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Introduction

Use this guide to replace the power supply.

    • With the hinge free to move, the iMac will be unbalanced and hard to work on. Repairs are fast and easy with an iMac service wedge, but can be completed without one.

    • If you are using the iFixit cardboard service wedge, follow these assembly directions to put it together.

    • Before beginning any work on your iMac: Unplug the computer and press and hold the power button for ten seconds to discharge the power supply's capacitors.

    • Be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.

    The wedge is an extremely tight fit for this model. I was worried that the amount of force needed to use it as shown might damage the stand, so I used it with the long side down instead. It worked fine that way and didn’t need anywhere near as much force to insert.

    roberttrevellyan - Reply

    Here’s a good YouTube vid on upgrading the RAM: Can a Normal Person Upgrade the RAM in the 2017 21.5" iMac?

    Dan - Reply

    Here are a couple tips from me:

    1) Expose the adhesive to extreme temperatures. I did this by transporting my iMac in my car, screen-down on a piece of cardboard on a cold February morning (in Chicago). When I went to pick up the iMac, the screen practically fell off the chassis. I would have been distraught by this if I hadn’t already planned this replacement. So it was a happy accident.

    2) Remember to expell the residual power from the power supply by pushing the power button while the iMac is unplugged. This does NOT guarantee it’s safe to touch, but when I accidentally brushed the solder and exposed capacitors, I didn’t get shocked.

    jerrid_foiles - Reply

    Instead of using the wedge, I placed the iMac faced up with the top side (web cam) facing me while I ran the pizza roller around. It worked out great!

    Sam Fung - Reply

    “All iMacs also come with a traditional hard drive” mine doesn’t!! it’s HDD bay is completely empty, no SATA cable or anything. I guess I’ll have to upgrade the PCIe SSD instead.

    Chris Hughes - Reply

    There is no replacement glass for this model, it is part of the LCD and impossible to remove or replace- the entire LCD has to be replaced unfortunately if the glass is cracked or damaged. You will have to Google search for a replacement. Also be careful with some of the lock tight tork screws as I broke one of my screw mounts taking one out.

    Phil Tesone - Reply

    I used this service wedge but also found it a very tight fit. The same stabilization can be achieved by using a big rolled up towel.

    Ernst - Reply

    While this is a good instruction guide, I recommend to also look at OWC’s instruction video about drive installation, before starting the exercise. Those install videos are very detailed and useful.

    Ernst - Reply

  1. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 2, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 2, image 2 of 2
    • 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.

    • The hub on the iMac Opening Tool will keep you from pushing the wheel in too far. If using a different tool, insert no more than 3/8" into the display. Otherwise, you risk severing antenna cables and causing serious damage.

    Don’t get too worried about starting exactly where the picture says. The glue is stronger in some parts so just start wherever is easier and then work slowly and patiently around in the direction shown.

    Richard Cook - Reply

    As this guide doesn’t cover replacing the adhesive strips, I found referring to the following was useful (noting that it’s not for the same model of iMac, so the modification they mention wasn’t necessary): iMac Intel 21.5" EMC 2544 Adhesive Strips Replacement

    Alan Digby - Reply

    It is very easy to crack the glass in front of the LCD during this step. I used the guitar pick, maybe it was too thick… crack is just on the frame but anyway it is disappointing :(

    Nikolay - Reply

    This part of the exercise should be done with extreme patience. I took my sweet time with the opening tool, rolling it through the entire panel and enclosure gap over and over again, until I was very sure no parts were sticking together anymore. And when I thought I was I done, I decided to do it over again.

    Ernst - Reply

    You can "warm up" the adhesive before try to cut it with the tool using a hair dryer. Heat the edges for about a minute, keep moving it so you don't cause stress in the glass. Also the above note.. use the tool and then the cards. Do not use a guitar pick or other objects as the thickness will cause you to break the front glass, which is a bonded part of the display (expensive).

    Carl Schultz - Reply

    In korean, 아이맥 오프닝툴을 이용하여 화면과 뒷본체부 사이에 틈사이, 전원버튼이 있는 디스플레이 왼쪽부터 분리를 시작한다

    Ethan ryu - Reply

  2. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 3, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 3, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 3, image 3 of 3
    • Use the tool like a pizza cutter—roll it along through the gap, and it will cut the foam adhesive through the center.

