PowerBook G4: Unexplained problem with excessive brightness

Posted by Pierre Igot in: Macintosh
April 16th, 2005 • 12:51 am

After years of family arguments and jokes about the relative merits of various computer platforms, I finally managed to convince my dad to make the switch to Mac OS X about 16 months ago. He was a computer science professor from the very early days (late 70s) and had been a PC user for a long time, although he also had a decent background in Unix. The combination of an advanced user interface and a Unix base definitely appealed to him — although he is retired and doesn’t seem to be doing much in Unix these days… I suspect it was more an issue of knowing that he could always have access to the Unix underpinnings if he ever needed to.

In any case, he got himself a nice little PowerBook G4 during the Christmas 2003 season, along with a copy of Microsoft Office X and Virtual PC, of course. (He still has a couple of custom-made accounting applications that he needs to be able to run.) He initially had trouble with the wireless connection to the third-party router that he had for his ADSL Internet connection, but that was eventually sorted out.

As far as I could tell, everything else in the transition went smoothly for him. But I was not there and had never been able to see the PowerBook in action… until the day before yesterday, when we came for our family visit.

When I had a look at the machine, I immediately noticed something strange with the display. It was quite clear to me that there was a severe “washed out” effect, with very little — if any — difference between light colours (especially light grey) and white. In fact, you couldn’t see the gradient effect in window titles bars at all. You couldn’t see the subtle stripes in the menu bar or in various backgrounds. In System Preferences, you couldn’t see the alternating backgrounds for the rows of preference panes. The brushed-metal effect in Safari and the Finder was also seriously affected, with the middle part being pretty much white. Even for bright colours, there was a definite lack of subtlety. And text looked just horrible to me.

I checked various settings. His brightness was set to the maximum, but turning it down didn’t help. It just turned everything grey and even more washed out. He was on million of colours, and he was using the right resolution. I had never seen anything like it. I told him that there was definitely a problem — but to him it had always been like that and he obviously assumed it was normal. (His previous laptop was a pretty old PC, so the quality of the LCD screen wasn’t great. And my dad has never been very adept at detecting relatively subtle visual problems…) He told me that it had always been like this and that he had never noticed a sudden change in display quality.

I noticed that his font smoothing settings were still on CRT and I switched them to LCD, but it only made things even worse, because you could now see all kinds of coloured smears around the character shapes.

It should also be noted that the lighting conditions in his office are not ideal, with the table on an angle and very close to the window on the side.

I put my old Titanium PowerBook next to his and, while my laptop’s brightness levels are obviously significantly lower than his (due to the age of the machine and the lower quality of the older LCD display), he had to agree with him that his display was missing quite a bit of detail that was clearly visible on mine.

I started worrying that it was a hardware problem with the back light. Of course, he didn’t get the extended AppleCare warranty, so there was no way to get this fixed under warranty now.

The obvious next step was to try and recalibrate his screen, which he had never done. I tried it again and again, with the “Expert” settings in the Calibration Assistant, but to no avail. For some of the steps in the calibration, I couldn’t even get anywhere close to the range where the Apple logo fades into the striped background.

To me, this appeared to confirm that it was a hardware problem, and that any kind of repair would likely be quite expensive. My dad was used to this display and clearly didn’t seem to be at all interested in spending hundreds of dollars on this.

Out of desperation, I installed the latest system update. His machine was still running 10.3.3, because he had had no reason to update it and, of course, he was more than familiar with the Windows system updates causing all kinds of problems, so his approach was to leave good enough alone, for which I can’t blame him.

After the system update, the machine restarted, and all the way to the login window, things seemed to look alright to me. You could definitely see the darker grey of the inside part of the windows. But it was hard to tell from that single window without a title bar or a menu bar whether the problem was fixed. We logged in, and unfortunately had to admit that the system update hadn’t fixed anything.

That was all that we had time to do on that day, so it was a disappointing trouble shooting session. Of course, I couldn’t really leave it at that, and I kept thinking about the problem in the evening and the next day, while we were doing other stuff. I thought that this difference during the login stage was suspicious and that I should start booting from a system CD just to see what the display would look like with a clean system and with all the user interface controls visible (menu bar, window title bar, etc.).

Then this morning while my dad was away I tried to login, but didn’t have his password. I noticed he also had a “Visiteur” user and my mum knew the password for that one, so I logged in with that user configuration. Much to my relief, I discovered that everything look perfectly alright with that other user configuration! The colours and brightness levels were perfectly fine!

So clearly it was a problem with the specific user configuration that my father was using, and not with the display itself. This changed everything. I now knew that, at worst, I could simply reinstall the system.

When my father came back and gave me the password, I went in and deleted a number of system preferences, including all the ColorSync stuff and many other things that I suspected might be related to the display.

Unfortunately, none of this helped. I then told my dad that the easiest solution would probably be to back up all his important stuff, delete the user, and recreate it from scratch, only copying back the documents and third-party settings.

I did all that, and everything was fine after that. He now has the exact same user configuration, but without the brightness problem.

He readily admits that everything looks much better — and I suspect he will realize it even more when he starts using the machine again with his various programs and documents.

