Before disassembling, you can verify if the schematic's main rails are functioning using a basic multimeter:

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.

Always use a discharge tool (like a high-wattage resistor) on the primary capacitor before touching the board.

Professional technicians often use a DIY Test Box with a series lamp (60W/200W) to prevent catastrophic shorts during testing.