Marx steam locos like the 333, 666 and 999 have e Units that are very reliable but some times the get stuck in one direction and can not be freed up. One way to repair is to remove the motor, force the sides out and remove the e Unit and the force the sides of the e Unit open and clean the electrical contacts of the two position switch. I have decided to go the easy way with four of my stuck e Unit Marx motors and bypass the e Unit. This converts the engine to one direction operation but the eUnit can be wired back in if needed. Others have details on how to do the bypass but I have attempted to make is more clear and easy to under stand below.
First wire to run described below
- 1 Cut the wires from the main motor field coil, leaving about 1 inch of wire on each. Scrape off about ¼ inch of the varnish off the ends
- 2 Cut the black wire from the brush holder that has a wire, leaving about 1 inch of it and remove ¼ inch insulation.
- 3 For forward operation, solder the main motor field coil wire towards the front of the motor to the wire from the brush. I installed a ½ inch piece of shrinkable insulation on one of the wires first to provide insulation to the soldered connection.
- See picture below: Follow the black wire. This is the black wire coming from the brush holder with a spring on the bottom and going to the front motor field coil wire near the e Unit
For the second wire to be run below
- 1 Use 3 inch piece of insulated 20 or so gauge flexible wire and solder it to the rear main motor field coil wire and add a ¾ inch piece of shrinkable insulation over the soldered joint.
- 2 Solder the other end of the 20 ga flexible to the headlight outer shell with the screw threads
- 3 If you wish to reduce the amps or increase the speed of the locomotive, cut the wire to the top of the e unit solenoid coil
- See picture below. Follow the lavender wire. The 3 inch piece of wire is lavender in color, the solder connection to the rear main motor field coil is shown on the left and the lavender wire is shown soldered to the headlight outer shell to right.
See it is as easy as 1, 2, 3.
Another write up is below giving more complicated details if you can follow them
https://dfarq.homeip.net/wire-...ithout-reverse-unit/
Charlie
