Question Finding pinout of propriety front IO connectors (SUN Ultra 45 Sleeper build)

Aug 14, 2020
Hi all,

I've posted about this on various forums across the internet recently, and had some good responses but the issue remains ultimately unresolved.

I'm doing a sleeper build in a Sun Ultra 45 workstation case. I've managed to pretty much complete it (drilling new mobo standoffs, finding cooling solutions, etc) but there's one problem that remains: the front panel IO. Now this uses very nonstandard connectors - ribbon cables infact - to connect to the original Sun board. The IO and it's internal PCB + connectors can be seen here.

I've already began to figure out the pinout. I was told to follow the lines on the PCB and use a DMM to find the ground ports by touching a negative capacitor then touching each pin till I hear a beep on continuous. I've made a doc of my current version of the pinout here.

However this is where I stand at the moment. This pinout is quite clearly wrong in areas and there's info missing (bottom right of 26 pin / also 'from usb bus'). The pins on this diagram that represent Power on / off, USB data, Firewire Data, and the Speaker don't show which of their respective pair's pins are positive or negative; I'm not sure how I discover this using a DMM although I'm sure it's possible. My second issue is the audio pins I've marked there are quite clearly wrong, as I've heard they wouldn't be situated so close to each other on the 26 pin pinout - so I'm not sure how I'd test and find their location either. Here's a closer look at what I've attempted to find so far in regards to that.
I can provide more photos if necessary.

Either way I'd super appreciate someone taking a look and pointing me in the right direction. I'm pretty lost at this point.