Dear all,
Recently, got a used 2011 27" iMac LCD from one of my colleagues as the one I have is broken. When I connect that LCD to my iMac, it lites up (backlight) for less than a sec on iMac startup and then goes and stays dark. The image is there and can be seen using the torch light. When system is up, putting the LCD to sleep and then waking it up gives the same short blink of the backlight.
I know this symptom usually means the faulty LED driver board, but this case may be a bit more complicated.
When I put the original broken LCD, the backlight works perfectly well. Also I have the spare LED driver board, which gives the same results. However I noticed, that the original LCD has the vsync wire at the top and the secondary one I does not. This probably means the latter is supposed to work with LED driver board V2, which had 8pin vsync wire connected to logic board, not the LCD. Unfortunately I do not have such version of this driver board.
I have also noticed, that when connecting external monitor, or when connecting remotely to that iMac, there is no backlight control slider and also F1/F2 do not work (although I'm not sure if it is not disabled when second monitor is connected or when I'm the remote session)
Hence my question - does any of you know if the V2 boards were capable of either higher voltage or current/power? I'm wondering if the backlight goes off due to too high current draw done by that other LCD, because it is supposed to work with the V2 driver board or maybe because there is a faulty LED/short in it?
In other words - are all 2011 iMac 27 LED driver boards and LCD interchangeable (except the vsync), or are some LCDs working only with the V2 driver boards?
Thanks in advance.
Recently, got a used 2011 27" iMac LCD from one of my colleagues as the one I have is broken. When I connect that LCD to my iMac, it lites up (backlight) for less than a sec on iMac startup and then goes and stays dark. The image is there and can be seen using the torch light. When system is up, putting the LCD to sleep and then waking it up gives the same short blink of the backlight.
I know this symptom usually means the faulty LED driver board, but this case may be a bit more complicated.
When I put the original broken LCD, the backlight works perfectly well. Also I have the spare LED driver board, which gives the same results. However I noticed, that the original LCD has the vsync wire at the top and the secondary one I does not. This probably means the latter is supposed to work with LED driver board V2, which had 8pin vsync wire connected to logic board, not the LCD. Unfortunately I do not have such version of this driver board.
I have also noticed, that when connecting external monitor, or when connecting remotely to that iMac, there is no backlight control slider and also F1/F2 do not work (although I'm not sure if it is not disabled when second monitor is connected or when I'm the remote session)
Hence my question - does any of you know if the V2 boards were capable of either higher voltage or current/power? I'm wondering if the backlight goes off due to too high current draw done by that other LCD, because it is supposed to work with the V2 driver board or maybe because there is a faulty LED/short in it?
In other words - are all 2011 iMac 27 LED driver boards and LCD interchangeable (except the vsync), or are some LCDs working only with the V2 driver boards?
Thanks in advance.
