This article details the modification of the Hornby surface mounted solenoid point motor to  provide a simpler way of connecting the motor to layout wiring.

The wires provided with the motor are short, of fine gauge and easily break off. This modification replaces the wires with a small socket that can be wired with heavier gauge wire more suited to the task of operating a solenoid motor.

Parts required are an industry standard PCB 3-way header socket and matching header pins for each motor. The pitch is not critical as the pins are reworked to fit the solenoid motor PCB. The pins can be purchased in long strips and cut down to 3-way. The sockets are best purchased as 3-way to simplify the task.

Caution: The plastic lugs securing the metal base-plate of the motor are very fragile and easily broken. Great care should be taken when dismantling the device. In addition the small bell-crank that actuates the point tie bar is a loose fit to the solenoid core and will fall out on dismantling of the device. Take care not to lose it and remember to refit it correctly before you put the base-plate back on.

ROB’S RAILS            

Article 13 - Hornby R8243 Point Motor Modification                      

© Rob’s Rails 2020

Dismantling and Modification

Carefully ease the plastic clips outwards and slide the base-plate away from the housing. A small flat bladed screwdriver will help with this. Note on this motor one of the wires has already fallen off.

Remove the small bell-crank having noted its orientation and keep in a safe place for later. Ease the PCB upwards fully out of its slot. There is enough slack wire on the solenoid coils to allow for this.

Note the wiring colours attached to PCB - J5 (common), J6 (one way) and J7 (other way) and compare with the device instructions for reference later when attaching the socket to your layout wiring.

Desolder and discard the existing wires and clear the holes in the PCB with a 1 mm diameter drill bit, taking care not to drift off the hole centre as I have done at J6. Using a fibreglass pencil clean off the PCB tracks to give more soldering grip. Note there is not much space between the tracks around the holes. Whilst the PCB is out of the housing, trim the PCB slot and motor housing as shown to clear the header pins using the socket shape and size as a guide.

Remove the plastic boss from three header pins as these are not required and push the pins into a 3-way header socket. Joggle the pins into a triangular configuration as shown below to fit the motor PCB holes. This involves dog-legging the centre pin up and the outer pins inwards. Check for fit against the PCB.

Using the socket as a holding jig, solder the reworked header pins to the holes in the PCB. This is easier with the PCB out of the housing slot. Once soldering is complete, refit the PCB into its slot and check the pins do not interfere with the solenoid core, if necessary trim or adjust to suit. Also check the socket  and off the pins smoothly. If not reshape the pins to suit.

At this stage it is wise to check the device operates by briefly touching a 9v block battery against the centre and one outer pin then the other outer pin. The solenoid core should snap across each way.

Refit the bell-crank to the solenoid core pin and refit the base-plate taking great care not to snap off the plastic clips. If you are unfortunate enough to break a clip then a dab of UHU or similar universal glue will retain the plate until the motor is installed to a layout. Check the base-plate does not touch the header pins. If necessary place a piece of insulating tape across the pins. It is wise to recheck operation of the motor again.

You can now install the motor to your layout. The header socket simply pulls off the pins so you can more easily solder it to your points wiring. Heat shrink sleeves are recommended over the solder joints to ensure insulation. The centre pin is the coil common and the outer pins are directional. In the event a motor goes unserviceable it is easily removed without having to mess about desoldering wires or disconnecting at terminal blocks.

Remember when fitting these motors to your layout not to screw them down too tightly or they will jam. Slight movement is recommended.

Although the motors will fit on the inside curve of a point they are best placed on the straight side where they cannot interfere with any low slung loco parts.

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