Atlas GP15 Headlight Issue

@C.Vigs posted:

Hi all,

I have an Atlas O GP15 with TMCC, Conrail 1656, item number 0329-1. I purchased it off of ebay a while ago with no-functioning headlights. Everything else works - TMCC, sounds, and electrocouplers.

Marker lights and headlights are attached to the same PCBs, and the marker lights do function. The photos below depict the problem.

Front headlight and marker lights while in forward (the headlight LED is still in the housing in-between the number boards):

Front headlight and marker lights while in reverse:

Rear headlight and marker lights while in forward:

Rear headlight and marker lights while in reverse:

What I've tried so far:

1. Aux2 on my Legacy remote in TMCC mode. IIRC this is a lighting command. Tried it while the engine was powered up in both directions.

2. Conventional operation - no change

3. Disconnected the wiring harness and checked continuity of each wire, from the main TMCC board connectors to each lighting PCB. All showed good.

4. Cleaned contacts on the main PCB and reseated the connectors.

What voltage do these LEDs operate at (so I can test them with a direct DC input without risking any further damage)?

Any other ideas for testing and troubleshooting?

As a last resort, does anyone know where I can get a new light package / wiring harness? On these engines the front and rear lighting PCBs and the roof mounted TMCC antenna are all one harness. I see it drawn on the Atlas part diagrams on their website, but it is not assigned a part number and doesn't appear to be available from their parts list.

Thanks,

~Chris

Ifit is two LED's check the connections. I have had a few where the connection between the LED's was bad. Set a meter to DC lowest setting and see if you get a bump. Also since they both do not work (front and back) the chances are good the board is a dud. Take a close look at the solder joints on the board. Lionel has had voltage as low as 1.5 to up too 14 volts. stay very low a A battery would not harm them with a quick touch. I bet thinking that the LED's are ok.

3 volts to the LEDs or use a meter with a diode tester.   Its just a single LED that powers the whole numberboard/headlight assembly.  If the LED is good, solder a resistor (500ish ohm?) in the cathode leg of the LED, bypass the lighting board and just splice the headlight directly into the TMCC wiring harness. Obviously there's power to the light board if the markers work, so tapping it into the red and black wires should make the LED light up.  If the LED is bad, its a "sunny white" or "golden white" LED. You'll pull it out of there and probably find that its orange in color.  I like to toss those and replace with the TCS sunny whites.  https://tcsdcc.com/1650

BTW, the numberboard assembly pops out of the cab face. Makes it a little easier to work on that bulb.  There's a latch finger on each side and 2 locator pins towards the top face.  If you can get one side started, you should be able to wiggle it out of there. Especially if you end up needing to change the LED out.

The unit may have been used in a consist, (running backwards) .  Assign the unit, to train zero (TR0), which should clears all light commands.   Information available  Lionel document 71-2911-250, pages 22-27, advanced operating techniques,

(Consists or Lash-ups).

Thanks everyone for your suggestions.

Updates:

1. Mike - Assigning the engine to train 0 did not work - I tried it a few times just to be sure. I also tried a TMCC reset / full reprograming.

2. ThatGuy - The front LED appeared to be unresponsive when tested with a AA battery. The rear LED lit up. I ended up breaking the front LED while trying to remove it from the clear headlight lends it was wedged into, so that one is out of the picture completely. The rear LED easily slid out of its lens.

3. Boilermaker - I actually had removed the number boards already, it's not obvious in the photo but it is just resting there. I broke the LED trying to remove it from the clear headlight lens, so that one is being replaced regardless.

Current plan, if I can't figure this out, is to just tap into the power feeds directly as Boilermaker suggests. Tap into the feeds that power the rear marker lights for the front headlight, and the feeds that power the front marker lights for the rear headlight. I have 3 mm LEDs that will fit. Wires will be all over the place, but it'll work.

I'm still also willing to swap out the complete harness if anyone has a lead on the part.

~Chris