14 February 2010

Installation of a Digitrax DZ143 in a LifeLike EMD GP38-2

After my recent work to put drop-in replacement decoders in DCC-ready locos I decided to dive into a more difficult project: to install a Digitrax DZ143 decoder inside a LifeLike EMD GP38-2.

I felt a little more confident in taking away loco shell and the other parts based on the experience made with previous installations. So, I decided to give it a try.

First of all, though, I searched on the Internet looking for someone else -maybe more experienced than I am- who already did this installation. Actually I found two or three interesting website but the most well-done document -actually a real tutorial- is the forum post "Decoder Install: Walthers/LifeLike GP38-2" from pastoolio on trainboard.com.

Actually, you can simply follow the installation instruction and you're almost done.

So, I decided to start disassembling the loco. Overall it wasn't very difficult. As shown in the tutorial after having removed the fuel tank, the cover made by the dynamic brakes -hope those are actually dynamic brakes- and the cab I removed the shell by simply raising it with a small screwdriver on the bottom of the loco.

Then, it was the turn of the stock PCB board with front and back LEDs and few other electronic components. Again, as explained in the tutorial I used the board, LEDs and two SMD resistors for the loco head and back light when using the decoder.
While removing the PCB I made an error and I broke the front part of the PCB where the front LED is soldered. I was lucky enough I could reuse the PCB and glue the broken piece to the loco frame as you can see further on.

Then, I took away the two screws holding the frame together and removed trucks, motor and gear worms as well as two washers used to isolate the two frame halves.

Following the tutorial I put some isolating tape on front side of the motor "seat" in order to isolate the motor armature from the frame.

It was time for the motor. Here the difficult part begun. In order to have a way to let one of the motor wire reach the bottom motor contact I had to create a "groove" on the black plastic part of the motor body. I used small triangular and round files. Overall it wasn't that difficult but I felt very scary to damage the motor completely. However, everything's alright up to this point.

Then, I begun to cut the copper cladding on the PCB in order to isolate the components and be able to re-use LEDs and two SMD resistors.

I did that on both sides always following the well-detailed tutorial. Though, here I made my first real error. I thought I could avoid to cut the two notches on the back of the PCB in order to pass the decoder wire through them. Instead I thought to lay the decoder with wire facing on the back and bend them on top of the PCB. That was something made me do the work twice!
Lesson learned: do not always think you're smarter than a very experienced modelers and think twice before taking a different approach with respect to what they do.

So I started soldering the motor wires -here you can see the "groove" on the motor body much better- and putting some isolating tape on the motors contacts.
To test the "great" idea I had I did a test installation assembling the motor, PCB and decoder in place. All looked fine.

So I went on soldering the power wire -black and red- and then the front and rear light wires along with the common blue wire.
I also glued the broken PCB part with the front LED to the loco frame.

Time to put back on the loco shell. No way! There was no space for the wire to bend and go on top of the PCB inside the shell. That's why I had to cut those two notches on the PCB.
So, I unsoldered all wires, took the PCB off the frame and cut two notches as shown the tutorial. Then, I cut and soldered again all wires -this time pay attention to the clearance required by wires.

A quick test on the track to check everything worked fine and tried to put the shell back on. This time is much better. I could fit all wires on top of the PCB rather easily.

I put back in place the cab, PCB cover and hand rails and I was almost done. Still few small adjustments of the cab and cover to sit them in the right place.

Well, overall this small project went fine and I'm rather satisfied with results. However, it could be much harder without the wonderful tutorial from pastoolio and without stupid errors I made.

So far so good, I've got another loco digitized and ready to run.

See you soon...

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