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This guide details removing the logic board in a 2017 iMac 4K in order to remove or replace the RAM.
Some images in this guide use a 2015 iMac, which has minor visual differences. These differences do not affect the repair procedure.
This guide is marked "potentially dangerous" because it requires you to handle a power supply that contains large capacitors. Unplug the iMac and hold the power button down for at least 10 seconds to help discharge the capacitors. Handle the board by the edges and do not touch surface components.
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crwdns2935267:0crwdne2935267:0iMac Intel 21.5" Cardboard Service Wedge$4.99
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Starting on the left of the display, near the power button, insert the iMac Opening Tool into the gap between the glass panel and the rear enclosure.
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Use the tool like a pizza cutter—roll it along through the gap, and it will cut the foam adhesive through the center.
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Run the tool up along the left side of the display.
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Continue running the tool up around the top left corner.
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Cut the adhesive along the top left of the display.
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Continue along the top of the display.
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You may want to run the tool back and forth through what you've already cut a few times, to ensure you get as much of the adhesive separated as possible.
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Push the tool around the top right corner of the display.
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Wheel the tool down along the right side of the display.
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Finish pushing the opening tool to the bottom of the right side of the display.
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crwdns2935267:0crwdne2935267:0Plastic Cards$2.99
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Starting from the top right corner of the iMac, wedge a plastic card between the display and frame.
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Gently twist the plastic card sideways to create a gap between the display and frame.
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Move slowly and be careful not to stress the display glass too much—you only need to make a gap of about 1/4".
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Slide the card toward the center of the display to cut any of the remaining adhesive along the top right corner of the iMac.
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Wedge the plastic card into the top right corner once again and let it stay there to keep the adhesive from resettling.
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Insert a second plastic card into the gap between the display and frame located at the top left corner of the iMac.
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Gently twist the card upward, slightly increasing the space between the display and frame.
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Slide the plastic card toward the center, again stopping just before the iSight camera.
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Wedge the plastic card back into the top left corner.
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With both plastic cards inserted as shown near the corners, gently twist the cards sideways to increase the gap between display and case.
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Begin to lift the top of the display up from the frame.
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While holding the display up with one hand, use the other hand to unplug the display power cable. Make sure that you pull the cable out from the plastic tab, and not by pulling on the color wires.
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Use the tip of a spudger to flip up the metal retaining bracket on the display data cable.
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Carefully pull the display data cable from its socket on the logic board.
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Lift the display up to a near-vertical position.
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Grasp the small tab at the end of one of the bottom edge display adhesive strips and pull the adhesive toward the top of the iMac to remove it.
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Repeat this step with the other adhesive strip and remove it.
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Lift the display up from the frame and remove it from the iMac.
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It may be necessary to slowly lift from one side, to peel against the remaining adhesive.
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Remove the following five Phillips screws holding the lower support bracket in place:
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Four 3.2 mm screws
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One 1.7 mm screw
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Remove the lower support bracket (a.k.a. "chin strap") from the iMac enclosure.
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Remove the following T10 Torx screws securing the hard drive brackets to the iMac:
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Two 21 mm screws
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One 9 mm screw
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One 27 mm screw
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Remove the left and right hard drive brackets from the iMac.
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Use the tip of a spudger to push each side of the power button cable connector and gently walk it out of its socket.
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Use the tip of a spudger to push each side of the power supply control cable connector and gently walk it out of its socket.
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Remove the two 7.2 mm T10 Torx screws securing the power supply to the rear enclosure.
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Pull the power supply slightly up and out from the rear enclosure.
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Rotate the power supply counterclockwise, lifting the right side up about an inch higher than the left.
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Slide the power supply to the right to clear the screw posts on the rear enclosure.
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Rock the power supply forward and remove it from its recess in the rear enclosure.
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Squeeze the tab on the back side of the DC power cable connector and pull it straight out of its socket on the back of the logic board.
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Use the flat end of a spudger to press the clip on the side of the AC inlet cable connector inward.
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While pressing on the release clip with the spudger, grasp the AC inlet cable, and pull the connector straight out of its socket.
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Remove the power supply from the iMac.
