Greetings to everyone,
who may have been waiting (indefinitely), for the right answer to come around the corner;
It was finally confirmed, first - by a skilled repair technician, followed shortly by Delta Tech Support - the fan pinout on Delta DPS-1050DB A PCB is reversed ! It's just as I suspected - the wiring colour scheme of AD0812VB-A7BGP fans in Z800 PSU follows the oddball pinout of fan headers.
Image may be NSFW.
Clik here to view.
NOTE: The drawing detail of the fan connector, to the left of descriptio of the signals, shows this connector from the bottom-up perspective, not a top-down !!
To wrap up: The wires of replacement fans (AVC DL0825R12U-PS14 - standard PWM pinout) just needed to be rearranged - pins pulled out then reinserted into fan connector in a reversed order.
I hope this will save somebody a great deal of time and frustration ...
Kind regards, Sebastian
