imac intel 17 black screen

[kodavis]

machine powers up, light steady, can hear sounds (volume buttons), no picture. Reset SMC and now light strobes. 3rd diagnostic LED does not illuminate, and no video on separate monitor (RCA analog connection through vid port adapter). Do I source a logic board or are there still other possibilities?

 

[_Tony]

Did you try reseating the LVDS cable? See step 9 in this guide if you need instructions. Other than that, it would appear the logic board needs replacement.