Mac 128k/512k/Plus Logic Board Cable to ATX (Video + Audio)

I do a little bit of work on compact mac logic boards and found I needed a convenient way to power them up and get video without fussing with a case, so I made this adapter which allows me to use an ATX power supply and an RGBtoHDMI.

Referring to the schematics for the 512k, you will see the pinout from the logic board for the cable connector is like this (digibarn).





It's a bit hard to read on the schematic, but you can see it's ordered like this:

1. Video Out
2. Empty
3. HSYNC
4. SPKR
5. VSYNC
6. +5V
7. GND
8. -12V
9. GND
10. +12V
11. BAT (4.5V)

When it comes to parts, I only needed the following:

• ATX Extension Cord (Amazon)
• Molex 09-50-3111 (Mouser)

Of course, if you don't own a compact mac or ATX power supply none of this is helpful. The RGBtoHDMI is a big help, but you could also use something whacky like a Power R adapter.

You can either get a fancy-pants tool to remove the connector clips from the plastic housing on the ATX connector or use a staple (tutorial). Either way, I was able to shove the ATX wires directly into the molex connector and they stay in snugly (win!).

After all of that I end up with a cable with a "female" ATX connect and a "female" molex for the mac logic board.