Baffling DCC / decoder issue


JeffH

JeffH

Well-Known Member
Quick question as I'm still a newbie regarding decoder installations and programming.

I have a DCC ready Atlas N MP-15 and have a drop-in NCE decoder I have installed.

When I put it on the track, F1 F0 will turn on and off the headlight, but I get an error, something like "no decoder" by NCE PowerCab/JMRI. No matter if I try JMRI, or if I use the PowerCab directly, the loco will only respond to the headlight button on the PowerCab.

When I added the loco to the roster in DecoderPro, I chose the exact decoder I installed (NCE NMP15). JMRI let me add the loco/decoder to the roster, but when I try to read any values, I get, in red text at the bottom of the JMRI window saying something to the effect of it not seeing the decoder.

So... what could be allowing the decoder to respond to the headlight command from the PowerCab, but when I try to read or write CV values, I get an error, saying the system hasn't detected a decoder?

Other locomotives work just fine using the same track, same JMRI session, just a different loco, and I can read & write perfectly fine.

I'm afraid my decoder may have arrived DOA, but I don't have a tester... Hoping someone here may have a suggestion before I keep spinning my wheels.
 
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F0 should be the headlight command.
the decoder uses motor pulses to verify programming changes. If the motor contacts aren’t good, the decoder won’t be able to verify programming.
Check to make sure the engine runs on dc before trying to use/program it on dcc.
 
Thanks for that suggestion!

I think I may have the decoder installed upside down. The contact areas look different on one side of the board versus the other, but I ran out of time to test that theory before I had to go to work.

Either that, or I may have buggered up the thin motor contact strips that reach up to touch the decoder.

Hopefully, I can stop obsessing about this issue long enough to let me focus on my job, LOL
 
JeffH said:
Thanks for that suggestion!

I think I may have the decoder installed upside down. The contact areas look different on one side of the board versus the other, but I ran out of time to test that theory before I had to go to work.

Either that, or I may have buggered up the thin motor contact strips that reach up to touch the decoder.

Hopefully, I can stop obsessing about this issue long enough to let me focus on my job, LOL
Click to expand...

As bnsf971 says run it on DC first, if it runs ok, with no issue and the lights work in the correct direction of travel then check that the decoder is Locked/Unlocked would be my first point of interest, as according to the manual I just checked, if it's locked, you can't read or programme the decoder.

NOTE
After fitting any decoder always run the locomotive on DC for a few minutes, before doing anything else. And the same goes if later you have a problem, revert it back to DC first, then at least you know where to look for the issue.
 
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Didn't work on DC either.

I confirmed the decoder was installed correctly, as there is only one orientation that Aligns the motor pickups.

I put the OEM light board back in and it ran just fine on DC.

Put the decoder back in and same thing. Only the headlight works.
 
JeffH said:
Didn't work on DC either.

I confirmed the decoder was installed correctly, as there is only one orientation that Aligns the motor pickups.

I put the OEM light board back in and it ran just fine on DC.

Put the decoder back in and same thing. Only the headlight works.the
Click to expand...
Contact the supplier and return it, it's rare, but it does happen, seems you have a dud.
 
I'll reinstall the decoder again and see if I can program CV 15 to zero to see if that helps. Supposedly, if the decoder is locked, CV15 is not equal to CV16. But if the decoder is locked, CV15 is still programmable. I'll play around with that to see if it makes a difference
 
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I have other locos with decoders, but nothing that will fit this small. The decoder in question is a drop-in solution.
 
Here's a pic. Sure looks like it gave up the magic smoke to me. Is that normal? Perhaps I fried it. I'm pretty handy, and have good dexterity, but I also have fat fingers.

Attempted to program CV15 to zero but that didn't change anything. I think it's toast, quite literally. I also think I probably toasted it, so I'm chalking it up to the cost of tuition and ordering another decoder.
1668869643217.png
 
JeffH said:
Here's a pic. Sure looks like it gave up the magic smoke to me. Is that normal? Perhaps I fried it. I'm pretty handy, and have good dexterity, but I also have fat fingers.

Attempted to program CV15 to zero but that didn't change anything. I think it's toast, quite literally. I also think I probably toasted it, so I'm chalking it up to the cost of tuition and ordering another decoder.
View attachment 156234
Click to expand...
The decoder is definitely not supposed to look like that, and explains all your trouble, do you know how this happened ?
 
No not sure. I installed and re installed several times. It's possible I put it in upside down. It's also possible the motor pickups shorted against the frame.

If I was sure it wasn't my fault, I'd return it. But I probably fried it.

For now, the original light board is back in and it is functioning perfectly using a DC transformer.
 
JeffH said:
No not sure. I installed and re installed several times. It's possible I put it in upside down. It's also possible the motor pickups shorted against the frame.

If I was sure it wasn't my fault, I'd return it. But I probably fried it.

For now, the original light board is back in and it is functioning perfectly using a DC transformer.
Click to expand...
I'd send it back anyway, sometimes, even if it was your fault they will replace it as they look at as "Good Customer Relations", worth a try at least, most they'll say is no, so your no worse off.
 
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