AML GP60 electronics / DCC

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'm going into these details to document the interface presented on the 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)

So this page is documenting the arduous process of:

• understanding the pinout of the OEM decoder
• thus allowing the documentation of the socket
• reinforce the understanding and the operation of the "dummy plug" for DC operation
• production of an adapter to facilitate the installation of ANY decoder (in such a way that ordinary hobbyists can do this)

Table of Contents: (with links)

• Starting: document Loksound decoder pinout
• Documenting GP60 motherboard / socket pinouts from step above
• Document other motherboard connections - the actual devices connected to the socket

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.

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, the top (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

 Below is a picture of the motherboard, notice it's 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 will add a formal  table here eventually, only for the servos, perhaps 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 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

Modifying the Bachmann Dash 9 adapter for the GP60 socket

Casual inspection will show that since J1 pins 1&2 are connected together (to not overload the socket current rating), plugging a decoder so wired into the GP60 would immediately short the 2 rails together, no to mention the connections are completely different.

The Bachmann enhancement of the Aristo socket builds on the Aristo standard, and also somewhat standardizes the J2 connector opposite.

So, there is no decoder or adapter other than the ESU that will plug into the loco without some changes

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
• J2 "end" has all 11 pins with independent wires

Look carefully at the pictures below and you can see the copper that jumpers these two pairs of pins on J1;

Steps to modify:

1. Cut away insulator from pins on J1
2. Remove the pins from the J1 side (see below)
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
5. connect separate wire to pins 1 and 12
6. finally cut the adaptor in 2, and trim to fit

Step 1: Cutting away the plastic from the connector:

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:

Now use solder wick to remove the solder on all 12 pins, 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 2:

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 3: solder new pin strip in:

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

Step 4: 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 5: cut adaptor 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

You need to notch J1 to clear other socket

Installation and connections:

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

test connect decoder:

• track pickups
• motors
• speaker

if this works, then finalize 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)

Table 6 - J1 and J2 wiring in order - green is what needs to be connected to my Titan

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)

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:

Modification overview:

So the plan is:

• cut the adapter in half (since the distance between J1 and J2 is also different from the Aristo/Bachmann standards
• the 11 pin piece is ready to use on J2
• the 12 pin piece needs to be modified to remove the "shorts" between 1&2 and 11&12

Modifying the J1 "piece"

• first cut away the plastic header that kept the pins together for assembly
• remove the pins one by one
• remove the copper that contacts pins 1 and 12 (leaving the wire and copper intact for pins 2 and 11
• replace the pins with a header with long pins on both sides
• cut the extra pins on top that are not needed (pins 2 through 11)
• solder 2 new wires to pins 1 and 12

 (picture here)