Odd Software for Odd Jobs

Replacement Sony MiniDisc remote, part 2

The RM-MZ3R MiniDisc remotes I ordered on eBay arrived today so I got to work pulling one apart to start figuring out how to emulate one so I could have a nice large control box rather than a fiddly little remote.

MD remote2

It's simply a bunch of resistors (and one capacitor), with the audio L/R channels passed through.

MB remote1

The audio uses three wires - ground (brown), left (white), right (red). The controls use two wires - grey (KEY) and yellow (+B). Two remaining wires were cut short and not terminated on the circuit board - these, I assume, are for the display information (the RM-MZ3R doesn't have a display).

The resistor values are:

  • R1 = 1KΩ
  • R2 = 1.3KΩ
  • R3 = 1.3KΩ
  • R4 = 47Ω
  • R5 = 1.5KΩ
  • R6 = 62Ω
  • R7 = 2KΩ
  • R8 = 1.3KΩ
  • R9 = 1.5KΩ
  • R10 = 2KΩ
  • R11 = 2.4KΩ
  • R12 = 2.4KΩ

There are ten switches:

  • S101 = hold switch
  • S102 = reverse, select left
  • S103 = FF, play, select right
  • S104 = pause, CAPS
  • S105 = stop, ENTER
  • S106 = VOL -
  • S107 = VOL +
  • S108 = TMARK
  • S109 = DELETE
  • S110 = EDIT

Various combinations of the resistors lead to the MD unit understanding what command was sent. This is what I'm working on now (yes, I can just find it on the Internet but I learn more this way).

To make it easier, I've removed the wires from the circuit board and replaced them with headers. I've also soldered the tiny wires onto a breadboard in preparation for tinkering with an Arduino. I used a hot glue gun to try to make the wires a bit more robust - let's see!

You can see the two shorter wires on the right - these are for the display information. Should be interesting to figure out how that works.

2016-02-15 20.32.23

I'm almost ready to start tinkering …

MD remote3