Brightness control noise problem

Just got a new iMac 24". The default display max brightness is way too bright. The problem is that reducing the brightness is accompanied by a very annoying electric hum at a frequency around the middle C on a piano. It sounds like a typical trafo electric hum, and it grows louder as you reduce the brightness.
In a busy office or work environment it would probably not be noticed, but in a quiet private workroom it becomes unacceptable. The hum also happens when the display is dimmed before going in sleep mode.
I am wondering if there is a way to adjust the general range of brightness, so instead of going from bright to very very bright it would go from say soft to a comfortable brightness. In this way I could leave the brightness at or near max where the hum is absent.
I've looked into the coloursync-control utility, but have not found a way to change the brightness settings.
Anyone recognizing this issue or have any suggestions?

I bought the 24" imac 3.06 Ghz in the beginning of June. About 3 weeks later when I reduced the brightness of the screen, which I had done in the past, I noticed an annoying hum that increased in volume as I decreased the brightness. I called Apple support and the tech, thinking it could be electrical interference, had me unplug any peripherals. That did not solve the problem. I tried every other outlet in my house and that didn't help either. I was also instructed to zap the pram and to unplug and hold power button down for 15 seconds with no success. He said to take in to a repair center for testing. The repair center could not solve the problem and told apple it was an acceptable, "normal" issue. Then Apple refused to fix it. I called back, spoke to a supervisor, He arranged to have a tech come to my house, replace the power supply and inverter cable. That did not solve the problem. After calling apple again a few more times, and speaking with another supervisor they finally agreed to exchange my imac. That solved the problem, no more annoying hum. Fyi, the old imac I had was a week 9 build made in china, the new one, a week 26 build made in the US.

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Brightness control problem after returning from Stand By - T500

Hi,
I have a Lenovo ThinkPad T500 under Windows XP SP2.
In Power Manager, I have created a custom power management scheme and set the brightness to 80%. This works fine when I boot up the machine, but when I return from Stand By mode (sleep) the machine automatically sets the brightness to 100%. I will then have to use to brightness control buttons to set it back to 80%. This is very annoying and obviously a bug.
I have the latest BIOS and Power Manager version installed.
Can someone offer a solution please?

I found your post after searching as I hae the exact problem you describe - I turn off the screen using Fn F3 and later when I wake the display the brightness jumps to 100% and I cannot get it to turn down to any level. It's stuck at 100%. Yup, just tried closing-n-opening the lid the screen goes to my previously set brightness level.
my drivers are current as at 2010-03-26 (today)
Running a downgraded XP W500 model...
a bug for sure!
Rick
W500 4058-CTO WinXP

Hey Admin(Karl) Still have brightness control problem w/dual ACDs on G5

Can someone on the administrator or tech 3 or 4 guru level from Apple Please tell me what I need to do to access the brightness controls of my two previous generation "clear with/ white frame" apple 23" cinema displays ? I posted here two weeks ago - had no responses.
Went to AppleCare via phone for an hour - Indian person trying to help said it is available in the monitors prefs tabs/and monitor pull down menu on the menu bar next to the time ( nothing but resolution/arrangement/color profile there ).
I have since re-installed 10.4 from the original disks AND upgraded to 10.4.3 - Hoping that something would change. Nothing did.
Nothing shows up on screen when pushing the brightness buttonon either monitor, OR when I go to the monitors control panel - no brightness slider or tab on top.
It is driving me crazy to have to review my work ( digital photography ) on my old G4 system to be able to judge the proper density of the images.
I can profile the pair with a Spyder2 calibrater, and load the profiles fine, but again brightness is the issue, not the color. One of the displays is about 30% brighter than the other, and there in lies my problem.
Since the same difference in the screens is the same across various applications ( Final Cut Pro / Adobe PS / DVD player ), can I assume that this is a system issue software issue ?
Am I the only one having this problem ? Or is there just a glitch that no one has managed to tackle and fix even this far into Tiger ?
Please someone reply and save my sanity !
Mel
NEW Powermac G5 2.3 w/ dual port stock video card Mac OS X (10.4)