    • Be sure to always push with the handle behind the cutting wheel. If you pull, the wheel might get pulled out of the handle.

    • Run the tool up along the left side of the display.

    Erreur de traduction: "de bas en haut" et non de" haut en bas" sur le côté gauche de l'écran

    Moreau - Reply

    If re-opening a screen that was opened and re-attached using iFixit’s adhesive strips, I would strongly recommend heating it first with an iOpener, heat gun or hair dryer. 20 minutes after attaching with the iFixit adhesive I tried to open it again with the pizza slicer to fix something and cracked the screen on the left-hand side.

    plasticpool - Reply

  3. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 4, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 4, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 4, image 3 of 3
    • Continue running the tool up around the top left corner.

    Ne pincez pas l’écran avec l’autre main. Vous exercez une pression inutile sur le verre et empêchez la roulette de couper le joint.

    phfoglia - Reply

  4. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 5, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 5, image 2 of 2
    • Cut the adhesive along the top left of the display.

  5. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 6, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 6, image 2 of 2
    • Continue along the top of the display.

    • 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.

    In this step can I cut along the display without make any damage to the front camera?

    arisnordico - Reply

    Hi! Actually - there is no need to cut the tape around the camera area - there is no tape to cut at all! And so, the way go is easy - just pass 10 mm to the left and to the right from camera and start cutting!

    P.S. Just did the whole procedure to replace a RAM and to add SSD on PSIe an hour ago! Seems to be different reading the instructions... you know - 2/10 and so on. But it's really not that hard, trust me. I'll give it 5/10.

    P.P.S. By the way there is one trick to pass the difficult steps. Any action which requires pulling smth (motherboard, speaker, power supply unit) from the narrow crack (or should i say - slit?) at the bottom of your Imac is really not so easy.

    And the trick is to first remove a thin metal stripe with some kind of insulation on it which held by 5 small (very small!!) screws at the bottom of your Imac. After you done it - it's easy to pull everything! Pay attention to the fact that one of this 5 screws at the center are more shortly than others.

    dv1977 - Reply

    After doing the replacement the adhesive still sticks quite good enough to hold the screen in place. Maybe this isn't rock-solid, but enough for me.

    Mirko - Reply

    I did all steps like this manuell but now the Display wont work only some colered strips are to see! Whats happend??

    Can anybody help me ? Maybe the connector cable is broken?

    djfanta - Reply

    Check both connectors, probably one of them not seated well

    pzhivulin -

    You can add a SATA SSD if you already have a PCIe SSD Factory?

    kaserlik - Reply

    If you're changing cracked EMC 2638 display to new assembly, there's two more steps:

    Step 24: Use the tip of a spudger to flip up the metal retaining bracket on the display data cable.

    Carefully pull the display data cable from its socket on the display assembly.

    Step 25: Use the tip of a spudger to unplug bracket of the thermal sensor small cable near display data cable.

    Carefully remove scotch tape covering thermal sensor. Using iSesamo or flat tip of the spudger carefully peel the thermal sensor away.

    pzhivulin - Reply

    omg - forgot to switch the termal sensor from the old display...

    now fan runs like crazy...

    Andrei Balotescu -

    The key thing is to never put any force on the opening tool when working through the tape. Just roll it back and forth with ease.

    Ernst - Reply

  6. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 7, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 7, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 7, image 3 of 3
    • Push the tool around the top right corner of the display.

  7. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 8, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 8, image 2 of 2
    • Wheel the tool down along the right side of the display.

  8. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 9, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 9, image 2 of 2
    • Finish pushing the opening tool to the bottom of the right side of the display.

    • At this point, you'll want to run the tool back around the entire display, to ensure you cut as much adhesive as possible.

    Yes, do it many times to loosen the adhesive.

    Noah Ralston - Reply

    Would be good data to show the 3 areas (wifi antennas where the "tape" is larger and covers them. The rest of the "tape" is 1.4" and easy. Also after removing the display, be sure to remove the old "tape" from both the display and the rubber parts of the case. Use the spudger to start an end and it should pull off easily. Careful on the baackside of the display as you can scratch off the black paint/covering.

