Help! iMac G5 screen issues and shutdowns!

Discussion in 'PowerPC Macs' started by Mainyehc, Sep 25, 2007.

  1. Mainyehc macrumors 6502a


    Mar 14, 2004
    Lisbon, Portugal
    Hey guys!

    My Rev. A 20'' 1.8GHz G5 iMac, bought on Oct.'04 (yes, it is eligible for the repair extension program) has been acting up weird lately...

    First, the screen started flickering since a few months ago, whenever an app displayed moving graphics (like an animated OpenGL-based screensaver or the Apple DVD Player) or "moveable" graphics, like iTunes' CoverFlow (curiously enough, when flicking covers or when iTunes changes or skips tracks, even if they're within the same album). And this was a permanent state, it would never stop doing that, ever, as long as CoverFlow was selected... Even stranger, when switching desktops with VirtueDesktops, even with transition effects turned off (I deactivated them as they were kinda buggy and thus looked terrible - by the way, they seem to be based on OpenGL too), the screen sometimes flickers, too. Automatic desktop picture switching also produces the same effect.

    If this wasn't bad enough, now, when I turn on my iMac or wake it from sleep, if I proceed to trigger the screeensaver straight away, the screen will display a great amount of horizontal, pixel-thin garbled lines of dark colours, and if I'm not fast to leave the screensaver on time, or lucky enough, the computer just goes "'pop!", as if I just pulled the plug from the wall. It just shuts down for no apparent reason (apart from the messy screen, that is).

    You can check it on YouTube, I just posted a video where you can see the problem during the first few seconds, though it didn't shut down that time. To make things worse (and weirder), now, sometimes the problem swiftly goes away after a few seconds of "warming up", to the point it stops flickering, even with iTunes & CoverFlow open or while running the screensaver, as you can see on the video.

    As I write this, both the screensaver and iTunes make it flicker, but just last night they didn't!

    Now, what I wanna ask you people was what do you reckon the cause for this problem is... A dying PSU? That new surge-protected power-strip I've been using? Faulty capacitors on the logic board (not likely, as they don't seem to be bulging and are marked with "K" instead of "X", which should mean they are from a good batch)? Some other random issue?

    Either way, I'm going to back up everything now and take the iMac to the repair center ASAP, especially since the repair extension program ends for me just five days from now, but thought I'd just share this story with you...

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