Display Brightness Preference

This is a well-reported problem with 10.4 - my PowerBook G4 DVI exhibits it too. You'll also notice that you only have one displayed resolution available! Hopefully Apple will fix this in the next update (10.4.3).

One thing I have found which sometimes fixes it is to start up using battery power (i.e. mains adaptor disconnected) - most times the brightness controls are then available.

Well documented bug with no solution anticipated anytime soon. Note this has been an issue since the Tiger launch and remains unresolved after two upgrades. If you must use these controls or be able to change resolution only fix is to go back to Panther.
-rgds
-RG

adding new features, losing basic features.

We are having the exact same issue with our iBook. Since upgrading to Tiger 10.4, our screen brightness keys no longer adjust the screen's brightness.

Just to say I have new issues with this on either my iBook or my G5 with the Cinema display, so this problem obviously doesn't affect everyone. COuld it be that previously installed third-party software has edited some preferences that 10.4 thinks should be the same as they used to be? If you vreate a new user and log in as him/her, does the problem persist?

clearly its with a limited set of hardware... if it was a simple user preferences issue the fix would be fairly straightforward. However, the problem seems to be at the driver/hardware level as the LCD pretty consistently gets mis-ID'd as a CRT by video hardware/driver. The result is that the preference pane, thinking you have a CRT, does not offer Brightness controls since that is a Monitor function and not under control of the CPU.

We've been down the Create New User path in numerous threads before... in addition throwing out preferences files from both User and System, installing ATI drivers versus Apple's... the issue is fundamental somewhere in the system.

The only clue I can give is it seems to me to be related to Quartz/Quicktime interactions. And seemingly most specifically when images are animated with Quicktime functions or Movies are played via QT. It as that time I get other interesting artifacts in video presentation to the screen that can be corrected by simply putting my PB to sleep or disconnecting another monitor. (Like my 20" LCD I use at home. (Which seems to always be correctly identified and always has brightness control associated with it regardless of the attached 15" LCD's settings.)

I just got bitten by this. I'm sure I was able to change screen brightness since upgrading to 10.4.3

But today it suddenly stopped. I used to be able to push the brightness button on my monitor (early apple LCD connected to dp 2G G5) and the display preference pane would open. I'd move the slider to adjust brightness as abient light changed through the day. Now push the button - nothing. Manually open the display preference pane. I could move the slider around, but it did nothing. So I tried another account. It still worked there. I looked for a file that had changed in the test account today, and could find nothing relevant. Then I went back to my main account to see if had magically been fixed. Instead the screen brightness slider had completely disapeared. It was not there any more!
Back to the test account. The brightness slider is missing there as well. I can't think of anything I might have done to cause this.
Is this still an unresolved issue?

I tried reseting the PRAM, it didn't help.

Then I tried unplugging the monitor while the
system was on. When I plugged it back in the brightness
control started working again. Strange.

The whole time the system profiler had the monitor
listed correctly (apparently some people have this problem
when the system starts thinking the display is a CRT.
That was not my problem. . .

Displays:
Apple Studio Display:
Display Type: LCD
Resolution: 1280 x 1024
Depth: 32-bit Color
Core Image: Supported
Main Display: Yes
Mirror: Off
Online: Yes
Quartz Extreme: Supported

I'm posting just in case somebody runs across this problem on a machine other than a powerbook. I hope it keeps working . . .

My Tiger upgrade from 10.3.9 wiped out my brightness control on my iBook G3 600 MHz. I'm running 10.4.3 and my F1 and F2 keys don't work and I have no brightness slider in my preferences panel. So I'm stuck with a dim screen. I've had no brightness control in any version of Tiger.

To troubleshoot, I started up my iBook from my iMac, which is running 10.4.3 and has no brightness control problems. I still had no brightness control on my iBook. However, a repair shop started up my iBook from its network, which is running Panther. The brightness control slider and the F1 and F2 keys worked fine. This leads me to believe it's definitely a bug and not a hardware problem.

I've done an erase and install. I've reset PRAM. Nothing worked. Any suggestions?

After sending a screen capture and a data capture to Applecare, which sent it on to an engineer, Apple decided my screen brightness control problem in Tiger was a hardware problem. I sent in my machine and here's what they replaced:
590-5067 CABLE,ASSY,LVDS, 14.1
600-9020 TOP CASE ASSY
646-0135 DISPLAY, LCD 14.1 XGA (SAMSUNG), IBOOK

I've got my brightness control preference slider back and the F1 and F2 keys also are working.

So the solution is an entire display replacement? That seems absurd for an issue which seems to be a hardware button controlling a software driver issue...but who knows. At least one of us has resolved this issue.

My TiBook 400 is exhibiting the same symptom, only since upgrading to 10.4.x. I suspect the "Reduce the brightness of the built-in display when using this power source" option in the Energy Saver Preference Pane might have something to do with it. Any suggestions (other than paying more for a new display than my PB isworth)?

One other nugget of info: when mirroring my PB's monitor to an external LCD, The Spple System Profiler says that the external LCD is the "master Mirror", and the PB's display is a "hardware mirror":

Displays:
Color LCD:
Resolution: 1152 x 768
Depth: 32-bit Color
Built-In: Yes
Core Image: Not Supported
Mirror: On
Mirror Status: Hardware Mirror
Online: Yes
Quartz Extreme: Not Supported
VG175:
Resolution: 1280 x 768 @ 75 Hz
Depth: 32-bit Color
Core Image: Not Supported
Main Display: Yes
Mirror: On
Mirror Status: Master Mirror
Online: Yes
Quartz Extreme: Not Supported

I have the same problem with my PB/Ti G4 400.

this is not just a power book problem

The brightness slider disappeared on my Cube with LCD studio display.

In addition hitting the brightness button on the monitor fails to bring the brightness slider up.

it is annoying