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Yet another dead(?) Power Mac 9600/300


New Member
Jul 30, 2023
I recently got a 9600/300 (tested stock 300mhz cpu, Kansas logicboard, tested ram sticks /4*128MB/, ixmicro 128m8, GOOD pram batteryS, good psu, 4gig hdd, cd, zip, floppy).

Chimes, but thats it.

No video, no keyboard (no response to cmd-opt-p-r, can power on with keyboard).
I tried evertything, cuda reset, logic board reset, another CPU (Sonnet 400), ram, different videocard (fw modded radeon 7000, mac rage128pro), disconnect scsi (hdd termination jumper set, last in cable - no difference when scsi cable plugged in or not) etc.

Chime comes almost immediately after i press the power button.

Without the ram sicks no broken mac sound, just chime.

Tried to get to OpenFirmware, with cmd-opt-o-f, holding down looooong the power button, but the system shuts down after 1-2 secs.

Anybody have any idea what anything can i try?

Have you recapped the logic board and verified the power supply is putting out clean power? Just because the power supply puts out what looks like the correct voltages, doesn't mean it doesn't also have crazy ripple on the power rails, or falls on its face under a load.
Thanx for the replies. The board is recapped, and clean. I left the machine on all night long, no change. I cant see anything wrong with the psu, but i building a new one using a new atx psu.

The case is 9,6" (24,6cm) wide.