Fault Finding Fun With DCC

My DCC layout is just a standard Hornby oval with additions up to F. It uses two accessories modules to operate the points. Of the 7 sets of points 6 are under the baseboard and one is above. That one needed the above table installation because a part of the baseboard framing was in the way. This prevented under board installation.

Ok! It worked fine at first. The layout had only one power connection to the track at one side of the oval. No soldering of fishplates was done. One day when I was using it, the second accessories module stopped working. On investigation, the module had lost its address ID. It was reprogrammed and everything was fine. It continued to work for a time.

Then it failed again. What could it be that keeps setting the address of this module to (0)? After much searching, I found that it would set itself to (0) when there was a power problem. I presume this is to protect itself. The Hornby Elite does not recognise any units that are programmed to (0). However if you use the Elite with JMRI the points controlled by this module worked. The first module would follow up at position (4).

This had me stumped for a while until I figured out what was going on. I went on the internet and checked some of the Hornby forums. Eventually, after much reading, I came to the conclusion that it was a power supply problem. So I decided to put in an extra power connection to the rail on the opposite side of the oval. This being done, there was still no joy on testing. What could be wrong?

Well, the track had been down for a year or so. I reasoned that the fishplates might be the cause. There was plenty of time to build up some corrosion.  The next thing to try was to solder the fishplates. I don’t like doing this because it distracts form the look of the layout up close. After biting the bullet, soldering just the three joints (6 fishplates); the second module was virtually hard wired to the Elite.

At last a successful outcome. Over the course of time the three joints has built up corrosion enough to cause problems while switching. Now I know why many people recommend soldering all fishplates on DCC layouts. They also recommend running feeder wires all the way around under the layout. This might be ok for large layouts but the Hornby oval is so small it doesn’t need this.

Soldering the fishplates is a tedious task. It makes it hard to pull track up later should it get damaged or you want to make changes. I find that soldering a jumper wire around each fishplate, under the table is a better option. There is less likely hood of inadvertently damaging adjacent track if you want to change things. You can just cut the jumper wire and join it again later. Jumper wires don’t need to be real thick either. It’s the feeder wiring that needs to be heavy gauge. I have heard of 10 amp fuse wire being used to connect around fishplates. I prefer to hide my wiring on the layout. Wiring on a layout can spoil the whole illusion should it be seen.

If you are going to solder your fishplates, do it outside the rails. The reason for this is that any build-up of solder between the rails can cause derailments. If you are too young to remember fuses in the house wiring then I will explain. It is a short piece to tined copper wire fitted across a porcelain holder which fitted into a socket made for it. The size of ten amp fuse wire is about 80 sgw. This is quite small. I was in Bunnings the other day. I came across a circuit breaker designed as a plug in replacement for the old fuses.