12v lights not working

[WhiteRose158]

Evening all,

 

I've just re-wired my layout and have hit a snag with my 12v lights.

 

I have only a basic knowledge of wiring and electrics, but have wired it up according to my knowledge of the basics as I normally would. However, despite my circuit checker detecting a 12v supply at all terminals, junctions and right at the light input themselves, none of the lights come on. When I wire them up individually, they all come on. I've tried to illustrate my map below and should add that I've tried using T-Tap junction clips for the first time with this setup (if that's a relevant point). I've tried powering it with the 'track' output from an NCE PowerCab and also a simple 12v supply from a cut plug, which has previously worked.

 

On the circuit are two buffer lights, a small LED light strip and three tiny LED lamps.

 

If anyone has any ideas I would be very appreciative. Forgive me if I've omitted any key details...

Edited November 23, 2020 by WhiteRose158

[WhiteRose158]

N.B. I've also reduced the number of resistors in the whole circuit to just one, but to no avail.

[smokebox]

If these are LED lights, have you got the wiring the right way round? 

 

[WhiteRose158]

I believe so. If one of the lights in the circuit was the wrong way round, would it stop the whole circuit?

[DCB]

You could disconnect them and reconnect one at a time, ensuring each one works before adding another.  If the first one does not work  reverse the connections and see if it works.   You may have blown the LEDs with the experiments so re check each one works before continuing.  LEDs don't last long on 12 volts without a resistor, milliseconds.

[WhiteRose158]

I've found that the T-Tap's haven't cut properly through several of the wires....which, in theory, would explain why there is a problem.

 

I'm going to re-check them all tomorrow to make sure they're properly cut and will provide an update

[WIMorrison]

Sound like you have used the wrong size of IDC

[Tricky Dicky]

32 minutes ago, WIMorrison said:

Sound like you have used the wrong size of IDC

Got to agree, if you are using 7/0.2 wire  which is the equivalent of 24 AWG then even the smallest of the T-taps (Red) will struggle to displace the insulation as its minimum range is 22 AWG.

 

Richard

[KeithMacdonald]

They're not Lucas light bulbs are they?

[WhiteRose158]

11 hours ago, KeithMacdonald said:

They're not Lucas light bulbs are they?

 

No, I've got a basic LED strip from Maplin (I think), small TMD lights (the origin of which I can't remember) and two buffer stops from express models.

 

I've checked all of the T-Taps, cut the wires more in the ones that weren't conducting, tested all of the junctions etc. and still nothing. I've also just blown one of the buffer stops when individually testing each light (I put the power to the wrong side of the resistor and it went pop).

 

I'm at a loss as to what's happening, especially considering the fact that there is power clearly going through the whole circuit in very much the same way as it was before I re-wired things 

Edited November 24, 2020 by WhiteRose158

[WhiteRose158]

The problem is almost certainly the lack of agreement between the T-Tap and wire width. I've manually cut through the wire cover down to the strands, pushed them right down into the tap and hurrah. Lesson learned  as my layout has been ten years in the building (with several of those years spent abroad so no progress made) I've got a mix of wire widths and types going on, which in the end will need standardising!

[KeithMacdonald]

@WhiteRose158 Glad you've fixed it.

 

Just in case anyone didn't get the Lucas reference, the thread title "12v lights not working" reminded me that Lucas was colloquially known as the Prince of Darkness.

 

http://mez.co.uk/lucas.html

 

The Lucas Replacement Wiring Harness Smoke kit might still available on eBay.

[Tricky Dicky]

3 hours ago, WhiteRose158 said:

The problem is almost certainly the lack of agreement between the T-Tap and wire width. I've manually cut through the wire cover down to the strands, pushed them right down into the tap and hurrah. Lesson learned  as my layout has been ten years in the building (with several of those years spent abroad so no progress made) I've got a mix of wire widths and types going on, which in the end will need standardising!

I think you do need to look at your wiring and make sure it matches the specification of the T-taps you are using. If you are going to the lengths you describe above to make the splice then the long term prospects are that you will have the same issue again as a loose connection between wire core and displacement blade will simply produce a high resistance join similar to rails and rail joiners. IDC connectors are a very simple way of splicing wires but if you do not match your wires to the specs then they can be troublesome.

 

Richard