Hi Mel,
Sorry to hear that you are having problems.
I feel I have to point out that most of the 3 or 4 level Gurus don't actually work for Mac. We tend to obtain our knowledge from our own experiences plus sharing other peoples' experiences in this forum.
The reason I haven't responded to your issue myself is because I have no first hand experience of your problem, and I haven't been able to find anybody else who has had this problem and has been able to fix it. I'm always reluctant to respond unless I feel I have some information that will really help (or, at least, not possibly make things worse).
Anecdotally, this issue appears to have surfaced with the release of Tiger, so it may well be a software issue.
I don't know how old your G5 is - will it function with Panther? If that is the case, then installing Panther on another drive or partition (i.e. keep Tiger for now), and then booting up with Panther may give you an interim solution while the issue (hopefully) gets resolved in Tiger.
The fact that the brightness options are not available probably means that the drivers bundled with the Tiger installation for the graphics card that is in your G5 do not support the displays you are using properly. I believe that the stock video card you are using is an ATI card (you might want to check this via system profiler). At this stage, it would certainly be worth your while to contact ATI support and see whether they have drivers available that will assist you. This link may help get you started:
http://www.ati.com/products/mac.html
I acknowledge that I haven't really given you a solution, and I apologize for that. Hopefully, what I have given you will give your quest some direction.
Please let us know how you fared. All the best.
Cheers!
Karl

Problem with brightness control on Toshiba Satellite R830 [SOLVED]

Ever since I've been using Linux on my Toshiba Satellite R830 laptop I had problems with the brightness setting after wakeup from sleep. The solution I had found was to use a custom xorg.conf setup. Actually I was creating a 20-intel.conf file in /usr/share/X11/xorg.conf.d/ with the following content:
Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "intel_backlight"
BusID "PCI:0:2:0"
EndSection
This worked until today. Now I realised that Xorg is somewhat ignoring this configuration file. I looked in the wiki and this suggested that any such config files should be in /etc/X11/xorg.conf.d/. I copied the file there and rebooted. I opened a terminal and checked the value of /sys/class/backlight/intel_backlight/actual_brightness. Modified the brightness with the Fn + F6/F7 and checked again and it was controlling these.
But after closing the lid and leaving it for a while, and wakeing up the PC the Fn +F6/F7 keys started controlling /sys/class/backlight/toshiba/ which never worked after sleep. Somehow on wakeup the custom config files are being ignored. It seems this is related to the upgrade to Gnome 3.16. I'm using linux-lts kernel.
How do I make Xorg use intel_backlight instead of Toshiba for brightness control?
Last edited by entodoays (2015-05-18 15:21:04)

It seems that the culprit is /usr/lib/gnome-settings-daemon/gsd-backlight-helper. In this page: http://ubuntuforums.org/showthread.php?p=11910629 there's a procedure to patch the source file (for an older version). There's a section of the code like this:
/* available kernel interfaces in priority order */
static const gchar *backlight_interfaces[] = {
"nv_backlight",
"asus_laptop",
"toshiba",
"eeepc",
"thinkpad_screen",
"acpi_video1",
"mbp_backlight",
"acpi_video0",
"fujitsu-laptop",
"nvidia_backlight",
"samsung",
NULL,
Patching this file, eliminating the toshiba device from the preferred list and adding intel_backlight to it might solve the issue.
On another page, https://github.com/mate-desktop/mate-po … issues/135 they suggest another possible hack: changing the priority of device type
file plugins/power/gsd-backlight-helper.c
/* search the backlight devices and prefer the types:
* firmware -> platform -> raw */
path = gsd_backlight_helper_get_type (devices, "firmware");
if (path != NULL)
goto out;
path = gsd_backlight_helper_get_type (devices, "platform");
if (path != NULL)
goto out;
path = gsd_backlight_helper_get_type (devices, "raw");
if (path != NULL)
goto out;
Changing the order to firmware -> raw -> platform would solve the problem for me too.
Unfortunately I've never done any patching yet. How would I go about it?
Last edited by entodoays (2015-05-12 07:22:06)

Problem with my macbook air brightness control key

i have a problem with my macbook air.my brightness control key ( F1 & F2 ) dont work.what can i do ?

