Imac buzzing/screen dim

Hi,
I wonder if you guys can help me with a problem im having.
I don't want my screen to dim after a certain period of time if fact I would rather it never dim at all. I have been in the system>energy saving>options.automatically reduce brightness... and unchecked that but it still keeps doing it?? Can anyone suggest what I might be doing wrong here?
Also when the screen does dim I get a kind of buzzing type noise, but when i moving the mouse or click a key it stops?? Anyone en counted that problem or know what it might be?
I have also noticed that the problem occurs when I change the brightness setting. I have done a search and see that this has been a problem for a few imac users. I am a little concerned as to what I should do? I have the 3 year warranty and the unit is about half a year old, I really can't be going without my mac for for weeks, should I call support? What will they do?
Many thanks

I did some more searching and found this!
http://www.xlr8yourmac.com/archives/mar06/032806.html
I also just now found this thread http://discussions.apple.com/thread.jspa?messageID=3182688&#3182688 on Sept. 26 2006 at 8:33pm "someone" gave Splasm Brightness Control as a possible fix, to try for display buzzing or did I read that wrong.
It never hurts to check, maybe one of these Brightness Control App's will make difference for those that may have a slight buzz or humm????
Dennis (-:
17" iMac Intel Core Duo 1.5GB Ram Mac OS X (10.4.9) Maxtor 300GB FireWire Creative Inspire 2.1 2G Nano

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The DEFINITIVE iMac 20" Screen Dimming Thread

Ok, so I've been going through this board for a while now, looking for answers to why the top half of my iMac 20" screen goes dim, after about 5-10 minutes of use. (from starting up or waking from sleep)
I have read several threads in this forum from other people who seem to be experiencing the same issue, however I have not been able to find a SOLUTION.
Do I need to send this thing away for repair? Am I going to have to spend $800 on a new LCD? I am starting to get a little annoyed when this happens. When I first received my iMac it would do it once a month maybe, however in the last 2-3 weeks it has started to go dimmer at the top half of the screen ALL THE TIME.
Could it possibly have anything to do with the sleep light firmware fix? or the fact that I have installed 2 1gb sticks of ram?
I need an answer please.

Hi again, Ryan,
The most probable cause of your problems, I would think, would be an inverter board failure (which I think falls outside the extended repair program, but check with Apple first) . The inverter board appears as a user replaceable part in the User Replaceable Parts listing
The relevant instructions for replacement of this part appear HERE .
Cheers
Rod

24" iMac Screen Dim Humming

I have recently noticed that when my iMac's screen auto dims, a faint humming noise comes from within the iMac. Is this normal?

I have heard of this happening but I do not know how normal it actually it because mine does not do it. I would do a little forum searching because I know the topic has been discussed here before.
George

IMac screen dims itself automatically; all attempted fixes fail; how can normal brightness be restored?

