I have just installed 2 Digitrax DH163LO plug in decoders in my 2 Proto 2000 GP20 engines. All works well except the reverse lights do not work any more (they did work before the decoder install) Because the problem is identical in both units I am guessing that there is a compatability problem?
Could it be the lights couldn’t take the voltage? I know on some of those conversions you have to put a resistor in line with the bulb.
Lights are LED’s and the front lights are working fine. My guess is that LED’s are polarity sensitive and that they are wired backwards in the chip (haven’t checked it out yet)
It could be a simple fix then. Reverse the polarity and see if it works. If it doesn’t, all you’ve lost is some time and maybe some of your sanity.
Some of P2K’s engines have a wiring defect that affects decoders. Here is the text:
Life-Like GP38-2 locomotives have an additional lamp added for the number boards which, as wired, causes problems on DCC (it does not adversely affect DC operation). Since the bulb is wired to the gray (negative motor) pin and the black (track pickup) pin, your DCC system will see this as a short circuit. Disconnect the bulb from both pins and wire it to one of the function leads on the decoder to solve this problem.
Jim
Thats probably your problem, you must have somehow mixed them up on the plug that plugs into the decoder. The DH163L0’s have resistors in them so you don’t need to add them to your LED’s.
I just installed an NCE P2KSR decoder in a new Proto 2000 GP 20 High Hood unit - the LED’s don’t light at all. The locomotive is designed to run long hood forward and when I select ‘Forward’, the locomotive is actually going in reverse. Since the lights are LED’s, would the decoder being reversed prevent the lights from working at all or did I blow out the LED’s by using the P2KSR decoder?
Don Z.
Don Z,
If the locomotive is running backwards and the lights don’t come on, just turn the decoder plug around and all should be well.
Cacole,
Thanks for the tip…I’ll give it a try. I may have to select a different decoder since the position of the existing socket won’t allow the length of the P2KSR to extend in the opposite direction.
Don Z.
Update 3/5/07 6:15PM I reversed the position of the decoder and still have no working lights. The manual that came with the loco states:
Step 2: Remove the 2 screws holding the large circuit board to the chassis and discard the large circuit board and the 2 screws.
Step 3: Plug your DCC decoder into the small circuit board and protect to prevent accidental grounding to the chassis.
Step 4: Place the DCC decoder and the small circuit board in the area previously occupied by the large circuit board.
Nowhere does it state the voltage of the LED’s. With the decoder reversed, the loco does move long hood forward when ‘forward’ is selected on the throttle. I noticed, however, that the crew members are installed facing the short hood of the loco, even though the long hood is marked with the red “F”. I guess I need to turn them around so they can do their job properly.
I guess I’ll place a call to Walthers tomorrow to see if they can straighten this out.
Don Z.
I would go to tonystrains.com and do a proto 2000 search did that with a with a protr 1000 rs-2 and came up with the fix on my lights
dave
Gee, thanks Life-Like/Walthes for changing things YET AGAIN. Mid-vintage P2K locos with bulbs take the DH163L0, no modifications except on the GP38-2 with the screwy number board lights. The DH163L0 is designed with the correct resistors for the P2K light bulbs. Depending on what resistors are included with the factory LEDs, the combined resistance might be too much. Of course, for DC operation a typical resistor for an LED is 470 ohms or 560 ohms, mainly because you would rarely operate with a full 12 volts. However, with DCC, the lights will get at least 12 volts on a constant basis, as soon as you turn them on. The various white LEDs work well with 1K resistors, a typical red or green LED will want a bit more.
I’m throwing my hat in with the idea that the LED for the reverse light is wired backwards. Depending on the wiring for the DC circuit that reverses the lights, it’s almost guranteed it’s wired backwards for DCC operation. The blue lead on the decoder is the common. It’s reasonable that the free end of those LEDs would have one connected to the right rail and one to the left rail for directional operation under DC. Switching in the decoder will result in one LED having the + side on the blue wire and - side on the function, and the other LED having - on the blue and + on the function wire. End result - one LED will work, the other will not since the blue wire on a decoder is always +. Flippign the 8-pin plug ont he decoder won’t do anything with this. But you should be able to pull the plastic caps off and swap the leads from the rear LED. Having it previosuly wired backwards should not have damaged it.
–Randy
Randy,
Thanks for the in-depth analysis. In double and triple checking, I did have Pin 1 of the decoder lined up with Pin 1 of the socket board. Since the engine travels in the opposite direction that it should, I’m assuming I can swap the orange and grey leads from the motor to correct that issue.
As far as the leads from the lights, the correct rear of locomotive light has the blue and white leads while the front light has black and white leads. The leads appear to be regular insulated wire - they don’t appear to be the rigid leads of an LED. At this point, I’m assuming I did manage to blow the lights because they took the full voltage from the decoder.
Thanks for your help,
Don Z.
Hello there, it is unbelievable, I have just run into the same problem with my HO GP20.
It seems to me, that in this loco a) there is the rear LED polarized the wrong way (according to NEM 652 it should be with the Anode on pin 7, with the cathode on pin 2), and b) there do not seem to be current limiting resistors in the LED-wires!
I understand from other replies, that there are some decoders which have these resistors incorporated, but definitely not all of them (e.g. LENZ). If used with one of the decoders without resistors, this would probably burn out the LEDs or the decoders or both.
I have just written to Walthers, I will keep you posted.
For future reference, when you want to run an engine with the long hood forward, the simplest solution is to change CV29. I believe you change CV29 to 7, but that might not be right. I’ve already done it with several Geeps which I run in pairs. The owners manual should have a table for CV29, showing what value to program in for the way you want to use it.
Just received an incredibly silly reply from Walthers. They basically repeated the instructions which came with the loco on how to install a decoder and admittedly didn’t understand what I wanted. Surely, english is not my first language, but sometimes I really wonder whether this is the problem … Fobbing-off people seems to be more and more companies preferred way of dealing with customers enquiries.
So, if you want to get your rear LED going, just try swapping the two wires that go to the rear LED. Don’t change anything else. You can’t do damage by doing that.
Let me know, how you are getting on.
Antonius
When did Proto 2000 loco’s start coming with LED lights?