If keys on your keyboard don't work:
http://support.apple.com/en-us/HT203162

Windows 8.1 kills screen brightness control

I have a touch smart 23 computer that came with windows 8.0. An auto upgrade to 8.1 caused the screen brightness control to stop working and the screen stays on super bright. I could not get a response on how to fix so I had to re-install 8.0 which fixed the problem. I set the system to not upgrade without my approval and yet it did it again last week (about 4 or 5 months later). When I have to reinstall 8.0, I have to re-install several primary programs as there are no restore points left except back to factory settings. Question one is - has there been a fix installed on windows 8.1 that will again let me control the brightness on my screen? If not, question 2 is how did the update override my setting to not allow updates to install without my approval. I have a full day of re-installs that I don't want to have to do a third time.

Hi:
You probably have to install the W8.1 graphics driver for your specific model.
Normally when you can't control the screen brightness, that means the graphics driver isn't installed.
As for your second question, that I do not know.

My screen gets dim and the brightness control buttons don't work

My screen is frequently dim. The brightness control buttons display that they are working, but the brightness doesn't actually change. Any ideas why and what I can do?

Thanks for the suggestion. Actually, I had tried that but still had to go into preferences any time I wanted it brighter. After I posted, I found a thread using some different keywords and found that people were having the same problem with OS versions up to 10.7.2 but solved it with the latest update (10.7.3). I just installed it and now seem to be able to adjust the brightness with my keyboard no problem. I appreciate your reply anyway!

Satellite C650-I5011 - Brightness control is not working

Hi,
I have a Toshiba C650 - I5011 model with Ubuntu 10.3 . I have a problem that even after pressing the Fn + F6 key, the brightness of my LCD does'nt change.
It remains at maximum.
I have installed both Toshutils and hotkey daemon. My volume control key (on numeric alternate) works perfectly fine but none of the Function keys work. Pls help.
Also, I had errors during installation of Ubuntu on my laptop because of which I had to permanently disable ACPI, else it won't boot. Following is the lspci output :
00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 02)
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)
00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06)
00:1a.0 USB Controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 05)
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 05)
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 05)
00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 2 (rev 05)
00:1c.4 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 5 (rev 05)
00:1d.0 USB Controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 05)
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01:00.0 Ethernet controller: Atheros Communications AR8152 v1.1 Fast Ethernet (rev c1)
02:00.0 Network controller: Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) (rev 01)

Hello,
The backlight detection depends from acpi options selection on your kernel. Which kernel version do you use ?
$ uname -a
(Use at least a 2.6.36 kernel since a lot of improvement for recent Toshiba laptop have been done during summer 2010)
This done, ACPI options beeing compiled into kernel or loaded as module, this line should appear in your /var/log/Xorg.0.log :
"found backlight control interface /sys/class/backlight/acpi_video0"
Having a C650-15Z, my brightness control works well.
regards,
alex

Windows 8.1 update and brightness control

I have a DELL XPS L521X with Windows 8.1 (I had windows 8 some days ago) and I have had two problems:
1) I did not allow Windows to upgrade to 8.1 and it forced me to do it. It gave me 15 minutes to save progress and do it. I was watching the NBA finals on my computer and it was the only thing I had to watch the game. The installation lasted the whole second
half the game and I WAS NOT ABLE TO WATCH IT DUE TO THIS, YOU CAN IMAGINE HOW I AM FEELING ABOUT NOT USING WINDOWS EVER AGAIN... How can I prevent it from ever upgrading anything without my consent? I had already turned off updates from Control Panel\System
and Security\Windows Update but it didn't help.
2) My brightness control became broken after the 8.1 update. I had to manually pick the older Intel HD 4000 driver to have it working again or else my eyes would stop functioning after such a bright display. I had to switch to the 9.17 driver version from
September 2012. Where can I get the lastest WORKING version of the driver?
Please stop making me loose days fixing Windows issues...

Hi,
We have set the GP to disable Windows 8.1 update in Windows store, you can check it here:
How to Disable “Update to Windows 8.1 for Free” Notification in Windows 8 Store?
http://www.askvg.com/how-to-disable-update-to-windows-8-1-for-free-notification-in-windows-8-store/
For your second issue, it's not only related to Windows, but also the driver provider. Microsoft is working together with the device manufacturers and partners to deliver update package and try the best to solve the compatible issue and bring a great improvement
on user experience. But you know, it will take some time.
Thanks for your understanding.
Kate Li
TechNet Community Support

IMac G5 (iSight) with 10.4.11: Screen always dimmed. Starts at full bright and a second later dimms and stays like that forever. Brightness controls work normally under this circunstance. Please help !!!

iMac G5 (iSight) with 10.4.11: Screen always dimmed. Starts at full bright and a second later dimms and stays like that forever. Brightness controls work normally under this circunstance. Please help !!!
Please don't tell me to adjust anything on the preferences, since I have tried all. I think it may be anoter kind of problem, maybe hardware related or anything.
I ran the Hardware repair DVD and everything was ok, but when the imac restarted the screen was very lit again, but when it went sleep, when it went awake again the screen got dimmed again. Because of that I think that the problem could be software related, but who knows. Excuse my english.