Machine and OS:
2007 white plastic iMac with 20" screen and 2 GHz Intel Core Duo, running OSX 10.6.8.
The problem:
The screen dims itself for no known reason. It is especially noticeable when waking from sleep: for the first second or two after waking up, the screen is at normal brightness -- but then after a second the computer seems to "remember" some setting or command, and the screen unquestionably dims itself to be about 20% or 25% darker.
Because the screen for a brief moment after waking is at full brightness, that proves to me that there is nothing physically "broken" about the display that prevents it from illuminating fully; it could be at full brightness if it "wanted to," but some kind of software or firmware glitch is telling it to be dimmer.
The fixes I have attempted so far -- ALL of which have FAILED (so please don't recommend them again):
- Reset the NVRAM or PRAM by holding down Command-option-P-R upon startup. For some reason this technique doesn't cause the second chime, so it doesn't appear to be zapping the NVRAM or PRAM or whatever, and consequently has no effect on the dimness, which persists unchanged after restarting.
- Reset the NVRAM using the terminal command ' sudo nvram boot-args=”-p -r” ', as recommended on this page: https://discussions.apple.com/thread/2172681?start=0&tstart=0. I can't tell if this really did reset the NVRAM (it doesn't cause a second chime upon restart), so I'll just have to assume that it "worked" -- but except for one instance, it had no effect on the screen dimness. (That one instance went like this: after issuing the Terminal command and restarting, the screen did go back to full brightness -- but only until the first sleep. After waking from that sleep, the screen once again dimmed itself as before. And no, I have not been able to repeat this momentary "success"; on all subsequent attempts following the exact same steps, no brightness has ever returned at all since.)
- Reset the System Management Controller (SMC) as recommended on this page: http://support.apple.com/kb/HT3964 . Basically this just entailed shutting down the computer waiting a few seconds, then unplugging it, waiting a few more seconds, then plugging it back in, then waiting a few more seconds, and then finally starting it up again. Result? No change: screen still dims itself.
- Pressed the "brighter" and "dimmer" keys on the keyboard; those do make the brightness go up and down, but the top brightness setting is much dimmer than it should be (and used to be). All the way to brightest setting = still noticeably dimmer than normal.
- Used the "brightness" slider in the System Preferences > Displays > Display window. That also does indeed adjust the brightness up and down, but as with the keyboard brightness keys, the highest setting is still too dim.
- Readjusted the "Calibration" in the System Preferences > Displays, which had no noticeable effect; even when going into Expert mode and adjusting every little aspect of the screen display's default settings. Those all seem to be about color balance anyway, not about brightness. I now have three different new calibration settings, and clicking back and forth between them and the default setting makes no real significant difference. Whatever setting I choose, it is still dimmer than it should be, even though in all my attempts at calibration I tried to make it brighter.
- Tried going to System Preferences > Universal Access > Seeing and adjusting the "Enhance Contrast" slider and trying out "Black on White" vs. "use Greyscale"; none of that helped, and did not seem to be relevant to the problem.
- Tried going to System Preferences > Energy Saver, and clicking the "Automatically reduce the brightness of the display before display sleep" check box on (and then closing the preference pane) and then off again (following the advice at http://support.apple.com/kb/TS2309?viewlocale=en_US) -- but it had absolutely no effect whatsoever on the brightness level.
Final note: The keyboard and mouse are both Apple products and work perfectly, and the machine has no other performance issues. Just the dimming, which started a few weeks ago inexplicably and without warning.
I can't imagine what is causing this problem, and I've absolutely run out of ideas about how to fix it. One thought I had was that maybe the screen is dimming itself due to detected ambient illumination, but I'm not sure 2007 iMacs even have that feature, and also the screen remains dim whether the room is dark or bright. Maybe there is an ambient light detector somewhere that is malfunctioning?
Help! How can I solve this? The screen is not so dim as to be unusable, but it's annoying enough that I'll have to get a replacement machine if this is not fixed eventually.

Does an external display also act in a similar manner as the internal one?
Some earlier Intel-based iMacs had graphic processor card issues; not sure what
the symptoms of the majority of them were, but some had odd patterns, others
went black, and some would range from OK to totally unusable. Among others.
So there is a chance the graphic processor may be going out; or just the circuitry
that controls the backlight. An inverter may be weak or other circuit to the display
could be wearing out.
http://www.apple.com/retail/geniusbar/
If you have access to an Apple Store with Genius bar, they can perform some kinds
of diagnostic tests there even though the computer is out-of-warranty; that may be
of help to narrow down the cause of the symptoms you've noticed. They may not be
able to repair it, however, at an Apple Store; as it is rather old by today's standard.
An Apple Authorized Service Provider could do repairs and testing on older models
the Apple Store's Genius and other may not be set up to handle due to vintage.
Find an Apple Authorized Service Provider
Visit an Apple Retail Store
There is a country locator page to help find either of the above in regions outside
of the US & Canada, not sure how the above links would work; and it appears my
bookmarks to the country locator page may not be accessible now to post here.
You may be able to get an idea about what kinds of parts support the display
function by name by looking into an iFixit.com repair guide for your iMac series.
Hopefully the parts supporting the display are the reason it is dimming down, as
a graphic processor failure likely would exhibit other behaviors than just dimming.
PS: I see you've added content to your thread after I'd started working on this
& the answer likely is a hardware repair; professional testing is worth the time
and you seem to have at least one other thread on the same topic....
Good luck & happy computing!
edited 2x

