Both the front and rear headlights have a resistor. Something must be different though because I tried the front lamp in the rear headlamp socket just to see and it didn't work there.....but both bulbs originally worked.
I just tried the front headlight point again and checked voltage. I must of not had the test prods on the prongs that well. I am now getting - 12.9 V for the rear headlight (that works) and zero volts for the front. Sounds like no juice from decoder circuit to the front headlight point (J1). Sounds like something beyond me...I"m assuming it's a fault in the train's pcb?
Before attempting to switch front and rear light boards, make sure htey both have resistors on them, the pictures I've seen of other Atlas Silver locos show the rear light with a resistor ont he board and the front LED just plugs directly to the main board which has the resistor. And anyway that won't accomplish anything - you already know neither LED is blown out. If there is a polarity problem it would be caused by the diodes ont he circuit board used for directional lighting in DC mode.
--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'll test the rear plug in point from the rear headlight to board. As well, I'll plug the front headlight into the rear connection point on the pcb and see what happens.
Both the front and rear lights have their own boards which are screwed vertically into the aluminum framing. If I need to reverse the polarity of the front lamp wires I can use a couple of small test prods and stick them in the front headlight plug and reverse the polarity and touch them to the main pcb connection points, to see if this works.
I'm at work so I'll attempt this when I get home in about 3 hrs. Thanks!
That's why I suggested testing the voltage at the pins for the rear LED which works. If it's also just .308 volts, the low number is caused by the meter interacting with the circuit design and the probem indeed is the polarity on the front LED. Or just reverse the front LED and try it, it won;t hurt anything.
Although looking at pictures of the insides, it seems that the front LED attaches right to the board, and the rear LED is on a seperate circuit board that attachs to the main board, so testing at the connector where the rear LED plugs in may not be an apples to apples comparison.
The wiring from the DCC plug to the front LED is 'fine' since the front light works on DC. There really isn;t much else that could be wrong other than polarity - unless there is another jumper you need to move for DCC operation. But none of the installation pictures shows anythign like this. You won't be able to just flip around the plug for the LED - the shell for the plug is keyed. But if you look carefully you will see tha tthe metal pins int he connector have a tiny tab on one side that keeps them from being pulled out the wire side. You need to dpress this tab and pull the pin out from the wire side, one at a time, then put them back in the opposite way (red ont eh side that was black) to reverse the polarity.
When I get home today I'll give it a try but wouldn't reversing the two wires just give me + .308V at opposed to - .308V that I'm getting now? I just thought the LEDs took more power to run....it almost sounds like I'm not getting juice at this switch. In any event, I'll give it a go and hope for the best. Steve
Steve.
Can you reverse the 2 wires going to the front LED?
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Randy; to confirm, yes I got + 13.1V on blue and white wires at the 8-pin decoder when connected in and - .308V at the connector where the LED plugs into. So it sounds like there's no juice from 8-pin to connector where LED plugs in.....maybe something in pcb circuit route going from 8-pin to connector where LED plugs in?
If you have 13 volts on top of the 8 pin connector then the issue is somewhere in the rest of the wiring from the main circuit board to the LED.
And you now see why almost ALL of my locos have the decoders hard wired instead of just plugged in - there's always some silly problem despite the "DCC Ready" on the package.
SO, to make sure I'm following correctly, on the blue and white wires on the 8 pin plug you get 13V. But on the pins of the connector where the LED plugs in you only get .308V? Or is the ,308V on the board with the LED? It COULD simply be backwards and you only get .308 volts because of the dropping resistor - test the working rear LED the same way and see if it is also .308 volts. If so, the polarity is wrong for the front LED
Don't use the recover option, or the NCE Lighting Effects options, with non-NCE decoders. They set CVs which may or may not be present and perform the same functions in other decoder brands. It syas specifically in the manual that these options are for NCE decoders - don;t do ANY of the special procedures mentioned in the PowerCab manual on non-NCE decoders - for example one of them sets NCE motor control, which uses CV116 to adjust the 'dither' for smoother operation. CV116 on a Digitrax decoder control the function of the F6 output. CV116 on TCS decoders controls the Mars light effect. You may get unexpected reults using those system options on non NCE decoders.