I can't see another possible answer - the longer your machine is up, the more the power supply is stressed, it protects itself by dimming the screen to lower the draw on it.

[Solved]Brightness control doesn`t work anymore

Hi!
I`ve made my 3rd update of Arch since installation, and... where previous two succeeded, the third one failed. It messed up my system
The problem is, i cannot change brightness any more through my function keys (and since i`m using Openbox as my DE, i cannot change it at all ). The brightness now is so low that i can barely see what i am typing. And it is not only in my Arch, it also messed up Windows and everything else: grub, bootup screen where i can select bios properties - everything. I ran xev and now i see that FN+Right/Left are not detected anymore as brightness keys. It says:
FocusOut event, serial 32, synthetic NO, window 0x3200001,
mode NotifyGrab, detail NotifyAncestor
FocusIn event, serial 32, synthetic NO, window 0x3200001,
mode NotifyUngrab, detail NotifyAncestor
KeymapNotify event, serial 32, synthetic NO, window 0x0,
keys: 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
However, FN + Win + Right/Left are now detected as brightness control function keys
KeyRelease event, serial 35, synthetic NO, window 0x3200001,
root 0x13c, subw 0x0, time 521221, (348,-43), root:(1219,884),
state 0x40, keycode 233 (keysym 0x1008ff02, XF86MonBrightnessUp), same_screen YES,
XLookupString gives 0 bytes:
XFilterEvent returns: False
But pressing them doesn`t work either. I thought that it was xfce4-power-manager problem, but changing to gnome-power-manager didn`t help either.During the update pacman also upgraded kernel to latest version.
Any ideas?
P.S. My notebook is Acer Aspire 7720g with Nvidia 8600M GT. I tried solutions from this topic: http://bbs.archlinux.org/viewtopic.php?id=73889 but none worked for me... The problem is that the system is completely unusable at this point, since i barely see anything on the monitor, and that sucks
Last edited by K0tuk (2009-06-27 08:02:56)

I can't see what you did in Arch affecting your windows installation at all. If you try to boot into windows and increase the brightness (since most laptops store the brightness level of the laptop as it was set, on battery, at least my 2 laptops do), does the new brightness level "stick" for all things? If so, the only issue you have is to re-map the function keys properly, and to configure a script or something to increase/decrease lcd brightness. You can make a simple script that echoes a value into your /proc/acpi/video/LCD/brightness file (the file path will vary, so it may be under UVGA or so). If, however, it doesn't increase again, it may very well be a hardware issue, and not a software (since, as I said above, it's highly unlikely that an Arch update has affected Windows in any way).
Last edited by lswest (2009-06-26 12:28:04)

Failure of Shades, DarkAdapted and Brightness Control

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I've tried 3rd party software. Brightness Control continually loses it's setting when the screensaver starts. Shades doesn't work for me because it leaves the pointer undimmed and that small too bright area is right where I need to look. And DarkAdapted is limited by the same screensaver problem as Brightness Control.
I sure wish Apple displays could dim adequately as in the past.
Any suggestions appreciated.

I have DarkAdapted Pro, with registered version, it load your profile at mac os login, and darkadapted its a real bright control, not like brightcontrol (deform colours)...
One question, do you have bright gradient left to right on your mac 24 alu?.. more bright at left side of your monitor, to view this, move one window at the left, and then move it at the right, if you see one variation of white values then the gradient is there!... ok it is my problem and a lot of people are at the same situation like me... not sure if it is a general problem...
Ok see you bye!

Display brightness control not in Prefs Pane

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Based on cycle count and capacity your battery is in great shape. You might check the adapter and port for debris, and try an SMC reset:
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24" Display Brightness Control

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Hi guys,
could you kindly verify whether your screen have uniform color?
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Has someone else experienced the same problem?
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Stefano

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