Just finished install of TCS MC2 decoder in a Bachmann RF16A Sharknose. Replacement decoder obviously a great improvement over OEM decoder. Everything works fine except I can't turn the headlight off. I've got it set up for Rule 17. I've tried various CV adjustments using my tried and not so true "shotgun" approach. I'm running a MRC Prodigy Advance system and I did use the stock LED with a resistor on the negative lead. LED is wired to white and blue leads from TCS decoder. So.......at this point I'm open to any and all suggestions.
Thanks, Jon
Have you tried resetting CV49 to 0, which is plain old directional headlight ont he white wire? F0 or the headlight button, whichever the PA has on the handheld, should then turn the light on and off. If that works, then you may have misinterpreted the settings for Rule 17. For Rule 17 all you should have to do is set CV49 to 8 and leave the rest alone. You can also try resetting to defaults and starting over - with the factory defaults the headlight should come on moving forward and turn off when you go in reverse. Set CV30 to 2 to reset the decoder (resets all CVs to the defaults shown in the instructions, and sets address to 03).
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy,
I'll give CV49 to zero, it will be a good sanity test. I did try CV49=8, I think, I was fiddling with so many CV data points that...... I'll try your suggestions about starting over if necessary.
Guess I'll go to reset mode; neither CV=zero or CV49=8 made any difference. LED stays on going in reverse and does not respond to F0. Keep you posted on situation.
Jon
Could be a bad decoder. Usually when a function fails it stays OFF though. Hmm, could a small strand of wire from cutting the leads gotten in the decoder? The MC series aren't wrapped like the T series, are they? Seems VERY unlikely but hey.. Regardless, you are in good shape since TCS has a goof proof warranty and will repalce a decoder even if you broke it while installing it.
Now I need to get a new TCS decoder - I used some T1's a while ago, before they had BEMF, and they worked well, but I like BEMF. I just don't want to go back to DH1763L0's in my P2K, that odd 'hump' in speed is annoying even when mostly tuned out. Curious to see how good (or bad) TCS' BEMF control is.
This would be second decoder to return to TCS for light function problem. It's annoying because everything else works absolutely perfectly. Tomorrow I'll do the reset and carefully go through the process for a resolution. Could the "wrong" size resistor on the negative lead of LED be the problem?(I'm grasping at straws here )
Re your question, yes the MC series has a plastic insulating wrap around the decoder body.
Thanks again,
What sort of LED, and what value resistor are you using? Which leg of the LED the resistor goes on does not matter. You don;t have the LED wired backwards because it would never turn on if it was hooked up backwards.
If you have a golden white or sunny white type of LED, a 1K resistor is pretty much the right one. White LEDs tend to be VERY bright, there's no sense runnign them right at their current limit. I can't imagine a second decoder having the exact same fault, so it must be a CV issue of some sort. i always reset mine (any brand) before the first programming, in case there are some goofy values in odd CVs left over from factory testing. There isn't any sort of sneak path to the LED from a stock circuit board or anything is there?
I just looked at the bulb/led/resistor chart TCS has - those resistor values are WAY too low. The 390 ohm recommended for a 'single 20ma 3.4V white LED' results in over 22ma to the LED.
Also, once you get the Rule 17 dimming to work - it might not dim an LED with the CV64 default of 16, you probably have to use a lower value.
It's getting weirder and weirder, the loco started going backward then forward when given the command to go forward and some throttle......so I reset to factory defaults via CV30=2 and stuttering on command to go forward is now its mode. It's OK running in reverse. Once underway it smooths out. I sure as heck wouldn't want to be the HO scale crew in the cab when it's starting up-whiplash and massive facial trauma! I'm wondering with this new stutter step if that would indicate a short somewhere? Oh, the original light problem remained even after reset to factory default values. What I did notice with the LED headlight is that it is bright when stopped and goes dim when underway. This is a Bachmann unit and I did remove the two capacitors as recommended by TCS. The LED is original via Bachmann and is yellowish and resistor I put in place is 470 ohms.
As further background the original decoder in place by Bachmann was weird also. You would open the throttle in either forward or reverse and the engine would just sit there for several seconds before responding. This is what drove me to replace it with TCS MC2. All other locos I have with decoders, P2K, BLI, Bachmann 2-8-0, Kato all run on the same section of layout without a problem
Arggh....I'm going to check for any wiring screw ups before giving up on the decoder.
Thanks,
Those bachmann light boards also have some choke coils that need to be bypassed. Either they or the capacitors are in series with the motor and so can;t just be cut off, they have to be jumpered around.
Better yet, remove it ALL, hook the orange and grey wires to the motor, the red and black to the truck power leads, and the white and blue to the headlight and be done with it. That board serves absolutely no purpose with DCC. If you run the wires directly you KNOW they go to the right place.
Last iteration as of 1 minute ago. I again reset to default values and address 3. I set desired Start V, Accel, Decel and Top V, set CV61 for BEMF and CV64 for LED value. If I leave F0 unactivated, nominal headlight off(even though it's actually on) the engine behaves perfectly-no stutter. It will creep along at speed step 1 and will accelerate smoothly through entire speed range and likewise will decelerate smoothly to a stop whether going forward or reverse. If I activate F0, nominal headlight on(even though it's already on) the stutter comes back. So........I'll leave the headlight always on and leave it to HO scale vandals to put it out with a good sized HO scale stone.
Now that I know how to get desired engine performance while forgetting about headlight option I'll explore assigning headlight to another button and see what happens. I can always reset to what is now baseline performance parameters. Weird or what? To satisfy curiosity it would be nice to know if problem is original Bachmann LED or the decoder that is cause of the problem.
This link from TTE speaks to a problem with decoder application in Bachmann 44 tonner. As stated previously I removed the Bachmann board and two capacitors but did not remove the ceramic resistors in line with motor-per your message and the link below it sounds like I should have also removed the resistors. Want to be absolutely sure disposing of them will be appropriate(sure sounds that way).
http://www.tonystrains.com/download/PopLocosFlaws.pdf
Bachmann's solution to RF interference sure makes life interesting for decoder amateurs like myself.
Thanks for your help. I see the light at the end of the tunnel and I'm pretty sure it's not a locomotive coming at me.
Yes, this 'resistors' are actually coils, not resistors - and they will interfere with the pulse drive output of the decoder, causing erratic operation. Some Bachmann locos have these and the capacitors all on a circuit board, others are liek yours where they are wired to the motor independent of the circuit board. They should be bypassed for proper operation on DCC.
Most of the Bachmann DCC OnBoard stuff will have the capaciters on the motor. At least all the ones I've seen do.
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
Randy, Jeffrey,
As they say in Japan, "go with the consensus". Sometime today I'll bypass or remove the choke coils that looked to my eye like resistors and report back. As I said previously, with no use of F0 function it runs great but as you have pointed out it still isn't right. Nothing ventured, nothing gained.
Thanks yet again for your counsel,
P.S. On this new Trains.com format the "smiley" box comes out truncated with no way to access all the "smiley" icons. You guys having this problem?
Nope! I got access to 'em all.
Got rid of choke coils and wired directly from decoder to motor. Didn't change anything as regards non cooperative headlight LED. I figured I'd do a sanity test and see what I was getting at output for rear LED(if there was one for this unit), I'm getting nothing so........I figure I've got a bad decoder. As of this moment headlight is always on but engine runs like a champ(love that BEMF) so maybe I'll just live with it. Hey, what's a layout without something that irks you. At some future date I may remove decoder and exercise the warranty. For now I've got other locos that need my "expert" decoder installs.
Thanks for all the help, we certainly gave it a shot.