iMac G5 20" Model A1145 Logic board Replacement

Schritt 1

Orient the iMac face-side down on a table with the bottom edge facing yourself.
Remove the two Phillips screws securing the access door to the bottom grille of your iMac.
The screws are captive in the access door.
Before beginning the repair, unplug the computer and press and hold the power switch for 20-30 seconds, to discharge internal capacitors.

As you remove the screws during these steps, place them on a towel or a piece of cardboard. With a Sharpie label a piece of masking tape with the step number from which they were taken from. Then place the removed screws under the tape.

This ongoing step will aid in you having control on your reassembly without searching for and identifying the size and length all the screws that you are about to remove.

R51801 - 05/12/16

Schritt 2

Remove the access door.

Schritt 3

Remove the three T8 Torx screws securing the front bezel to the rear case along the lower edge of the iMac.

Schritt 4

Turn the computer over.
Use your thumbs to press both RAM arms in past the front bezel for enough clearance to lift it off the rear case.

Schritt 5

While holding the RAM arms in with your thumbs, lift the lower edge of the front bezel enough to clear the rear case.

you might have more luck by gently leveraging the stand up

Joseph A Borg - 29/08/15

Schritt 6

Re-orient your iMac so it sits upright on the stand.
Insert a plastic card up into the corner of the air vent slot near the top of the rear case.
Push the card toward the top of the iMac to release the front bezel latch.
Pull the front bezel away from the rear case.
Repeat this process for the other side of the front bezel.
It may be necessary to apply several layers of duct tape to the top of the access card to aid in releasing the latches.
If the bezel refuses to release, try pressing the lower edge back onto the rear case and repeat this opening process.
Alternatively, you can use a strong magnet by holding it to the front top left/right corner of the display. You will hear a snapping sound when the hatch is released.

If it still does not release try pressing in and out (like an accordion) with the card in one hand and the screen bezel in the other until it pops loose.

rick -

If your computer has ever been worked on by an authorized Mac repair shop, this step may not be needed. I was able to skip this step after lifting the lower edge of the front bezel. Front bezel lifted off easily.

Timothy Walsh - 04/08/20

Schritt 7

Lay your iMac stand-side down on a table.
Lift the front bezel from its lower edge and rotate it away from the rest of your iMac, minding the RAM arms that may get caught.
Lay the front bezel above the rest of the iMac.

My A1145 seems to be attached, somehow, on the top via some silver looking strips. It does not seems to want to come off. Is that the wireless?

Chris Arnold -

NO they are clamps on each of the top inside corners of the outside bezel (frame ) if you use a Heavy Spudger Tool & pry not too hard just slightly between the bezel (side) and the display (side) this should pop each off usually by just popping one or the other sides the second will automatically pop as well.

Mark Meininger - 05/05/15

Schritt 8

If necessary, remove the piece of kapton tape wrapped around the microphone and camera connectors.

Schritt 9

Disconnect both the camera and microphone cables.

Schritt 10

Peel the lower EMI shield off the lower edge of the iMac and off the two vertical 4" sections on either side of the iMac.
It is not necessary to peel the lower EMI shield off the display.

Schritt 11

Tape the lower EMI shield up against the face of the display to keep it out of the way while you work.

Schritt 12

Remove the two T6 Torx screws securing the display data cable connector to the logic board.

Schritt 13

To disconnect the display data cable, grab its connector's black tab and pull it away from the face of the logic board.

Schritt 14

Peel back the two EMI tape strips from the left and right edges of the display.
During reassembly, it is helpful to use several small strips of tape to hold the EMI shielding along the left and right edges of the display footprint out of the way before lowering the display into the rear case of your iMac.

Schritt 15

Remove the four recessed T10 Torx screws securing the display to the rear case.
Bit drivers tend to be too short to reach these screws. Be sure to have a magnetic thin-shafted T10 Torx screwdriver on hand.

When I removed the 4 screws, my bit wasn't magnetic enough to pick them out and they fell in. I could only retrieve 2 of them. Have a strong magnetic bit! Lucky for me, I was only using this guide to remove the hard drive so I could recycle my old computer.

Ruth - 11/05/16

The 64 Bit Driver kit does not include a thin-enough, thin-shafted T10 Torx screwdriver. Where to get one of these?

Timothy Walsh - 04/08/20

Schritt 16

Lift the lower edge of the display slightly out of the rear case.
Disconnect both inverter cables (shown in red) by pulling their connectors toward the bottom edge of your iMac.

Schritt 17

Lift the display until it is nearly perpendicular to the rear case.
Disconnect the remaining two inverter cables (shown in red) by pulling their connectors toward the top edge of your iMac.

Steps 17 and 18 are not strictly necessary if one simply props up the LCD display into a vertical position while the hard drive is removed and replaced. It worked for me anyway!

