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iMac Screen Problems

3994 Views 9 Replies Latest reply: Jan 7, 2011 4:08 AM by dave2889 RSS
dave2889 Level 1 Level 1 (5 points)
Currently Being Moderated
Dec 25, 2010 9:36 PM
I have an iMac DV SE 500 MHz (2000), which works OK, but the screen picture moves most of the time I shut it down or restart. I have to use the screen positioning control panel to fix it. I'm using OS 10.4.11

Notice the two black bars on the side, they weren't there before I restarted: http://dl.dropbox.com/u/5339497/Other/photo.JPG

Could it be the PRAM battery? It has the original as far as I know. Just hoping it's something simple like that, and not video problems.

Message was edited by: dave2889
Mac mini (2010), Mac OS X (10.6.5), iMac DV SE G3/500 Mac OS X (10.4.11) 32GB iPhone 4 (4.2.1)
  • Allan Jones Level 7 Level 7 (29,575 points)
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    Dec 26, 2010 7:12 AM (in response to dave2889)
    The PRAM battery is a good and cheap place to start. The computer could simply be forgetting the last geometry settings. You can, with care and a non-conductive grasping device, reach the PRAM battery through the RAM door. If that doesn't work, you'll need to pull the case bottom.

    That's the good news. If a battery doesn't fix it, then you probably are looking at video problems that are hard to overcome. The slot-loading iMacs with only passive, convective cooling seem to be killing off their PAV (power/analog/video) boards from heat at an alarming rate. Ours took a nosedive after installing OSX and a bigger hard drive. The boards available are all used so it's unlikely you can get one that hasn't been "in the oven."
    PowerMac G4 MDD 1.25G SP;, Mac OS X (10.4.11), MacBookPro Late2007 2.2G 15" (10.6.5); PowerBook G4 1Ghz 17" (10.4.11)
  • Jeff Level 6 Level 6 (11,160 points)
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    Dec 26, 2010 12:06 PM (in response to dave2889)
    If you can find a dealer in Australia that carries this (made in France) SAFT 3.6-volt battery (shown here), it's a better one - having 25% more life (1,200 mAh compared to 900 mAh). Otherwise, the battery that you've found is suitable for your iMac. While a weak/dead battery will often cause a blank screen at startup, I don't think it will cause screen anomalies. That sounds more like it's related to the PAV board or the CRT's circuitry itself. Do you also disconnect the iMac from electrical power, after shutting it down? This causes the internal battery to preserve the PRAM settings while disconnected, which ultimately shortens the battery's life.
  • spudnuty Level 5 Level 5 (5,250 points)
    Currently Being Moderated
    Jan 6, 2011 8:45 AM (in response to dave2889)
    Dave,
    as it emits a very high pitched whine after it's turned off

    Hmm that sounds like a flyback problem. There's wires in those smaller than a human hair so they go bad a lot.
    Around Chicago the iMac G3s are so plentiful and cheap that my repair philosophy was to find a running cheap one (usually less that $10 or more likely free) and swap faster logic boards into it. (500 or 700).
    I used to replace those flybacks but it's a pain and more than the cost of a used one.
    Richard
    2-iMac G5s 2.0 GHz, G4s; MDD 2X1.2 , iMac 800, iBook G4-1.2 14" ,2 X P-IVs, Mac OS X (10.4.11)
  • spudnuty Level 5 Level 5 (5,250 points)
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    Jan 7, 2011 12:00 AM (in response to dave2889)
    Dave,
    Replacing the flyback is not something I'd want to attempt. I'm not risking electrocution.

    Good idea but really not much of a danger if you understand what you're doing. I don't do it anymore since it's a massive pain and the part is no longer available.
    I have an iMac DV SE 500 MHz (2000), which works OK, but the screen picture moves most of the time I shut it down or restart. I have to use the screen positioning control panel to fix it. I'm using OS 10.4.11

    So like you say a PAV board problem (of which the flyback is a part). Looks like the horizontal size is shrinking:
    Notice the two black bars on the side, they weren't there before I restarted

    and
    Eventually I'll want the RAM and hard drive for the PowerMac

    both would work in that 350 G4. I'm personally on a MDD G4 dual 1.2 GHz machine. My ol' work horse!
    When the iMac G3 finally dies I'd pull the logic board and mass store in case you run across a working 350 - 400 iMac G3. It's easy to swap that board into either.
    Instructions can be found here:
    http://www.macmanuals.co.uk/index.htm
    (You might see some other goodies there)
    Good luck!
    Richard

    Message was edited by: spudnuty
    2-iMac G5s 2.0 GHz, G4s; MDD 2X1.2 , iMac 800, iBook G4-1.2 14" ,2 X P-IVs, Mac OS X (10.4.11)

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