[joakley]

Have a Beige G3/233 running OS 9.1 or 9.2.2. Has run almost perfectly since 1998. Three years ago, added a 400MHz G3 processor upgrade and a CD burner, and a year ago, a combo firewire/USB card.

A couple weeks ago, I found it wouldn't power up. No sound. The power button didn't light up green. The keyboard power switch had no effect. Made no changes hardware or software-wise since the previous time that I booted it.

Over the past couple weeks, I've tried the following...
-replaced the PRAM battery
-held the CUDA button down, both for 1 sec and then separately 20 seconds (as suggested to someone else on this board)
-changed electrical outlets
-changed power cords
-changed keyboards
-bought a new power supply on eBay and replaced the original power supply
-reseated the memory
-reseated the ROM chip
-reseated the connection where the power switch plugs into the motherboard

Nothing has changed the situation.

Interestingly, both with the original power supply and the new one, the monitor that draws it's power from the computer (not an outlet) powers up for about a second when I plug it in, but then quickly drops to 'power save' mode. But at least I know power is passing though.

Any ideas what could be wrong?

[BurpetheadX]

Guess a transistor somewhere crapped out.

[electropura]

its probably the logic board....
heres and excuse to buy the G5 you have been drooling over

[reader50]

Try removing PCI cards and everything but mouse / keyboard from the ADB bus. Peripherals that go bad can prevent bootup - this has proven a real problem on some USB Macs. You might even try unplugging the mouse and keyboard, then try to boot from the power button, in case it's the keyboard that has gone bad.

If you still have your original CPU sitting around, pop it back in. The upgrade might have died.

[eyadams]

If you still have your original CPU sitting around, pop it back in. The upgrade might have died.

I'll second that. I had a string of bad processor upgrades in my old G3, and found that if a chip was overclocked too far it wouldn't boot, and that it a chip went totally bad it wouldn't boot.

At the very least you should try clocking it down to the original MHz and see what happens.