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The Original iMac 233mHz Tray-loading computer is one of my favorites to tinker with. This powerhouse of a machine can be made to do almost anything, short of running modern 3D games. My little Bondy Blue is now over-clocked to 300mHz and running OS X 10.3 quite nicely, thank you very much! And that is on 128 Mg’s of ram. I have a 256 Mg sodimm on order, but as of this writing its not here yet.
Ok! Lets get our hands dirty! (Actually there is very little dirt
involved) You need to start with a nice work area, my dinning room
table works for me, lots of light and a soft surface for your beloved
to lay on...that is your iMac, not your wife. I just use a folded table
cloth as there is one on the table anyway.
Place the iMac CRT screen down, on the tablecloth, with the bottom
facing you. Grab your trusty phillips screwdriver and remove the screw
under the clear handle that is now at the top. Ok, this is a little
nerve wracking to do... but trust me on this... grab the clear handle
and quickly pull up and toward you in a snapping motion and the beauty cover will come off.
This exposes the try that holds the heart and sole of your iMac.
Remove the two screws inside the clear plastic handle at the top of the
tray. You will then need to remove the cables, start with the large
white cable that looks like a monitor connector (Because that’s what it
is) then the round cable, and finally the two black
rectangular connectors. There is a screw clamp holding one of these
that will have to be removed also. Now grab the clear handle and slide
the "guts" out straight up and place on your table, logic board side up
please. What you now have should look like photo number one.
This tray contains the logic board and processor, memory, video, modem and both hard drive and CD rom.
Place the tray with the CD rom facing away from you. Close to the
plastic handle you will see a shinny metal cage, remove the top, it
should just slide off with little effort. Under this you will see a
sodimm slot, and a heat-sink and a metal clip holding the heat-sink
down. Using your thumbnails release the clips on the sodimm chip so it
pops up and remove it. Using a regular screwdriver release the right
side of the clip holding the heat-sink and lift it to the left to
disengage it from the cage. Then simply pick up the heat-sink. Now you
are looking at the processor!
Up till now this has been pretty simple. But I warn you from this
point on you are traveling a dark road that if you are not very careful
can render your iMac a very large door-stop! I take no
responsibility and offer no warranty for these instructions. Alright,
deep breath and here we go! Turn the tray around with the system module
away from you, gently slide your fingertips under the far edge of the
system card pry up using only your fingers. There are two connectors
under the board near the back of the card, this is what we are
un-plugging. When you get it out, flip it over and remove the ram on
the other side. Look for the resistors you will be working with. See photo 2
Now these things are Tiny! I need my glasses And a
magnifying glass to work with them! The first thing I had to do was
sand the tip on my soldering iron to a fine point. And find a small set
of tweezers, I mean really small, I used the ones from my Swiss army
knife and they could have been smaller. Now study the diagram below to
see where the little resistors need to go.
For 300mHz you should only
have to move two.
Set up your magnifying glass and grab your iron and start by
un-soldering the two resistors. I really cant give you much to go on
here, if you have never soldered before I suggest you get someone
experienced to give it a shot. Or like me, you can throw caution to the
wind and give it a try!
After you are done soldering, just reverse the instructions above to
re-assemble your iMac. Leave the beauty cover off for now, just incase
something goes not right. Plug it in and push the button, if you hear
the "Bong" you are in good shape. It should boot to the os, go to
"About this Mac" and you should see "Power PC at 300 MHz!"
Congratulations! And welcome to the dark side!
By Anil8tor
David Jackson
Destroying computers since the late ‘70s
Ok after some requests, I am posting the resistor settings for all the original iMac G3s. Use at your own risk!Black Block=Shorted
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