Carnegie Mellon University > Robotics Institute > Garth Zeglin > Web Log > G5 Video Problem

Garth Zeglin: PowerMac G5/Hitachi CM721F Color Problem

Summary

2005-02-09: I recently purchased a refurbished PowerMac from Apple. I soon discovered an odd problem with the graphics, documented in this page. Most of the time everything looks normal, but sometimes colors are completely distorted, as shown in the images below.

The machine is a dual 2.0 GHz G5 with a GeForce 5200 graphics card (the base model option), and apart from this problem seems to be working fine.

2005-02-10: I figured it out: the CM721F color profile is broken, and simply changing the selection in Preferences wasn't enough, I had to reboot and reset PRAM too.

Diagnostics

I have taken a number of steps in an attempt to isolate the problem:

• upgraded from OS 10.3.3 to 10.3.7 to 10.3.8
• booted from an external drive with 10.3.5, prepared on a different system
• upgraded the system firmware
• tried all three color resolutions (millions, thousands, 256)
• tried various screen sizes
• tried different users, including a clean default account
• ran Apple Hardware Test 2.2.5
• checked the Universal Access preferences
• tried the three default color profiles: CM721F, Generic RGB, and sRGB
• tried creating a new color profile
• deleted Library/Preferences/com.apple.desktop.plist
• reset the PRAM
• switched from a Hitachi CM721F CRT monitor to an Optiquest; each connected to the DVI port through the supplied adapter

I noted that JPEG files seems to view fine, until I finally found one with the problem, and figured out that it had a color profile included in the file, which pointed toward a color profile problem.

My final clue came from this message.

I set the Monitor profile to Generic RGB, then rebooted and reset the PRAM, which finally fixed it.

Finder example

I first noticed strange colors in Finder windows, visible in these screen grabs. This is the color labels preference pane, notice the strange colors of the Red and Orange labels:

Notice how the active view select button has a strange pink underside:

Notice how the selected disk in this inactive window has strange pink streaks:

Preview.app example

The big surprise was opening several PDF files in Preview.app and seeing colors that were grossly distorted. Here is one example:

Curiously, the Finder preview pane showed the right colors in the thumbnail. For comparison, here is a screen grab from my G4 laptop:

For reference, here is the original document:reference PDF

Page revision: 2006/03/23 17:01:42.