Issue with Kato N-scale Charger

[POVC]

I'm having issues with decoderizing a Kato N-scale ALC-42 Charger.  I purchased a DC locomotive, which runs fine with the original board.  Installed a Digitrax DN163K4A, which according to the Digitrax website is the correct decoder for this locomotive.  With the decoder installed I am able to program the locomotive and have control of the headlight; the problem is the locomotive absolutely refuses to move with the decoder installed.  My assumption is that the issue is I'm not getting proper contact between the wings on the decoder and the motor contacts, but it's impossible to see into the locomotive to check.  If I squeeze the sides of the locomotive opposite the motor contacts, o9r push down on the board, I get a buzzing sound but no movement.

I took the bare decoder and connected it to the track with alligator clipped leads, then connected a DCC Rampmeter to the wings, and I see the voltage change as I move the throttle, so it looks like the decoder works.

Anybody have similar problems installing a board in their Kato Charger, or have any suggestions as to what I'm doing wrong?

Tim

[peteski]

I am familiar with ESU LokSound decoder (similar in shape to Digitrax) install in that loco, and the motor contacts can be problematic.  The brass wings come very close to the loco's frame (which carries the track voltage). I would recommend covering the outsides of the wings with Kapton tape to prevent any possible shorts of them to the loco's metal frame.

Those wings snap onto the PC board.  If the Digitrax PC board is slightly thinner than the stock Kato light board, those wings might not make good contact with the pads on the PC board.  You could trying to gently adjust (bend) the clips on the wings to tighten their grip on the decoder's PC board.  You could also choose to solder the wings to  the decoder's motor pads.

I also had some issues when installing the decoder where the wings were prying off the thin metal clips on the motor's brush holders.  Those clips retain the brush springs and the brush.  Just something else to watch for.

[POVC]

I am familiar with ESU LokSound decoder (similar in shape to Digitrax) install in that loco, and the motor contacts can be problematic.  The brass wings come very close to the loco's frame (which carries the track voltage). I would recommend covering the outsides of the wings with Kapton tape to prevent any possible shorts of them to the loco's metal frame.

Those wings snap onto the PC board.  If the Digitrax PC board is slightly thinner than the stock Kato light board, those wings might not make good contact with the pads on the PC board.  You could trying to gently adjust (bend) the clips on the wings to tighten their grip on the decoder's PC board.  You could also choose to solder the wings to  the decoder's motor pads.

I also had some issues when installing the decoder where the wings were prying off the thin metal clips on the motor's brush holders.  Those clips retain the brush springs and the brush.  Just something else to watch for.

Thanks Peteski,

I did try the installation with Kapton tape on the outside of the wings; that eliminated the buzzing when I squeezed the locomotive, but it still didn't move.  I also tried tightening the wings as much as I could, but that didn't seem to have any effect either.  I guess the next step is going to be taking the locomotive apart so I can see what's going on with the motor contacts.

Tim

[peteski]

Tim,
Now that you mentioned the buzzing sound, I realized that what you were doing was shorting the motor contacts to the frame halves (you were basically connecting the pulsing DCC track voltage to the motor (and to the motor driver circuit on the decoder).  It caused the motor's armature to buzz. That  is not a good thing. I hope that you didn't blow out the motor driver circuit on the decoder!

As for examining the motor, there isn't much there.  Only the brush holders and the clips on those holders which retain the brush spring (and the brush).



It looks similar to the lower motor in this picture, without the thin metal contact coming out on the right side. It will be just the brass brush holder with that tri-sided clip.

[oakcreekco]

These decoders have isolation protection, but for what length of time shorted to failure? Idk

Agreed that just buzzing can be a bad thing.

[mmyers]

Tim,
 I am going to take one of mine apart to try and find out why mine started working. I had the same buzz. Then on another try I found that the motor would run when the sides were pressed in. Finally the engine worked after another removal and installing the decoder. As we discussed last month I left the kapton tape on the decoder as it came out of the package. I am still not sure why it finally worked. My second one took as many attempts too. I hate just getting lucky and want to know why. Keep you posted.
Martin

[POVC]

Quick update - I bought another decoder and installed it today with kapton tape on the outside of the wings.  I could read and write to the decoder, and had light control, but still no movement, so I disassembled the whole locomotive.  As soon as I separated the frame halves, one of the 3-tabbed brush holder clips fell out, followed by the brush and the spring (although I didn't see the spring at the time).  Tried to reinstall the clip, but just managed to break off two of the three tabs.  Tried to put the locomotive back together, and in the process managed to knock off the other clip when I reinserted the circuit board (which is how I know there was a spring in there).  Managed to find both brushes and both springs, but the tabs on the clips are broken and they won't hold in place.

So, do I have any options besides buying a new motor for this beast?

Tim

[peteski]

Quick update - I bought another decoder and installed it today with kapton tape on the outside of the wings.  I could read and write to the decoder, and had light control, but still no movement, so I disassembled the whole locomotive.  As soon as I separated the frame halves, one of the 3-tabbed brush holder clips fell out, followed by the brush and the spring (although I didn't see the spring at the time).  Tried to reinstall the clip, but just managed to break off two of the three tabs.  Tried to put the locomotive back together, and in the process managed to knock off the other clip when I reinserted the circuit board (which is how I know there was a spring in there).  Managed to find both brushes and both springs, but the tabs on the clips are broken and they won't hold in place.

So, do I have any options besides buying a new motor for this beast?

Tim

Yes, the three-sides brush/spring snaps can come off rather easily from the round brush holder.  In this particular model (due to very limited open space between the brush holder and the side of the frame, when you slide the decoder in, the metal contact tab on the decoder can pry those snaps off.  A solution I found is to spin them on the motor (they spin easily) so one of the sides that clips the snap on the brush holder is pointing straight up.  That way the contact tab will not be able to accidentally slide between the brush holder and the clip to snap it off.


As for replacements, I think that when you buy replacement brushes (with springs), those tri-sided clips are also included.  If not, you can call Kato and ask if they will sell you some replacements.

[POVC]

Yes, the three-sides brush/spring snaps can come off rather easily from the round brush holder.  In this particular model (due to very limited open space between the brush holder and the side of the frame, when you slide the decoder in, the metal contact tab on the decoder can pry those snaps off.  A solution I found is to spin them on the motor (they spin easily) so one of the sides that clips the snap on the brush holder is pointing straight up.  That way the contact tab will not be able to accidentally slide between the brush holder and the clip to snap it off.


As for replacements, I think that when you buy replacement brushes (with springs), those tri-sided clips are also included.  If not, you can call Kato and ask if they will sell you some replacements.

Thanks Peteski!

I guess a call to Kato is in order...  Based on the difficultly I had trying to put things back together with my thick fingers and questionable eyesight, I might just go ahead and buy a new motor, depending on price.

Tim