Repair manual

3
update; your precise symptoms (see below); and any other information
you think may be relevant. Please give as much detail as you can.
We want to help everyone with these problems but unfortunately don’t
have enough time (this is not a paid job for any of us! If only!) so do
please help us to help you by reading this document before you post in
the forum, or you will be summarily despatched back here. If you manage
to fix your problem using the suggestions here or have any further
insights, again, please post in the forum.
We know how frustrating it is when the computer just won’t behave, but
much as we’d like to provide a 24 hour instant response service please be
patient waiting for replies in the forum as we do actually have other lives,
just like you. You can always post an update with more symptom details
to move your topic to the top of the list again. Finally remember that at
the end of the day we can’t fix your problem – you do that!
We must point out that the “advanced” and “last resort”
suggestions may expose you to high voltages and are therefore
potentially dangerous to you, unless you take proper precautions.
They may also cause damage to your iMac. We cannot and do not
accept responsibility for any operations you may perform on your
iMac after reading these pages nor for resultant damage to your
computer. If you have any questions then ask for help in the
Usage forum or seek the assistance of a qualified Apple technician
or electronic engineer.
The symptoms
The symptoms seem to vary slightly between the different iMac models
but the following are often reported.
S1. iMac starts up but with blank display. You should hear the chime,
the HD spin up, and the chatter of the HD as the OS loads. You
will probably not hear the “thump” of the CRT coils loading up nor
the crackle of static which can sometimes be heard as the high
tension voltage builds up in the CRT. If your iMac didn’t perform a
proper shutdown the last time, in order to complete a successful
bootup you may need to press the <Return> key to a clear a
dialog telling you the hard disk is going to be checked, and again
when the check is complete.
S2. iMac starts up normally but with dim or strangely coloured
display. The full iMac fruit flavour spectrum has been reported.
S3. iMac does not respond following a warm reboot/reset or if the
power is turned on after a shutdown without pulling and replacing
the power cord first. After the reset/reboot/power on the LED
shows green but nothing else happens and the screen is blank.
There is usually no startup chime. You may hear a very faint
clicking (from the hard drive?).