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N scale Kato P42 with Digitrax Decoder making un-scheduled stops.

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  • Member since
    July 2008
  • 1,206 posts
Posted by mfm37 on Tuesday, January 19, 2016 9:31 PM

At some point you will most likely wind up soldering. I tried arcing the tabs a couple of years ago. Worked for awhile.

 

 

  • Member since
    November 2007
  • From: Columbus, OH
  • 122 posts
Posted by NSColsMP6 on Tuesday, January 19, 2016 12:26 PM

I did some further testing and established that this is a design flaw with the Kato P42 (according to a phone call to Kato). 

The problem is that the Digitrax drop-in board is a little thicker than the native board so the plastic plug that holds the motor power tabs to the contact points on the board sometimes isn't enough to make contact.

You can test for this by removing the shell of an affected locomotive and pressing down on the plastic plug while setting the throttle to a level high enough to make the locomotive move.  When you press on it, contact will be made and the locomotive will move.

Some have suggested that I solder the tabs - which I considered, but in the interim I decided to try the following - which seems to have fixed the problem...

  1. Fold the tabs up so they are vertical.
  2. Bend the tips (maybe 1-2mm) toward the contact surface.
  3. Bend the tabs back down on top of the contact pads.
  4. Re-install the plastic plug on top of the bent tab ends.

This helps to make the flat tabs a little more dimensional and ensure that they make contact even if there is a little room between the plastic tab and the contact pads.

Time will tell if it works - and if not, I'll just solder the pads but for now the locomotive was running great again.

Thanks for all of your thoughts and suggestions.

- Mark (NS Columbus, MP 6)
  • Member since
    July 2008
  • 1,206 posts
Posted by mfm37 on Thursday, December 31, 2015 1:51 PM

I'm with Randy on the starting and stopping issue. Suspect the engine is selected on two throttles. At least one of them being a UT or Zephyr throttle.

That being said, the little plastic clip is also an issue. I gave up trying to get reliable continuity between the two little motor contacts and the pads on the decoder. Most times they run for a while then just quit running. Never had one start up again without working on it, though.

I have a dozen or so E8's, about the same in P42's, FP40's, and PA's. They all use the same decoder. I soldered every one of them and have zero trouble since. In fact I just did a new P42 and DN163K0A last night.

I simply tin both of the decoder pads and the two brass contacts. Then I hold the contacts down tight on the decoder with a metal pick. Touch a hot solder iron to the contact for a second and the solder will flow. Remove the iron and hold the contact for a few seconds while it cools. Installation done. You can then either insert the plactic clip or just leave it off. Your choice.

To remove the decoder just put the iron on the contact and it will spring loose when hot enough.

Martin Myers

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Thursday, December 31, 2015 10:17 AM

 What DCC system are you using? Stopping and starting my itself is classic "same address selected on more than one throttle" with Digitrax, with at least one of those throttles being the Zephyr console throttle or a UT4.

                           --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    July 2006
  • From: The Villages, Fl
  • 59 posts
Posted by bavrail on Thursday, December 31, 2015 8:12 AM

Check the plastic clip holding the motor contacts to the decoder. I've had to solder those on some engines. 

WS

  • Member since
    November 2007
  • From: Columbus, OH
  • 122 posts
N scale Kato P42 with Digitrax Decoder making un-scheduled stops.
Posted by NSColsMP6 on Thursday, December 31, 2015 2:50 AM

I was running my Kato P42 (N Scale) with Digitrax decoder around the layout at a decent pace and suddenly it jerked to a stop.  While I realize that this may indeed be prototypical for Amtrak, I'd like my trains to run on a more regular schedule. ;)

At first I thought it was a spot of dirty track or something... though that would have made it pause, not stop.

After what I thought was fiddling on my part, the locomotive continued on it's journey - this time it stopped at a different place.

I got distracted doing other things and the locomotive startled me by starting suddenly (I was expecting to have to fiddle with it).

Think it's a problem with the decoder or the locomotive itself?  I had an Atlas locomotive running on the layout at the same time (it's a double-track loop) and it never skipped a beat.

Tags: Digitrax , kato , N scale , P42
- Mark (NS Columbus, MP 6)

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