Bentley MRG Library - Peco Point Motor (Switch Machine) Armature Replacement

	Older Peco point motors (switch machines) had an armature fitted with an activating pin just long enough to operate a turnout when the motor was attached directly to the tunrout base. If the motor is mounted on the underside of a baseboard it is neccessary to extend the pin in some manner. Fortunately it is (or at least was) possible to obtain replacement armatures from Peco, I believe these are what is now fitted to their point motors as standard, which can with care be used to replace the old short pin armatures.
To remove the fibreboard from each side of the coils first straighten the lugs on the coil frmaes so they line up with the slots in the board.
	Then gently prise the boards of the coil lugs. I grip the board with a pair of snipe nosed pliers and gently rock it back and forth such that it 'walks' up the lugs. The reason for the caution is that the wires from the coils to the board are very thin and just long enough to allow the board to be freed, usually. If you break a wire don't panic, they can be fixed (see the bottom of the page).
With the boards free it's just a case of pulling out the old armature and replacing it with the new one. I found it easiest to ease a coil off one end of the armature then turn the other coil slightly so the armature slid out, the wires aren't long enough to simply pull each coil away from the centre. You'll see what I mean when you get to this stage, just take things slowly and gently.
	With the new armature in place we reach the easy bit. Push the lugs on the coil frames through the slots in the fibreboard and, gently pressing the board home, give the lugs a little twist to lock things in place. I would recomend fitting both boards before bothering to twist the lugs. With the boards in place you can hold the point motor between the finger and thumb of one hand whilst operating the pliers with the other.

More than once either I've not been careful enough or the wires are too short such that one or more of the wires from the coils to the fibreboard breaks. So far for me the break has always been at the point the wire attaches to the board. To fix these clean up the very tip of the wire, it's enamelled wire so I do this using very fine emery paper in which I pinch the wire then very gently twist the paper around. Next tin the bared tip of the wire.
	The contact on the fibreboard is actually a rivet through which the wire passes. To make the repair I just melt the solder in the hole and pass a piece of fine tinned wire through, then trim the wire so there's just 10 or so millimetres and ensure the tip of this is also tinned. Personally I use the wire sold for wire wrapping, an alternative method of building circuits dating from the days before PCB's and solder baths.
Then it's simply a case of bringing the tinned tips together and a quick touch with the soldering iron. A little practise and you'll be doing it with no trouble. As you can see the length of the repair wire is important, long enough to make the repair and allow movement of the board but short enough to tuck away when the board is remounted and without shorting on the coil frame.