power for points

[stevieedge]

this is my first layout and I have made a few mistakes, my main problem is getting the points to work properly

All my wiring to the points is within the foam of the model so its impossible to change.

all the wiring has been checked and has good continuity but the power drop on the runs wont power 2 surface mounted soleniods.

I am using a dcc concepts decoder which clearly states its easily capable of firing 2 together but they also reccomend using a certain size wire. which in ignorance I did not. It fires one solenoid very positevly but not 2. If I remove the little spring wire under the plastic cover on both points it will power the points but they dont snap into position and tend to spring back a little from the side of the rail. has any body got any suggestions as how I can get over this as I have 7 pairs of points.

 

 

[Gitter]

hi stevie, could you let the knowledgable people know what your set-up is . controller , railmaster? and whatever, . It's all relevant. No doubt they will be on after Sunday breakfast. 

[stevieedge]

railmaster

elink

4amp power supply

Colbalt ADS-8FX Decoders

Hornby points

hornby surface point motors

probably 25 foot runs of 6 core alarm cables but dont know actual size

I hope there is an easy fix with wiring but fear not. Is there any way to make the points more positive when the little spring has been removed

[stevieedge]

just a bit more on the cables

if i use 3 wires for one motor it works fine when i try to use 3 wires to fire 2 motors probably one the first in line will fire but with not such a positive click of the solenoid

hope thats understandable

[Chrissaf]

probably 25 foot runs of 6 core alarm cables but dont know actual size

.

I've installed Alarms and used this cable. The CSA (Cross Sectional Area) is 0.22mm2 this is very small and in my view totally unsuitable for the high current requirement of a solenoid point motor. You say re-cabling is impossible, but again in my view this is the only practical resolution. There must be some way of finding a route to the point, even if not using the one you previously used. Can you not use the alarm cable to pull in the thicker replacements (remember you need three wires of about CSA 1.0mm2 each).

.

PS - 24/0.2mm wire is equivalent to CSA 0.75mm2

[Fozzy Bear]

What Chris said, and put the spring back or the points will never be any good. They will always pop back open a little bit

[96RAF]

Ive used cat5 network cable pairs to wire doubled up point motors including the little black ones with great success over several metres.

 

I dont know the exact csa of these solid wires though.

[Chrissaf]

Their diameter is 0.63mm, if Area = Pi x r2, then CSA = 0.312mm2

[walkingthedog]

When you say the wiring is in the foam, what type of foam? 

[NormanQ4]

Expanded or extruded polystyrene foam is incompatible with the PVC insulation of electrical wire.

Over time the polystyrene will eat away the PVC insulation.

To avoid this you have to create separation between the two by using a membrane.

A simple method that I use is to wrap the cable in regular paper masking tape where it passes through the foam or any place that they may touch.

[walkingthedog]

That's why I asked Norman, and it is amazing how quickly it affects the insulation. 

[stevieedge]

Thanks for all the advise,

unfortunately it does not sound good

The cabling is sandwiched between polystyrene sheets and is in contact with the sheets. have been looking up the problems of pvc cables in polystyrene to get an idea of time. but it is not very clear as to time scale

from your comments it does look like i may have to find alternative routes to the points and keep an eye on the other lighting cables, as i understand the problem is the plasticisers leech out of the cables and they then can become brittle. the only reference i can find is talking in terms as a reduction in the numder of years the cable has before it goes brittle, has anyone got a better idea of how long it might survive. ie  6 months 1 year 2 years 5 yearrs.

the initial cables were put in appox 4 months ago and i cant see or feel any change as of yet

 

 

 

[walkingthedog]

I got to know about the problem fitting out a narrow boat. We had to wrap all cables in masking tape where they touched polystyrene that was used for insulation. I believe the problem could occur fairly quickly, say 6 months or it could be years. The trouble is the cable looks OK but crumbles when touched or moved.

[RDS]

I had problems right from start with surface mounted motors, so much so that a opted for larger solenoid types, mounted under my board, which is out of the question with your layout.  Another problem I had though was voltage and I solved that by powering all my point motors from an old lap PSU, that provided 18v. I use the ESU decoders that do allow a separate PSU.