St. Blazey's - My first layout - Stage 3 Building

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Here is a rough diagram of which droppers are connected and which are allowing (and not allowing) me to run the routes previously posted.
The red and white lines are roughly where the DCC bus sits, albeit in real life the DCC bus is red and black and so are all the droppers. There are some dropper pairs missing as to the plan, as I ran out of dropper wire, which I now have but did'nt want to jump in and add before the short circuits were solved.

PickupLayoutDroppers.JPG (32.81 KiB) Viewed 5508 times

No = Not connected to bus / Yes connected to bus.
I do see a pattern here,but most if connected cause the short.
Thanks
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Just to make sure
I am running each dropper pair at 25cms each on 7/0.2 with the DCC bus using 32/0.2. Being the size of the layout, this, taken on the advice of previous posts is i'm hoping sufficient?
Thanks
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Just to extend the trust nothing prove everything they are all Hornby or Peco set track points, not previously used or modified.

Sorry Bufferstop I missed this. Yes all Peco ST-240's or ST-241's (LH/RH) and 7 of the 18 are used, but not modified as far as I am aware and hardly used. The rest brand new, carded.
Thanks
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A very quick check with all droppers disconnected. The V rails at the frog should have no continuity between them. It's the point at which the two rails are closest together. The Peco ones come closer together than Hornby, just the spot for a whisker of wire to lodge. Then if you connect all the red droppers first, you can check that there's no continuity between the red bus wire and the opposing rail.

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I think you should disconnect all of the droppers and do continuity checks across the rails. With insulfrogs you shouldn't find a connection anywhere between left and right rails. If there is you will have to start lifting rails. If it's not to difficult to do start by lifting the diagonal track at the centre, and see if the short cct is confined to one half of the board.

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This is where using streamline rather than settrack has an advantage. Joiners(fishplates) aren't spot welded onto streamline points. If you have to isolate a section of rail by cutting off a couple of the moulded fixings you can slide the fishplate clear of the joint. Ain't hindsight wonderful.

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A very quick check with all droppers disconnected. The V rails at the frog should have no continuity between them. It's the point at which the two rails are closest together.Then if you connect all the red droppers first, you can check that there's no continuity between the red bus wire and the opposing rail.

Sorry Bufferstop I am a little confused how to check for continuity?

If it's not to difficult to do start by lifting the diagonal track at the centre, and see if the short cct is confined to one half of the board.

Unfortunatly to remove the middle section at least a quarter of the layout has to be lifted which is what I am trying to avoid if at all possible.

This is where using streamline rather than settrack has an advantage.Ain't hindsight wonderful.

No doubt true. Unfortunatly due to space limitations, the geometry of streamline is too large.
Thanks
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Just re-checking all the frogs and even under very close scrutiny using a small paintbrush I found no rouge wires or any metal touching both rails anywhere.

Thanks
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[Bufferstop]

Sorry Bufferstop I am a little confused how to check for continuity?

Do you have a multimeter that includes continuity tester, or a dedicated "wire tester" .you set a multimeter to OHMS and apply the leads to (in this case one of the bus wires, and the rail you are checking), the multimeter will register either almost zero ohms for continuity, or OL "Over Load" for no continuity. A dedicated continuity checker buzzes or flashes to indicate continuity. You'll get either for around a tenner from Maplin. You are looking for something creating continuity between red and black. Unfortunately you've reached the point where only visual inspection or disconnecting things will isolate the fault. On a DCC layout a single connection between red and black is going to effect everywhere if the rest of the wiring is correct, so isolating the fault is going to involve disconnecting things.

[mjb1961]

Hi End2End ,I suppose you've had no luck as you haven't said ,anyway just to clarify ,on dcc the whole layout has to be live permanently,and there is no such thing as isolated track ,so you do need to fit dcc clips to all the points ,so just try what I said earlier ,fit the clips and just connect one set of droppers/ power feed from controller and try it ,if it doesn't work then I will say no more ,but just before I go ,I know your capable of wiring because of your profession ,but try and picture this ,one side of the track is side A = red wire ,other side is side B = black wire ,over the layout I've connected a couple of power feeds and ensured they are all connected same track to same colour wire ,one of the sidings lead to the turntable ,the tt is dcc fitted ,it has two exits for loco storage ,both of these exits had to be connected to the main track to make them live ,so I connected them again ,same side to same colour,now then when connecting these the first one ok ,the second one short circuit ,why !,so I reversed the red and the black wire on the one exit track and all was good ,that is what I meant when I said they may look ok but they might not be,,,,,,,,all the best ,,mjb ,would like hear if you get it sorted and please correct me if I'm wrong ,,

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MJB if he fits the clips before he's traced the short circuit he'll never find the damned thing, they'll just make it appear everywhere. As long as there's a dropper on any dead end the clips only supply an extra feed through the point blade. They are intended for use on a small layout only fed by one pair of wires. A short circuit is a connection you don't want, adding more connections won't send it away, it will just stop anything working until the original fault(s) is/are found.

