A small resistor often acts as a fuse for the standby IC. If the IC shorts, this resistor usually burns out as well.
For specific disassembly layouts, refer to HP's Maintenance and Service Guides .
Short the green wire (PS_ON) to any black wire (Ground). ps42419ha schematic work
Before disassembling, you can verify if the schematic's main rails are functioning using a basic multimeter:
Once the motherboard sends the "PS_ON" signal (by shorting the green wire to ground), the main PWM (Pulse Width Modulation) controller starts the high-power DC-to-DC conversion. Critical Components and Common Failure Points A small resistor often acts as a fuse for the standby IC
Incoming AC passes through a fuse and an EMI filter to remove noise. A bridge rectifier then converts it to high-voltage DC (around 145V–160V depending on load and region).
If the schematic is working, you should see a stable 12.2V to 12.3V on the yellow wires. Safety and Repair Precautions Short the green wire (PS_ON) to any black wire (Ground)
Large electrolytic capacitors on the high-voltage side can fail or exhibit high ESR (Equivalent Series Resistance), leading to fluctuating output or startup failure.
Measure the voltage on the purple and green wires. You should see roughly 12V (standby) on the purple wire and a low logic voltage (approx. 4.4V) on the green wire.