iMac black screen A1418

[Tenz]

Hi there, I have an iMac A1418. When trying to boot I get the apple chime a black screen followed by a loud fan. I have tried the following replaced lcd screen, lcd cable, and pram battery. 3 of the bottom 4 leds on the motherboard come on, but not the top led.

I’m at a loss on what to try next. Anyone have any ideas?

Thanks in advance.

 

[Junkieneedsafix]

I have the exact same problem. Have you found a solution ? Anybody have any tips ?

 

[herrdude]

I bought a used 2014 A1418 with the same problem. Apple told the previous owner that the motherboard was shot. It took me a month to get together with the owner at the Apple Store to remove the firmware password *what a pain*. After that, I installed a SSD drive and hooked it up to another display. It worked fine. So then, I pulled the cables on the back of the LCD out and reconnected them. I think I even flipped around the backlight cable (on my model it was a Y cable). I was blown away. I got this iMac for nothing.

Good luck!

 

[Jumme_Cph]

I have the exact same problem. Have you found a solution ? Anybody have any tips ?

When you turn on the mac, do you have 3 out of 4 leds like OP??

that means that imac is started up, Found a grapics card, but is not correctly communicating with the GPU.

usually that might mean a defective graphics cable, defective graphics card or defective LCD, plesse follow THIS GUIDE.