I suspected the integrated TNY278 that I tried to replace with a new one but after replacing the component the defect persists.
The voltage on the green wire at the source output does not exist.
The voltage over the electrolytic capacitor of primary after the rectifying bridge is around 175V (B+) or so.
I tried to find the schematic diagram but couldn't
175V suggests the unit gets power from house voltage.
Is your question about a conventional computer power supply?
Do you have a duplicate supply so as to compare voltage readings, component values, etc.? Is it low-cost? Is your time worth more than the effort to fix it?