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jtsiomb / sgikbd

PS/2 keyboard/mouse converter for old Silicon Graphics computers.
GNU General Public License v3.0
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Reported lack of -8V DC on an R3000 indigo #2

Open jtsiomb opened 1 year ago

jtsiomb commented 1 year ago

I got a report via email of at least one Indigo R3000 which lacks the -8V DC power rail on pin 6 of the mini-DIN keyboard/mouse port (see doc/sgi_man7_keyboard). This board will not work without it. We need to figure out how many machines are affected by this.

A hack to overcome this problem would be to make a cable to grab -12V from an unused serial port, and connect it to one of the pins marked "V-" on the back side of the sgikbd board, on one of the D-SUB connectors (not the mini-din). Then remove pin 6 of the mini-din connector, to avoid back-feeding the computer through it, or cut the two traces going to pin 6 of the mini-din on the top side of the board.

jtsiomb commented 2 weeks ago

The way to overcome this problem by modifying the sgikbd board is documented here: http://nuclear.mutantstargoat.com/hw/sgikbd/indigo_r3000_hack.html

Not closing this issue until I redesign sgikbd to integrate the hack.