He’s not really satisfied with the fact that we have not discovered the source of the problem, but he had to agree with me that there was little point in trying to find out. I did all the more or less obvious trouble-shooting stuff, including the system update, the trashing of the prefs, etc. Clearly the problem was with one or several corrupted files somewhere in his user configuration — but which ones? It doesn’t really matter. I have never seen this problem before, and will probably never see it again. The only reason I’d want to find out more about this would be if it were a recurrent problem and I needed to be able to find a way to fix it without having to rebuild the entire user environment. But as I said, I have never seen this problem before. I also went on-line and did a number of searches in both Apple Discussions and with Google. I couldn’t find any reference to an “excessive brightness” problem with the PowerBook G4. I am well aware of the so-called “white spots” problem with this generation of machines, but this is something completely different — and very strange indeed.

I joked with my father that the reason why only his user config was affected was probably that he was still using Virtual PC on a regular basis :-). But joking aside, it could very well be part of the problem, since this is pretty much the only thing that distinguishes his user environment from the “plain vanilla” stuff that I usually have to deal with on the machines that I trouble-shoot. Who knows?

It was definitely an interesting and unusual trouble-shooting situation for me. And I am quite sure that, even though my dad is not too attached to subtle visual details, this PowerBook will now feel like a new machine to him! Part of me really can’t believe that he’s been living with this problem for 16 months without even being aware that there was a problem. But that’s what happens when you give a brand new PowerBook to a person used to cheap and cheerful PC hardware and he has nothing to compare it to. Other experienced Mac users like me would probably have noticed the problem on his machine right away, but I was clearly the first experienced Mac user to see his machine since he’s bought it.

My dad joked that it was like going to see the doctor and being told that you have a disease when you are feeling perfectly fine and haven’t noticed anything wrong with yourself…

Anyway, all is well that ends well! This PowerBook was definitely “sick”, but it’s been cured, and it didn’t cost anything beyond a couple of hours of backing up and rebuilding stuff. I guess that has already made my visit worth it for my parents!

9 Responses to “PowerBook G4: Unexplained problem with excessive brightness”

  1. Jussi says:

    Did you check the Universal Access settings? There is a contrast slider that can cause some of the problems you mentioned, but perhaps not all.

    Nice to hear that the sick mac was cured.

  2. Pierre Igot says:

    Good lord… That must have been it! It produces exactly the problem that we had! I had no idea that this setting existed… My dad must have accidentally changed it, and never realized it. And I never thought of going through that particular pref pane.

    Well, I guess I did all that backing up and rebuilding for nothing… Still, it can’t have hurt to have done this in-depth “spring cleaning”.

    Thanks for the pointer!

  3. Olivier says:

    There are keyboard shortcuts to increase and decrease contrast (Command-Option-Control-, and Command-Option-Control-.) so it’s quite easy to change this setting accidentally.

  4. Paul Ingraham says:

    Oh, woe! It’s too bad you didn’t write to ask me first, Pierre! Not that you had any reason to think I would know the answer to that one. But yes, it was certainly the Univeral Access contrast setting… with its exasperating hotkeys. I’m not sure how I accidentally manage to hit Opt-Ctrl-Cmd-. almost regularly, but it’s now a familiar ritual to notice the blasted contrast has gone up again and toodle off to the Universal Access Control panel to turn it back down. I can never actually remember the hotkey when I need it, of course.

    The first time I had this problem, I had just finished a harrowing negotiation with Apple to get a faulty Cinema display replaced — the backlights had gone. I can’t even remember why they weren’t replacing it now, but I do remember that I lost the battle, and it was ultimately the generous retailer that replaced the display at their own risk. About two weeks after I got the second display, I noticed that it was strangely bright, and my heart nearly stopped as I confirmed that it really was in fact freakishly bright and “washed out”…

    It took me hours to troubleshoot as well, although found the answer through sheer technical genius (read: fluke) just before I was about to start over with a new account.

    My stomach still churns for a moment every time it happens, until I remember that it’s harmless. I hope this posting and the comments save a few other Mac users from the same agony that we have suffered!

  5. Olivier says:

    You can turn off the keyboard shortcuts in the Keyboard & Mouse preference pane.

  6. Pierre Igot says:

    It’s most definitely the keyboard shortcuts, because I don’t think my dad would have deliberately gone to the Universal Access PP to change this “accidentally”.

    To add insult to injury, the shortcuts on my dad’s French keyboard are not what the interface says they are.

    Fortunately, as Olivier said, they can be removed.

    I am surprised that, keyboard shortcut freak that I am, I never accidentally used these myself. It’s probably because they are again different on the Canadian CSA keyboard and for once almost impossible to hit accidentally. Who knows?

  7. Paul Ingraham says:

    Thanks, Olivier, good tip. I sort of knew that was there (one of those “I should probably check that out sometime” things) but didn’t realize it was so straightforward to turn off a problematic hotkey. Nice. No more “contrast creep” for me!

  8. sdimbert says:


    Just goes to show that we all need reminders… I believe I’ve read, on your blog, that one of the first troubleshooting steps you should try is to log in with a different User Account! :)

  9. Warren Beck says:

    On the use of a different account: when I had trouble with the trackpad on my Powerbook G4, the technician on AppleCare had me create de novo a new user account and enable fast user switching in order to remove the possibility that my problem was due to user settings.

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