Sudden White Screen - Won't Recover

Question

My iMac G4 hadn't given me a lick of trouble until last night. I left it on, as I usually do, while I was gone for about 45 minutes. When I got back, the screen was white. Restarting it didn't help. Unplugging it and starting it didn't help. When I restart it, I get the start up sounds, but just a white screen. Any help or suggestions for my monitor? It's about 4 years old now...
Thanks
Meg

Answer 1

Hi there...
I'm not sure which reset may affect displays in the iMacG4 computer; in
that some may help if there is no hardware defect, just a minor logic issue
and not a component failure.
Have you tried on startup to reset the PRAM? That is a handful, since the
power button is on the back of the computer and you need to hold 4 buttons
down on the keyboard simultaneously just after the startup tone sounds;
and then keep holding them until you hear two more startup tones. The 4
buttons are Opt + Apple + R + P.
My computer had an odd video issue after installing the recent security
update; but only in open application windows. I tried several things to
hope to be rid of it; now it looks OK. My AppleCare goes until September.
I am not sure if something as drastic as "Resetting the PMU" would help
resolve this kind of issue. If you have the original video VGA adapter
and a 17" or so VGA (cathode ray tube model) computer display, you
could attach an external display to see if the video card is working that
far; and may be able to see other control panels; and further troubleshoot.
Usually if something such as the clock battery goes dead, you could still
get a computer to work; the date and time could be way off (unless it is
able to reset them automatically by the Apple Time Server online) and
a few other clues would normally be present. Some models may have
a display issue if the 3.6v lithium battery on the board goes dead. But
it should not wink out the display while you are using it, or while it is
powered-up. There are a few occasions where a issue may develop
in one of these, when it may have tried to sleep, but for whatever reason
the display does not go out. I am not sure if that's anything to do with
the symptoms you've experienced; but things can happen.
At some point, it may be necessary to contact a local authorized service
provider and see if they have a qualified product specialist or (?) some
person capable of further troubleshooting; and get an estimate. They
may just try to throw parts at it, if they can't diagnose the true issues.
If so, you may have to rethink what to do next; perhaps find an honest
shop that is an Apple Specialist in the first place, with a reputation.
Wish I could be of more help; and I hope some keyboard or PMU reset
can help wake up your semi-comatose iMacG4 so the LCD works again.