05-04-2006, 08:21 PM
12" PB, 1GHz, 512MB RAM, OSX.3
my computer isn't starting up or even trying to boot and none of the standard resets seem to help. i do not think it the the HDD, rather, i think it is the power management unit:
i have tried resetting the pram (multiple times), resetting the pmu (multiple times), and tried booting off the system disc but it doesn't even try. in fact, if i do a PRAM reset, i don't get a nice mac "gong" but an annoying "beeeeeeeeeeeeeeeeeeeeep" and a rapidly flashing sleep light. what does THAT mean!?!
i have had a couple episodes in the past where my computer was very stubborn to wake up - or it was stubborn in that it didn't go to sleep all the way. i would close the lid and the screen would turn off (most of these times) but the HD and cpu were still cranking away. i would return in a couple hours to find my computer smoking hot because i left it on my bed (insulation).
now when i attempt to turn it on, it goes through a standard hardware check; where the disc drive and HDD give a quick whir, and the startup chime dongs, but the screen doesn't come on and the cooling fan blasts like crazy - which is wrong because the computer is ice cold. and the HDD and disc drives are conspicuously silent (after the mac chime).
HDD usually give different kinds of signals - and usually time. i don't think my hdd is even getting signals to boot.
i thought maybe the PRAM battery needs to be replaced but then i read on apples website that all ibook G4s and 12" powerbooks don't have batteries, rather a capacitor that can keep the clock going for 20 seconds. i have unplugged it and pulled the battery for a couple hours in effort to drain the capacitor and any other power storage device, but that didn't work either.
i also read that the 12" powerbook is unique from the 15" PB in that it doesn't have a separate PMU board, rather everything is on the logic board (analogous to mother board).
i am about to look for used replacement logic boards (i am attached to this old horse), but before i do are there any other key combination, clever resets that i can try?
thank you in advance