Busted component hi, i have a psu with model LC-B500E and pcb model Y-500ATX ver:A-1. a componet was burned and i wanted to replace it. ca u help me find a schematic diagram so that i can know the value of the component so i could replace it. i think it was mark as L9 n the PCB. thanks a lot.

Getting a schematic is rather doubtful. You might be able to get a general idea of the circuit from somewhere on the 'net.

Was the power supply dead?

ATX style power supplies have both a standby and main section. The standby supplies a low current +5 volts to a small portion of the motherboard.

If the component failure is in this section, this standby voltage will be missing or incorrect, and the computer will be dead- won't power on at all.

I've seen a number of catastrophic failures in this standby circuit, and repair isn't suggested or economically feasible, especially as some parts often poof beyond identification.

When the pwr button is pushed, the main section comes on, and supplies +5 (Red wires), +12 (Yellow wires), +3.3 (Orange wires), -5, -12. Look here for this info http://pinouts.ru/Power/atx_v2_pinout.shtml

Voltages are precisely regulated, and any substantial deviation (more than a few 10ths of a volt) indicate a problem, especially on the +5 & +3.3 lines.