AML GP60 electronics / DCC install

Overview

This is a LONG technical page, and needs to go into details due to the weird electronics in the loco, and COMPLETE lack of documentation.

I've gone into these details as I used this page to document my investigation to DECODE the interface presented on the GP60 motherboard, specifically to adding any decoder.

Apparently the choices made were because ESU was the only decoder company to do all the design (I assume free) of the motherboard. A really poor choice in my opinion, DCC is popular because it is a standard, and allows we consumers to make our OWN choice of what electronics.

But in not-so-infinite-wisdom, AML decided to use a non-standard socket in the GP60, even though there are thousands of Aristo/Bachman socketed locos and several decoders that fit THAT STANDARD socket:

• Phoenix SM-18 decoder
• TCS Wowsound 501 decoder
• Digitrax DG583s QSI Revolution decoder (out of production)
• QSI Titan decoder (out of production)

To make this worse, there are NO screw terminals to connect to the loco "peripherals", and to top it off, unusual connectors in the areas that the lighting is connectorized.

• So this page documents the arduous process of understanding the pinout of the OEM decoder, and verifying the socket, and the other plugs on the motherboard
• you have to understand the pinout of the decoder first, thus allowing the documentation of the socket
• at the end of this page, I "decode" the understanding and the operation of the "dummy plug" that is supplied for DC operation and is likewise UNDOCUMENTED
• production of an adapter to facilitate the installation of ANY decoder (in such a way that ordinary hobbyists can do this)

So, you can read how I got to the answer, or jump ahead to the section where I make the plug in adapter.

Table of Contents: (with links)

• Starting point: document Loksound decoder pinout
• Document the GP60 motherboard / socket pinouts from step above CLICK HERE
• Document other motherboard connectors - the actual devices connected to the socket CLICK HERE
• The strategy to make a plug in adapter CLICK HERE
• Final wiring - connect the adapter to the decoder CLICK HERE

The starting point: LokSound 5XL decoder connections

Clearly the starting point is the ESU decoder, since no document on the motherboard socket is provided. 

Below is the pinout of the LokSound 5 XL decoder... pay attention to the fact that pin 1 has a square outline on the silkscreen.

I'm calling the leftmost connector J1, as it maps similarly to the industry standard Aristo and Bachmann sockets. This is where track and motor and headlights are.

I'll call the rightmost connector J2, again following the Aristo and Bachmann conventions.

Further I call the top connector (in this illustration) J3, and the bottom J4

(Note, THE FOLLOWING ILLUSTRATION IS FROM THE "BOTTOM SIDE" of the decoder)

Now map the GP60 motherboard socket connections to the decoder

You think this would be easy, but there are unused pins and other weird stuff. Below is a picture of the motherboard (thanks to RLD Hobbies),

Notice the orientation is such that pin #1 is nearest the bottom on the left and right connectors. Also pin#1 on the lower horizontal connector is on the left. The top connector is not labelled the same way, but we don't care since it is mostly servos.

Again using my nomenclature:

• Left Side: J1, #1 pin at bottom
• Right side: J2, #1 at bottom, but NOTE:
  • the first pin of the decoder does NOT have a socket hole...
  • so the J2 socket starts with the rear light, not AUX 11, weird.
  • likewise the last connection does not appear in the socket, so the 14 pins on the decoder are only matched by 12 on the motherboard
  • You can see on the motherboard there are clearly 2 unused holes in the board, that the socket does not utilize
• Bottom side: J3, pin one on the left
• Top side: J4, pin 1 on the right, but the numbering is screwed up when looking at the decoder illustration. No matter, mostly servos.

Listing of the pins in the socket J1: (notice I reference the actual pins in the socket)

Table 1

So most of what we want is here, the U+ things are not identical on the motherboard, so several things to check out.

J2 socket pins: (again I am referencing the pins in the socket, which are NOT numbered the same as the decoder, the decoder has 14 pins, the motherboard socket only has 12)

Table 2

J3 socket pins, (bottom) again 12 pins, starting from the left

Table 3

J4 socket pins

Table 4

15,14,13 servo 1

11,10,9 servo 2

7,6,5 servo 3

3,2,1 servo 4

(I may add a formal  table here eventually, only for the servos, perhaps used for uncouplers, or if there is a high current output for a smoke unit on J4

GP60 motherboard other connectors

There are a number of connectors on the mother board.to get the signals and power on and off, below is the legend mapping the silkscreen to functions
The bright green pins are the J1 and J2 pins needed to connect to a decoder are in green

 Table 5

Plug in adapter strategy:

Summary: what is needed from the motherboard for adapting a DCC decoder:

• we need a 12 pin connector on J1
• we can get away with 6 pins for J2
• we need to find a way to feed the +5 volt pins that go to the LED lights

Why start with the Bachmann adapter?

• It already has two 12 pin male connectors with wires.
• even though the distance between J1 and J2 is different from the Aristo/Bachmann standards, it appears simple to cut it in half to fit
• the 11 pin piece is ready to use on J2
• the 12 pin piece only needs slight modification to remove the "shorts" between 1&2 and 11&12
• basically it saves a lot of time

Modifying the Bachmann Dash 9 adapter for the GP60 socket

The Bachmann adapter has 2 ends:

• J1 "end" has 12 pins, but only 10 wires since J1 has pins 1&2 jumpered as well as pins 11&12, so it needs modification to separate these pins and add 2 more wires
• J2 "end" has all 11 pins with independent wires, it's ready to go.

