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...
Был ли этот ответ полезен?