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Model A1312 / Mid 2010 / 3.2 GHz Core i3 or 2.8 & 3.6 GHz Core i5 or 2.93 GHz Core i7, ID iMac11,3

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LVDS Connector replacement; still no display

I am attempting to repair the logic board from my mid-2010 iMac (820-2901). The LVDS connector was damaged and two pads were lifted (pins 1 and 2).

I have replaced the connector:

Block Image

Pin 1 is a ground pin, so should not be required to make it work and while I have bridged pin 2 to the corresponding via, but according the the board schematics, this is only connected to an unpopulated resistor position (R9050) so should also be non-essential.

Unfortunately the display still fails to function (external display works fine and have tried two different GPU boards) and only 3 of the diagnostic LEDs are lit. I have tested all ground pins on the connector and all pins that have nearby uncoated vias (pins that go straight through the board are much more difficult to test; is there any advice as to how to do this?), as well as checking pin-to-pad continuity for all pins and confirming no pins are shorted to their neighbors (except for pins 23-26 and 26-30 which are groups of ground and power pins respectively). I have also tested all connections on the LVDS cable.

I’m really at a bit of a loss as to what else to check. I’ve even already purchased a replacement board, but annoyingly it was damaged in shipping and is being returned.

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Bu iyi bir soru mu?

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Did you check for shorts of neighboring pins?

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might want to try and clean up pins 23 - 24 they look like they might be shorting?

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So, lacking any other ideas, I went and replaced the LVDS cable despite having previously “bleeped out” all the connectors on it. This actually worked!

My current theories are that the old cable either had an internal short or intermittent connection or, since the new LVDS cable has a slightly different connector design with narrower contacts, maybe a short was occurring in the connection…

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