Modifying electric points

 The biggest problem with Dublo points, both electric and manual, is the size and position of the mechanism. If you want to fit several pairs of points close together, you can't do it - the solenoid (or the lever) is in the way! Fine if you have lots of space, not so fine if you have barely two and a half feet of fiddle yard space and want to cram in as many tracks as possible.

Several folks over the years have posted guides on how to overcome this. This is how I converted my electric points to overcome the problem. As ever, I accept no responsibility for any trashed points that occur from following this, it worked for me!

We need to mount the solenoid on the opposite side so that it's out of the way. There's two methods of doing this. The quickest and easiest is to take the solenoid from a left-handed pair and graft them onto right handed points, and vice-versa. It can also be done using the existing mechanism, which I'll cover later.

So we start off with two pairs of points, one left-handed and one right-handed...

Before any work is carried out, make sure that the points actually work! - 12v DC from a Marshall or A3 is more than enough to operate the mechanism. If it doesn't or if it's stiff, resolve this before you go any further.

Dismantling is simple, flip them over and undo the single screw holding the back plate, remove the plate.

This exposes the mechanism and the two operating coils are now visible. The points operate via a pivoting, see-saw like mechanism. As each coil is energised, the arm is pulled to that coil, opening or closing the point blades via a small connecting wire and held by a small latching mechanism.

The coil resistances can be checked by attaching a test meter between the centre and outer terminals. Expect a resistance of around 25 ohms between centre & outer terminals and by metering the two outer terminals together should give you the sum total of both coils (so expect about 50 ohms)

The wire that connects the solenoid to the point blades needs to be removed. It will just lift off the pivot mechanism quite easily. It can be extracted from the other end but there is a risk of breaking the paxolin.

Now the latch mechanism needs to be removed. Carefully undo the single retaining screw and support the latch fork & spring as these are under tension. Failure to do this will mean that you'll probably end up firing the mechanism across the room and you'll never see it again!

Lift off the holding cover and then slide out the fork.

Now there's just two more screws to remove, then the solenoid will drop away.

That's everything disassembled, now time to modify...

You will require a drill, a cutting disc or sharp side-cutters. Offer up the solenoid and mark the holes, we need to allow adequate clearance for the latch mechanism - if it's too close it'll jam the points. Here I've actually drilled the hole slightly too close (although I did cheat and used the original holes as a guide and just drilled through!)

With both holes drilled, time to remove some metal. This can be done neatly with a small cutting disc, alternatively use side-cutters, the metal isn't that strong and will bend & snap out quite easily once the verticals are cut. (In this pic I needed to remove more metal on the left side before I refitted the solenoid) 

 Now the connecting wire has to be bent to extend it, it now has further to travel. This is probably the most fiddly bit and it will be trial & error until the point blades can move completely in each direction and the pivot still operates correctly. It'll end up looking like this (if it's too straight it'll be too long and won't work)

 Bear in mind that once the wire is hooked back onto the pivot mechanism, the only thing that will keep it attached to it is the outer cover, so refit this once you're happy with the operation. Then re-attach the latch mechanism, adjusting the cover so that the point blades snap from left to right without too much friction. If this mechanism is too close and the tension on the spring is too tight it will affect the operation. Remove the solenoid and elongate the screw holes if this happens.

Then test the points under power. Again the 12v DC output should be able to handle this. Don't rely on higher voltage or CDUs to move them if they won't function at 12v.

So that's the quick method. Now for the slightly more involved method, which uses the existing solenoid.

The process is exactly as per above but this time we also need to modify the internals of the solenoid.

At first glance, it doesn't look like this can be modified easily, but it can!

We'll need to move the terminal connections to the other side and we'll need that little locating hole for the connecting wire to be moved.

Swapping the terminals & blank end is simple, these just pull out and there's enough wire to swap ends. Be careful with the wiring, it's old and if it snaps off you'll have to re-solder. Not difficult, just annoying!

Now flip the solenoid over and undo the middle screw (there are three), this releases the bracket that holds the pivot mechanism and now it can be withdrawn from the housing. 

Again, at first glance, this doesn't look like it can be flipped over...

...But it can! - Hiding underneath is a second mounting hole, folded over. Straighten this one and fold over the old one (sorry for the blurred picture)

Now refit the pivot arm and retaining bracket, we now have a solenoid mechanism that can be fitted to the opposite side without having to rob one from another pair of points! 

And this is the final result. These have been used extensively in the rear fiddle yard and more recently in the extension yard at the front of the layout.