Look carefully at the picture below and you can see the copper that jumpers these two pairs of pins on J1 (lower left corner in the picture below):

Steps to modify the Bachmann adapter:

1. Cut away insulator from pins on J1 (it will be easier to fully remove the pins to "split" the copper shorting pins 1&2 and 11&12)
2. Remove the pins from the J1 side (see below) (now easy to remove the pins individually)
3. grind away the copper that shorts pins 1&2 and 11&12
4. put in new pin strip with long pins on both sides (strips found on Amazon)
5. connect two new separate wires to pins 1 and 12
6. finally cut the adapter in half, and trim to fit

Step 1: Cutting away the plastic from the connector pins:

Below you see the black plastic insulator that holds the pins in alignment before insertion:

If you take a sharp X-Acto knife and slide along the pins, 3 at a time, you can cut away one side of the insulator, and when you get done, the insulator on the other side of the row of pins will fall away:

Step 2:

Now that the pins are no longer all held by the plastic, you can remove them one by one. However you do this, you will probably want some "solder wick" to clean up the old solder, and ensure the holes are completely open.

I used solder wick to remove the solder on all 12 pins first, and then you can pull them out one by one easily with a bit of heat. Clean up the board as best as you can with solder wick and a brush etc. Depending on your level of expertise, you might just heat and remove the pins one by one, and then cleanup the board with solder wick later. This is the way I did it.

Step 3: remove copper shorting 1&2 and 11&12

Now cut away the extra copper that links the outer 2 pins... I used a small cylindrical grinder at slow speed:

Step 4: solder new pin strip in:

Now solder the new strip back in: (bought from amazon with 7.5 mm pins on BOTH sides

Step 5: add on wires for pins 1 & 12

Trim pins 2 through 11 (easier to get to new pins 1 & 12

Add in new wires for pins 1 and 12

Step 7: cut adapter in half and trim to fit

Cut the adapter in half and you have your 2 plugs to access all the "peripherals" needed for ANY decoder installation.

You will need to trim bottom margin to white line on both halves, and make them narrower, look at the silk screen for a guide.

You need to notch J1 to clear the "bottom" socket

Use the picture below as a guide:

Installation and connections:

Final pin connections for J1 & J2 for connecting any decoder (no servos)

1. test connect decoder, just connect:

• track pickups
• motors
• speaker

2. if this works, then finalize "forwards" wiring: (do in the following order)

• test for DCC direction, and complete wiring to motors (reverse motor wire connections)
• test for DC direction, and complete wiring to track pickups, adding in a polyswitch to EACH track pickup wire (4 total) (reverse track pickup connections if wrong)

3. Now, add the lighting functions and the +5 volt supply (from QSI to motherboard)(you do this to simplify the powering of the common for the LEDs)

Table 6 - J1 and J2 wiring in order - green is what needs to be connected, yellow is optional

The picture below shows the basic connections.

You have the #1 pin reference on the silk screen on each board

The wires in the black tube are unused. I may add a rotating beacon at some other time, so I have not cut away the rest of the wires from the adapters.

 Review of QSI LED light ports for reference (and double check):

• Port 1 - front headlight
• Port 2 - rear headlight
• Port 3 - front left ditch light
• Port 4 - front right ditch light
• Port 5 - reserved for front overhead beacon (1 of 4)
• Port 6 - front number boards
• Port 7 - reserved for front overhead beacon (2 of 4)
• Port 8 - front cab light
• Port 9 - smoke unit fan (using truck lights feature)
• Port 10 - reserved for front overhead beacon (3 of 4)
• Port 11 - reserved for front overhead beacon (4 of 4)
• Port 12 - reserved for smoke unit heater (special high current port on QSI) (using step lights)

Note all 12 LED ports are mapped

Smoke Unit Install

I used a feature of the QSI decoder that allows directly driving the fan and heater separately, and provides a high current output for the heater.

I used the stock bracket with just a little modification and it fits like it was designed to go there.

I've made a separate page for this install: CLICK HERE

Reference - GP60 Dummy plug notes

Investigating the "dummy plug" will yield some more clues

Below is a picture of the "dummy plug", shown below (as shipped for DC operation)

Dip Switch labeling/mapping:

Closer inspection shows dip switches apparently mapped to headlights and AUX functions, and the default settings:

The silk screening indicates the 2 headlights (upper left switch position 3&4 and 5&6) and then AUX outputs A1 through A11.

It would seem that only AUX 1 through 7 have something connected. (by the switch positions)

I will verify this, but it's clear there are 2 switches per "output" (normally a led)

So every switch has either: (this indicates what function is controlled)

• LF or LR (light front, light rear)
• A1 through A13 for AUX1 through AUX13 (the A is missing on some switches

In addition every switch has:

• F or R (meaning operation in forward or reverse)
• ON/OFF (move to ON to enable the desired direction)

Looking at the switch positions as shipped:

• front light is on only in forwards
• rear light is on only in reverse
• the rest are on only in forwards (that is weird)

Reference: Bachmann / Aristo socket wiring

This is background to help understand the standard socket wiring, since I will use a modified Bachmann adapter plug.

Therefore a "mapping" between the Bachmann nomenclature may be helpful to use the silk screened data on the plug.

Showing the standards for J1 and J2:

Note: The basic Aristo socket only uses J1 electrically: