Author Topic: NCE erratic behavior  (Read 523 times)

0 Members and 1 Guest are viewing this topic.

kc9jts

  • Crew
  • *
  • Posts: 136
  • Gender: Male
  • Respect: +14
    • my blog of miscellaneous info:
NCE erratic behavior
« on: August 18, 2016, 10:36:50 AM »
0
I recently bought an Atlas SD7 that came with a NCE decoder from the factory (It is from the 2010 SD7 release).  The engine is new so the decoder had not previously been programmed.  When I try programming it (NCE powercab system) I get a "cannot read CV" message.  If I rock is back and forth a little while trying to program it I can get it to go through the programming cycle but then it does not take the long address or anything.  I can get it to move using the factory address of 3 but when I do that it has very jerky-performance and if I hit the reverse button while running it will not reverse unless I also adjust the speed or come to a complete stop and then reverse.  It also has issues that sometimes as soon as I turn the DCC system on it will start back and forth very rapidly and will not stop regardless of any buttons pushed.  Any ideas?

jdcolombo

  • Crew
  • *
  • Posts: 1802
  • Respect: +569
Re: NCE erratic behavior
« Reply #1 on: August 18, 2016, 01:10:49 PM »
0
Sounds like poor electrical contact.  The poor contact could come at many points.  Here is a list.

1.  Dirty wheels.  Check and clean if needed.
2.  Poor contact between the trucks and the phosphor-bronze pickups - could be caused by dirt between the contact "fingers" on the truck and the phosphor-bronze pickup; could also be caused by insufficient downforce on the strip.  Clean everything (a wire brush in a Dremel would be ideal; otherwise, use 90% alcohol and if anything looks oxidized, clean with 400-grit sandpaper) and bend the pickup strips down some to provide better contact force to the truck.
3.  Poor contact between the frame and decoder board.  This is a common problem with "drop-in" boards.  To check this, wedge something between the board and frame (folded paper or cardstock) to put upward pressure on the board where the pickup pads on the board contact the "fingers" on the frame.  If this solves your problem, the next step would be to put a thin coat of solder on the pickup pads to make them slightly thicker.
4.  Poor contact between the motor brush contact strips and the pads on the bottom of the decoder that contact these pickup strips.  First, make sure they are clean (again, if there is any oxidation, clean with some 400-grit sandpaper and 90% alcohol).  Then bend up the motor contact strips so they will put more pressure on the contact pads on the board. 

Given the behavior you describe, 1 and 2 are less likely the problem than 3 and 4, but to truly eliminate all the possibilities, follow the above in order.

If you still have problems after all of the above, you may have a bad decoder board.  Replace, either with a TCS or Digitrax drop in, or with a hard wired decoder (my preference, but I'm a bit crazy about potential electrical pickup problems and hard-wiring eliminates many of the failure points).

John C.

« Last Edit: August 18, 2016, 01:13:20 PM by jdcolombo »

peteski

  • Crew
  • *
  • Posts: 21464
  • Gender: Male
  • Honorary Resident Curmudgeon
  • Respect: +1996
    • Coming (not so) soon...
Re: NCE erratic behavior
« Reply #2 on: August 18, 2016, 03:05:47 PM »
0
What John said.  :D

As far as the weird behavior at power up goes, that is probably due to the analog mode being enabled on the decoder. Some decoders on some DCC systems "think" that the DCC signal is full 12V DC so they start running. This could also be due to the actual booster supplying short burst of DC power to the track while it initializes.  Whatever the cause is, disabling the DC model on the decoder should eliminate the uncontrollable movement while powering up the system.
--- Peteski de Snarkski

-"Look at me, I'm satirical!!!"
-"Look at me, I'm anal retentive!!!"
-"Look at me, I have the most posts evahhhh!!!"
-"Look at me, I'm snarky!!!!"
-"Look at me, I have OCD!!!"
-"Look at me, I'm a curmudgeon!!!!"
-"Look at me, I'm not negative, just blunt and honest!!!"

kc9jts

  • Crew
  • *
  • Posts: 136
  • Gender: Male
  • Respect: +14
    • my blog of miscellaneous info:
Re: NCE erratic behavior
« Reply #3 on: August 19, 2016, 09:40:28 AM »
0
Thanks guys, I'll give those tips a shot and hopefully it solves it.