Imac 27" mid 2011 black screen internal and external video. Main 820-2828-A

Good morning. This imac has the following problem.
By giving the power on, it turns on, emits the dong and the screen turns on the matrix and I believe the backlight but remains black. Removing lcd and connecting externally with adapt on hdmi lcd the screen is always black. I thought about a problem of the bga Video (216-0810001) I replaced it but same defect.
I also tried the ram singly but same defect. I only noticed one detail. The imac has two external video outputs. By connecting the adapter in the one on the right (near the ethernet port) my monitor gives me the message no video signal, if instead I connect the adapter in the port on the left, in my monitor it will it turns on the blue led as if the signal arrived but I always have a black screen.

robgerr napisał(a):I thought about a problem of the bga Video (216-0810001)

Please double check it - should be 216-0811000.

robgerr napisał(a):Removing lcd and connecting externally with adapt on hdmi lcd the screen is always black.

This is completely normal and fine.

robgerr napisał(a):and the screen turns on the matrix and I believe the backlight but remains black.

Please double check if your screen turns on the backlight as those 2011 screens often struggle with backlight LED strips connectors failure (there are 2 connectors - left and right). If it's the backlight problem, you should see some picture (logo etc) when illuminating the screen directly with a strong flashlight.

Hi Vogelek. I try reprogram spi firmware and iMac work perfect. Thank's