I tested the decoder points at the decoder plug and found +13.1V for blue/yellow (rear) and + 13.1V at blue/white wires (front) so juice is there.......I cleared the chip using NCE recovery step which sets the chip to original settings and re-programmed a loco assignment (didn't program any options, don't know how to do this yet). Again, rear light works, front light doesn't. With the NCE F0,F1 I think is built into the light switch so no programming of basic headlights need to be done (I assume).
The leads going from the train's pcb to the light are red and black wires. At this plug, their should be juice to power the light. I wanted to see if this point J1 on the train's pcb had power...it had -.308V., this point powers the LED (not incandescent bulb). I'll test the board at the 8 pt. connector.
.308 volts is not enough. The BLUE wire from the decoder is +. Yes it is common to all functions but it is POSITIVE not negative. How are you determining which is the positive and which is the negative connection on the wire? Polarity DOES matter for LEDs. They won't light up if it's backwards.
Test on the top of the 8 pin connector - who knows what resistors and other bits may be on the loco's circuit board to support the LEDs. ANd don't forget to reset the decoder again if you didn't after messing with those "nce recommended settings". Also, make sure the lights are ON and you've moved the loco forward a bit. Defualt lighting ont he decoder is directional and unless a forward command actually got to the decoder the function may not be activated. If you only get .308 volts directly from the blue and white then somewhere along the line you shorted the function output and damaged the decoder.
To refresh my memory, the front headlight doesn't work on my Atlas Trainmaster # 7810 loco using a NCE DCC starter kit and a Digitrax DH123P decoder. The connections and solder points look good as tested last night, the reverse headlight does work.
As mentioned last night, I planned on removing J1 plug on train's pcb (which goes to the front headlight) to see if I have juice. I found .380V DC with the light option "on." Interesting enough, it was -.380V. I checked my + and - leads to the wired plug and I had the correct polarity, so there is voltage but negative or reverse. Does this matter on a LED...especially if it does work in DC (yesterday I tested the front headlight w/ straight DC and it worked). Or, since I have DCC now...I'm wondering if the reverse polarity is causing it not to work. Should I reverse the wires on the LED, plug in and test? Thanks, Steve
Thanks guys what I plan to do is check the voltage at the pins which go from the decoder that lead to the pcb on the non-operational light (to see if I'm getting voltage there) under DCC. If so, then I can assume a bad solder at the white wire (since blue is ground and controls both front/rear lights......and the rear is working) so the blue should be good. Or may have to reverse the wires ......I think this is what Pete/Randy are mentioning on the front head light to reverse the polarity.
In any event tomorrow will be a down day until I get home from work.....tomorrow I'm back to work after 9 days off, ouch! So by trying this and letting you know if I'm lucky, most of you will probably be offline since in on MT here in Arizona, so any responses will probably be time delayed. In any event, I'll respond as soon as I can. Much appreciated thanks for all the help! Steve
Functions outputs on DCC decoders are DC. Blue positive, each function lead is the negative. Voltage should be around 12V depending on the track voltage.
Randy suggested changing the polarity of the front LED. DCC is DC square wave but reads as AC on a digital multimeter. The decoder rectifies it into solid line DC. All the outputs of the decoder will be DC. Here is a link to what a DCC signal looks like and some that have problems. You will notice it looks similar to AC but without the rounded humps and valleys.
http://www.wiringfordcc.com/dcc_waveforms.htm
The length and width of the squared off humps and valleys is what the decoder decodes to move and operate lights and sounds.
The decoder color codes are available from a number of sources. Orange and gray to the motor, White and yellow to front and rear bulbs/LEDs negative, Blue is the positive to all the functions/lights/LEDs. Black and red are rail pickups. Purple, green, brown, and tan are other accessories/lights/LEDs/smoke units negative. This is the NMRA standard.
When programing a decoder regardless of maker of said decoder follow the directions and CVs for the decoder. NCE lighting FXs are only for NCE decoders. Digitrax uses different CVs for lighting.
Randy, stupid question but I'm assuming that I'm measuring in AC not DC at the pin (this is what I planned to do earlier, just didn't know voltages, polarity...etc).....and do you know roughly what voltages to look for?
Most any current decoder is "dual mode" meaning it will work fine on DC provided CV29 is not configured to prevent it. Even so it wouldn;t burn out the decoder.
There is still that third possibility that I mentioned, the light works in DC so the LED is fine, and you DO have power at the pins where the light board gets connectect.. That woudl tell me the polarity is backwards.