I would like to send out a big thank you to Andrew Bookholt for submitting this extremely helpful guide!

Mark Orwoll

Mark Orwoll -

Prop the screen with something soft (plastic or wood) so as not to scratch the screen coating.

Mark -

Schritt 18

While holding the display perpendicular to the rear case, pull it upward to peel off the EMI shield stuck to its upper edge.

If you are changing the power supply - this is a good point to remove the screws to the old power supply to see if the connectors (both of them) are accessible. If you can gently (but firmly) pull the power connector out from under the chassis, you can install the new unit at this step - saving hours of work.

philaro -

See note to step 44 to easyly remove the power supply without dismantling the whole computer (as also suggested by philaro).

danman -

Schritt 19

Disconnect the IR board cable by pulling its connector away from the socket on the IR board.

Schritt 20

Remove the two T6 Torx screws securing the IR board bracket to the IR board.

Schritt 21

De-route the IR cable from under the aluminum heat sink and tuck it behind the optical drive to keep it out of the way.

Schritt 22

Remove the single T10 Torx screw securing the left speaker to the rear case.
The screw for the left speaker has coarse threads.
Lift the left speaker out of the rear case and de-route its cable across the logic board.

Schritt 23

Remove the single T10 Torx screw securing the right speaker to the rear case.
The right speaker screw has fine threads.
Lift the right speaker out of the rear case, minding the short cable between the speaker and its connector (located slightly above the right speaker).

Schritt 24

Disconnect the speakers from the logic board by pulling their connector toward the top edge of the iMac.

Schritt 25

Remove the two Phillips or two T6 Torx screws securing the AirPort/Bluetooth board to the logic board.

Schritt 26

Use your finger to lift the AirPort/Bluetooth board from its left edge, disconnecting it from the logic board.
Lift the board from its left edge only.

Schritt 27

Use the flat end of a spudger to pry both antenna cable connectors up off the AirPort/Bluetooth board.

Schritt 28

Disconnect the DC-in cable by simultaneously depressing both locking arms and pulling its connector away from the socket on the logic board toward the top of your iMac.
After both locking arms pass their retaining tabs, it is helpful to push the arms toward the top edge of your iMac while wiggling the connector.

Schritt 29

Disconnect the ambient light sensor by pulling its connector away from the face of the logic board.

Schritt 30

Disconnect the optical drive fan from the logic board.
To aid in removal, it is helpful to use both of your thumbnails to push the ears on either side of the connector toward the top edge of the iMac.

Schritt 31

Disconnect the IR/camera cable from the logic board.
This connector is especially wide and prone to breakage.
To aid in removal, it is helpful to use one hand to pinch the cables against a spudger and pull up toward the top edge of the iMac while pulling up gently on the cables with your other hand.

Schritt 32

Disconnect the optical drive thermal sensor cable from the logic board by pulling its connector toward the left edge of the iMac.

Schritt 33

Remove the two T6 Torx screws securing the optical drive connector to the logic board.

Schritt 34

Use the flat end of a spudger to pry the optical drive connector up off the logic board.
It is helpful to insert the spudger under the top or bottom edge of the connector and twist to separate the connector from the logic board.

Schritt 35

Disconnect the CPU fan from the logic board by pulling its connector toward the top edge of the iMac.

Schritt 36

Disconnect the hard drive thermal sensor from the logic board by pulling its connector toward the top edge of the iMac.

Schritt 37

Disconnect the hard drive fan by pulling its connector away from the face of the logic board.

Schritt 38

Disconnect the power button cable by pulling its connector away from the face of the logic board.

Schritt 39

Remove the two T6 Torx screws near the top of the heat sinks.

Schritt 40

Remove the following seven screws securing the logic board to the rear case:
Three coarse-thread T10 Torx.
Three fine-thread T10 Torx.
One long coarse-thread T10 Torx.

Two T10s are reversed. The bottom T10 to the right of the RAM should be fine-thread. The one directly above it should be coarse-thread.

mike -

Confirmed - is the same in my computer.

Ulf Springer - 06/06/20

Schritt 41

Tuck the RAM arms into the iMac so they rest on the perforated metal grille along its lower edge.

Schritt 42

Rotate the top of the logic board toward yourself slightly.
Pull the right edge of the logic board toward yourself slightly to free the I/O ports from the rear case, being careful not to bend the board.
Continue rotating the board toward yourself until you have enough room to reach the SATA connector, shown in the next step.

Schritt 43

Continue rotating the board toward yourself until you have enough room to reach the SATA connector (shown in red).
Insert the blunt end of a metal spudger between the SATA connector and its socket. Twist the shaft of the metal spudger to separate the connector from its socket.
Disconnect the SATA cable from the logic board.
Lift the logic board out of the rear case by its edges, minding any cables that may get caught.

iMac G5 20" Model A1145 Logic board Replacement

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