    Carl Schultz - Reply

  9. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 10, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 10, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 10, image 3 of 3
    • While the opening tool cut most of the adhesive, the display will still be slightly adhered to the case. A plastic card will be necessary to free up the last of this adhesive.

    • Set the iMac face-up on a table.

    • Starting from the top right corner of the iMac, wedge a plastic card between the display and frame.

    • Be careful not to insert the plastic card more than 3/8", or you may damage internal components.

    this step is extremely important NOT to stick in the cards too far….. doing so, you risk a 600 euro replacement as I experienced………

    Edgar Broekema - Reply

    I drew a 3/8” line on my cards with a marker first.

    Max Romano - Reply

    I’m reading this on the EU store, please change all measurements to cm/mm.

    Morgana Devina - Reply

    @ifixit The next batch of cards you create should have a line printed on the card 3/8” in from the edges. Would make a nice reference.

    Richard Giratd - Reply

    Here’s where OWC provides glass removal suction cups, which is a better solution than plastic cards.

    The suction cups help to easily lift the glass panel, without risking the damaging of any internal wiring that the plastic cards could cause.

    Ernst - Reply

    Better to remove stand wedge at this point? Can’t see from pics

    derekrobinson - Reply

  10. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 11, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 11, image 2 of 2
    • Gently twist the plastic card sideways to create a gap between the display and frame.

    • Move slowly and be careful not to stress the display glass too much—you only need to make a gap of about 1/4".

    This part must be done very carefully or you can damage the flat cable from display, despite it was under a iron cover.

    Cassio Machado - Reply

  11. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 12, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 12, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 12, image 3 of 3
    • Slide the card toward the center of the display to cut any of the remaining adhesive along the top right corner of the iMac.

    • Be sure to stop before the iSight camera, or you may damage it.

    You don't need to do it like this, simply open the iMac bendidng the LCD completely and use the pizza cutter to remove the adhesive.

    Felix - Reply

    Agreed. The card is too thick to cut through the adhesive in this way. Use the pizza cutter or a sharper blade at this point.

    Max Romano -

    Using glass removal suction cups will avoid running this risk of damaging the camera (or any wiring).

    Ernst - Reply

  12. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 13, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 13, image 2 of 2
    • Wedge the plastic card into the top right corner once again, and leave it there to prevent the adhesive from resticking.

  13. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 14, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 14, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 14, image 3 of 3
    • Insert a second plastic card into the gap between the display and frame near the top left corner of the iMac.

  14. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 15, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 15, image 2 of 2
    • Gently twist the card upward, slightly increasing the space between the display and frame.

    • As with the other side, twist slowly to allow the adhesive time to separate, and be careful not to over-stress the display glass.

  15. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 16, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 16, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 16, image 3 of 3
    • Slide the plastic card toward the center, again stopping just before the iSight camera.

  16. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 17, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 17, image 2 of 2
    • Wedge the plastic card back into the top left corner.

  17. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 18, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 18, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 18, image 3 of 3
    • With both plastic cards inserted as shown near the corners, gently twist the cards sideways to increase the gap between display and case.

    • If there are any sections that seem to stick and won't separate, stop twisting and use one of the cards to cut the remaining adhesive.

    • Begin to lift the top of the display up from the frame.

    • Only lift the display a few inches—the display data and power cables are still connected to the logic board.

  18. iMac Intel 21.5" EMC 2638 Power Supply Replacement, Display: step 19, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement, Display: step 19, image 2 of 2
    • While holding the display up with one hand, use the other hand to unplug the display power cable.

    • Lift the display up enough to have easy access to the connector, but not so much that you stretch the cables and stress their connections (about 8").

    Pulling the display power cable by the wires makes me nervous..

    bstaud - Reply

    I had a small flight light ready so I could see. Follow the directions - don’t blindly pull.

    Noah Ralston - Reply

    Head lamp gives you the best hands free view!

    Macrepair SF - Reply

    bstaud - The display power cable has two squeezable levers on each end of the cable’s width.

    Squeeze the left lever with your thumb while you simultaneously squeeze the right lever with your

    index finger, and gently pull the cable straight back and out, and the cable comes out very easily.

