Installing a Digitrax DN163K0a decoder into a Kato DF 200-50

[alpineaustralia]

Below is a pictorial on installing a Digitrax DN163K0a decoder into a Kato DF 200-50.

1. Take off the shell by running your fingernails along its outer edge. Once off, you will see the light board with its SMD lights (ee Photos 1. and 2.)

[alpineaustralia]

2.  Remove the light board by removing the little grey clip and sliding the lightboard the along its axis until it is free of the grey recessed holder that holds it in place and up.  You will see that the motor contacts are short and sit underneath the light board rather than come up over the sides like other Kato locomotive models.  This makes the installtion simpler because the contacts do not come into contact with the copper pick up rails and will not need to be isolated.  They will contact the decoder on the two small copper pads on the underside of the decoder rather than on two larger pads on top of the decoder like other Kato locomotive models (see photos 3)

3. Place the light board alongside the decoder to get a sense of how short to cut the LED stalks so that the decoder fits within the same length as the original light board (see photo 4.)

[alpineaustralia]

4. Cut the LED stalks down to size. To ensure that the LEDs are re-installed with the correct polarity, I cut the stalks at an angle so that there is no mistake as to how the LED should be re-installed (see photos 5. and 6.)

[alpineaustralia]

5.  Solder the LEDs back onto the shortened stalks (see photo 7.).

6. Install, the decoder by putting it in place of the decoder and replacing the clip. Make sure you place it in the same orientation as the original lightboard. The easiest way to know that you have done it the wrong way is that the clip will sit over componentry rather than on the shiney clean copper part of the decoder, as is shown in photo 8. 

[quinntopia]

Wow.  How timely is this! I should be getting one of these in the mail any day (and already have the decoder!)! I'm really glad for this as I just know that the lengths of the LED leads on the decoder would have caused me to 'panic' (well, not quite panic, but I would not want to start cutting up a decoder if I wasn't 100% sure that it was the right thing to do! Some of this is not necessarily intuitive for 'DCC- ready'! :-)).  Thanks!

[alpineaustralia]

No problems mate. There are two tricks:

1.  is to ensure that the decoder is oriented in the same way that the original sound board. Please note that the photos shows the decoder wrongly placed, rather than correctly placed.

2. To ensure that the after you have cut off the LEDs you install them with the correct polarity as they were on the decoder before being cut off. That is whay I clip them at an angle to avoid being confused later on.

[CaptOblivious]

Alpine, nice work. Cutting the LED stalks like that is an interesting move. I usually desolder the entire LED, trim the soldery-bent-up ends off the stalks, reinsert them and bend the stalks at a new location so that the length of the LED is right, solder it back in place, and trim off the excess.

Desoldering the LEDs is not particularly dangerous to the decoder, but is kinda tedious (desolder wick is essential).

This looks quite a bit easier, and I doubt that weaker joint produced by your method really matters in this application. How hard did you find solder the LED back on?

[quinntopia]

Alpine... a question on this install.  :)

You will see that the motor contacts are short and sit underneath the light board rather than come up over the sides like other Kato locomotive models.  This makes the installtion simpler because the contacts do not come into contact with the copper pick up rails and will need to be isolated.  They will contact the decoder on the two small copper pads on the underside of the decoder rather than on two larger pads on top of the decoder like other Kato locomotive models (see photos 3)

As I'm reading the Digitrax instructions and following your post, I'm a bit confused.  Did you isolate the electrical contact rails (the copper strips that run along the sides of the chassis) with Kapton tape near where the motor contacts are? I can't tell from your photos if you did use tape to isolate or not.

It appears that this needs to happen according to your post, but that could be a typo, and as the Digitrax instructions give some specific areas where the Kapton tape should go (albeit for an Amtrack loco, which as you mention, this engine has a different set up than other Kato locomotives), I'm a bit confused on where/if the Kapton tape is applied!

[CaptOblivious]

Normally, the brass tabs from the motor stick up from the engine's innards, outside the brass rails, and fold over the rail to make contact with them—that's how the engine gets power. So you put some tape around (not just on top, but all the way around!—it's actually the edge of the rail that poses the greatest danger of a short!) the brass rails where they meet the motor tabs. That way, the motor tabs only make contact with the special contact points on the decoder, and don't short out on the brass tabs.

However, as Alpine mentioned (and this is interesting…), this loco doesn't work that way. Look at Alpine's third photo, and you see the motor tabs stick up, not outside of the rails, but inside of them, and are already isolated by bits of plastic. How handy! No Kapton tape necessary, no risk of a short.

[alpineaustralia]

This looks quite a bit easier, and I doubt that weaker joint produced by your method really matters in this application. How hard did you find solder the LED back on?

I used to do this but a few times now I found that I applied too much heat to the decoder and as a result the light wouldnt work. I instead opted for this because it is easier, safer and I could unsolder it, cllip off a bit more stalk and resolder if I got the length wrong. In terms of weakness, there is no pressure brought to bear on the LED and so there has been no occassion for the light to fall off.
Total time about 5 minutes.

Did you isolate the electrical contact rails

Capt answered this correctly. I didnt have to isolate the motor contacts becasue they are already isolated. I  apologise. My post should have read "do not need to isolate" rather than "need to isolate". I will correct it shortly.

[quinntopia]

Great!  Thanks for the responses, that was a very easy install!  Everything is working great! Well almost, I have another issue.....(unrelated to the install)