Introduction

Keep those electrons flowing by replacing your broken power supply!

Video Overview

Lay the iMac display-side down on a flat surface.
  • Lay the iMac display-side down on a flat surface.

  • Loosen the three Phillips screws securing the rear panel to the iMac.

  • These screws are captive in the iMac. The center screw will stop turning after about 3.5 turns and the outer screws will stop turning after about 5.5 turns. Do not try to remove these screws from your iMac.

Some models (with light sensor) have only the two outboard screws.

Robert Huber - Reply

Lift the rear panel slightly near the bottom of the iMac. Pull the rear panel toward yourself and remove it from the iMac.
  • Lift the rear panel slightly near the bottom of the iMac.

  • Pull the rear panel toward yourself and remove it from the iMac.

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Remove the three Phillips screws securing the power supply to the chassis.
  • Remove the three Phillips screws securing the power supply to the chassis.

  • The two leftmost screws are captive in the power supply.

  • To aid in removal, it may be helpful to lift the center screw slightly away from the midplane.

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Rotate the center Phillips screw on the bottom of the iMac clockwise until the rear panel clamp contacts the edge of the case. Rotate the center Phillips screw on the bottom of the iMac clockwise until the rear panel clamp contacts the edge of the case.
  • Rotate the center Phillips screw on the bottom of the iMac clockwise until the rear panel clamp contacts the edge of the case.

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While depressing the connector lock, use a heavy duty spudger to pry the power supply connector away from its socket on the logic board. It will be necessary to work from alternate sides until the connector is free. Your power supply may have an ambient light sensor cable attached from the power supply to the logic board. If so, carefully use a spudger to push out the cable towards you using the sides of the cable alternatively to help you slide it out.
  • While depressing the connector lock, use a heavy duty spudger to pry the power supply connector away from its socket on the logic board.

  • It will be necessary to work from alternate sides until the connector is free.

  • Your power supply may have an ambient light sensor cable attached from the power supply to the logic board. If so, carefully use a spudger to push out the cable towards you using the sides of the cable alternatively to help you slide it out.

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Lift the power supply slightly from its left edge, then grab each side and rotate the power supply toward yourself. The power supply requires a large amount of force to remove.  You may need to bend the edge of the front case toward yourself for enough clearance to remove the power supply. There are several capacitors mounted to the logic board in close proximity to the power supply. Try not to disturb them, as they are delicate and may break off the board.
  • Lift the power supply slightly from its left edge, then grab each side and rotate the power supply toward yourself.

  • The power supply requires a large amount of force to remove. You may need to bend the edge of the front case toward yourself for enough clearance to remove the power supply.

  • There are several capacitors mounted to the logic board in close proximity to the power supply. Try not to disturb them, as they are delicate and may break off the board.

Smooth move not noting that there may be an ambient light sensor plugged into the board here. In the "large amount of force", I ended up yanking the cable right off the %$^@&$# sensor here - and took the contacts with the cable. So totally !@^@@& the thing up.

Matt Falcon - Reply

Quick tip: If you keep the captive screw on the right side held up, it helps a lot. Also, taking it completely out when reinserting the PSU helps a lot too.

coffee - Reply

Conclusion

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

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3 Comments

As usual, trickier than the video suggests. In addition to these notes, also check notes on similar power supply installs.

1. It is very hard to disconnect the optical sensor cable from the motherboard. There's no hidden catch, you just have to insert your spunger/thin screwdriver blade between the fittings and gently twist. I used a surgical clamp to also pull on the cable -- that did it. (The cable is being replaced, so you don't need to worry about it).

2. The top right screw is hard to remove. I had to partly remove it, then lever the power supply up as in the video while continuing to loosen it.

3. I used thin wide screwdriver blades to disconnect the power supply connect, my spudger wasn't rigid enough.

4. The supply has clearly been used before. In the context of something this old "new" means Apple refurbished. That's fine.

5. Beware the optical sensor, it's glued to the power supply. Look for it. When you insert the new supply place it first.

John Faughnan - Reply

Thoughts about using an industrial strength air duster to rid the power supply of free radicals? Wonder it's impact on the capacitors.

acohen25 - Reply

This completely fixed my issue. Took all of 5 minutes and I was back up and running. Just take your time and anyone could do this. Perfect instructions and I saved $100 in repairs.

Teresa - Reply

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