    Ted Horodynsky - Reply

    When reassembling, make sure you get a “click” confirmation that both the levers have locked AND the pins have seated on this connector. I was treated to a black screen upon startup, and had to re-cut my newly installed adhesive strips to get back in to firm up this connection. Better would be power up with the bottom adhesive in place, screen resting in place and held on top with blue painter tape to confirm connections, THEN pull off screen-side adhesive tape covers for final re-bonding.

    Robert McKillip - Reply

    Can someone post a link to actually purchase these cables?

    Jay Hernandez - Reply

  19. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 20, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 20, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 20, image 3 of 3
    • Use the tip of a spudger to flip up the metal retaining bracket on the display data cable.

    • Carefully pull the display data cable from its socket on the logic board.

    • Be sure to pull the display data cable connector straight out of its socket.

    Sure could use a magnified picture of this connector and socket, especially the first time you go in. And it is the most critical step of the whole operation — bung it up and we’re toast.

    bstaud - Reply

    Hi bstaud! If you hover over the image you can click on the magnifying glass and get a large image of any guide photo. Hope that helps!

    Sam Goldheart -

    To clarify, the connector pulls out in the plane of the logic card, not perpendicular.

    David Thompson - Reply

  20. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 21, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 21, image 2 of 2
    • Lift the display up to a near-vertical position.

    • At this point there is still a strip of adhesive along the bottom of the display, that will hold the display to the frame like a hinge. You can loosen this adhesive by working the display up and down a few times.

    Where can I find a replacement display for my iMac?

    Braydon Boyce - Reply

    iFixit has listings for replacements. Go to the Parts section

    jerrid_foiles -

  21. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 22, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 22, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 22, image 3 of 3
    • Be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply (boxed in red).

    • 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.

    • Repeat this step with the other adhesive strip and remove it.

    • If either adhesive strip breaks before it's removed, use a plastic card to slice through the remaining adhesive.

    Cutting through this extra adhesive on the bottom took a bit more effort than the step and picture implied (to me). Unlike the other edges, here don't be afraid to really push the card in there to break the seal, there's nothing behind that adhesive that is breakable.

    phil - Reply

    cutting through the adhesive is unnecessary if it's not been opened before (outside of an apple store) there will be a tab at the end of each VHB strip that you can use to simply pull the vhb strips off.

    Rory McKenna - Reply

    YES, exactly the same here. more but more simple.

    Lucio Alves -

    To save a few steps and a bit of time, if you have a helper, they can hold the display at a 90° angle while you unscrew the brackets and remove/replace the hard drive rather than remove the display entirely. Also reduces the likelihood of damaging the display as you remove and handle it.

    marty - Reply

    The proper way to remove the display according to the Macintosh tech manual and videos is as Rory McKenna and Lucio Alves have learned is to pull the tab at the end of each VHB strip until it is off.

    Ben Varela - Reply

    This worked great! look for small left over adhesive on either edge of the bottom of the screen and pull each one towards the center. Screen assembly removes after that with no fuss.

    Miguel Rivas -

  22. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 23, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 23, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 23, image 3 of 3
    • Lift the display up from the frame and remove it from the iMac.

    • It may be necessary to slowly lift from one side, to peel against the remaining adhesive.

    • Be very careful handling the display—it's big, heavy, and made of glass.

    • During reassembly, head over to our display adhesive guide to install the new adhesive.

  23. iMac Intel 21.5" EMC 2638 Power Supply Replacement, Lower Support Bracket: step 24, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement, Lower Support Bracket: step 24, image 2 of 2
    • Remove the following five Phillips screws holding the lower support bracket in place:

    • Four 3.2 mm screws

    • One 1.7 mm screw

    • On at least some EMC 2544 machines, all five screws are the same size.

    • You may need to peel up the display adhesive lining the bottom edge of the iMac enclosure to access the screws.

    I used the CR-V 4.0 standard screwdriver head to help peel away the adhesive lining. My fingers were too big to grab it, and my fingernails too short to get the removal started. This 4 screw head worked perfectly.

    airshack - Reply

  24. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 25, image 1 of 1
    • Remove the lower support bracket from the iMac enclosure.

    Of all the parts of this entire procedure, replacing this one piece is the hardest part! The screws are tiny and they just don’t seem to want to grab the support piece. Also it seems to perform no function which is also annoying.

