Here is the procedure that I used to replace the capacitors on the Apple iMac G5 MOB.

When you take it apart, start with this order:

  1. Lay the iMac face down on a soft, protected surface.
  2. Back cover removal. (Loosen the three screws on the bottom lower edge, then lift up carefully from the bottom up).
  3. Take close up pictures of your G5 mother board and inside the iMac for your reference in case you need to refer to something for proper installation.
  4. Power supply removal ( http://manuals.info.apple.com/en/imacg5_17inch_Power_Supply.pdf ).
  5. Verify Power Supply capacitors are not bulging or blown out.
  6. Hard drive removal.
  7. CD removal.
  8. Memory cards removal.
  9. Right fan cover removal.
  10. Lower left two small plug connectors undo by carefully taking needle-nose pliers and tug the plugs upwards to disconnect them.
  11. Fan plugs – disconnect.
  12. Airport option removal, being careful not to break the very delicate antenna wire clip. You might want to leave the wire attached and just move the Airport out of the way.
  13. Then remove the Torx mounting screws. See the special 12-in-1 screwdriver with Torx and Phillips bits.
  14. Carefully lift out the MOB, making sure all the mounting screws were removed. Do not force it.
  15. Heat up the soldering iron, with a wide tip attached, and working from the bottom and the top of the MOB, with the MOB tilted up on edge, heat up one leg of a capacitor on the backside and rock the capacitor slightly from the top. Then do the other leg, and the cap will come out of the hole.
  16. Remove all capacitors in the groups.
  17. Once the holes are clear, (pins work well), then place the high quality low ESR capacitors in the holes, making sure the positive and negative legs of the capacitors are properly situated in the holes. Do not install caps backwards. Major damage will most likely result.
  18. Apply Arctic Silver thermal paste heat sink compound to the small area (make sure it is cleaned with isopropyl alcohol), on the bottom of CPU. Cover it and the matching heat sink area with a thin layer (not to excess). Use a small razor blade as a scraper to remove the excess. Keep it thin, thin, and thin.
  19. Reassemble the motherboard, (don’t forget the white light tube that displays the “power on” light on the front cover of the iMac), hard drive, DVD/CD Super drive, cables, plugs, fan covers, memory modules, and make sure you don’t have any extra screws left over.
  20. Double check and triple check your work.
  21. Place the back cover on.
  22. Plug everything back in and turn it on.

Important Notes:

  • Don’t forget to put new heatsink compound back on the bottom of the processor chip, which is located on the bottom of the MOB, and the solid plate heatsink assembly located on the chassis: Arctic Silver. Several heating up and cooling down cycles is required for maximum thermal heatsinking effectiveness.
  • At least a 60 watt soldering iron is recommended and a good solder sucker and some plastic headed sewing pins for heating up and push removing solder from holes. Read the article: Soldering Tips for Lead-Free Solder for more detailed information.
  • Use rosin core solder only. Do not use acid core or acid flux. Use lead free, or, in my opinion even standard 60/40 leaded solder will work (although there are few lead-free caveats) for soldering the new caps. Just make sure there are no cold solder joints.
  • How to Tip: Use a few small pins to clear the holes when the soldering iron is used to heat up the holes to remove the old solder.
  • Don’t try to bypass this advice. Highly recommend replacing all the caps in both groups. Even though one or two caps might be visibly bad, the others are more than likely weak or on their way out too.
  • It’s up to you if you want to attempt the repair. It depends on how comfortable you feel about doing it yourself. The degree of difficulty on MOB caps replacement on a scale of 1 to 10, with 1 being the easiest and 10 being the hardest; a 7.
  • Double check your power supply unit. Open the PSU to check those capacitors too.
  • Degree of difficulty on PSU caps replacement on a scale of 1 to 10; a 3.


The procedure above is going off of memory.

Suggestions:

  • Layout your screws as you go.
  • Have lots of room to lay it out.


Refer to my articles, read carefully, and suggest printing them out for reference.

iMac G5 Motherboard repairs procedure
iMac G5 power supply repairs

Feel free to contact me if you have any further questions.

Jim