Randy, the original wiring was simple. Wires from each track. from both trucks, went to a tab on the motor, and the wires went to the headlight assembly from there. So the juice to the headlight assembly was whatever the track voltage was. I suppose there could be a bulb with a diade, less likely an LED with a resistor. It looks from the outside like there's a lightpipe from inside to the headlamp lens, so I would have to take things apart inside the cab interior. Would they cement the interior stuff in or might it pry off? Maybe call Walthers??
I guess the bottom line will be that it's time for me to learn how to install a LED headlight (w/resistor). But I'm inclined to do something like swap the wires first to see it work again. In theory, it could be the decoder settings, a poor solder connection, or non-functioning decoder light output, but those are less likely I'd guess. Maybe the bulb burned out when powered, but I thnk I'd have seen that.
Paul
Modeling HO with a transition era UP bent
Were there any circuit boards, or any components, between the light wires and the motor> Or were the wires going up to the light position in the shell literally soldered to the motor wires? If the latter, and on DC it only lit up while going forward, there must be a diode in there somewhere. If this is the case, maybe you do just have the wires backwards. It won;t hurt anything to flip the white and blue wires. If there is a bulb in there though, with DCC it will get full power, equivalent of full throttle, at all times, and may melt something, especially if it is fully enclosed. Pain though it may be, it will be better in the long run to pull out the bulb and replace it with a golden white LED and 1K resistor.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Today I put a TCS M-1 motor decoder in this item that I recently acquired, new in box DC (about 15 yrs old) which ran ok on DC and the headlight worked when going forward. Since the headlight was wired in parallel to the motor, I presumed it was a bulb and that no resistor was required since it could see 12+ volts DC.
So I put in the TCS, wiring to the motor and track ok and it runs ok on DCC. But the headlight, wired to the white and blue (function common) wires does not work. I doubt it is an LED and I burnt it out with excess voltage. I don't think I can get it going with a CV change, thought I have only fiddled with it via the NCE cab and could put it on the program track with DecoderPro. Resetting it with the NCE did not help.
One thing I wonder is whether it is a bulb with a diode, since on DC it only functioned going forward. How else could it only work one way on DC? If there was a diode, maybe I need to reverse the wires? I can't easily put a meter or test voltage (a battery) on it without cutting wires as everything is soldered and the joints cover with shrink tubing. It would be hard to get at the bulb as there may be cemented covers on it in the cab roof interior, and really getting at it may require somehow removing the roof (from the shell).
Any suggestions are most appreciated.