    John M - Reply

    I left mine out. LOL

    jerrid_foiles -

    Line up the screw holes and press on the bracket from the back to help the screws grab. If your fingers are too big, press with the flat side of your spudger. As long as there’s no gap between the bracket and the iMac’s frame, the screws should grab easily.

    Jeff Suovanen -

    I put it in at a slight angle lining up the right hand side holes, screwed in the two screws and gently pressed my finger behind it on the rest

    jmorphett5 - Reply

    If you only want to replace the HD and RAM, take a big shortcut and leave the logic board in, as well as all the parts needed to remove it (speaker, power supply etc). Once the display is removed, just take out the fan and the top two logic board screw. There is than sufficient space to gently remove and insert the two ram modules. HD can easily be replaced with an SSD by just removing the HD mounting brackets...

    diddl14 - Reply

  25. iMac Intel 21.5" EMC 2638 Power Supply Replacement, Hard Drive Brackets: step 26, image 1 of 1
    • Remove the following screws securing the hard drive bracket to the rear enclosure:

    • Two 21 mm T10 Torx screws from the left-hand hard drive bracket.

    • One 9 mm T10 Torx screw.

    • One 27 mm T10 Torx screw.

    Pay attention to this photo and where the fan is. It is 180° from where the previous step shows it is oriented to you.

    Max Romano - Reply

  26. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 27, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 27, image 2 of 2
    • Remove the left and right hard drive brackets from the iMac.

  27. iMac Intel 21.5" EMC 2638 Power Supply Replacement, Power Supply: step 28, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement, Power Supply: step 28, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement, Power Supply: step 28, image 3 of 3
    • The next few steps bring your hands close to the exposed face of the power supply. Do not touch the face of the power supply or any of the exposed solder. Touching it risks a high voltage shock from the many large capacitors attached to the board.

    • Use the tip of a spudger to push each side of the power button cable connector and gently walk it out of its socket.

    I would advise that before removing the PSU unit and all other components from the bottom of the case that you remove the 5 screws at the bottom of the display which hold an insulation strip in place.

    The guide shows this piece removed, but does not tell you how to remove it.

    There will be 5, small J1000 screws. The middle one, which goes over Apple Logo is the shorter one of the 5, all others are the same length. Once this piece is gone removing the components is much easier, and chance of damage lessened.

    [deleted] - Reply

    Added to the guide. Thanks for the tip!

    Jeff Suovanen -

    No need to remove power board and logic board and all other components, just remove the fan and it is quite "easily" accessable to change the RAM. Just need to use the tools to remove the old RAM and carefully install the new RAM.

    I just did it without removing the logic or power board

    Oleksandr Trokhymchuk - Reply

    could you elaborate a little more, I would love to skip the rest of these steps. How did you accomplish this?

    ej P -

    Oleksandr Trokhymchuk,

    Thank you! You just saved me so much time! I wouldn’t call this “easy” but it saved me a lot of time and effort.

    Joshua Ericson -

    ej P: remove the fan assembly first. Then remove the connector that runs from the iSight camera to the logic board on the left.

    the RAM is located right near that cable. It’s tricky to remove but you can pop open the connectors with a black nylon stick and the RAM chip will pop up at 45 degrees. Make a mental note on which way you will need to install the new ram as it’s tough to see. For the Crucial memory I got it was label side facing away you (facing towards rear metal enclosure).

    the second chip has a plastic adhesive piece on it that you should probably attach to the new ram.

    remove both chips then install the new ram in sequence from the board out.

    Wizdom On Wheels - Reply

    In the photo for Step 28, the power button cable connector is placed around the power board screw hole on the top left of the power board.

    However, on the iMac I upgraded, the power button cable connector was “fed” through the power power screw hole on the top left of the power board. The cable was too short to run around and below the hole.

    Hence, I had to ensure the cable was “fed” through the hole during re-assembly and the screw carefully screwed back through the hole.

    I guess every iMac is assembly just a bit differently, just to make repairs that much more fun.