WHen testing for power at the light board pins, be extremely careful not to short your test probes. A short on the function outputs will pretty quickly blow the function output on the decoder, and then it defintiely won't work. You may be better off leaving the llight board connected and touchting two traces on it near where the cable attaches.
I didn't know you can put the train on a DC charged track with the DCC decoder in, I thought it would burn the decoder out. The bulb does work w/ straight DC just not DCC. I wanted to check the jumper plug going from the decoder DCC board to the light board to see I'm getting juice there..........if so, then it's the light board, if not then it's something with the decoder or main pcb.
If the light works on DC it's not burned out. Is it working on DC with the decoder installed, or only if you replace the decoder with the dummy plug? Voltage to the headligh will be somewhere around 12V DC depending on the track voltage. Bue is positive, white is negative. It could be the LED is backwards for DCC use. The little 2 pin plug is probably keyed so it can't be flipped, but if you get voltage there with the loco in forward and F0 turned on, the decoder is putting out power, and if the light works on DC, the LED is fine. so that's about all that would be left.
If you messed around with some NCE recommended light settings, reset the decoder again. Some of the basic lighting CVs are fairly standardized but the factory default for Digitrax absolutely is that the white and yellow wires work as directional headlight controlled with F0, no special effects or anything. That's the factory default settings with no programming. What the PowerCab manual mentioned may be applicable to NCE decoders or some other brand but for a factory out of the package Digitrax decoder there is nothign needs to be done to make the lights work as basic lights. In fact that applies to any of the NCE decoders I've used as well as the ones I use most, TCS. The only time I need to program things is if I want some other effect like Rule 17 dimming.
HAZMAT9 Sorry Rich, what I meant was the Atlas DCC Ready loco I've got. The bluebox is finished and ready to go, the front bulb on the Atlas Trainmaster is the one out. The front/rear bulbs are mounted on individual pcb boards and plug into the main board above the motor where the decoder is located....sorry I wasn't clear.
Sorry Rich, what I meant was the Atlas DCC Ready loco I've got. The bluebox is finished and ready to go, the front bulb on the Atlas Trainmaster is the one out. The front/rear bulbs are mounted on individual pcb boards and plug into the main board above the motor where the decoder is located....sorry I wasn't clear.
You were clear, I just recalled wrong.
Here is a link to a discussion on the Atlas forum. It may help you clear up your problem with the front light bulb.
http://forum.atlasrr.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=37773
Rich
Alton Junction
Oops, I just noticed. You are talking about the Atlas Trainmaster front light?
You may want to look closely.
Unless it was modified, I believe that all the Athearn Blue Box diesels used 1.5 volt bulbs so you need a resistor to keep from burning them out. Could be mistaken, though.
Bulbs are wired into a pcb, I'm assuming that they are LEDs.
How many volts is the front light bulb? Incadescent, I assume?
I reset the decoder, no luck. I also went into the NCE lighting options since the manual said that some decoders aren't recognized for both forward and reverse lighting. So I went in and set these, still nothing. On the pcb installed in the engine, there is a female plug that goes from the board to the LED lights (small black and red wires). If I remove this plug, I can probably check if there is power here going to the front lights. Does anyone know what to set the voltage on (and I'm assuming that this juice is AC)?
Shazam I got the blue box working! It seems that with my Atlas and bluebox, part of the problem was that the decoder chip wasn't in all the way, I guess I was being too careful, lol. Anyhow after pushing the decoder in and sanding down the frame and re-connected the black wire it worked fine.
Now I'm just trying to deal with my front light on my Atlas Trainmaster. frustrating!
Reset the decoder. Through messing around perhaps you set the white wire to NOT be on when the loco is going forward. Since it's a Digitrax decoder, program CV8=8 and then take it off the rails briefly. This will reset the address to 3, and set the white and yellow wires to be simple directional headlights that turn on and off with F0 (the headlight button).
Great, I'll order one next week. I checked my decoder on wires white and blue for front headlight. Blue was obviously good since it's the ground for both lights and rear light works. The white looks fine, checked the solder point all wires and decoder plug in...in fact I put the engine on a test track with straight DC and both headlights work, hate to be a bother any ideas? I'd hate to re-solder the point but I can do it if I need to, it looks good. Steve