Chosen Solution

A friend of mine replaced the digitizer in his HTC Evo 3D, but when he powered it on the LCD wasn’t working (as seen in picture) but the phone seems responsive with sound Ect. So i doubled checked all the ribbon cables and they were fine, so i’m assuming it may have something to do with the LCD. Has anyone else had this issue or knows how to fix it?

Yes this tends to be an issue after removing any LCD and reinserting it in small devices such as an iPod or phone. 99/100 times this is fixed by turning the device on and off as the LCD isn’t actually damaged it just needs resetting. If this does not work then try it again just to be safe. If you still get nothing then remove the battery and reinsert it. If still nothing then the LCD or the Logic Board has been damaged during the repair, with any luck the LCD is to blame. Post back with the results and I’ll give you another suggestion but chances are the reset will work :)

the problem with these type devices is the multiprong connections where they mate to the ribbon cable end headers. The contact patches are around 10-12 for supply line connections and 30-80 or more on the logic signal headers. as the overal width of the headers on these multi conductor ribbon cables are less than 2 cm mostly, this makes the contact patches on the headers and their corresponding pin sockets freekin tiny….with the pins very close together. All it takes is a bent pin or a smudge of foreign material -conductive or non conductive to foul up the works. Non conductive foreign debris creates an open circuit, and conductive foreign debris (biological finger oils and whatnot) creates short circuits and logic errors as they cause stray logic signals to trigger gates and switches fouling up the logical works. Assuming you dont have debris contamination, and pins and headers and ribbons are all ok, its the correct path of troubleshooting to inspect very closely (good magnifier, microscopes etc) with LOTS OF LIGHT to see if circuitboard traces and solder joints have been opened (broken) or if smc components (surface mounted) have been broken or dislodged. its a literal nightmare at this scale which is the driving force in modern repair and diagnosis of these devices being relegated to an art of “swap-tronics” instead of traditional “electronics” repair. These days you “swap"assemblies and sub-assemblies carefully to diagnose or repair…not having these spares and stocks simply means you aint gonna fix it… :0) may the force be with you -padiwan…

I have the same issue and this just adds to the list of reasons why I hate repairing the HTC Evo 3D.

I do have a HTC EVO 3D, was a excelent phone until the screen went black, I change the LCD and the front screen, but still have the screen black,