Have 2 LEDs installed. The one with the white wire is lit, but the one connected to the yellow wire won't light.
When CV 49 and 50 are set to 0 on the program track, both leds flicker, but when loco is set on the main line, the white led lights but the yellow led one doesn't light. Am I missing some CV setting or what?
reverse the led. are you using the blue wire?
The blue decoder wire is the positive input and must be connected to both LEDs. The white wire is controlled by CV 49 for the headlight and the yellow wire is controlled by CV 50 for the backup light. Do you have them wired this way?
With a value of 0 in both CV 49 and 50, the lights will be "directional" -- e.g., the headlight will be on only when the locomotive is going forward, and the backup light only when backing up.
The leds are wire correctly with the blue wire in common to both. The yellow does light at all except when tested and when being programmed.
Meant yellow does not light.
It is a Digitrax DH123 and has been installed for a while. Lights worked fine. When problem started, completely replaced both leds today and started from scratch. Since only the one lights and operates normally, can't figure it our. Guess I could change decoders but this loco is part of a consist and would have to speed match again.
How did you test the LED hooked up to the yellow wires? Did you apply power to the blue and yellow wires while the decoder was still connected? That's probably bad. If you disconnected the decoder first and tried this, and the LED lights, that means the LED and wiring are OK - now, which side of the power supply did you connect to which wire when testing it? Since it flickers when programming, it's probably wired with the correct polarity, but double check. You can compare it to the front light which you say works fine - make sure the blue wire is connected to the same terminal of the rear LED as the front - if you look in the LED you will see one metal part inside is significantly larger than the other, so use that as a guide. The blue wire should be on the SMALLER piece, and white or yellow on the lerger one.
Since you said this decoder is speed matched, you probably don't want to do a CV8=8 reset on it. You cna try just setting CV49 and CV50 both to 0 for simple basic directional lighting and then see if it works. Perhaps some different feature got programmed in accidently. Also set CV33 to 1 and CV34 to 2 to make sure the yellow and white wires are under the control of the F0 function. These things only change the lighting, they won't mess up your speed tables.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I tested the leds out of the circuit with a 9 volt battery. Each lit in one direction and not when leads were reversed. Will check 33 and 34. Working on two different locos with different problems. Thanks.
If you connected the LED to a 9V battery with no resistor I'm surprised they still work at all. LEDs work a lot different than an incandescent bulb, they need the voltage to exceed a certain threshold, but once that level is reached they will pass all the current the power source can provide up to their limit of about 20-25ma for most typical LEDs. If the power supply can provide more, the LED keeps taking, until it goes poof and becomes, in technical terms, a dark-emitting diode, DED, dead. This is why a resistor is used, to limit the total current that can flow through the LED - for a typical white LED a 1K resistor connected to the typically 12V output of a decoder will result in about 9ma flowing through the LED, plenty to light the LED and well within the safe limits.
1k resistors are installed before testing with the battery. Changed CV 34 to 2 and got both leds to light.
Always good to hear about a happy ending. Don't consider it a problem but a learning experience. For me it makes the hobby more interesting.
Springfield PA
paxton58 1k resistors are installed before testing with the battery. Changed CV 34 to 2 and got both leds to light.
That'll do it, somewhere along the line CV34 must have gotten set so some other number which means F0R was no longer controlling the yellow wire. The ability to change just which button controls which wire is great, but if it gets inadvertantly changed it can be a real pain to track down. Especially if you've done all sorts of speed matching and don't want to just reset the decoder.