G4 867dp & studio power outage...now wont start?

[Dean Bohana]

Maybe someone has a clue. Mac G4 was powered up, ready for today's sessions. Suddenly, a total power outage at the studio. After resetting the studio's circuit breaker, Mac wont start up.

When I push in the power button, IT DOES Light up but only while I'm holding it in...once I let go, the light goes off and the computer remains OFF.

So it seems that on some level, power IS getting through hence the light, but nothing more. Anyone familiar with the resetting of the PMU? Someone suggested this fix but I'm not sure what's entailed. Any help greatly appreciated!

Dean in Distress

[Sean Halley]

Does the fan start up when you're holding it in as well, but stop like everything else when you "remove your finger", so to speak?

I've seen that behaviour a couple of times: once was it bad RAM (sticks of which are obviously highly voltage and static sensitive), but it's usually a bad power supply. You can try resetting everything on the motherboard, doing a PRAM reset, and holding your breath, and you can also try yanking a few sticks of RAM at a time to see if one of them either came unseated or was zapped...


Hope that helps,

S..

[myshell]

Resetting your PMU is pretty straightforward. Just make sure you've discharged yourself. This is from Apple support. You can find answers to most your Apple computer problems there. The PMU switch should be right by the battery (You should be able top find the diagram for your model there).

Resetting the PMU Chip Procedure

1. Disconnect the power cord and check the battery in the battery holder (BT1). The battery should read 3.3 V to 3.7 V. If the battery is bad, replace the battery, wait ten seconds, and then reset the PMU (refer to the next step). If the battery is good, go to the next step.

2. Press the PMU reset switch (S1) once on the logic board. Do not press the PMU reset switch a second time because it could stop the PMU chip from responding.

3. Wait ten seconds before connecting the power cord and turning the computer on. If the computer turns on, go to the next step. If the computer does not turn on, there is something else wrong with the computer.

4. Run MacTest Pro and return the computer to the customer.

Note: This entire procedure resets the computer's PRAM. Be sure to reset the computer's time, date, and other system parameter settings before returning the computer to the customer.

Good luck,

Myshell