IMac Screen Dimming

About a week ago my screen started to randomly dim and then get bright again. The auto brightness is turned off. Its very random when it does it, Im worried the screen is starting to going bad or something. I purchansed the computer new at the end of 2011. Its a 27" iMac 2.7 GHz Intel Core i5, Graphics AMD Radeon HD 6770M 512 MB. Is anyone else having this issue? All of my software is up to date.

First, some commentary:
http://news.cnet.com/8301-13579_3-57609897-37/apple-sued-over-alleged-imac-scree n-dimming-issues/
https://discussions.apple.com/message/22938701#22938701
This issue results usually from two things: the brightness settings, or the graphics card. It seems you've already accounted for the brightness settings, so you might want to investigate the latter.

Any news on imac G5 20" screen dimming?

I have been living with the top half of my screen dimming intermittently for the past 4 months or so. The bottom half stays bright. I have to sleep the computer to bring it back and it's a pain. I brought it to the Apple store a couple months ago (my machine falls into the recall serial #s) and the genius said the capacitors are fine and that it was due to bad memory. I pulled my aftermarket memory - and it still does it. I saw a lot of people asking about this months ago but never saw any definitive answer. Thanks - 1st post
imac G5 20" Mac OS X (10.4.5)
imac G5 20" Mac OS X (10.4.5)

gdan7:
I had this problem when Apple replaced my screen for the "white banding" on the lower half of the screen. Take a look at these instructions for replacing the inverter. If your comfortable with working around the internals of the machine this may help.
http://manuals.info.apple.com/en/imacG5_20inchInverter.pdf
When you open the document it will show you the internals of the G5. If you go to page 11 it shows a little connector inside a little grey box. If that connector is not seated properly you'll get the half-screen dimming. All I did was reseat the connector and made sure all the twists were out of the cable to make sure there was no stress on the connector. It worked fine after that.
Good luck.
Dan Reilly
Sarasota, FL

IMac 24" Aluminum screen dims like notebook

So this is kinda weird. For some reason if I do not do anything for a minute (move mouse, touch keyboard) the screen dims like on the notebooks when they try to save power. Something tells me this isn't right... Anyone have any ideas or experiencing the something?

Google: [10.4.12 ?|http://www.google.com/custom?q=10.4.12+?&sa=Search&client=pub-626330033301395 7&forid=1&ie=ISO-8859-1&oe=ISO-8859-1&cof=GALT:%23008000;GL:1;DIV:%23336699;VLC: 663399;AH:center;BGC:FFFFFF;LBGC:336699;ALC:0000FF;LC:0000FF;T:000000;GFNT:0000F F;GIMP:0000FF;FORID:1;&hl=en]

The screen dim on 24 inchs imac

The screen dim before sleep on an Intel-based Mac's built-in display, even if the Energy Saver setting "Automatically reduce the brightness of the display before display sleep" is disabled. This setting may no longer be in effect after restarting the computer.
any body has a fix for this.
see the bug description at.
http://docs.info.apple.com/article.html?artnum=304092

Yes, I do, I am hoping for a permanent fix from Apple, but in the mean time I have a script which will run each time you reboot to disable the screen dim.
I have posted this as a separate thread.

Screen dimming delay . . .

