Inspect the top side of the PCB near the main transformer. Look for burned or blackened components. Testing the standby IC and the 1Ω or 2.2Ω fusible resistor often reveals an open circuit. Replacing the TNY279PN and the feed resistor will typically restore the +5VSB. Symptom 2: Missing or Fluctuating Main Outputs
The PS-4241-9HA is built around a IC, manufactured by Silicon Touch Technology Inc. (SITI). This IC is a 3-channel secondary monitoring and protection controller responsible for: ps42419ha schematic top
It boasts a 90.51% efficiency at 50% load, making it remarkably power-efficient for its age (originally released circa 2009). Common Faults: Inspect the top side of the PCB near the main transformer