Original post by Chris,
Blank LCD, external works - LCD,LVDS cable & video card are good
My iMac powers on and boots up but there is no image on the screen. Not even a faint image is visible, it's completely black. An external display does work. I also get a video signal when logging in via Remote Desktop. That all suggests the video card is good. I've also ruled out a bad display cable (LVDS cable) and a bad LCD panel. That leaves the inverter and logic board.
Does the inverter have any influence on whether or not the LCD panel is recognized? In other words could a bad inverter keep the logic board from supplying power to the LCD panel? My testing shows that there is no power being supplied to the LCD panel on pins 28,29,30 of the LVDS connector. (see LCD panel specs here for details on pinout http://www.50amp.com/imac/LM201WE3-TLF1.pdf). Also diagnostic LED #4 is off (no comm between logic board and LCD)
Everything I've read about a bad inverter suggests that an image should still be visible, it just won't be backlit. Is that always the case with a bad inverter or is it possible the inverter is keeping the LCD from being powered on?
iMac Intel 20" EMC 2133 and 2210