Display Issues: related to sleep, boot

I hope my tendancy towards 'full disclosure' doesn't prevent you from reading this lengthy post... Thanks in advance!


Ok so my display is currently having intermittent problems, showing no picture. Occasionally when I boot up, or wake from sleep, (again this is only sometimes, for both) the display stays black. F2 does not help (duh), nor does a reboot, NVRAM reset, PMU reset, etc. When its a wake-from-sleep issue, the screen shows up for maybe half a second, then turns black.
Sometimes the display is simply not backlit (picture visible with flashlight) but sometimes the display has no video nor backlight at all. It does seem to like to give video to my TV (s-vid) tho. I do not regularly use external displays (only when my screen is black and i'm troubleshooting!) or a billion USB dongles, i use nothing but the charger and ipod cable. I know my DC-in board is bad (won't charge) but this has happed about 2 weeks before any screen problems--one is on order, hopefully it gets here soon, and have been swapping batteries with the GF's computer until my part arrives.
While plugged into the TV the trashing of 'powermanagement' pref file immediatley made my screen work (its never come out of its 'screen coma' w/o several reboots before) but this does not seem to be a repeatable fix. Also, I think I have ruled out the display's inverter-board as a probable problem - With the top case off and computer off I plugged in (but did not install) a second (working pull from one of my computers) inverter board, plugged it into the LB and screen, and the screen still stayed black.

I then tried swapping out the DC-DC board, however there was no chime with my backup board, i got it from a shady seller on eBay and i'm guessing its blown...
Resetting the nvram SEVERAL times THEN rebooting has worked for me, as has plugging in an external monitor (tv), but nothing consistently cures this 'display coma'. I'm sure the computer is on, as i can here the HD spinning away, and a powerbutton-enter results in a shut-down about 8 seconds later so-def a display/video problem of some sort!

I have also had strange sleep behavior , as in sleeping every 5seconds or so, the computer would sleep before it even finished booting up, sleep before it shut down, sleep before i could open any application. removal of the hall-effect sensor (i now manually sleep) at first seemed to cure this sleep problem AND the display problem, but the display problem is back without the sensor in the computer--so it cannot be the only cause of this wretched malfunction.


Any help would be greatly appreciated, as I am a broke-@$$ college student about to graduate and REALLY DEPEND on this computer for my classes, and cannot afford the 2weeks at the apple store (we have 10-week classes... plus countless $$$). I am comfortable with replacing any components of the computer by myself, or doing any software/firmware, etc fixes as long as I'm given some direction/guidance!;D

Which model powerbook do you have?

Having just been down that path with a video problem - i managed to get 3 useful periods before sending it in by resetting PRAM then running the supplied hardware check on install disk. No problem picked up even tho Logic board was replaced finally but each sequence of checking gave me use of laptop until i started a video iChat when it locked up again. Now this was for a MacBook pro so not sure if it is applicable to a powerbook but give it a shot - it might give you limited use for a while.

Thanks for the interest, This is the 1.5Ghz 12" PB, the last 12" made. I have never had the screen 'go out' on me, nor 'come back' while in normal use, only during boot or wake will it break/fix itself. The problem takes quite a few 'common fixes' to fix it' making me suspect I'm not really fixing it, nothing really solves it consistantly. Is it possible the 'little' battery on the LB has died? What are common symptoms of that part's failure??

This has happened maybe 6 times in the past week, and is a real hinderance. Also let me say I use my computer A LOT! Also for completeness I recently wiped my seagateHDD and cloned from a backup due to volume structure problems. I've also added a 1GB iRam chip and a DL DVD burner from japan. Those were all well before this problem, by 2mos to a year. TechTool Pro 4 shows no problems, I'm running 10.4.11, and have not yet done the apple hardware test.

You might try replacing the hall effect sensor. It reacts to a magnet in the display to put the computer to sleep when the cover is closed. If it's going bad it can prevent the computer from waking up properly.

Yes I thought that as well, and one is on it's way, however I have removed the sensor and am still having issues

The problem seems to be fixable by flashing PRAM/NVRAM--what could cause this to go corrupt/haywire about once per day???

I left the computer w/out a battery for one day and the clock had reset-- so how do I replace the clock battery??

After replacing the charger board, display inverter and hall effect sensor the computer now works as new.

I have a question for you all: can the battery charge the NVRAM battery ordoes only the charger charge this battery?? Thanks