I upgraded my iPhone 3G to 4.0.1 (quick and painless unlike the 4.0 release which was 9+ hours) last night and have noticed this morning that the time it takes for the screen to dim (before eventually turning off) after a period of inactivity has dramatically reduced. I can't remember the time that it took before as it was quite a lengthy delay, but now I reckon it's a period of approx 40 seconds before the screen dims. I think it used to be a couple of minutes. Has anyone else noticed this? Also is there any way to alter this timing (just like a MBP or iMac display in the Energy Saver System Pref Pane).
As always, any advice appreciated.

Neil was correct - auto-lock controls how long before the screen dims, followed shortly after by the phone locking. Passcode lock is a separate function. If you set auto-lock to never your screen won't dim. I suspect it's set to 1 minute at present =0)

Screen dims

I have a 20" duo-core imac (white) at work and a 20" duo-core (aluminum) at home and have the same issue on both machines where the screen will dim if the computer is inactive for a brief period. Its not that the computer is going to sleep with the screen going black but more that the brightness level changes suddenly from normal to the lowest setting. If I move the mouse or use the keyboard the brightness level pops back up. The screen dimming almost seems like an energy saving feature but I cannot find any reference to it in the help section and there is no setting or control that I can find in system preferences. A friend of mine with a new MacBook reports the same problem.
Thanks

Hi Reid
DML is correct "System Preferences / Energy Saver / Options" and uncheck : Automatically reduce the brightness...... But you also need the have a look at the following Apple article:
http://docs.info.apple.com/article.html?artnum=304092
Note: The issue will return each time the computer is restarted.
Dennis

Mac Pro screen dimming

My screen is dimming after 5 minutes. I've read through the forums and found a few answers, but I have my display set to never sleep, and I do not have the option of "automatically reduce brightness before display goes to sleep" like my iMac and Macbook Pro do. Please help, it's really annoying watching a movie and 5 min the screen dims.
Thanks,

Hi,
I had the same issues when I bought my macbook pro a few weeks ago.
Its a feature built in that dim and brightens the screen with an ambient light sensor.
The sensor is underneath the speakers so when your hand goes over and effects the lighting your screen will dim/lighten.
To turn this off go to System Preferences > Displays
then at the bottom it will say Automatically adjust brightness as ambient light changes, uncheck that.

Dvd player screen dims while playing a DVD

It is happening on both my iMacs (a G4 and the new dual Intel. while watching a movie the screen dims a bit every so often and then brighten up again. Any suggestions?

Hi,
thanks for checking in. I have had the other screen dim issue where the mouse needs to be moved to power the screen up full. It is not this issue. The screen dims for one second and then brightens up again on its own, too quick to know if moving the mouse would also restore the brightness. The issue happens on all movie dvds, home made or professional.
I have not tried another dvd player as this iMac is in the living room and it is front row, with it's sweet little remote, that makes the iMac our replacement for a TV. (It happens in both front row and dvd player.)
I am hoping to solve this problem rather than switch players, but fdor laughs, when I get home Monday I will download another player and see what happens, it will be an interesting experiment.
I will keep you posted!

Blue screen on start up. The wheel spin and the blue screen gets brighter for a second, then the blue screen dims and it repeats with the wheel.

When I start up my imac, I get a blue screen. The wheel spin and the screen gets brighter for a second, then the blue screen dims and it repeats with the wheel.

