G4 Cube shutsdown unexpectedly.

[iamMacPerson]

I'm scratching my head over this one. I rebuilt my Cube with used parts a few years ago because the original owner spilled coffee in it. Everything was fine, but I went to fire it up a few months back and it would get to the Starting Mac OS X... screen then shut down. I tried it again today (but replaced the ADC display I was using with a VGA), and it seemed to be running fine until everything cut out. What's even weirder is the LED stays on for a quick second or two before going out after the display has stopped displaying video.

Every time I try to boot it after that, the run time gets shorter and shorter to the point where it won't even post and the LED goes crazy blinking. Should I look at replacing the PSU or does it sound like something internal (VRM?)?

 

[weckart]

I had the same symptoms with a PowerBook 520. I tried everything, including futzing with the power supply. Nothing worked until I replaced the logic board.

The worst thing was that I still could not see where the problem lay. I checked for popped caps, leaking components or worn traces on the board and could not find a thing wrong.

 

[Intell]

It's likely a problem caused by the touch power switch. This is a common problem with Cubes. A simple fix is to put a piece of paper on top of the power switch assembly before putting the Cube's out shell on.

 

[iamMacPerson]

It's likely a problem caused by the touch power switch. This is a common problem with Cubes. A simple fix is to put a piece of paper on top of the power switch assembly before putting the Cube's out shell on.

Tried that with an anti-static bag. Was doing it before I put it there, and still continued after taping it down.

 

[Gav2k]

Have you considered a heat issue as this would explain the recycle time being shorter each time?

 

[iamMacPerson]

Have you considered a heat issue as this would explain the recycle time being shorter each time?

Yeah I asked about it on the LEM Facebook group and someone recommended that. I'll have to see about installing one. Anyone got a link to a good manual just in case?

 

[MikeatOSX]

http://tim.id.au/laptops/apple/powermac/g4cube.pdf

http://cubeowner.com/kbase_2/index.php?category=11

 

[flyrod]

I would guess the power brick is going out. You could test with another one, or maybe stick it in the fridge/freezer briefly to see if the behavior changes. There's been some success with opening them op and replacing caps. You could also replace it with some other 28v power source if you can confirm that it's the problem.