Hello!
(I know it's long, but please read the whole thing. I want to make sure nobody needs to spend a month asking questions because I wasn't clear)
I'm new to this forum (and sort-of new to DCC), so sorry if I am posting this wrong.
I recently bought a Soundtraxx TSU-2200 DCC decoder that I am installing in an old S gauge train. I have replaced the headlight with an LED and I have added a reversing light to the back. I added lights in the cab and I have also added alternating ditch lights. The only incandesant lights are the cab lights (I did the math, they pull 100ma, and they aren't part of this issue). The rest of the lights are LEDs connected with 1000ohm resistors (except the headlight, it's 470 ohms because it was too dim). They all work perfectly... except the ditch lights.
You are now probably expecting me to go on and on and on about CVs and function mappings and Hyperlight Effects, but no. I have been there.
The problem I am having is much more unusual. I have done lots of research on this, and nobody is having similar issues. This might just be some simple thing that is so obvious it's just a given and it's never written about (When I first wired this, I googled like 6 times if the function common is + or -. Nothing told me, so I assumed it was -. Worst mistake of my life, considering my love for super glue...), but I've been working on it for weeks without any progress.
Okay, here's what's going on: When I turn on my ditch lights (wired to FX5 and 6), they come on as usual. It's fun to watch them flash when I blow the horn. But, when I turn on the headlights, the ditch lights go out. I first thought it was just a misconfigured function key, but I quickly ruled that out considering I still hadn't even touched the function mapping CVs. I tried dimming the headlight to see if it's a power usage problem. When I blow the horn, the ditch lights come on briefly whenever one of them reaches it's brightness peak. I tried replacing the 1000ohm resistor with a 470ohm resistor to see if they weren't getting enough current. They still didn't work. I enabled 'LED compensation mode' to see if that would change how the power flows to the LEDs, but it still didn't work. I honestly don't see what would be wrong with pwm. I have absolutely no idea what could be wrong with the dcc decoder and lights.
Something I need to make clear is, I have been working with LEDs for a long time. I started using microcontrollers when I was 9. I know what an amp is, and I also know that LEDs only require about 5 milliamps, so it's extremely unlikely that the LEDs are pulling too much power. If you remember the cab light I mentioned earlier, I have tried it with it on and off with no new results.
If anybody has any suggestions or is experiencing something similar, please reply. Thank you for your time.
I wonder if a different combination of functions would work. Not sure how SOundtraxx does it but TCS decoders have a couple of different PWM generators that tie to the function outputs for LED lighting effects and if two of them are on the same PWM output then they will always flash in sync. Kind of like having multiple timers in a micro and trying to use the same one for multiple events. Since the problem happens only when you turn on F0, AND you can barely see the ditch light glow when it's at max while this happens, it sure sounds like something along these lines. Perhaps the Soundtraxx documentation will reveal some clues.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hi!
I didn't know someone would reply so quickly!
Unfortunatly, I have read that manual too many times, and the only thing related to this issue is the warning on not exceeding 100ma per function (LEDs use less than 5).
I could try hooking them up to different function outputs, but I will need all of the outputs to make this train work so fixing the ditch lights that way will only temporarily solve the problem.
Thank for trying!
--Lax
Is this decoder hardwired or are you using some type of plug in?
Headlights turning ditchlights off is handled with CV57.A value of 1 should enable FX5 when front HL is on.If only one DL turns on,then add 16 to enable FX6.
To have the DL enabled in reverse,add 2(FX5) then 32(FX6) if needed.
It's hardwired.
Don't worry, I've tested all the lights. There are no short circuits.
Wow! I didn't think it would be an issue like that! I haven't messed with any of the direction settings, so that could be the problem.
There is just 1 thing that wouldn't explain: Why would the ditch lights fade on and off when I turn the headlight off and on? I know this isn't something with Hyperlight Effects, because the ditch lights do come on for a very short burst at the top of their cycles when the headlight is dimmed, meaning it's probably something related to the current changing when the headlight is on (These are LEDs, if you don't remember)...
Good idea though, I'll try it!
Wow! I just tried it, and it worked!
I had no idea they weren't enabled by default! Thanks for all the help!
By default,CV57 enables the ditchlights.It may have been accidentally changed.