N scale RDC decoder install

[Jimbo]

I’ve had a pair of Kato RDCs for many years that I finally got around to installing decoders.

I purchased two Digitrax DN143K2 decoders, and I thought my first installation went well.  BUT… when I went to try it out, it appears that there’s an issue with the lights.  It SHOULD have the headlights yellow and the marker lights red.  BUT… I get either BOTH lights yellow or BOTH lights red.  At first I thought it was a CV issue, but it isn’t… on one end, the red light shows up where the headlights are, and the yellow light shows where the marker lights are.

I’ve installed the light boards EXACTLY like the photos in the instructions, but either I installed one of the light boards backwards (which doesn’t seem likely) or there is a manufacturing defect where they installed the red and yellow LEDs wrong on one of the boards.


Has anyone else had this issue, and if so, what was the resolution?

(I’m holding off on installing the other RDC until I get this one figured out.)

Many thanks,

Jim

[peteski]

IIRC, the LEDs on the Kato board (and likely on the Digitrax boards) illuminate different set of light pipes.  If they were installed incorrectly on the light board at the factory, you would end up with red headlight and yellow marker light.  On yours are the LED on both boards illuminating  the proper lights (i.e. the red LED is located in a place on the light board which illuminates the marker lights)? Maybe the wiring between one of the light board and the decoder is wrong.

I don't think it would be decoder's programming since I believe the LEDs between the light boards are hardwired so red on one board is hardwired to yellow on the opposite end board.  If you get this figured out, this would also be a good time to replace the yellow LEDs with nice warm-white ones.  Yellow headlights look a bit cheesy.

[Jimbo]

IIRC, the LEDs on the Kato board (and likely on the Digitrax boards) illuminate different set of light pipes.  If they were installed incorrectly on the light board at the factory, you would end up with red headlight and yellow marker light.  On yours are the LED on both boards illuminating  the proper lights (i.e. the red LED is located in a place on the light board which illuminates the marker lights)? Maybe the wiring between one of the light board and the decoder is wrong.

Actually, on one end I DO get red headlights/yellow marker lights.  I thought I explained it this way, but upon re-reading it, I see I wasn’t clear.

I didn’t realize the two light boards were hardwired this way; I thought they were wired across two outputs in parallel (and therefore would behave independently.)

I sent a note off to  Digitrax; I’ll report back what they say.

Thank you for your reply!!

Jim

[nightmare0331]

It's been a long while, but I seem to recall a few batches of these decoders actually being wired incorrectly that required modification.

I'm not sure how old your DN143K2 decoders are, so that doesn't help narrow it down.

Kelley.
www.dufordmodelworks.com

[peteski]

They are hardwired because this setup only used F0F and F0R headlight functions.

For F0F function output is  hardwired to the front LED board's yellow LED and rear LED board's red LED, and F0R function is wired to the rear LED board's yellow headlight and front LED board's red LED.

Each pair of LEDs (and their resistors) are actually wired in parallel (so each function output drives 2 LEDs).  At least that is how I remember things (I have looked at that decoder some time ago - not using one myself).

You might be able to trace the wires and then re-solder them to the correct solder pads.

[Jimbo]

It's been a long while, but I seem to recall a few batches of these decoders actually being wired incorrectly that required modification.

I'm not sure how old your DN143K2 decoders are, so that doesn't help narrow it down.

Kelley.
www.dufordmodelworks.com

I just bought them, but who knows how long they’ve been sitting around; I doubt there’s much demand for them right now… so they are likely old stock.


Jim

[Jimbo]

Following up:  Digitrax told me to send it in for repair.

It’s definitely a hardware issue.

Jim

[N Scale Train Boy]

Good to know, I'll probably have to do the same then, since Im having what seems to be the same problem.