Repair manual

7
mac or you might be able to connect another compatible HD). Make
sure the firmware updater is fully unpacked and ready to rock and
roll.
After the iMac has started up OS 9.x and the firmware updater has
started (and HD activity has stopped), press Return a couple of
times to accept the licence agreement and to accept the system
shutdown. Then restart the iMac using the programmer’s button, as
described in the firmware install instructions. The update takes a
couple of minutes after the long beep. With any luck this will get
you going again.
1.4 With symptom S3 you just have to do the obvious and pull the
power cord for about 10 seconds after shutdown if you need to
reboot. Avoid rebooting if possible.
2. If the iMac doesn’t boot up at all
OK this is where it can get tricky. Presumably you have tried holding down
the SHIFT key to turn extensions off on bootup.
In this situation (symptom S4), you will probably find that you can’t even
get into Open Firmware mode (hold down Alt-Apple-O-F during and after
the startup chime). (If you can then it will display the firmware (or Boot
ROM) version at the top of the screen.)
If you are having trouble booting up then obviously it’s a good idea not to
reboot unnecessarily in case you can’t start up again.
2.1 If you have a tray loader (Rev A – D) then you may find that if you
unplug the internal video cable (the “larger gray cable” in the
second diagram here) the iMac starts up OK. This is a good sign,
but there is a chance that this is indicates the monitor flyback
transformer has blown or has dry joints. This is not so good – see
the earlier comments above, or search for “flyback” in the 2 forums
linked above. You can always connect an external mac monitor and
you might then be able to resolve firmware and other problems. Or
just use the external monitor as a permanent solution if the PAV
card or the MFT on the PAV card really has blown. Note that this
video connector is a 15-in Mac style connector (2 rows of pins). You
can get a convertor if necessary, e.g. Belkin MAC-VGA Adapter part
no. F3H1381, which looks as though it will fit.
2.2 If you have a slot loader try the following:
Simple
a) Do you have a startup chime? If not, you may have a memory
or other hardware problem. Try removing/changing/swapping/
reseating memory. In particular try removing any additional
memory, especially it not supplied by Apple. If that fails to help
you may need to jump direct to “last resort” below.