Ipkblsr 35w | Schematic

If you have a genuine IPKBLSR 35W board with no documentation, reverse-engineer it using these steps:

Optocoupler (PC817) Transistor Side (Primary) <------ Optocoupler LED (Secondary)
        |                                                              |
    [VCC of PWM IC]                                             [TL431 Cathode]
        |                                                              |
    [FB Pin of IC] <-- Pull-up resistor                         [Anode to GND]

Before diving into the schematic, understand the five stages of this 35W supply: ipkblsr 35w schematic