Sony MiniDisc® RM-MZR30MP
Remote Control Hacked

by Leon Woestenberg <leon@stack.nl>.

Introduction

The RM-MZR30MP remote control is a cable remote control for Sony MiniDisc portables. It connects to the portable unit, such as the MZ-R30, using a plug that both connects with the mini-jack stereo connector, as well as Sony's proprietary 4-pin remote control connector. The remote control has a coaxial output for Sony proprietary coaxial headphone plugs.

There are several reasons why you would want to make changes to this remote control thing, but mostly just because Sony has made a very clumsy design:

Schematics

Remote control commands are issued by switching a resistance between two of the remote control pins (pin 2 and 4). The value of the resistance determines what function is issued.

When no button is pressed, the resistance is unlimited (i.e. open switch). The hold button is merely an extra switch (S101) that ensures the other switches have no effect.

The rest of the remote controls buttons is connected in a resistor network (R101-R111), providing a relatively large number of functions with a relatively low number of resistors.

Here are some quick schematics I drew. Hope my scribbling is somewhat readable; I will eventually draw it with some decent software.

Resistor Table

This table shows each of the resistor values, which resistors are used by which functions, and the resulting total resistance for each function.

functionR totalR101R102R103R104R105R106R107R108R109R110R111
[Ohms] 100013001300271500561800150150015002000
Prev/Back 10001000
Next/Forward362710001300130027
Pause 5156100013001300150056
Stop 705010001300130015001800150
Volume - 8400100013001300150018001500
Volume + 99001000130013001500180015001500
Track Mark 1190010001300130015001800150015002000

Other res mistor values, as found by Andy James <andy.james@virgin.net>. These are not present in the RM-MZR30MP remote control, but which are understood by the MZ-R30. WARNING: Use on your own risk!

functionR total
[Ohms]
Mode 14000
Display 17000
Record 19500
Test Mode 24000

Details to come later. Please see the MiniDisc Community Page for more info on remotes.

Questions

If you have any further questions or suggestions, ask me. I'll also be following the MiniDisc Mailing List.

Regards,
Leon Woestenberg <leon@stack.nl>.

Minidisc® is a registered trademark of Sony Corporation.