Notes for A4000D Skynet power supply
The available schematic has no component values or part numbers


Original switchmode controller IC1 is Unitrode SK8085
Replacement is UCC28085 (DIP8 package) available from Mouser

Q1 is Toshiba SK2038 high voltage MOSFET

R1 is 0.27 Ohm 1/2W current sense resistor, will fail open circuit if Q1 fails short circuit

R6 is 0 Ohm wire link

Optocoupler IC3 is Sharp PC111, suitable replacement is NEC PS2652

Output voltage is set by ratio of fixed value resistors R12//R14 and R13//R15
R12 = 5.6k
R13 = 3.9k
R14 is not normally fitted or 220k
R15 = 220k
Increasing the R12//R14 total resistance increases the 5V output voltage
Increasing the R13//R15 total resistance decreases the 5V output voltage