Fixing No Video on iMac G3 After Mac OS X Install

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This is a common problem localized to iMac G3s. After installing Mac OS X the iMac will restart with no video. This problem has been attributed to not installing the latest iMac G3 Firmware Update



Affected models

iMac G3s with slot loading CD, DVD, or CD-RW drives without iMac Firmware Update 4.1.9


After a successful installation of Mac OS X 10.2, 10.3, or 10.4 the iMac will restart with no video at startup. The screen will remain dark, however the power light will turn on and the computer will continue to boot normally without video

Preventative measures

If your iMac G3 is still running a pre-OS X system there are several measure you can take to prevent this problem before installation:

  1. Update the iMac to OS 9.2.via Software Update
  2. Download the iMac firmware update via Software Update, or from Apple

Installing the Firmware Update

Your iMac must be running OS 9.1 or later to install the firmware update

  1. Double-click the iMac Firmware Updater icon to start the update.
  2. Read the onscreen instructions and follow them carefully.
  3. On a /A configuration, a message will appear explaining that your iMac's firmware needs to be updated.
  4. On all other configurations, a message will appear saying you need to shut down your computer and insert the end of a straightened paper clip into the Programmer's button hole, follow steps 5 through 9 to complete the update process.
  5. Click Shut Down in the dialog box to shut down your computer.
  6. Open the port cover door on the right side of your iMac and insert the end of a straightened paper clip into the Programmer's button hole, the lower of the two button holes.
  7. Continue to hold the paper clip in the hole and press and release the Power button on your iMac or on the Apple USB keyboard to start up your iMac.
  8. When you hear a long tone, remove the paper clip. A progress bar will appear at the bottom of the screen as the update takes place.
  9. After your iMac starts up, if the update process was successful, a message appears saying the firmware is up-to-date. Click OK.

Full instructions are available at How To Install iMac Firmware Update

You can continue to install Mac OS X normally after the firmware has successfully been installed.

Fixing no video after installation of Mac OS X

If the iMac does not have the firmware update installed, the iMac will boot with no video after Mac OS X has been installed. There are several things that can be done to fix this problem, however it depends on your iMac model.

For iMacs lacking a VGA Video Out

Certain iMac G3s did not have a VGA video out on the back of computer. If there is no video out on the iMac must be taken to an Apple Authorized Service Center, or Apple Store to have the proper part replaced. Another option would be to download VNC software, such as OSXVNC, and copy it to the iMac via USB thumbdrive. Once on the iMac, attempt to start OSXVNC and connect to it via software such as Chicken of the VNC. This remote connection may allow you to re-install from an OS 9 disk, update the firmware, and then re-install OS X.

For iMacs with VGA Video Out

If your iMac has a VGA monitor port, you can connect an external monitor.

Connecting an external monitor to the VGA monitor port

  1. Turn off the computer.
  2. Find the VGA vented cover that came in the computer's accessory kit. If your accessory kit does not have a VGA vented cover, your iMac computer may not have a VGA monitor port. See Operational Note 1 for a list of iMac computers that have a VGA monitor port.
  3. Remove the vented cover from the computer.
  4. Replace the vented cover with the VGA vented cover provided in the iMac accessory kit. (This step is not required)
  5. Connect the monitor cable to the VGA monitor port.
  6. Turn on the computer.
  7. Hold down the option key as the computer starts up, this should bring up a system selection menu with two icons, one for the Mac OS 9 system, and one for the System X system. Click on the icon for the Mac OS 9 system and press the arrow.
  8. The iMac should boot into Mac OS 9
  9. Follow the instructions for installing the Firmware Update above Installing the Firmware Update
  10. Using the Apple System Menu (The Apple Icon in the top left hand corner) select control panels and then start up disk
  11. There should be an icon showing the iMac's hard-drive and an arrow next to it, click the arrow to show the startup options
  12. Select the startup folder showing the version of OS X installed
  13. Restart the computer, the video should turn back on

If these steps do no work

  1. Insert the Mac OS X installation CD 1 or DVD, and startup using the CD or DVD, make sure to press the "C" key when turning the computer on
  2. Allow the Mac OS X installation screen to appear then restart the computer, this should turn the video on
  3. If all of these steps do not work consult an authorized Apple Service Center, or the nearest Apple Store