13 Replies Latest reply: Apr 21, 2012 1:49 PM by u2canfreefall
u2canfreefall Level 1 Level 1 (0 points)

I bought an IMAC  (old snow ball desk top) years ago and never had any problems with the machine.  The other day I was working on it and left the room and came back hours later.  The machine had gone to sleep with the small white light in the lower right corner.  I tapped the keyboard and it would not wake up so I held the power button in and turned it off.  Today I turned it on and I thought the screen flickered and the machine sounded like it booted up, but the screen is black.  Any suggestions?


iBook / iMac, Mac OS X (10.3)
  • Kenichi Watanabe Level 7 Level 7 (30,460 points)

    The first thing you can try it to unplug it from power for about 15 minutes (or longer), then connect it back and try to start it up.  When you connect it, if you have been using an old (or overcrowded) power strip (surge suppressor), try connecting it directly to the wall outlet.  Also, initially press the power button with only the power cable connected; disconnect all other peripherals.

  • u2canfreefall Level 1 Level 1 (0 points)

    Did as you said and turned off all the lights in the room.  The computer sounded like it was booting up and the screen turned from black to very lite silver gray.  Did notice that the normal sound of full boot up did not seem to take place, but I could be wrong.  Any other ideas?

  • Jeff Level 6 Level 6 (11,315 points)

    It could be that the PAV (Power-Analog-Video) board has gone bad (a common failure in those old iMacs), which would leave you with a darkened screen.  If this is the case, I'd pull the hard drive and retire the computer.  It's a dangerous repair for someone to attempt who isn't experienced with CRT-type TV repair, because of the danger of severe electrical shock.  Because that part is now-discontinued, I wouldn't pay for professional installation of a used part with unknown mileage and equally unknown remaining service life.  In six months, you could be in the same situation.

  • Kenichi Watanabe Level 7 Level 7 (30,460 points)

    You described it as "old snow ball desk top."  I was thinking it was a white slot-loader iMac G3 (with a CRT display).  But I just realized that could describe the dome-shaped iMac G4 that has its LCD display on an "arm."

     

    So, can you clarify which model iMac you have?  This list may help to identify the exact model.

     

    http://www.everymac.com/systems/apple/imac/index-imac.html

  • u2canfreefall Level 1 Level 1 (0 points)

    I'm sorry, it is the LCD screen with the silver arm G4.  I bought it a number of years ago for photo work, which I still do and love it for the big bright screen.  Have up graded the hard drive and memory one time.  As I said I have had NO problem with the machine all this time. 

     

    Thanks

    John

  • Kenichi Watanabe Level 7 Level 7 (30,460 points)

    You can try resetting the PMU (power management), following this procedure

     

    http://support.apple.com/kb/HT1712

     

    Other possibilities - The Mac performs a hardware test at startup.  A component, such as the power supply, may not be passing the test, so the startup does not proceed.

     

    A dead or weak PRAM battery can cause startup problems.  The procedure to replace the PRAM battery can be found here (select your particular iMac G4 model)

     

    http://www.ifixit.com/Device/iMac_G4

     

    The PRAM battery looks like this

     

    http://eshop.macsales.com/item/Newer%20Technology/BAA36VPRAM/

     

    Does it sound like the iMac is starting up completely and running, with the display dark?  OR does it not start up beyond a certain point?  If it seems to startup and run, with a dark display, the iMac's backlighting for the LCD may have gone bad. 

  • u2canfreefall Level 1 Level 1 (0 points)

    Ok, took the bottom plate off and reset the PMU button and no change.  Still the light siver gray screen.  Do you think it could be the battery as it has never been changed.

     

    Thanks

    John

  • Kenichi Watanabe Level 7 Level 7 (30,460 points)

    Since the battery has never been changed, it is probably weak or dead.  But that may OR may not be the cause of your immediate problem. 

    Still the light siver gray screen.

    Does that mean the screen is lighting up?  In a darkened room, does the screen obviously light up from behind?  If it does, the problem may not be the screen.

  • u2canfreefall Level 1 Level 1 (0 points)

    Thanks

     

    I will order the battery tonight as it is the least expensive next step.  I will let you know how it works out in about a week.

     

    John

  • u2canfreefall Level 1 Level 1 (0 points)

    Ok, got the new battery in today and installed it tonight and the screen will go from black to the silver gray as before.  You can hear the drive booting up, but nothing on the screen. Just for kicks I put in my user name and password not seeing a thing and I heard it sound like it was loading programs.  Soooo, my question is, do you think it is just the screen being bad and I should look for a replacement.  Could it be a power supply problem to the screen?  Am I just throwing money away and should write off the snowball machine with its 20” screen as wore out due to its age.

  • Kenichi Watanabe Level 7 Level 7 (30,460 points)

    It sounds like the iMac is working as a computer, but the screen is not working.  I asked about whether the screen was still being backlit previously.  I asked because, if the screen is not working only due to the backlighting not being ON, that might (?) be an easiler (less costly) fix.  At the place where you entered your user name and password "blind," shine a bright flashlight on the screen.  Do you see anything being displayed on the screen?

     

    If the backlighting is working, but nothing appears on the screen (except the "silver gray"), then it is more likely to be a problem that is not worth the cost of repair.  That would be unfortunate, because that 20" iMac G4 is cool looking.

     

    You don't have the "mini-VGA to VGA" adapter, do you?  If you did, plus an old VGA external display, you could connect it and confirm that it is still working (minus LCD).  That port is supposed to mirror the built-in display.

  • u2canfreefall Level 1 Level 1 (0 points)

    I checked with a flashlight and saw nothing.  I can assume that the screen is shot.  I cannot complain about the service the Mac provided and will look for a used screen, just for fun to see if I can get it going.  As you said it is a cool looking computer.  Did have a full back up so nothing was lost.  Thanks again for your help.

     

    John

  • u2canfreefall Level 1 Level 1 (0 points)

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