Replacing Amiga 9 pin D-Sub mouse cable

Question

I have an original Amiga "tank" mouse, the PCBs are good, but the cable is clearly faulty as the Y axis and left mouse click doesn't work when it is tilted to the right.

I need to replace the cable in order to have it working properly.

I know I have to get a 9 pin D-Sub female connector. But I don't know what type of cable I should get as it should be 9 pin but the mouse cable only has 8 wires + the ground that seems soldered to the metal mesh coating the wires inside the cable.

Also, I don't know which pin goes where on the PCBs, I could only find pinouts for the connector, and not for the PCBs.

So, what type of cable should I get as a replacement and how should I solder it to the PCB?

Answer 1

Unfortunately there were a few "revisions" of the mouse, and the pads on the mouse side were not always signed; the color coding isn't guaranteed to be repeatable either.

If your mouse has the pins marked on board, you can use the pinout of this extension cord to match them.

If there isn't, you'll have to match them "by hand".

Cut the mouse cable a very short distance from the plug, just enough to expose the wires and their colored shells. Using ohm-meter match colors to pins in the plug, write that down - and also match colors to pad order inside the mouse. That way you'll be able to re-create the mapping, unless the fault is right at the socket. If it is - you'll have some pretty arduous surgery at your hands, stripping the plastic from the plug with a sharp knife to trace the physical connection of the wires to pins.

Answer 2

Use an ohmmeter to determine the end-to-end mapping from D-sub pins to the connections on the PCB with the existing cable. Write this down and make sure your new cable has the exact same mapping.

Answer 3

I went to an electronics shop where the owner mapped the connections and replaced the D-Sub connector, which fixed the mouse. So using an ohmeter as recommended by Dave Tweed is the way to go.

Another thing I discovered upon closer inspection of the Amiga mouse PCB is that the soldering points labels (1 or 2 letters) actually indicate which wire to solder to each point according to its color. So here are the matching soldering points-wire color combination for the main PCB:

The format is Label = Wire color.

• w = White wire
• pu = Unused
• bk = Unused
• Pu = PUrple wire
• Ye = YEllow wire
• re = REd wire
• br = BRown wire
• or = ORange

The left and right click PCB doesn't use the same labelling scheme:

• U = Blue
• L = Dark blue