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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

imac power testing

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Member Since: Nov 05, 2011
Posts: 4
KeefyBoy is on a distinguished road
Mac Specs: imac G4 800Mhz

KeefyBoy is offline
Returned from holiday during which there had been at least one power cut. My old iMac G4 17" 800Mhz would not boot at all (nothing).

So, checked online and replaced the internal battery. Still nothing.

Looking at the service manual (page 117) there seems to be a helpful way to test the various voltages (battery, 12v and main); nice description and image.

BUT, my iMac does not have the voltage test points shown or anything remotely like them that I can see.

1. Has anyone else had this problem?
2. How else should I test the power supply (i'm assuming that power is the problem)

I am an electical engineer so quite happy digging about inside!

Thanks in advance
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Member Since: Jun 07, 2006
Location: NYC
Posts: 288
zacster is on a distinguished road
Mac Specs: Intel iMac 20" Core Duo 256mb VRam 115gb SSD 2gb Ram Finally!!!

zacster is offline
Nothing at all? Check the fuse? Is there a fuse? Must be. If you open it up you should be able to trace the PS to the motherboard. I'd assume there is some kind of switching PS in there so check the output from that. Since you're an EE I shouldn't have to warn you about safety.
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Member Since: Nov 05, 2011
Posts: 4
KeefyBoy is on a distinguished road
Mac Specs: imac G4 800Mhz

KeefyBoy is offline
Can't see any sensible fuse loaction inside the Mac. The power supply fuse is fine.

I was hoping for some guidance as to where the helpful power test points indicated in the service user manual had been moved to!

I really don't want to further dismantle the insides (remove drives etc) as i can tell its going to be a ***** to get back afterwards!

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