DC LGB Engine Forward with reversed polarity

B

Brian Stevens

Registered
HI
The YTM has a layout with DC controls and a fully automated 2 engine operation using hard wired logics (magnetic reed switches, solenoid switches for speed and turnout controls and fixed variable resistors for speed controls. The power system switches the polarity of the tracks and diodes to isolate the engines from both operating at one time. It is required that one of the engines is wired to run forward given the opposite polarity. Since I inherited the system and the engines ( and having to replace worn out engines) we are able to run only one engine in the normal forward mode.
Does anyone have information about how to change the engine to the opposite mode?
Engine LGB 25554 White Pass & Yukon ALCO Locomotive non digital model but with sound.
 
You need to swap either the motor connections, OR the pickup connections (not both or you're back to where you started!). You'll need to access the connections to both gearbox units on the loco, and they will most likely be in the form of a long black plastic plug with four terminals, wired to a four-way (all black) ribbon cable with then plugs into the loco's main circuit board. You may be able to see and access the spots where the four wires are soldered onto the plug's pins, if so then you can EITHER unsolder and cross over the INNER pair of wires, OR the OUTER pair; the inner ones are the connections from the track power pickups, the outer ones the feeds back to the motor.

Jon.
 
And..
You MUST swap the SAME pair of wires on each motor-block, else you will be cross-feeding into what (if any electronics) is in the loco..
The inner pair may well be the easiest, as the two connections are right next to each other..
This will also make the directional lighting correct, which switching the motor connections will not.
 
PhilP said:
And..
You MUST swap the SAME pair of wires on each motor-block, else you will be cross-feeding into what (if any electronics) is in the loco..
The inner pair may well be the easiest, as the two connections are right next to each other..
This will also make the directional lighting correct, which switching the motor connections will not.
Click to expand...

Couple of very good points there, Phil, thanks for adding them!
Jon.
 
dutchelm said:
Alternatively remove the motor, turn it upside down & replace it.
Click to expand...

Yes, that works too, but just be aware of the little locating lug that prevents the motor turning itself within its mounting..... on some models this lug is part of a small black ring that slips over one end of the motor casing... this lug has to be in the correct position in order for the gearbox to properly close up again.

Jon.
 
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