Fellas, It's happened again with a short circuit on my large HO scale layout. I've been trying to find a short video on YouTube on how to detect where the short is happening, however, all the videos are on a 2 track system. Can someone either explain how to detect the short and give me the link to a video on YouTube as this is a lot easier to understand.

Regards
Greg

First thing to do would be to remove ALL rolling stock from the layout.
If there is still a short, then you have eliminated all your locomotives and coaches/cars as the cause and the problem is with the track or wiring.
On a small layout, it is possible to detect the location of the track short by sound or smell. On larger setups and setups with complex wiring, this becomes more of an issue.
Listen for sounds (sizzling), look for signs of a short (heat damage, burn marks, etc)
With a digital layout, you normally have a few seconds before the system trips. Check areas where wiring is connected to the rails to ensure that a wire strand is not making contact with the ground/live.
I have seen this with K Track feeder sections. With C Track, it is more frequently bent tabs under the track which can cause shorts.
First question is what track are you using? M, K or C?

Can you describe your setup? How many transformers/boosters? What controller? Is the short affecting one section or the entire layout?
Are you powering accessories (lights, signals, etc). Is there a possibility of a short between that circuit and the track circuit at some point?
It can be frustrating to have to check every track section for contact issues.

Looking for Maerklin specific videos is often easier when searching in German (Maerklin Digital Kurzschluss finden or similar)

As Maerklin now uses DC power for digital operation, you can use the same instructions for short detection as for a DC/DCC layout.

One of the first things I would recommend is to swap out the power supply track section(s) and test to see whether the short occurs with the layout disconnected as well as with the replacement track section.
This will identify or eliminate the feeder track as the source of the short. If you have multiple power sources (transformers/boosters), repeat the same procedure for each one.

You can try submitting your question to digital(at)marklin.com to see if Curtis or Rick have any suggestions on how to narrow down your search for the cause.

Regards

Mike C

Do you still use old time wagon lights?
For many years ago when i did had Märklin train i did had short circuits caused of the lighting kit 7335!
You should check if there are fault with the trains, locomotive or wagons with the old time lighting are also possible troublemaker.