How can I tell if I "broke" the decoder?

[eja]

Last Christmas (yes, that long ago) I set up a passenger train running around the tree.  Having not run since the previous Christmas, my Kato P42  "Genesis", equipped with a Digitrax DN163K0a decoder, was growling rather loudly.

Assuming that it needed a little lubrication, I popped the shell off and tried to access the drive train.  The decoder is soldered to the contacts, so I could not simply remove it.  I pried up the rear and of the decoder and was able to get the long needle nose of the Labelle oil bottle where it need to be.

Put the loco back on the tracks and ..... nothing!  No lights and no movement.

So, ask, did I break the decoded ?  Is there way to test it ?  My NCE Powercab does not seem to recognize it all.

Any suggestions appreciated.   Gotta get it running before next December !

Happy Memorial Day and thanks to those who served or are serving now.

Ed

[MK]

I'm assuming the headlights are not working either as you said your command station won't recognize it at all.  This sounds like by you prying up the decoder to get to the drive train you may have bent the decoder *just enough* to not get track power.  Could be the decoder or the contact strip underneath (or both) that is slightly deformed.

Here's one way to test it.

• Removed the shell.
• Put it on the track.
• Turn on track power on your command station.
• With throttle at zero, gently press down on the two ends of the decoder.
• Does the headlight come on?
• If no, turn on headlight on your command station in case it was off to begin with.
• Press down on the two ends of the decoder again.
• Does the headlight come on?
• If yes, that means the decoder is not broken and you just have a connection issue.
• Remove decoder.  Give the power strips on the loco a slight bend upwards. Install decoder and test.

[mu26aeh]

I'm assuming the headlights are not working either as you said your command station won't recognize it at all.  This sounds like by you prying up the decoder to get to the drive train you may have bent the decoder *just enough* to not get track power.  Could be the decoder or the contact strip underneath (or both) that is slightly deformed.

Here's one way to test it.

• Removed the shell.
• Put it on the track.
• Turn on track power on your command station.
• With throttle at zero, gently press down on the two ends of the decoder.
• Does the headlight come on?
• If no, turn on headlight on your command station in case it was off to begin with.
• Press down on the two ends of the decoder again.
• Does the headlight come on?
• If yes, that means the decoder is not broken and you just have a connection issue.
• Remove decoder.  Give the power strips on the loco a slight bend upwards. Install decoder and test.

OP said contacts are soldered.  So don't think it's a connection issue

[eja]

Contacts ar.e soldered.

[POVC]

Contacts ar.e soldered.

While the contacts from the decoder to the motor may be soldered, the contacts between the decoder and the pick-up strips are not.  Decoder has contact pads on the bottom that must make contact with the pick-up strips to provide power to the decoder.  I have numerous KATO P42's and E8's and they can all be kind of finicky getting the decoder installed "just right" to get a reliable pick-up.

[MK]

OP said contacts are soldered.  So don't think it's a connection issue

Yes, it can be.  The motor tabs are soldered.  The fact that the command station cannot see the decoder means either the decoder is defective which I doubt because the OP said it was working before or there's no contact to the decoder.

Contacts ar.e soldered.

I'm pretty sure those are the motor contacts.  Can you post a picture?

If the decoder itself is soldered you wouldn't be able to pry the rear end.  The way it is designed it would be hard to solder the decoder to the power contact strip as that contact is at the bottom of the board.

Clarification on step 2.  Put the LOCO on the track, not the shell.   

While the contacts from the decoder to the motor may be soldered, the contacts between the decoder and the pick-up strips are not.  Decoder has contact pads on the bottom that must make contact with the pick-up strips to provide power to the decoder.  I have numerous KATO P42's and E8's and they can all be kind of finicky getting the decoder installed "just right" to get a reliable pick-up.

Ding, ding, ding!  We have a (potential ) winner!

[eja]

Picture of my P42 soldered decoder

[OrangeAnon]

Not sure how much contact there is at the front of the decoder, but there's certainly none towards the back, as the slot in the decoder isn't engaging the lug that holds down the back half. Hopefully this is all it will take to fix it!

[MK]

OrangeAnon found your problem!

The rear clip is UNDER the decoder.  It has to clip on to the decoder like the original light board.  I've seen this mistake so many times during this type of install.

Unfortunately, in your case, the motor tabs have to be unsoldered before you can readjust the board.  (Then resolder them.)

I am 99.9% sure that will fix your problem.

[peteski]

Yes, assuming that there is insulating Kapton tape wrapped around the pickup strip at the area of motor contacts coming up to the decoder and the decoder not engaged under plastic clip (as show in the photo), there will be very poor or no contact between the pickup strips and the decoder.

[eja]

Thanks everyone   .... now I need some time to work on it.  Hopefully next week.


Stay tuned...

ed