    Tim Telcik - Reply

    Just replaced the hard drive and RAM with SSD and 16GB respectively and did NOT remove the power supply or logic board. Tricky is a word to describe putting the RAM in without removing the logic board. You work in the dark with little room to get your fingers in between the logic board and the back of the case. I put the first RAM chip in without a problem (the one next to the logic board), but the second to four tries and dropped it behind the logic board three times before finally getting it to position correctly. Just impossible to see and must work but feel. Still it was faster than removing all the components… though did remove the fan (needed cleaning anyway). All in all I can’t say enough about the help the guide was through the upgrade ! Thanks !

    Ray Burgard - Reply

    I found this connector to be very tight and was afraid of breaking it off. I just kept slowly working on it—it did eventually come out.

    I did try to sneak the RAM in without removing the logic board but my fingers were too big. I found it too difficult and just continued on with this guide.

    Mikkif - Reply

    I was not able to install the memory without removing all the components. My fingers are too big and I could barely get in that tight spot to swap out the memory. The hardest part about the power supply is that one connector under the chin next to the Apple logo. Once it is out, you are home free because it is so easy to plug it back in when you are putting it all back together again. Ridiculous that Apple did not put a simple access door behind those memory slots because they are on the backside of the Mac! They did an access door on the PowerBooks and it did not ruin the appearance. They could have designed a cool looking pop out door that only had a thin seam around it so it would still look good. Then you could remove the access door to upgrade the memory easily.

    Peter Hillman - Reply

    Does anyone know if this is the same situation as in the 2017 model? I just changed RAM in the 2017 version and also skipped taking out the logic board. I just bent a pair of tweezers and put some tape around the tips to make them less scratchy and used them to place the RAM modules into the slots. Worked supereasy and much much quicker than performing the complete tear down of the whole machine.

    Nils Witte - Reply

    This step is impossible!

    Cecily Walker - Reply

    @wizdomonwheels, I don’t see how I can get the RAM shield off of the logic board to access the RAM without removing the logic board. What am I missing?? I’m guessing that those of you that are suggesting this technique are working on older iMac models that don’t have the RAM shield.

    jiclark - Reply

    Yes, you are correct. It is likely the various steps are a bit different on each model. If I recall I was likely working on a 2015 or older system. If there’s a shield in the way, I can’t think of a way you could get around it without pulling the logic board.

    Wizdom On Wheels -

  28. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 29, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 29, image 2 of 2
    • 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.

  29. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 30, image 1 of 1
    • Remove the two 7.2 mm T10 Torx screws securing the power supply to the rear enclosure.

    • In newer model iMacs these are 7.2 mm T8 Torx screws.

    • During reassembly, be careful not to trap the power button wire behind the board.

    In my case, the left side corner of the PS was caught against the Lower Support Bracket, and I had to remove the LSB in order to get the PS freed and out.

    I think the author Walter Galan should put this in the main section of his instructions. I have TWO identical iMac 14,1 / i5 2.7GHz / 21 Inch Late 2013 / Order ME086LL/A. They both required removing the LSB. Thank you very much Walter Galan & others for your contributions.

    Ted Horodynsky - Reply

    Those screws were definitely not T10 but T9 on my unit

    Vincent Monteil - Reply

    Those screws were T8 on my unit.

    jag32mobile - Reply

  30. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 31, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 31, image 2 of 2
    • When working on the power supply, be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.

    • Tilt the power supply forward.

    When replacing the PSU (on the re-build) take care not to trap the power button cable behind it - I did...

    Dave Hallett - Reply

  31. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 32, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 32, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 32, image 3 of 3
    • Pull the power supply slightly up and out from the rear enclosure.

    • Rotate the power supply counterclockwise, lifting the right side up about an inch higher than the left.

    In my case, the left side corner of the PS was caught against the Lower Support Bracket, and I had to remove the LSB in order to get the PS freed and out.

    I think the author Walter Galan should put this in the main section of his instructions. I have TWO identical iMac 14,1 / i5 2.7GHz / 21 Inch Late 2013 / Order ME086LL/A. They both required removing the LSB. Thank you very much Walter Galan & others for your contributions.

    Ted Horodynsky - Reply

  32. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 33, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 33, image 2 of 2
    • Slide the power supply to the right to clear the screw posts on the rear enclosure.

  33. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 34, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 34, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 34, image 3 of 3
    • Rock the power supply forward and remove it from its recess in the rear enclosure.

