Intermountain FP7A and Digitrax DN166I2B LED always on

[Big Train]

Installing decoder in this locomotive has been nothing but grief since I started the project. Nothing to do with Intermountain, other than they made a manufacturing decision to change how the light board is powered and that has been documented elsewhere.

So prior to buying the decoder, I removed the shell to determine if I needed the new style decoder without the brass "shoes" or the older version. My Ontario Northland F Units were produced during the production cut in for the updated board. So I wanted to be sure.No problem. I don't mind soldering a few wires.

Go to my supplier, sorted to all the available decoders available for the various configurations of F units. Package I selected stated (DN166I1D) it would fit my FP7A. Yay!

Get home and discover the Digitrax version was not shaped correctly for my F Unit. There was no way I could trim the PC board to make it fit.

OK, contact the supplier and he agreed to swap for the correct decoder. After several weeks, i got the decoder and installed it in the F unit. Isolated the motor, wired everything up and no headlight! Runs great, but an F unit without an illuminated headlight is like a smile with a missing tooth.

Gave the unit to a club member who is an expert at all things electronic and he determine the headlight wiring was reversed (but correct for the OEM wiring and as shown in Digitrax's instructions. OK, now headlight works. Then it didn't. Tested the LED and it was dead. Don't know if I fried it, but whatever.

Replaced the headlight LED from the F unit's sister unit and now have a headlight, but now it's always on even when in reverse.

Any ideas, guys? I suppose I could live with the headlight always on. Is there something in Decoder Pro that can correct this? I've triple checked the wiring, even reversed the leads but no change. Headlight is always on. FN FO function has no impact: the LED is always on

For future reference, this update from Intemoutains's web site:

http://intermountain-railway.com/IRC-DCC-Decoder-Information-V2.1-2016.pdf

[woodone]

Seeing that the 1st decoder you got was an DN series decoder I would guess that you are working with N scale.
What decoder did you end up with? If you reversed the wires to the LED and it is still on something is wrong!
Got a photo of the install?

[Big Train]

Yes, it is N scale. The correct decoder for this installation is the DN166I2B.

Unfortunately, it's all apart because I've decided the decoder is going back to Digitrax. I have only been working on getting this DCC'ed since the New Year. What's a couple of weeks more? I'm getting really tired of having my time wasted by these people. Could be better spent actually working on my layout......

Now according to their documentation, they  mention connecting the blue wire, but I don't see where that goes in this case. I guess this is what happens when you "cut and paste" instructions and never do a desk top validation.

[RBrodzinsky]

No, actually it is what happens the loco manufacturer doesn’t use NMRA standards for their wiring, and instead use normal electrical standards. In this case, Intermountain has used two pairs of red/black wires, with Red being + and black being -. The first pair is for the motor; the NMRA standard for these is Orange (+) and Grey (-). The second pair is the front LED, which is Blue (+) and White (-). Now, the Digitrax pictures show these correctly, but the write up refers to the NMRA standards.

So, if everything is wired per the photos, and the LED is now on, the next question is does it respond to F0? Can you turn the light on and off, irrespective of direction of travel? If yes, then we are in business. I would then suggest a factory reset of the decoder (set CV8=8), as it may have been programmed to ignore direction of travel.

[MK]

Headlight is always on. FN FO function has no impact: the LED is always on

[peteski]

As mentioned, perform a decoder reset. At that point the F0F( The front headlight function should be assigned to the F0 key on the throttle and be directional - only work when the loco is moving forward).   After doing the reset abd BEFORE trying it out on DCC take a 9V battery and touch it to the loco's wheels (to run the loco using pure DC power).  Try in both forwarrd and reverse (flip the batter).  If the headlight is always on when running on DC after the decoder reset then the decoder is toasted.  Well, most likely the F0 output transistor is shorted.

[Big Train]

Reinstalled the decoder and did a factory reset using JMRI. Locomotive runs under 03 but now headlight is off. Toggling FN FO did change anything. Did try the battery and still no light....so it's off the Digitrax. It's a good thing they has this super awesome warranty. But then, I gotta wonder why a company has a super awesome warranty.

Thanks for all the help, guys!

I'll let you now what happens.

[peteski]

Reinstalled the decoder and did a factory reset using JMRI. Locomotive runs under 03 but now headlight is off. Toggling FN FO did change anything. Did try the battery and still no light....so it's off the Digitrax. It's a good thing they has this super awesome warranty. But then, I gotta wonder why a company has a super awesome warranty.

Thanks for all the help, guys!

I'll let you now what happens.

"Toggling FN FO did change anything."?  You mean didn't?  But something did change - the F0F (forward headlight) function is no off (as opposed to being constantly on).  When I recommended a reset and DC test (using a battery) it was to verify that the headligt will tun off and stay off.  Reset turns the functions off, so they should stay off in DC.

You said that you reinstalled the decoder. Are you 100% sure that you wired the headlight correctly?
Try this:  in a dimly lit room put the loco on a DCC poered track. Now slightly tip the loco so wheels on one side are no longer in contact with the track. Then, while observing the headlight, put the lifted side back on the track. At the instant the decoder receives power, the headlight usually gives out a very fast and dim flash.  You can repeat this process few times to see if you can see the headlight flashing.

Or, put the loco on a programming track and either start reading or writing CVs from the decoder. (if you use JMRI just read all the CVs).  The loco will start twitching as the motor is being used for electrical load while acknowledging commands. The headlight should also be flashing in unison with the twitches.

If you see no flashes then the headlight LED is wired backwards (or defective) or the F0F output is now blown (it wasn't before since the LED was staying on), or the decider is defective.  Um, forget the above - just send it out for repair. 

As far as the warranty goes, TCS also has a good warranty for their DCC decoders. These things are fairly complex miniature electronic devices which are usually handled by regular folks (not electronic technicians), so it is nice of those companies to realize that things can go wrong and offer a good warranty.