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Gently pull the fan cable connector straight away from its socket on the logic board.
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Remove the three 10 mm T10 Torx screws securing the fan to the rear enclosure.
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Lift the hard drive from the edge nearest the logic board and pull it slightly out of its recess.
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Use a spudger to disconnect the single SATA power and data combo cable by gently prying its large plastic connector away from the hard drive.
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Remove the hard drive assembly from the iMac.
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Remove the 7.3 mm T8 Torx screw securing the hard drive tray to the rear enclosure.
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Gently pull the right speaker cable connector straight down and out of its socket on the logic board.
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Gently pull the left speaker cable straight out of its socket on the logic board.
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De-route the left speaker cable by pulling it straight up out of the retaining clip in the back of the rear enclosure.
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Similarly to the previous step, de-route the SATA and power cables by pulling the braid straight up out of the retaining clip.
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Peel up the piece of tape connecting the left speaker connector to the SATA power and data cables.
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Flip up the metal retaining bracket on the FaceTime camera cable connector.
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Pull the FaceTime camera cable straight out of its socket on the logic board.
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Remove the two 4.0 mm T5 Torx screws securing the four antenna connectors to the AirPort/Bluetooth card.
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Disconnect all four antenna connectors by prying them straight up from their sockets on the AirPort/Bluetooth card.
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Use the flat edge of a spudger to pry the headphone jack cable connector from its socket on the logic board.
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Push the cable up and out of the way of the logic board.
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Peel off the tape covering the exhaust duct.
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Remove the following T8 Torx screws securing the exhaust duct to the rear enclosure:
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Two 6.2 mm screws
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Two 4.7 mm screws
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Flip the latch on the microphone ZIF connector and pull the cable out of its socket on the logic board.
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Remove the four 7.3 mm T8 Torx screws securing the logic board to the rear enclosure.
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Tilt the top of the logic board away from the rear enclosure.
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Lift the logic board straight up and out of the iMac.
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Handling the board by the edges, flip the logic board over to access the two RAM modules.
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Two clips secure the RAM module in place, one on each side. Using your fingers, spread the clips away from the RAM module.
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Lift the RAM module to an angle of about 30 degrees and slide it out.
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Peel off and transfer the thermal pad from the original RAM stick to your replacement RAM before you install it in the lower slot.
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To reassemble your iMac, follow these instructions in reverse order.
To reassemble your iMac, follow these instructions in reverse order.
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An excellent guide - many thanks. The logic board was tricksy to get out - the card reader was jamming on the casing, but it came out with care. It's easy to trap the microphone cable and the power button cables when re-assembling, so they're worth looking out for. Successfully replaced the RAM and installed an SSD at the same time - many thanks.
Can a SSD or fusion drive be put in the place where the normal hard drive was?
An ssd can yes - that's what I did at the same time as upgrading the ram. As long as it's a 2.5" ssd it should be fine. The Samsung ssd I used was a but thinner than the hard drive that came out but that doesn't affect anything really. You'll need to either have a bootable clone of your drive, or install Sierra from a USB stick you've already prepared (which is what I did).
A Fusion drive is the terminology used by Apple when the use a board soldered 120ish Gb storage and a standard 1Tb 2.5 inch drive, and bind them together, if you throw in a 1Tb SSD in place of the existing standard hard drive you end up with 2 drives when you begin installation, you can find the instructions to merge the onboard and the new SSD back together again, and boy does it transform these machines, absolute pig with a factory fusion setup.
I also upgraded my hard-drive to a 512 GB Samsung SSD successfully along with installing the 32 GB of RAM. The guide was great, but I have a two comments.
1) The screws that hold the antenna connectors (Step 52) are were very tightly screwed into the board, and it is easy to strip the head of the screw. I stripped one of the screws… Luckily, it was easy to just pull up on the bluetooth/AirPort card and slide it out from its slot on the main board. Thus, an option to removing all the antenna wires, is to just pull the bluetooth/Airport card out. It was quite easy to slip back into the correct spot when reassembling as well.
2) It was only after I completed the repair that I realized that the top of the nice screwdriver provided in the repair kit contained more hidden bits!
