A few weeks ago I discussed the possible causes for odd video behavior
in machines with integrated graphics chips. This week, let’s talk
about other video issues I’ve seen in portables.
An iBook G4 brought in this week presented odd video: certain color
ranges would shift in hue. Feeling sure of the failure (and without
plugging the iBook into an external display), I ordered a logic board.
I’ve been doing this for about seven years, so I listened to my gut.
It became clear that my gut was wrong: after installing the board, the
problem persisted.
When pinched just so, the LDC would display the proper colors and
function as expected. As a general rule, the only way to isolate a
graphic anomalies to the screen or graphics processor/main logic board
is to plug in an external display. If the external display shows the
same problems as the internal screen, you know the problem is not the
internal screen. Similarly, if external video looks normal, then the
internal display is to blame.
Hey, can’t win them all. (But my gut is usually right! :))