DCC board won't stay in reverse on DC

[Hedron]

I'm guessing there's not much that can be done, but I'll ask.

I have decoder in an MP15DC that shows an Atlas ID (127), stamped NCE. It works perfectly on DCC. On DC, it goes forward fine, but on reverse, it wants to abruptly switch back to forward on its own. If I use a light touch, I can get it to stay in reverse for a while, but eventually it will suddenly go forward again. CV 8 reset has not changed the behavior. Any ideas for troubleshooting?

[peteski]

Has this loco worked ok on your existing DC setup (same throttle) in the past, or is this loco new to you?

What exactly is "light touch"?

If you have a standard 9V battery handy (most people do), try running it using that battery (instead of your DC throttle). Set up a piece of track on your workbench, then place the loco on it, then with the battery upside down, touch the terminals to the track.  Flip the battery 180 degrees to test the loco in the other direction.  Does the loco run reliably using the 9V battery?

What brand/model of DC throttle are you using?

[Hedron]

Has this loco worked ok on your existing DC setup (same throttle) in the past, or is this loco new to you?

What exactly is "light touch"?

If you have a standard 9V battery handy (most people do), try running it using that battery (instead of your DC throttle). Set up a piece of track on your workbench, then place the loco on it, then with the battery upside down, touch the terminals to the track.  Flip the battery 180 degrees to test the loco in the other direction.  Does the loco run reliably using the 9V battery?

What brand/model of DC throttle are you using?

This loco is new to me. It was in an auction lot.
By light touch, I mean if I slowly ramp up speed, I can sometimes get it to stay in reverse for a time, but eventually it will switch.
DCC is a Digitrax DCS 52. DC is an MRC Tech 7.
The battery gives the same behavior, abrupt shift from reverse to forward after a moment or three; forward works fine.

[peteski]

The battery gives the same behavior, abrupt shift from reverse to forward after a moment or three; forward works fine.

If the 9V battery (pure DC) gives the same results, then most likely the decoder is partially "fried".  If you normally run it on DCC then don't worry about that "problem". If you run on DC, then you will likely need a new decoder.  I have never encountered this type of failure, but with electronic circuitry, anything is possible.

[bobthebear]

Another answer is it could be caused by a pulse controller. I had the exact same problem before I went DCC, and changed to a different throttle without pulse.

[peteski]

Another answer is it could be caused by a pulse controller. I had the exact same problem before I went DCC, and changed to a different throttle without pulse.

That's exactly why I proposed running if using a 9V battery (can't get any more pure DC than that).  It behaved the same way, so the DC throttle is eliminated as the cause. I guess you missed the last few posts.