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)

 

The starting point: LokSound 5XL decoder connections

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

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)

LokSound 5 XL pinout

Now map the GP60 motherboard decoder socket connections

 

 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.

20240205 183919

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, J3, pin one on the left
  • Top, 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

J1 socket pin numberUSE                 notes                              
 1 left rail pickup 
 2 right rail pickup 
 3 right rail pickup (optional) duplicate of to pin 3
 4 right motor motor plus
 5 U+ (common pole) no idea - needs research
 6 U+ common pole tied to +UB on motherboard
 7 GND 
 8 left motor motor minus
9 wheel sensor input reference to ground or plus?
10 left motor duplicate motor minus
11 speaker 1 #1 speaker minus
12 speaker 1 #2 speaker plus

 

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

J2 socket pin numberUSE                 Notes                                                                                                 
 1 rear light 
 2 headlight 
 3 sensor input #1 
 4 AUX1 
 5 AUX2 
 6 AUX3 
 7 sensor input #2 
 8 AUX4 
9 AUX5 
10 auxilary board power control (reserved) 
11AUX6 
12 U+ tied to +UB, Pin 6 J1

 

 

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

Table 3

J3 socket pin numberUSE                 Notes                                                                                                 
 1AUX13 logic level
 2speaker 2 #1 says plus (notice silk screen reverse polarity of speaker #1, clearly an error)
 3speaker 2 #2 says minus
 4+10 volts really? what for?
 5+5 volts 
 6AUX7 
 7AUX8 
 8AUX9 
9AUX10 
10AUX11 also for SUSI data or servo5
11AUX12 also for SUSI clock or servo 6
12 UVAR regulated DC power common (+) 1.8 v, but can be set by changing resistor 1.5 to 3v

 

 

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 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

 connector "number"mb socket connection silkscreen meaning
X1 - right end (with the silkscreen right side up)
(rear of loco)

J1-1 - TRKL - left rail
J1-2 - TRKR - right rail

 TRKL and TRKRTRacK Left and TRacK Right
As delivered, not connected, see X14 for feed point
X2 - right end / rear J3-2 SPK2 plus
 J3-3 SPK2 minus
 SPK2 SPeaKer 2, note polarity is also on silkscreen
decoder lit says pin 2 is SPK2 #1, silkscreen is reverse of
 speaker #1.
As delivered, speaker on top of loco connected here, weird
X3 - right end/rearJ1-4 - MOT+ - motor plus
J1-10 - MOT- motor minus
 MOT MOTors, note polarity is also on silkscreen
As delivered, rear motor connected here
X10 - right end pin1 is +5v - onboard reg
J2-1 - pin2 is LMPR - rear lt
 pin3 is AUX 7 - J3-6
 pin4 is AUX 8 - J3-7
 pin5 is AUX 9 - J3-8
 pin6 is AUX10 - J3-9
 pin7 is AUX11 - J3-10??
 +5v / LMPR / AUX7 thru AUX11

5 volts, LaMP Rear, and AUX 7 through 11.
lmpr has a 1k resistor
J3-10 goes through an IC, so it might be connected to aux11
in some configuration

As delivered only LMPR (rear headlight) is connected in stock loco,
AUX 7-11 not connected

X12 - right end J4-9
 J4-10
 J4-11
 SERVO2 / +5v / GND typical servo pins for servo #2
As delivered, not connected
X14 - middle J1-1 - TRKL - left rail
 J1-2 - TRKR - right rail
 TRKL and  TRKR TRacK Left and TRacK Right (duplicate of X1)
As delivered, this has orange wires connecting to switch board,
track pickups also go to switch board
X7 - left endJ1-12 SPK1 minus
J1-11 SPK1 plus
 SPK1 plus and minus SPeaKer 1, note polarity is also on silkscreen, decoder lit says
pin 12 is speaker 1 #2, pin 11 is speaker 1 #1
As delivered, not connected
X8 - left end J1-4 - MOT+ - motor plus
 J1-10 - MOT- motor minus
 MOT MOTors, note polarity is also on silkscreen (duplicate of X3)
As delivered, connected to front motor
X9 - left end pin1 +5v common
J2-2 / pin2 is LMPF - front lt
J2-5 / pin3 is AUX2 - nbr bds
J2-6 / pin4 is AUX3 - rt ditch
J2-8 / pin5 is AUX4 - lft ditch
J2-9 / pin6 is AUX5 - cab light

 pin7 is AUX6 - J2-11
 +5v / LMPF / AUX2 thru AUX6

 5 volts, LaMP Front, and AUX 2 through AUX6

As delivered:
Pin1 common to all front lamps
Pin2 - LMPF - front headlight
Pin3 - AUX2 - number boards
Pin4 - AUX3 - right ditch light
Pin5 - AUX4 - left ditch light
Pin6 - AUX5 - cab light
Pin7 - AUX6 - not connected

X11 - left end  +UB / AUX1 / +5v / AUX13 +UB???, AUX1, +5 volts, AUX13
As delivered, not connected
X13 - left end  SERVO1 / +5v / GND typical servo pins for servo #1
As delivered, not connected

 

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

 

Final pin connections for J1 & J2 for connecting any decoder (1 speaker, no servos)

 

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

"J" socket
pin (n=1 to 4)
function corresponding motherboard "Xn" connector
(n=1 to
J1-1 Left rail pickup X1 and
J1-2 Right rail pickup 
 J1-3 Speaker 2 plus 
 J1-4 Motor plus 
 J1-5  
 J1-6  
J1-7  
J1-8  
J1-9  
J1-10 Motor minus 
J1-11 speaker 1 plus 
J1-12 speaker 1 minus 
J2-1 front headlamp 
J2-2 rear headlamp 
J2-3  
J2-4  
J2-5 number boards 
J2-6 right ditch light 
J2-7  
J2-8 left ditch light 
J2-9 cab light 
J2-10  
J2-11 AUX11 
J2-12  

 

 

 

 

 

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

 

 outstanding items:

  • test out if +5 volt supply on motherboard is operational
  • figure out if I can use the +5 volt common from the motherboard (connect grounds between motherboard and Titan or disconnect from pin 1 on X9 and X10 (safer)
  • work out smoke unit working from Titan in diesel mode..
  • get connector for disconnecting ditch lights - need 4 pins)
  • add in polyswitches (short circuit protection) for ALL four track pickup wires
  • correct DC direction if wrong

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:

 

 Pin #                      J1 function
(Aristo)              

 J1 function       (Bachmann)                                              

 J2 function
(Bachmann)
 1 Power Pick-up Right Side                          Power Pick-up Right Side Aux power
 2 Power Pick-up Right SidePower Pick-up Right Side F1
 3 Motor(s) Right SideMotor + F2
 4 Front Lamp Control    rear LED ??? F3
 5 Smoke On/Off*smoke - F4
 6 + Outgnd F5
 7  Ground CommonB+ train bus +
8Smoke On/Off*chuff train bus -
9Rear Lamp Controlfront LED?? SP-
10Motor(s) Left Sidemotor - Reed sw
11Power Pick-up Left Sidepower pickup left side SP+
12Power Pick-up Left Sidepower pickup left side XXXXXXXXX                                                                                                                                                                                       
 Aristo did not standardize J2 for power/control purposes
(but sometimes the speaker is wired to it), * Pin 5 & 8 must be bridged for DCC
  

 

 

 

 

 

 

bachmann adaptor

 

ezgif 5 15f01ba8bc

Modification:

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

 

 

 

 

 

 

 

 

 

 

 

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