Are you referring to the startup screen which is normally gray with the dark gray Apple logo or are you referring the login screen which is typically blue? If it's the latter you might give this a try:
Clearing Caches to Fix Login Problem
You will need to type some Unix commands. If you are not comfortable with this, I don't know of anything other than a re-install. But if you are careful, you should be OK. I recommend you print this out in a largish mono-spaced font so you don't miss any spaces (or add extra ones). Note that case is important.
Be careful. Some of these commands are dangerous, since you are going to be root.
Start up in Single-user Mode. When this has finished you will see a prompt ending in '#', although there may be other messages. Enter the following commands after the prompt:
/sbin/fsck -fy
Press RETURN. Wait a few seconds for 8-10 lines of output. If the last line says repairs were carried out, repeat this command until you get a message 'The volume <yourdiskname> appears to be OK'. Then continue with:
/sbin/mount -uw /
cd /Library/Preferences
rm com.apple.loginwindow.plist
rm com.apple.windowserver.plist
cd /Library/Caches
rm -r *
cd /System/Library
cd /System/Library/Caches
rm -r *
reboot
Press RETURN after each command.
This should now take you to a proper login screen after the normal boot sequence. You should then Repair Permissions by using Disk Utility (in your /Applications/Utilities folder).
If it's the former then reinstall OS X. For Snow Leopard:
Reinstall OS X without erasing the drive
Do the following:
1. Repair the Hard Drive and Permissions
Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
2. Reinstall Snow Leopard
If the drive is OK then quit DU and return to the installer. Proceed with reinstalling OS X. Note that the Snow Leopard installer will not erase your drive or disturb your files. After installing a fresh copy of OS X the installer will move your Home folder, third-party applications, support items, and network preferences into the newly installed system.
Download and install the Combo Updater for the version you prefer from support.apple.com/downloads/.

A magazine's app on my iPad has stopped working. When I open the Newsstand folder and click on the app, the screen dims briefly, then returns to the Newsstand folder. The other app in my Newsstand folder (Wall Street Journal) opens without any problem.

A magazine's app on my iPad has stopped working. When I open the Newsstand folder and click on the app, the screen dims briefly, then returns to the Newsstand folder. The other app in my Newsstand folder (Wall Street Journal) opens without any problem, and this magazine's app opens just fine on my wife's iPad.
I have deleted the app and reinstalled it from the Apple store and that makes no difference. I have also done a hard reboot on my iPad with no result.
Any thoughts about what might be wrong?

Hey everyone in Apple world!
I figured out how to fix the flashing yellow screen problem that I've been having on my MBP! Yessssss!!!
I found this super handy website with the golden answer: http://support.apple.com/kb/HT1379
I followed the instructions on this page and here's what I did:
Resetting NVRAM / PRAM
Shut down your Mac.
Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
Turn on the computer.
Press and hold the Command-Option-P-R keys before the gray screen appears.
Hold the keys down until the computer restarts and you hear the startup sound for the second time.
Release the keys.
I went through the 6 steps above twice, just to make sure I got rid of whatever stuff was holding up my bootup process. Since I did that, my MBP boots up just like normal. No flashing yellow screen anymore!!
(Note that I arrived at this solution when I first saw this page: http://support.apple.com/kb/TS2570?viewlocale=en_US)
Let me know if this works for you!
Elaine

Upgraded to Yosemite and can no longer remote into my work iMac through screen sharing- it is turned on in settings?

My screen sharing functionality did not show up in the dock with an updated icon. It had a question mark- shows my connections but nothing works, I did make sure screen sharing is on and also connected to VPN. Once I tried to launch screen sharing nothing happens. Such an elegant solution in Mavericks not does not work. Ugh. Help!

This is the post that got me set up- I too am running an older version at work vs. Yosemite. As soon as I followed is advice everything worked.
Upgraded to Yosemite and can no longer remote into my work iMac through screen sharing- it is turned on in settings?
I believe the location of the "Screen Sharing" app has changed, which explains why if you had it in the dock it has been replaced by a ?
Don't forget you can launch screen sharing (once your VPN connection is up) by typing in the Safari destination slot vnc://remotemachinename:portnumber (omit the :port number if you are using the default VNC port, 5900). This should launch Screen Sharing and put its icon in the dock. You can drag the Screen Sharing icon to the left of your dock and it will hopefully remain there after you exit Screen Sharing, or you can right-click on the icon when it's running and select Options->Show in Finder to find out its new location and drag its icon to the permanent entries in your dock.
Hope this helps; worked for me.

Imac buzzing/screen dim

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