Sleepy iMac

Preamble

I was provided with a second hand G5 iMac (A1144). Unfortunately, it overheats and then shuts down, or rather, goes to sleep, shortly after being powered on.   This self imposed sleep happens quickly, especially if the processor is being pushed, such as by running a full screen video in VLC.


Links

Looking to fix the iMac G5 PSU issues I used these links, which range in usefulness from merely confirming suspected fault, to showing how to upgrade the unit and fix the issue (in the case of Jim Warholic’s guides):

Opening the iMac

From iFixit repair page of the iMac G5:

Parts List

The following information is taken from Jim Warholic’s excellent guides for power supply and motherboard/main logic board: Apple iMac G5 Power Supply Issues and DIY Apple Repairs and Apple iMac G5 Motherboards DIY Repairs How to Fix Bad Caps Guide.

Power Supply

In total 9 capacitors need replacing:

  • 3x- 1000uf 6.3V 8mm x 16mm
  • 2x- 2200uf 10V 10mm x 24mm
  • 1x- 1200uf 16V 10mm x 24mm
  • 1x- 4700uf 6.3V 10mm x 30mm
  • 1x- 1000uf 35V 12.5mm x 20mm
  • 1x- 330uf 35V 10mm x 20mm

Motherboard

In total 20 capacitors need replacing, with 5 additional optional upgrades:

  • 20 x 1,800 uF 6.3 V DC => 1,800 uF 10 V DC
  • 5 x 1,000 uF, 16 V DC => 1,000 uF, 25 V DC, operating temperature range: -55º to 105ºC

Images

Power Supply

Apple iMac G5 Power Supply 17 Inch Model
180W – Apple P/N 614-0293

Apple iMac G5 Power Supply 17 Inch Model 180W – Apple P/N 614-0293
Apple iMac G5 Power Supply 17 Inch Model 180W – Apple P/N 614-0293

Capacitors’ Locations, Sizes, and Electrical Values For Apple iMac G5 Power Supply Unit Diagram Schematic.

Capacitors’ Locations, Sizes, and Electrical Values For Apple iMac G5 Power Supply Unit Diagram Schematic
Capacitors’ Locations, Sizes, and Electrical Values For Apple iMac G5 Power Supply Unit Diagram Schematic

Closeup View of Apple iMac G5 Power Supply Printed Circuit Board With Bad Capacitors

Closeup View of Apple iMac G5 Power Supply Printed Circuit Board With Bad Capacitors
Closeup View of Apple iMac G5 Power Supply Printed Circuit Board With Bad Capacitors

Motherboard

1st Generation Apple iMac With Bad Caps

1st Generation Apple iMac With Bad Caps
1st Generation Apple iMac With Bad Caps

Location of Capacitors on MOB Next to Power Supply on 1st Generation Apple iMac G5

Location of Capacitors on MOB Next to Power Supply on 1st Generation Apple iMac G5
Location of Capacitors on MOB Next to Power Supply on 1st Generation Apple iMac G5

Additional Information

For the 20″ iMac PSU:

Parts List – Power Supply

In total 7 capacitors need replacing:

  • 330uf    35v    10mm
  • 1200uf   16v    10mm
  • 3300uf   10v    10mm
  • 2200uf   10v    10mm
  • 1000uf   25v    10mm
  • 1000uf   10v    8mm
  • 120uf    50v    8mm
Power Supply iMac 20 Inch Model Apple Part Number — Apple p/n: 614-0326
Power Supply iMac 20 Inch Model Apple Part Number — Apple p/n: 614-0326
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