# LGB 20882 Uintah Mallet #51



## okmailing (Jan 11, 2011)

Experts,

Having enjoyed running my Uintah train for some years now, a particular issue keeps bothering me:
On my LGB 20882 the directional light works only in the backwards direction. Meaning, it is supposed to come on going forward but it will only come on going backwards.

Do you have any idea for me to figure out what is causing this ?

Thanks much,

Oliver


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## Axel Tillmann (Jan 10, 2008)

Oliver 

Maybe something int he electronic got screwed up, or the wiring got wrong.


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## Dan Pierce (Jan 2, 2008)

Does this model have MTS or some other form of digital control? If so, then there is a CV for light direction control. 

Also, there are connectors on the DC boards for forward and reverse lights. 

Or, were motors changed out and installed backwards?


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## Trains (Jan 2, 2008)

Bad bulb?


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## Madstang (Jan 4, 2008)

I agree with Don....remove the obvious, narrow down to what it really is, electronics is a much bigger problem!

Bubba


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## stevedenver (Jan 6, 2008)

heres a guess-
i have one and have had it apart and mine is analog-and i presume yours is too

the bulb seems not to be the problem because it lights steadily albeit in reverse

so somewhere a diode is reversed

and i presume this LGB engine runs the same direction as alll others using the same track polarity

heres a suggestion -cheap fix -your light will always be on 
if you dont want to find the offending diode

jump the light wires (little metal tab 'plugs' on the ends of the wires to the smoke plugs-both are 5v output
by jump i mean simply use the same pins that the smoke unit uses on the board-and put the lamp wires on these pins
(this presumes your smoke unit works) 
the plugs slide onto these pins

you could either solder onto the metal tabs which hold the wires on the smoke units plugs
-ie piggy back
or run a small piece of wire from each plug to the light plugs-ir wires if you decide to cut off the plugs (iinsulate well !!!! )

or could trim each plug to half its length and stack onto the smoke pins--but im afraid you risk crushing the plug unless you have some very sharp rail cutters and even then youll need to re-open the plug with a metal point/pick so they will again slide over the board pin

or if you simply get to the smoke units wires -strip a section and hook up the light wires -the sides /colors dont matter


dont think youll have a problem

i jumped classification lights (6 v total) to my Mikado's smoke unit and have had no issues for many years now

i would caution you however-as i did work on my german mallet with sound-the boards are very delicate-you must avoid bending any of the capacitors or other components-
the soldering is stiff and can crack with anything but very careful handling-the key with LGB is never ever force anything-everything fits easily -but sometimes there are tricks or things that need to be removed , aligned etc
some of the engines are like Rubrics cube in complexity


and dis-assmebly isnt tough-

SOOOO.......... youll need an exploded view and perhaps an schematic-go to champex linden and find the loco and open -then open the buttons with this stuff 

the smoke unit plug WILL work -your light wont be dimmer, and the smoke unit will work the same-this i know


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## Jerry McColgan (Feb 8, 2008)

Steve described it pretty well and his solution of using the smoke wires is a good and simple fix. You could add your own diode and get the light to work correctly with the connection to the smoke wires.

The wiring of the Uintahs is fairly simple:













http://1stclass.mylargescale.com/je...0882-1.PDF

LGB often puts the diode in the wires to the light (such as in tender lights).

I would wonder if the wiring to the headlight does not include the diode and if so using those wires will give you a 50/50 chance of having the same problem if you use the smoke connection. 

I also wonder if the solution is not as simple as reversing the wires at the circuit board to the light. If the diode is in the wires to the light this could be the cause of the problem and the solution to it. If the problem was elsewhere I would doubt that it would be in the circuit board but if the loco has a decoder I would guess that the problem could be in the decoder programming.

I have always been intimidated by the complexity of my Uintah (21881) and I have never taken it apart so this is guesswork on my part. I think there was a 2nd generation of the LGB Uintah and if so I do not know if the above wiring is correct for it.

The Uintahs did not originally come with factory installed decoders. 

http://1stclass.mylargescale.com/je...0Sound.pdf

If it was my loco I would first determine if it has a decoder and if so check the decoder (I am guessing that the decoder could control the headlight but I am not sure).

If there is no decoder then I would first try reversing the light wires where they plug into the circuit board.

Then again all of this may be dependent on your willingness to at least partially disassemble your loco.

Good luck,

Jerry


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## okmailing (Jan 11, 2011)

Excellent, 

This is what I needed. Thanks to you guys I have a few good leads to follow through. I will let you know what the problem was and which fix worked once I have figured it out. 

Oliver


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