Repair manual

2
Before going any further we suggest you print off this page and sit down
with a cuppa. Read, mark, learn, and inwardly digest. There is probably
more information than you want or need, and some of it is almost
certainly inaccurate; it will be too complex for some and too simple for
others; but your best chance of finding a fix is to understand some of
what has gone wrong with your iMac. So either read on … or take the iMac
to your Apple service centre.
The problem
On most CRT iMacs (especially the slot-loading CD/DVD models) it is
essential to upgrade the computer’s firmware before even attempting to
install OS X 10.2.x or higher (see this link on the Apple website).
Unfortunately the Panther documentation and the “read me” file on the
installation CD do not make this clear. In fact, the “read me” file may
make you think that it is safe to run the OS X installer as a way of finding
out if you need to upgrade the firmware. Don’t do it! But there again, if
you are reading this then it is probably too late to say that! Strangely,
there have also been reports of Panther installing successfully on iMacs
which don’t have the correct firmware – this shouldn’t happen. However,
the iMac may – a few months later perhaps – subsequently display the
tell-tale symptoms and stop working.
We don’t know what proportion of iMac (CRT)s are affected, but what is
clear is that many have been adversely affected by an encounter with the
OS X 10.2 or higher install CD.
Some users have ended up paying $/£ 200-300 to have their logic board
(motherboard) replaced.
The good news is that others have succeeded in repairing the damage. It
takes patience and may take some time, but if you are prepared to give it
a go then there is a fair chance that you will end up with a fully
functioning iMac that will give you a few more years of faithful service.
Resolving your problem
To resolve your problem, please read this page and try some of the
suggestions here.
If you need assistance then post in the Apple iMac (CRT) Usage discussion
forum. You may well have been directed here from there. You may well
find helpful comments there also. (For reference, you may also find a few
relevant posts in the Apple iMac (CRT) Displays forum.)
In order to post in the forum you will need to create an Apple ID. This is a
simple process that only takes a minute.
When you post in the forum make sure you identify your iMac version
(CPU speed, RAM, HD size, OS); whether you have attempted to install OS
X 10.2 or higher; your firmware version (find it using System Profiler, or,
preferably, Open Firmware mode – see below), or, if your machine won’t
start and you don’t know the version, whether you have done a firmware