Imac Won T Boot With Built In Display Connected Imac Intel 21 5 Emc 2308

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It had a damaged 30-pin display connector (torn off by previous owner) on the logic board & also some minor damage to the 30 pin ribbon cable. I bought a replacement connector and ribbon cable from eBay, just to be sure it would connect properly. Numbers listed on eBay for the ribbon cable: Part Number: 593-1006 922-9132 MPN: Y593-1006 922-9132 I reassembled the machine, but it would not boot at all. No startup sound, no beeps, nothing. However it does boot with the display disconnected. I have ordered an adapter, Mini DisplayPort (Thunderbolt) to VGA/HDMI/DVI, to see if will run with an external display, as a workaround. But I would much rather fix it properly, so it runs with the built in display. Can anyone shed some light on this? Update (02/07/2018) @danj, Only 1 LED’s is on with all 4 monitor cables which I think is LED #1 as it is a little hard to see through the vent.All 4 LED’s are on with LVDS cable disconnected.All 4 LED’s are on with LVDS disconnected & backlight power cable connected. All 4 LED’s are on with LVDS disconnected, backlight power cable connected & the vertical sync ribbon cable connected. I am also getting a very dull grey illuminated screen/monitor & 3 minutes 10 seconds later screen/monitor goes dark i.e. from the dull grey. Update (02/10/2018) Schematic mentioned below:

@ifixanythink - Barry, Thats pointing to a short somewhere. Did you get the external display adapter (mDP to VGA/HDMI/DVI) you ordered? I think you’ll need to wait until you get it so you can see if the external display works. If it does with the internal disconnected we know the issue is localized within the internal display logic.

hi, i tried to remove the broken connector from my 2010 iMac 27" and while removing the excessive solder using the solder wick, i realized that pin 23 to 26 are connected and pin 27 to 30 are connected. can you let me know if they are actually connected in the circuits? based on your schematic above, 23 & 30 are NC, the rest 24 to 29 are LED returns 1 to 6. Does this mean they can be connected together?