Large Scale Central

LGB Switch motors not always working on one direction

I have several LGB Switch motors where they don’t throw consistently in one direction. They throw fine in the other direction. They all have issues in the same direction. They do it no matter which of my 51755 control boxes I use, or which 17100 track contact I am using.
I have cleaned them with no change. I am using a LGB 50111 transformer solely for the EPL circuits so it should have plenty of power. The weird thing is my semaphore machines work fine.
Any ideas? Could the transformer be failing?

without much thinking - first thing, i would try, is to install them to the other side of the turnout. just to see, if they behave differently.

this has the potential for a long thread. there are so many possible factors.

do they simply not throw, or do not throw completely? (in the first case try to change the wiring)

are the turnouts/switches on a flat base?
did you take a look inside the switch-motors? (if they might be offcenter)
do they all have problems with the same direction? right or left?
how many switches are you turning with each impulse by a 51755 or a 17100 ?

so far just for starters, to try to get an idea, what might be th cause.


I took them apart and cleaned and centered them. One was very dirty but the other three not very bad.
Right now they are on a test circuit by themselves and not connected to the turnout so no additional load.
When installed I only have one 17100 or 51755 switch wired to throw one turnout.
They all seem to have the issue with the same direction which is weird to me. They are weak and sometimes will throw but mostly do not throw at all. They may throw if I tap lightly on the throwbar. When they do throw, after a couple of tests they stop. Like the coil has warmed up and got too weak to work. But again, this in only on the one side. They are all strong when throwing on the other direction.

I see the motors have two coils. Can one side of the coils go bad without affecting the other side? Just trying to think of all possible options.

Make sure your switch is clean… and the ties under the points are all clean. clean out all area’s of the point paths… can’t hurt

If they all have the same issue with the same direction, it sounds like your a/c source is putting out some dc. When they throw in the “direction of the dc” they should work fine. But “against the dc” is another matter.

This could also be a bad diode, but it seems unlikely that the diode in the reed switch attachment AND in the control box are both bad.

Differently try this. The diodes in the switch box (51755) can fail.

Todd’s theory makes a lot of sense. Try operating them from a battery source. If they work in both directions, then a bad diode or dirty power supply would be the problem.

I agree …with the above and also want to note the main purpose of a diode is to allow the current to flow in one direction only.

as Todd said: This could also be a bad diode, but it seems unlikely that the diode in the reed switch attachment AND in the control box are both bad.

i would beleive, that either the source is not true AC, or one of the cables has a bad connection, or is partly broken.
i would try to change the two cables at the AC output one against the other. if the fault is in the AC source, or the cable, the turnouts should get the problem in the other direction (if i’m not misstaken - so, better wait, if Todd aproves that. he knows wayyy more about electric-tricks than i )

I use the electronic spray that is sold just about everywhere, Home Depot, Lowes, Walmart, hardware stores, etc. It has repaired so many electronic items that I own and in most cases I don’t even have to take it apart, just use the spray tube that comes with the spray and shoot it up inside the switch, etc. It goes in wet and dries to a non greasy clear coating.

If it were me, I would take a known good diode and the a/c power supply and put the diode in series with one leg of the power ssupply and touch the other leg, and the other wire from the a/c supply, to the turnouts and watch their operation. The turnouts should throw to one direction.

If the turnout does not move, physically move it in the other direction by hand and try again and it should throw. Then turn the diode around and do it all again but this time they should throw in the other direction.

This will determine if there is a problem in the power supply or turnout motors.