I have a 2009 iMac, 27" screen, 80GB. Other specs cannot be looked up because the monitor is black. The light has been flickering and dimming for a few weeks and last night, it finally died. The computer is fine, near as I can tell, but unusable. Is the light source replaceable, or am I doomed to buy a whole new 'puter?
Not a Mac person at all but I was able to determine that your 2009 iMac has a miniDisplayPort. You can get an adapter (Apple, Amazon, Walmart, etc) to connect to an external monitor and use that.
Um, “monitor light on my iMac is out” does mean that your monitor screen is completely black, right?
If you look very hard, or shine a light onto the display, can you see what is supposed to be there? That is, is the display working, but the backlight off?
There are a number of possible failures if the backlight is off. Your Mac has a LED backlight. The power supply for it could have died, the ambient light sensor could be faulty, or there could be a simple cable failure. If you can get to the controls (ie plug in another display - you can get display port to HDMI and VGA adaptors so nearly any monitor you have can be used) you could try disabling the ambient light sensor in the control panel. That might force the backlight on. Resetting the SMC, whilst a long shot is a good idea too - it is possible it has gone nuts and is the cause of the issue.
Otherwise you probably will need to replace some part of the backlight system. Depends how handy you are. These iMacs are not hard to work on, and parts are available.
Screen flickering and eventual going dark seems to be a common problem with that model. If you can find a replacement display (The LCD and backlight are one unit) it’s an easy fix. Pull the front glass off with suction cups, guitar picks or strong fingernails, and the display is right there with a handful of screws holding it in. As usual, iFixithas great step-by-step instructions.
There might be a chance your problem is just a bad connection. This page has some notes on where you might try applying some pressure and/or connectors that tend to have issues.
Another thread at the Apple support forum makes it sound like the LED driver power board is the culprit. Again, the difficulty is in diagnosing to be sure it is the actual problem, and in finding a replacement.
Before trying to pull the thing apart, try an SMC reset. The SMC handles most of the basic hardware stuff like battery charging, power/sleep button behaviors, light sensors, etc. It’s free and simple:
Mac desktops (Mac Pro, iMac, Mac mini):
1.Shut down your Mac.
2.Unplug your Mac’s power cord.
3.Press and hold the Mac’s power button for 15 seconds.
4.Release the power button.
5.Reconnect your Mac’s power cord.
6.Wait five seconds.
7.Start your Mac by pressing the power button.
No promises this will help, but if it works, you just saved a few hundred bucks for 30 seconds’ effort.
As suggested above, using an external display might end up being the easiest and probably cheaper “fix” for a nearly five year old computer.
Thanks, gotti, but that didn’t help