I have a (mid-late 2009) base model 20 iMac that when booting, will randomly not turn the backlight on. If I shine a flashlight at the screen, I can see that the LCD is displaying the proper image but there is no backlight and pushing video out to an external monitor works flawlessly. Were currently running this machine with Boot Camp, primarily in Windows XP.
Depending on the iMacs mood it could either:
Be dark during windows xp boot screen but then light up upon arriving at login screen
Be bright during windows xp boot screen but then go dark upon arriving at login screen
Be dark the whole time
Be bright the whole time
Same thing when booting to OSX partition
The boot selection screen is bright half the time and dark the other half.
I've tried resetting the PRAM, SMC, and even replaced the inverter board. After replacing the inverter board last week I was still having the same issues. Now today after trying some troubleshooting on the iMac I heard some odd electrical noises. After opening the iMac again to inspect the hardware, I see one of the inverter cables leading to the LCD has melted/burned. It was fresh because it was still warm and smoking. Any indication what could have caused this, and more importantly, the root cause of the backlight not functioning?
Here's a (poor) picture of the cable:
Depending on the iMacs mood it could either:
Be dark during windows xp boot screen but then light up upon arriving at login screen
Be bright during windows xp boot screen but then go dark upon arriving at login screen
Be dark the whole time
Be bright the whole time
Same thing when booting to OSX partition
The boot selection screen is bright half the time and dark the other half.
I've tried resetting the PRAM, SMC, and even replaced the inverter board. After replacing the inverter board last week I was still having the same issues. Now today after trying some troubleshooting on the iMac I heard some odd electrical noises. After opening the iMac again to inspect the hardware, I see one of the inverter cables leading to the LCD has melted/burned. It was fresh because it was still warm and smoking. Any indication what could have caused this, and more importantly, the root cause of the backlight not functioning?
Here's a (poor) picture of the cable:
