This install guide will show you how to install a pause button switch inside the Sega Master System controller and a logic circuit inside the console that allows the switch to work. Mods using Mega Drive and NES controllers exist, but this pause button mod is designed to retain the use of original controllers whilst having the benefit of a pause button.
If pairing with a switchless region mod, the PS/PB solder pad needs wiring to the pause button before the region mod trace cut. Some old boards will say PS instead of PB.
Solder Maps
Sega Master System – NTSC-U / 837-6067 / 171-5379
Sega Master System – PAL / 837-6097 / 171-5385
Sega Master System – NTSC-U / 837-6629 / 171-5533-01A
Sega Master System – PAL / VA2 / 171-5672
Sega Master System – PAL / VA3 / 171-5535-10
Installing the Controller Switch
More details soon.
Logic
OR Gate
To have pause on one controller.
| OR Gate | ||||
| IN | OUT | |||
| Pause Button (Z) | 1A | 1B | 1Q | |
| Controller 1 | 1 (Default) | 1 | 1 | 1 |
| Controller 1 | 0 (Pressed) | 0 | 0 | 0 |
Quad NOR Gate
To have pause on two separate controllers that work independently.
| NOR Gate 1 | NOR Gate 2 | Outputs 1Q and 2Q feed inputs 3A and 3B. | NOR Gate 3 | ||||||||
| IN | OUT | IN | OUT | IN | OUT | ||||||
| Pause Button (Z) | 1A | 1B | 1Q | 2A | 2B | 2Q | 3A | 3B | 3Q | ||
| Controller 1 | 1 (Default) | 1 | 1 | 0 | 0 | 1 | |||||
| Controller 2 | 1 (Default) | 1 | 1 | 0 | 0 | ||||||
| Controller 1 | 0 (Pressed) | 0 | 0 | 1 | 1 | 0 | |||||
| Controller 2 | 1 (Default) | 1 | 1 | 0 | 0 | ||||||
| Controller 1 | 1 (Default) | 1 | 1 | 0 | 0 | 0 | |||||
| Controller 2 | 0 (Pressed) | 0 | 0 | 1 | 1 | ||||||
| Controller 1 | 0 (Pressed) | 0 | 0 | 1 | 1 | 0 | |||||
| Controller 2 | 0 (Pressed) | 0 | 0 | 1 | 1 | ||||||
Installing the Switchboard PCB
This is a quick step by step guide until I can get around to making a video and full guide with photographs.
- 1 – Open the controller and remove all the components
- 2 – Place the switch board over the two pegs. Do not install the switch into the switch board as it needs to be used as a drill template first.
- 3 – Using a 3.5mm HSS twist drill bit, hand drill the hole using the template provided on the switch board. The drill will occasionally bite the PCB but this should not be a problem and just means the drill bit needs to be straighter.
- 4 – Once drilled through, smooth out the drill hole if necessary with sand paper or file. If the switch bites or doesn’t press & return once finished, the hole needs to be slightly enlarged.
- 5 – Remove the switchboard from the pegs and install the switch onto the PCB making sure it goes on the correct side where the footprint image is. To remove the switch board lift each side only a small fraction at a time. If you go too fast or lift one end up too much it will get stuck or snap the peg. Be gentle, it does come off but needs to be lifted relatively straight.
- 6 – Cut three 5cm lengths of 28awg stranded wire. Strip and tin them.
- 7 – Solder the wires to the three pads on the board.
- 8 – Cut some spacers from the supplied tube. 3 are needed for the install. Install the first spacer over the lower peg.
- 9 – Put the switchboard over the pegs. The switch should protrude though the drilled hole.
- 10 – Replace the parts of the controller and controller PCB.
- 11 – Lift up only the D-Pad side of the PCB and fold it back over the buttons half of the PCB. This will allow you to solder the switch board wires to the Up, Down and Ground solder points on the D-Pad PCB.
- 12 – When done, lay the D-Pad PCB back down and install the two other spacers which go over the two pegs on top of the switch board.
- 13 – Close up the controller housing.