New To Mac-Forums?

Welcome to our community! Join the discussion today by registering your FREE account. If you have any problems with the registration process, please contact us!

Get your questions answered by community gurus Advice and insight from world-class Apple enthusiasts Exclusive access to members-only contests, giveaways and deals

Join today!

 
Start a Discussion
 

Mac-Forums Brief

Subscribe to Mac-Forums Brief to receive special offers from Mac-Forums partners and sponsors

Join the conversation RSS
Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

iMac - Screen goes very dim


Post Reply New Thread Subscribe

 
Thread Tools
jim6856

 
Member Since: Sep 14, 2009
Posts: 2
jim6856 is on a distinguished road

jim6856 is offline
My intel 17" mac has an almost black screen. It is too dark to see the mouse pointer but I can tell it is on. When I push the power button to force a shut down, the screen brightens for just a second and I can see a normal looking desktop before it shuts down. I have zapped the pram. I have hooked up an external monitor and it shows the desktop background but mirroring is not on so I can not use it to navigate. Any ideas?
QUOTE Thanks
chscag

 
chscag's Avatar
 
Member Since: Jan 23, 2008
Location: Fort Worth, Texas
Posts: 40,069
chscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond repute
Mac Specs: 27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, 3 iPods, OS X Mavericks

chscag is online now
If the external monitor shows a normal raster (video) with correct brightness, we can assume the GPU in your iMac is working OK. It also means your logic board is probably OK. That leaves us with the internal display of your iMac.

The symptom you describe may be a failing backlight (the CCFL which lights the screen) or it could be a defective inverter. Of the two, I would be more inclined to suspect the backlight. The inverter is a do it yourself replacement but does require care and skill. However, since replacing the backlight in the display, especially an iMac, is a daunting and difficult job, it's usually better to replace the entire display.

And there may be other reasons your display is not functioning correctly....

If your iMac is still under warranty, it would be best to have it looked at by Apple. If not, then you have a decision to make on how to go about repairing it.

Regards.
QUOTE Thanks
jim6856

 
Member Since: Sep 14, 2009
Posts: 2
jim6856 is on a distinguished road

jim6856 is offline
Thank you for the info.

I have taken the cover off and pushed in all the connections related to the inverter board.

I started it up again and no problem with the screen. It is bright and clear.

We will see if it stays that way.
QUOTE Thanks
chscag

 
chscag's Avatar
 
Member Since: Jan 23, 2008
Location: Fort Worth, Texas
Posts: 40,069
chscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond reputechscag has a reputation beyond repute
Mac Specs: 27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, 3 iPods, OS X Mavericks

chscag is online now
Sounds like you may have lucked out. Let's hope it was just a loose connection from the inverter. Keep us posted.

Regards.
QUOTE Thanks
johninsf

 
Member Since: Sep 14, 2009
Posts: 4
johninsf is on a distinguished road

johninsf is offline
It might have also been the act of disconnecting the power that fixed your problem, rather than wiggling the internal connections. I believe the power management unit (now called the SMC) is reset by unplugging all connections for a few minutes.

If it happens again, you could also try booting off the Mac OS X disk and see if it's software-related. (If it is, the screen should be bright when booting off the OS install disk.)
QUOTE Thanks

Post Reply New Thread Subscribe


« Apple Hardware Test | Adding memory to an iMac G4 »
Thread Tools

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off
Forum Jump

Similar Threads
Thread
Thread Starter
Forum
Replies
Last Post
MAC G5 interface with dell screen - please help!!!! Intravenusdemil OS X - Operating System 2 09-13-2009 06:44 AM
ibook g3 700MHZ dim screen greenapplebay Apple Notebooks 1 05-17-2008 04:15 PM
Question about Screen Mirroring/Spanning markwco OS X - Operating System 0 05-16-2008 04:07 PM
Isights and dim screen problems KB3GZW Apple Notebooks 1 10-06-2007 10:16 AM
Dim Screen at startup KB3GZW Apple Notebooks 5 09-28-2007 11:20 AM

All times are GMT -4. The time now is 01:37 PM.

Powered by vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
X

Welcome to Mac-Forums.com

Create your username to jump into the discussion!

New members like you have made this community the ultimate source for your Mac since 2003!


(4 digit year)

Already a member?