1
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Joe
13
Asked
Backlight turning off, inverter-board changed
Hi, my late 2009 iMac 27" is killing me. Display goes black 10 times a day. When I hold a flashlight to the screen I can see stuff on the screen. External Monitor works fine. Regarding to some other articles on ifixit, the backlightboard should be damaged.
So i ordered one from the US (I´m in germany) and replaced the old one... same failure *crying loud*.
Do you think i should change the backlight cable also? I can only find one on the internet and thats &##* expensive (more expensive then the board itself). Where do you guys get those cables?
Does anyone know why the display is turning off in such irregular intervals? Is it a heatproblem??
Maybe i should plug out the display-thermal-sensor-cable an see if it is still turning off?!
Thank you!
0
Score
Dan
6.3k
Answered
Check your display settings. Turn off the Ambient Light setting. Also check your Desktop & Screen Saver settings make sure the Start Screen Saver is put to never. Restart your system and see what happens.
so theres a second board i could change? I cant find anything on google on "backlighting board imac". Is it part ot the Display or maybe the board next to the driver board? thx
Joe,
ah .. didnt see your last comment. Screensaver is disabled. There´s no "Ambient Light" setting in the Displays preferences availible. I know the option to automatically adjust brightness from my macbook but the iMac doesnt have this feature( or the killd it in the Upgrade to MountainLion).
Joe,
Just want to make sure were not looking for snipes. Not all of the iMacs have an Ambient Light sensor so the option may not show up. Yes there is a second part here that could be the issue but I don't think it's the case here given the symptoms. The LED backlight panel which is part of the display unit. I still think something else is the cause here. The LED panel rarely fails and when it does its only an LED or two that die (depending on your system and display you have12 - 18 LED's along the edge).
Dan,
what do you think about the backlight cable? Could this be the reason for my problem? Hard to find one over here...
Joe,
No, I don't think its the cable. I'm starting to think its something on the logic board. Can you run Apple Hardware Test http://support.apple.com/kb/HT1509 to see what it tells us.
Dan,
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Score
donmoron
13
Answered
looks like the GPU, i had similar problem - check here: http://forums.macrumors.com/showthread.p...
Hey Don, thx for the link. This sounds interesting. I think i lack the skill to find that "enabeling" - pin and put voltage on it without killing some other parts. My Mac works most of the time. The display isnt´t permanently black as yours. I noticed that it fails more often in shorter periods the higher the brightness setting is. I was looking for a new logic board but the prices are way to high to be economic. Maybe ill come back to your method once the display fails permanently :) THx Don...
Joe,
Just in case, I would recommend you keep a good backup of your data and make sure you keep it updated.
Dan,
yes, im running a TimeMachine. I did a clean install algain to see if its software related. This Problem is solo annoying. Mostly the Display fails when i got the most work to do :)
Joe,
0
Score
Answered
It might be a faulty vertical sync cable, they say: http://www.ifixit.com/Answers/View/91217...
It´s cheap if you find a used one.
0
Score
Answered
Start by resetting the SMC - http://support.apple.com/kb/HT3964 See if that sets things right. Without knowing which model you have we can't answer this - Please give us the last four digits of your serial number so we can correctly identify your system.
Dan,
thx Dan, already resetted the SMC multiple times. My Serial ends with 55PJ. Greetz Joe
Joe,
iMac "Core i5" 2.66 27" Model No: A1312 (EMC 2374)
Dan,
Just to make sure were on the right track here. Your system has LED backlighting not CFL's. So to be clear here you replaced the display LED backlight unit 'backlighting board' as well as the LED driver board 'inverter changed' correct?
Dan,
I only changed the LED-Driver-Board by following this guide: http://www.ifixit.com/Guide/Installing+i...
Joe,
I just noticed that at a brightness-level of "4" the display doesn´t switch off. Yeay!
Joe,
The LCD display unit does have a thermo sensor. You could try monitoring the temp to see if it's shutting down the display due to heat. Go the Apple App store and download 'Temperature Gauge' it should help you here diagnose the root cause
Dan,
Joe, did you find an answer to this problem? I have the exact same issue. Backlight turns off several times a day. I can see the display if I shine a flashlight to it. The model is A1312, 27in iMac 3.2GHz Core i3 (550).
Stephan,
Hey Stephan, does your Display still turn black when you put your Brightnesslevel to 4?
Joe,
Till now a higher Brigtnesslevel than 4 will turn my sceen black after some minutes. I think the only way to fix this is to get a new logicboard. I didnt find an interesting offer for one of thouse on the internet. Should you find one... plz let me know.
Joe,
The LCD display unit does have a thermo sensor. You could try monitoring the temp to see if it's shutting down the display due to heat. Go the Apple App store and download 'Temperature Gauge' it should help you here diagnose the root cause
Dan,
nice.. didnt know that. Ill check that one out and give feedback. Thx
Joe,
ok, my screen just went black on 34°C so i dont think thats the Problem. :( But again it runs stable at a Brightnesslevel of "4".
Joe,
Joe - What was the temp when you have the display set at brightness 4? Is it the same or lower? If its lower then the sensor may be bad (prematurely shutting it down).
Dan,
Hi Dan, right now my Displaytemp is 29°C. And my room-temperature is 23°C. Doesnt sound realistic to me. I use the software "Temperaturmoni
Joe,
I have the same problem Joe, if I keep the display at 4 it runs stable. But anything higher than that is inconsistent. I have a "Hot Corner" set up to turn off the display, so I can restart it quickly. Happens about 10-15 times a day.
Stephan,
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