    • Do not try to completely remove the power supply from the iMac yet—it is still connected to the logic board.

  34. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 35, image 1 of 2 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 35, image 2 of 2
    • Be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.

    • Flip the power supply over to access the DC power cable connection behind the logic board.

    • 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.

    when pulled the cable, even slightly, the actual female piece that connects to the logic board came off. am i screwed?

    Racheal Major - Reply

    Repairing sockets that come off the logic board is possible, but very specialised work. Unless you have a magnifying lamp and the necessary desoldering and soldering skills, it will be difficult but not impossible.

    Charlie Nancarrow - Reply

    The tab is at the far end of the connector, so you’ll need to reach farther than you might think.

    lkollar - Reply

    When I pulled the disconnect, I pushed down on the disconnect, instead of pushing down on the tab on the disconnect and bent those pins… tried to straighten the bent pins and two of the pins broke off the logic board. Will I need a new logic board or can I purchase the pins…?

    Ray AA - Reply

  35. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 36, image 1 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 36, image 2 of 3 iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 36, image 3 of 3
    • You may find it helpful to set the iMac down on its back for the next couple of steps.

    • Use the flat end of a spudger to press the clip on the side of the AC inlet cable connector inward.

    • While pressing on the release clip with the spudger, grasp the AC inlet cable, and pull the connector straight out of its socket.

    I didn't disconnect the input cable to the power supply. Because I had the machine lying on its back throughout, I placed it on to the metal bit at the bottom of the machine instead (with a cloth to stop the metal getting scratched). The AC inlet cable was pretty tricky to get un-locked, and the PSU sat on the case fine. It didn't hinder anything else throughout the guide.

    Dave Hallett - Reply

    I thought from Dave’s comment that I could leave the power supply completely in place, but I was mistaken. In order to remove the hard drive assembly after you remove the center screw in it, you’ll need to at least unscrew it and the HD assembly will slip out. Like Dave said, you don’t need to unplug the AC or PSU, which I left hanging.

    Getting power supply to the logic board unplugged is also tricky without unscrewing the two bottom screws. They didn’t make this part easy.

    delacrj2 - Reply

    Kleiner Rechtschreibfehler - statt „denac“ muss es wohl „den iMac“ heißen

    Gonzalo - Reply

    Au ja. Du kannst so was selbst ausbessern. Einfach auf “Übersetzen" gehen und loslegen.

    VauWeh - Reply

    I would like to thanks Dave Hallett for his tip of not removing the AC inlet connector of the power supply. I simply wrapped the board in bubble wrap and taped to the iMac case, out of the way, thus giving access to the remaining disconnection procedures and preventing the board from scratching to the iMac case. It also made reassembly much simpler.

    Rob Hogan - Reply

    Yeah, that AC inlet plug was a nasty one to unplug, mainly because I was trying not to bump the solder joints on the PSU. After a few wiggles and pulls while manipulating the spudger tool to release the clip, it finally unplugged. Made it easier by removing the PSU completely so you don’t have to worry about it. Don’t worry, plugging it back in is a breeze!

    Peter Hillman - Reply

    With the right tool this plug comes out very easily. Forget about your tiny computer tools, go to the garage and grab a regular old needle nose pliers. Grab the clip and the plug at the same time. The plug will come right out.

    Carin Ann Loewen - Reply

    Carin Ann— The most helpful comment on this procedure. After reading what you wrote I maneuvered the board, grabbed the clip with my left hand (a little awkward because of the cooling enclosure), squeezed the front of the plug, and got it out.

    Glen Kohler - Reply

    +1 for needle nose pliers!

    Sam - Reply

  36. iMac Intel 21.5" EMC 2638 Power Supply Replacement: step 37, image 1 of 1
    • Remove the power supply from the iMac.

    erreur: retirer "la carte d'alimentation" et non" le disque dur" !!!!!

    Moreau - Reply

Conclusion

To reassemble your device, follow these instructions in reverse order.

12 other people completed this guide.

Sam Goldheart

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One Comment

Great guide. My question is this however, How does one test this PSU before they replace it? I can't seem to find a PSU pinout for this particular unit (661-7111)

Stephen De Tomasi - Reply

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