Dell optiplex PSU problem

[gizaha]

Hello. I have problem with Dell psu, outputs are ok but it does not give power ok signal.
It has a secondady board with wt7527s to check inputs. It doesn't give PGO because it doesn't take enough PGI.
It takes PGI from a voltage divider.

I draw a schematic for you to understand.
My first question is why 5v use two transformer pins, while 12v uses only one.
My second question, is pin 2 in transformer weak? After resistor, diode and voltage divider, result is 0.7v instead of 1.2v, so wt7527s does not output PGO.

[temyth]

is the diode between the voltage divider and the transformer a zener?
did you checked his integrity?

[gizaha]

I checked it as a diode seems ok but
I'm not sure if its zener.
I have a second psu and i will swap diodes just to check that.

In case its not the problem, any other idea?

[gizaha]

I tested a working psu because i no longer have the faulty one.
The diode is defined as diode in board and not ZD.
However i got 7.8v reverse voltage when injecting 14v through a 10k resistor.
Next time i will have a faulty psu i will compare the values or swap the diode just in case