Do I have a short?

[Carl L]

I think I know the answer, but where to start?



This morning I have had a look at my lift out section, which is on the left hand side of the image. It was tapped the other day, to move it a fraction to realign the tracks; this resulted in the top track on the right hand side (on fixed layout boards) becoming dead (despite having its own dropper feeds). With the lift out section tapped back again, and we are only talking 1mm max, the top track becomes live and the bottom track dead. The movement has occurred as a soldered section of rail, where the two lumps of solder are, which prevents movement, had sprung its soldered joint.

Resoldering the securing rail across the gap resolved the dead section issue (no idea why it should as the tracks have their own droppers). Just as I was tidying up the solder, the whole layout has died, I have no power. Looking at the NCE Power cab and the control panel, it appears as if I have a short, after a few seconds the system tries to power up and for a fraction of a second the board lights up before instantly powering down, as if there is a short.

So to try and resolve the issue, in turn I have; removed the soldered securing rail, completely isolated the lift out section from the rest of the railway, checked chocolates box connectors and bus feeds for any obvious shorts, removed all the stock which was running at the time, hoovered the layout looking for obvious shorts. I cannot resolve the issue, the system will not power up.

Have I assessed the issue correctly and is it a short, or is there another issue? Is there a way of proving the NCE Power cab before further exploratory work is done? Just what further exploratory work - I have no idea, I don’t really know where to start. It’s not as if I’ve done any rewriting, I haven’t, all I did was resolder the securing rail across the two copper clad pcb sections, and that has been there for years without issue.

Not a happy chap this morning, so any help and advice would be welcome. Or it’s the tiddlywinks league.

Sorry it’s been a bit long winded.

MOD NOTE: Moved to the DCC section

[Brian]

Hi
Trying to find a short circuit remotely is neigh on impossible and only best guesses can be made!
Have you left a metal tool somewhere that's shorting across the rails? Easily done, I have the Tee shirt!
Do you have a loco that's derailed anywhere?
Next...Are you able to sectionalise the layout into smaller areas to see which section has a problem?
I've enlarged the image and circled in red two areas that may have something shorting the copper tracks?



As you have a PowerCab try unplugging the PCPs rear small 'Track' connection plug. Does the short go away? If it does then there is a problem on the track or its wiring. If the short remains with Track plug removed then the issue is with the Powercab or its power supply. Assuming the PowerCab works OK with the Track plug removed refit it and look at the wiring to the Bus pair or rail feeds from the bus pair. Have any droppers got crossed over?

Always a daft question, but you are using the Flat cable between PCP and the handset and its plugged into the left hand socket on the PCP when the red LED is at the bottom.

[Mountain Goat]

First start with the control system. Remove the wires to the track and try it on a length of sectional track that you can see that they are the only two wires from the controller to the track. The controller should power up and run a loco that you may want to put on the track to test. Some controllers (Though usually cheapie DC Hornby ones have overload cutout that cuts power even after the fault is removed where one has to switch mains power off, wait for 30 seconds before switching mains power back on. (Whoever thought that one up clearly does not run trains as there is no warning light or other indication other than ones trains don't go! Hope other makes have not got a similar overload system. Just write this incase... (So if ones controller still has no track power after one has tried what I mentioned above, try switching it off and wait a while before turning it back on. Also when testing remove any other express bus or accessory wires just incase the fault is not to your track but elsewhere)).
Now if all works, we know the control system is fine. So we begin by connecting it to the track.
With DC where one wired to cab control, fault finding was easy (As long as one had a light indication or a sound indication on ones controller to tell one that there s an overload present (To me, a visual or audiable indication is essential for a controller, be it DC or DCC, as without this one is going blind), and one could switch off all cab control areas and by slowly switching on each cab control area one at a time, one could instantly tell which track area of ones layout the fault was at. I personally found this so useful and saved so much searching for stray small thin wires or stray trackpins etc that even on a DCC layout, I would still wire it into switchabl zones with each zone having a decent "ON/OFF" toggle switch.
Unfortunately, most DCC users wire their layouts without doing this so fault finding needs one to check every little area of ones layout which can take ages!

But I hope you find the issue. Can be frustrating!

AND NEVER FORGET THE OBVIOUS! Once had no track power. Checked controllers. No power. Checked wiring to the controllers. Nothing! Checked wire to 4 way plug. No power. Looked at switch (This was ages later as had checked everything) to find I forgot to turn the switch on at the mains. Never forget this as I discovered this something like nearly half anhour later which was smbarissing!

[Brian]

MG your lengthy post has a lot of DC (Analogue) chat in it.
This may well confuse the OP as they have a DCC PowerCab. Talking about 'second controllers' etc is pointless

[Carl L]

Appreciate the advice thank you, it looks like a day, or hopefully a couple of hours of testing.

Brian - I so much want to wear the t-shirt, but I think it look’s in doubt.

I’ll let you know.

[Steve M]

Carl, at the risk of adding more layers of confusing advice, you said the problem started when you moved the list out section.
If you can, disconnect and isolate that section completely to see if running returns to the rest of the layout. That may show that the issue is contained within the lift out. That can the be tested for continuity with a multimeter.
Hopefully you will track the fault down easily.

[Carl L]

Hi Steve,

I’m with you on this, I think it’s something to do with this lift out section, as this was where all the issues started with the dead sections. Yesterday I did isolate the section , unplugging the connectors giving continuity with wiring bus, but to no joy. But I’ll give it another go, and failing that, as much as I don’t want to, I’ll remove it ( it’s just a pain lining up 4 sets of double main lines - as you know, wood moves). I will however ‘prove’ the power cab as Brian suggests first.

Thanks for the input.

[Carl L]

EUREEKA! I now know how Einstein felt.

Firstly the short; the Power Cab was proved by disconnecting the track connection plug from the PCP, the short disappeared. ‘Do I have a loco that’s derailed anywhere?’ - nothing obvious, but just handling 5 locos in the shed yard solved the short, something wasn’t sat right. The Project Manager had suggested removing all stock, but did I listen to her……..no.

Secondly the dead section - checking the section which runs the full length of the shed 12ft, there is, unbelievably, only one set of droppers, at the far end from the lift out section. I can’t believe I’ve missed out three sets of droppers. But it gets better, I’d failed to pull the droppers through the baseboard and not connected them! That is beyond basics! The whole section has been powered by the securing rails soldered across the copper clad PCB at the lift out section, and they had spring the soldered joints in the heat.

So whilst is not the ‘tool across the tracks’ tee shirt it must be a basic wiring one!

Tiddlywinks league membership suspended- until next time.

Many thanks for all the contributions and advice.

[Brian]

Pleased to read you have found the problems.
Enjoy running your trains again
Modified Tee shirt in the post

[Carl L]

Thank you, it would be worn with pleasure

The errant loco has been identified, a Bachmann BR class 5. It is DDC converted, is programmed and has run without fault on the layout for a number of years. I have not run it for a few months and it has merely sat in the yard. Why would it suddenly develop a short? Looking underneath it does not appear to have picked anything up. Putting the bogie wheels on first does not cause issues, but as soon as the coupled, pickup wheels, are placed on the track it shorts.

It is currently in disgrace on the isolated programming track!