Chosen Solution
Hello After changing the disk on the SSD, a gray vertical bar appeared on my screen.After the next opening I had a few colored vertical stripes on the screen.I opened it again and I drank the tape on the power and plugged in. Now the screen is black. Make it start (dong ) there is a fan but no image. On the main board only 3 LEDs are light but the last 4 Led is off. Where do you look for a problem? Update (09/03/2018)
@suprnowa start with this LED 1 + LED 2 + LED 3 + LED 4 = Power is available, the system is turned on, the logic board is communicating with the GPU, and the internal LCD was found. If the fourth LED is not visible after the system is turned on: Verify the internal DisplayPort cable (eDP) connections between the LCD panel and the logic board. Inspect the LCD display cables for cable damage. Verify external video functionality and proceed according to the result: If an external display works, verify/replace the LCD panel. If an external display does not work, verify/replace the logic board
So i have one question. If there is an image on the external monitor, the system works very slowly. The LCD Panel could have broken down so that it is black and does not illuminate and display nothing? Did something else on the motherboard get worse from the power / control LCD Panel?
OK. A1418 2017 Lcd not powering or detected. External monitor works fine albeit slowly. You would think….its iMac the screen…right?! Well the screen works perfectly on another identical iMac. So screen ok, gpu ok…. but signal or power from imac to its own scrern., not working. Could it be a power to screen problem? Logicboard
