I've had this monitor since 2008, and I've used it daily until about a year ago, when the Mac Pro it was connected to pooped out. I just got the Apple Dual-DVI to Mini DisplayPort adapter, and have hooked the screen up to my 2015 iMac. The monitor does not power on. I can't get the light to turn on at all. The monitor is not recognized by the iMac, it lists the Thunderbolt port as empty. My suspicion is that the 150W power adapter has failed. I remember in the past that when plugged in, it got pretty warm, and this one is now room temperature. Are there any other diagnostic maneuvers I can try? A new power adapter is a little less than $200 online, I'd buy one if I had confidence the monitor would work after. Or is it not worth fixing with the thought that something else in this monitor will break soon anyways? I do not have an Apple store where I live. There is an authorized seller, with repair capabilities, but I have not really been impressed by their service. I expect it would cost me at least $150 for them to look at it.