"Hi, I saw this discussion and wanted to contribute. I have fixed quite a few PowerBooks and from what I read here and the things you have tried I would suspect the LCD. Since an external monitor works fine it seems to not be the graphic card. You can get a new LCD fairly cheap and the job is fairly easy (you wrote you already tried changing the display cable and inverter so you are almost there!):
For numerous reasons, I have not followed up on this issue until now.
Recap
I did replace the Display Data Cable, and saw no improvement. The display still showed…
objects with ripple-like outlines, mismatched colors — pink where white should be, green where black should be and a spectrum of color distortion in between — as though the system color table was hashed up, slight noise-like waves and fluctuations throughout all displayed details, occasional, unpredictable, short-lived moments where the problem cleared completely and everything looked perfectly proper.
All other functional aspects of the Powerbook have remained normal throughout this process, and the display continues to look normal both when using an external monitor and when seen through Screen Sharing and VNC.
Inverter Card Replaced
I replaced the Display Inverter Card, and the problem persisted. I replaced the new card with the old card, and the issue again remained unresolved.
Outlook
At this point, I am inclined to believe that the problem rests in the logic board, but the fact that the external monitor continues to function perfectly with this machine leaves me very uncertain of that possibility. The periodic reversions to normal operation of the display itself signals to me (perhaps incorrectly) that the problem does not reside there.
I love my Powerbook, but without a repair solution clearly evident, I'm at the point where the cost (in time and money) of additional repairs appears to exceed the benefits that would be gained in putting that money toward a new (or refurbished) MacBook Pro. I have a G4 Mac Mini which I can use for ""data legacy,"" so the Powerbook is not essential for that purpose either.
I gratefully welcome your comments and suggestions on this matter, but without those I will have to mark this problem as unsolved, and move on to other projects.
My sincere thanks go to all who have shown interest in this issue and shared there helpful thoughts and ideas."