Short on DCC?

[Carl L]

Neptune Street - well it was going far too smoothly, I believe now have my first short but would welcome advice. I'll include the image of the layout as it will help explain where I've got to. (If the image appears upside down again could someone kindly correct it - it appears right way up to me.)

Click on image to enlarge it.

The wiring bus has been installed and connected to a NCE PowerCab. I have started connecting the dropper wires to the bus, section by section to make sure each is ok, i.e. no shorts. I started with the two continuous running loops on the upper level, just under the trespass sign on the right. Things worked fine, I could run an engine anti clockwise all the way down to the lower level in the bottom left hand corner of the image, just up to the lift out section, and clockwise all the way back and to the upper level at the right hand side, again to a point just before the lift out section. I hope that makes sense. I have then wired up the upper level of the lift out section, connecting the droppers to the bus wires. Again no problems, the system is powered and the engine now runs across this upper level, but obviously stops after the breaks in tracks on the left.

Now to the problem, I have connected the droppers for the two upper tracks on the left hand side after the lift out section to the connection blocks I'm using, but as soon as I connect the blocks to the bus wires the red LED on the NCE power panel goes out. I take it this is an auto cut out and I have a short? It tries to restore power after 30 seconds or so but goes out again. Disconnecting the section from the bus restores the power. I have checked the wiring, red to red, black to black etc and all the remaining unconnected droppers to make sure they are not touching. All seems ok. I've checked the track topside and can't see any debris causing an obvious short.

Could the issue be the next set of points on the two running lines, the first is a curved insulfrog (oldish) for the left hand loop, and then a right hand crossover of new live frog points (3) into the goods loop. The points have seep point motors connected but are not wired up.

Any help or advice with the issues would be appreciated. If it is a short, how do I detect it or find it? Do I need a multi meter? DCC Has been a steep learning curve to me and obviously will continue to be.

Apologies for the lengthy post.

Carl

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[Walkingthedog]

One simple test to ensure all droppers are on the correct side is as follows.


Let us assume your droppers are red and black. Put a piece of red tape on one side of a wagon and black on the other. Put the wagon on the track with the coloured sides corresponding to a set of correct droppers. Push the wagon over all the layout checking the dropper colours correspond to the wagon. NEVER lift the wagon off the track to move it to a fresh section of track, ALWAYS push it along.

[Mountain Goat]

Just to state the obvious (Just incase it has been missed), the rails soldered onto the PCB strips. Have you ensured you have made a groove in the PCB between the centre of the rails to ensure the two rails are electrically isolated from one another? You may have already done that, but I thought I would mention it just incase!

[Walkingthedog]

Very good question MG. Sometimes the copper is thicker than you think.

[Paul-H]

And sometimes when the copper strip is wide enough for two tracks to be soldered to it, not only does it need slotting between each set of rails but also between each set of track as well, it's easy to miss one or the other, especially on a long and winding layout.

Paul

[Steve M]

The copper strips that can be seen in the photo look to have been cut correctly although it’s worth checking.

The OP also states that he was able to run locos until the last couple of droppers were connected - I know you said you have checked the wiring but it is so easy to get this bit wrong and not realise it. Try disconnecting the last wires that you connected to see if the problem goes away. WTD’s wagon and tape system works well for getting your reds and blacks in the right way round.

I used the same method but added a red dot on the baseboard with a felt pen at every place I needed a red dropper and a black dot for the other rail to give a permanent indication.

I see you have also used a mix of insulfrog and electrofrog points - have you put insulated joiners on the electrofrog V and anywhere else they are required?

[Tricky Dicky]

And sometimes when the copper strip is wide enough for two tracks to be soldered to it, not only does it need slotting between each set of rails but also between each set of track as well, it's easy to miss one or the other, especially on a long and winding layout.

Paul

Zooming in on those areas it appears the OP has done that, but it is always worth running the Dremel down each again in case there is a whisker of copper making contact. If the the copper strips are very near each other across the split a small burr could easily produce a short.

The OP has said his droppers are wired into terminal blocks before connection to the bus. If that is the case and as long as the OP has not gapped any rails or put in IRJs, disconnecting each wire in turn in the affected section should isolate the problem if it is a wiring issue.

Richard

[Carl L]

Many thanks for all the advice, today was the first opportunity I've had put it all into practice.

Re-groved the PCB, and checked the droppers again - no change.

Finally decided to disconnect the droppers on the LH troublesome side and reconnect each track independently and eventually found it. I have no idea why at the moment, but as soon as the droppers for the loop just to the left of the Class 20 on the goods are connected, it shorts. I've checked the droppers again, they are the right way round. The points at each end are insulfrog. Just a little baffled. But at least the main running tracks are functioning.

Admin - comment re the images noted, thank you.

[Rog (RJ)]

I'm pretty sure there have been a few reports of fairly recently made Hornby points being faulty from new, causing shorts. I'd check them out first.