Light not working on Digitrax 126D mobile decoder

[Hawks Rule]

Installed a Digitrax 126D decoder in a Proto 2000 FA2 Loco.

Eveything worked fine Fwd, Rev and then the light (LED+resistor) did not turn on.

Took the decoder out, checked the light  with a 9 volt battery and it worked!

So, it's not the light.

Emailed Digitrax with this issue and here is their response.

...You may have to bypass the resistors and/or diodes on the light board to get the lights to work properly.

I do not understand what they want me to do.

Need help.

Thanks

 

[RR_Mel]

I think they are assuming you are using the Proto control board in the locomotive.  Me too.  There may be several parts on the control board that are in series with the LED.

 

The Digitrax decoders provide a switched voltage so between the blue wire and the white wire with the headlight on there should be about 12 volts at 125ma max available.

 

Digitrax says 470Ω resistor in series with an LED, that is pushing the LED at close to max current.  A 1,000Ω resistor would drop the current to a bit under 10ma.

 

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

 

[BigDaddy]

LED's have a polarity.  Blue goes to the + side

[Hawks Rule]

Hi, I am using 1000 Ohm resistor and had no problems for about the first ten minutes that the Loco ran, then the light went off, but the Loco still ran Fwd and Rev.

[Hawks Rule]

I checked the light once again with a 9 volt battery making sure that the blue wire was + and the white on the - and it works!

[mbinsewi]

Sounds like a connection problem to me, maybe a loose wire, something not making a constant connection.

Mike.

[RR_Mel]

Do a decoder reset, CV08.  Set it to 008 for full reset or 009 for everything but the Speed Table.

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[Hawks Rule]

I did a reset CV 08, still the same thing. I am wondering now if it's the decoder.

[mbinsewi]

Well since none of us can see your loco, or how you wired the light, and the wire connections, the track, the wheels and if everything is clean, all connections are good, and the reset doesn't help, just go get another decoder, there not expensive, most places around here sell them for about $17.

I don't what else to tell you.  Are you wiring this through the excisting board? or did you remove it, and hardwire the decoder.  If your using the board, something must be wrong with it, take it out, and hardwire the decoder.

Like what Digitrax told you.  Since they didn't manufacture the locomotive or the original board in the locomotive, they are giving some possible work around solutions, and taking the board out of the equation.

Mike.

[RR_Mel]

I’ve beat up a 126 decoder pretty bad over a few years and they hang in there pretty good so I don’t think anything you did dinged it.  If it’s new it might have died from Infant mortally.  Check with Digitrax to see if they will replace it under warranty.

 

From the way you described it working OK then just quitting it sounds like it just died.  I would try the LED on the yellow wire and see if it works in reverse.  If it works in reverse you could swap the motor wires and make reverse forward.  Or change the CV 29 to reverse direction.

 

You might check closely and make sure the white wire didn’t or doesn’t accidently touch the blue wire, even a momentary contact with the light on would ding the decoder and takeout the decoder switched low for the headlight.

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[Hawks Rule]

Thank you all for your help. I will contact Digitrax tomorrow and get a new one under warranty.