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Sorry for the late reply members. As the weekend approaches my workload increases.

Do you have a multimeter that includes continuity tester, or a dedicated "wire tester" .you set a multimeter to OHMS and apply the leads to (in this case one of the bus wires, and the rail you are checking), the multimeter will register either almost zero ohms for continuity, or OL "Over Load" for no continuity.You are looking for something creating continuity between red and black. Unfortunately you've reached the point where only visual inspection or disconnecting things will isolate the fault. On a DCC layout a single connection between red and black is going to effect everywhere if the rest of the wiring is correct, so isolating the fault is going to involve disconnecting things.

Yes I do have a multimeter.... not quite sure how to use it..but yes I do have one I'll grab it and take a look at it after posting this.
For your plan of action Bufferstop, do I need to have the power on, on the bus to read the continuity and I should remove all droppers, test, then just add 1 red dropper at a time checking continuity each time? Or will the mutilmeter just show me without power to the bus?

you do need to fit dcc clips to all the points ,so just try what I said earlier ,fit the clips and just connect one set of droppers/ power feed from controller and try it ,if it doesn't work then I will say no more ,but just before I go ,I know your capable of wiring because of your profession ,but try and picture this ,one side of the track is side A = red wire ,other side is side B = black wire ,over the layout I've connected a couple of power feeds and ensured they are all connected same track to same colour wire ,one of the sidings lead to the turntable ,the tt is dcc fitted ,it has two exits for loco storage ,both of these exits had to be connected to the main track to make them live ,so I connected them again ,same side to same colour,now then when connecting these the first one ok ,the second one short circuit ,why !,so I reversed the red and the black wire on the one exit track and all was good ,that is what I meant when I said they may look ok but they might not be,,,,,,,,all the best ,,mjb ,would like hear if you get it sorted and please correct me if I'm wrong ,,

Thanks mjb1961. I have just purchased some Hornby DCC clips from jadlam so I hope for a delivery from them on Monday. Strange about the exit road on the TT. As I move round the layout with Bufferstops plan I shall try the Red's with faults in the opposite connection to see if removes the faults.

"Single fare to the next stop please guv'na......"
Thanks
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After checking, the multimeter has Ohm settigns of 2000k, 200k, 20k, 2000, and 200.
Sadly no buzzer so no audible reference. Hilix DT-830B.

My probes are plugged into the black and lower red sockets as in the picture.
Thanks
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Hi End2end, No you can do this testing without any power and ball droppers dconnected. Set the multmeter on OHMS touch the two leads together d itsho reger a very low value. Hold the leads apart and it should show OL if its a digital one, or the highest possible OHMS reading if it's a dial type. Hopefully if it's a digital type it will have a buzzer setting for continuity, (zero ohms) makes checking much quicker.
Apply the leads to each dropper in turn in, the same manner as I've set out below.

I can understand your reluctance to start lifting track. So lets try it another way. Arm yourself with one red and one black marker pens and a cloth and meths or some alcohol wipes to clean the rails. Make a long red and black lead long enough to reach the furthest dropper from the controller. WITH ALL OTHER DROPPERS DISCONNECTED connect one dropper to the long lead and connect the lead to the controller. If there's no short circuit move the blades of any points connected to that bit of track. If it's still OK disconnect the dropper tie a knot or somehow mark it as checked, do another dropper, until you get one that's short circuit.
Now you have a single connection to one piece of track, because all other droppers are disconnected, so your fault is an extraneous connection between the rails. with your red and black pens mark the heads of the rails with the appropriate colour, working away from the point where the dropper is connected until each rail runs into an open point blade (see why the clips wouldn't help) or a dead end, you'll have two ends for each colour. Now if there's a short circuit between the red and black, it's somewhere on the bits you've marked. There might be other short circuits somewhere else but with just that dropper the short is on those bits. This is the essential bit, don't test any more droppers until you fixed this short. Once you've found that short clean the rails, mark the dropper OK and move on to another dropper.It's gonna' be long and labourious but it will be thorough. I just can't see any other way you're going to find them. (my money is on three at least.

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After checking, the multimeter has Ohm settigns of 2000k, 200k, 20k, 2000, and 200.
Sadly no buzzer so no audible reference. Hilix DT-830B.

My probes are plugged into the black and lower red sockets as in the picture.
Thanks
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Oh well jsut remember it's zero (or nearly) ohms for a short circuit OL for an open circuit.