Please Help! I THINK I have a bad power supply (a bestec atx-300-12eb3 rev s2 from a Sony Vaio VGC-RB30). Power will no longer come on at all, however I do have a blinking green light on the back of the power supply. I have taken it apart and do see some evidence of high temperature near some plastic capacitor shielding, but who knows. I guess my 1st question before buying a new power supply or tearing down the PC further, is does anyone know if this model has a fuse or a reset switch? Cannot find any diagrams, etc. I do know a lot of people seem to have had similar issues, but in my experience, if a PSU is totally fried, it would be hard to flash that green light... then again I suppose that is what it is there for! Any help or suggestions would be highly appreciated. Thank you! WhiteHatH4x0r

Ok first you disconnect the power supply from motherboard then measure the output voltage if it is ok then there is two wires green and black at o/p of power supply short green and black and see fan is rotating or not if rotating then power supply is ok if not then open the power supply check ac voltage in the pcb if present then check dc voltage after bridge rectifier and ckeck part by part

First, If you know how to use a meter proceed. If not use caution when checking around the input as most run 400VDC Bulk at the large Cap and switchers. Check the output area on board for a -12V label. Trace it back to either an LM7912 (TO220 or TO92) they are usually in_Gnd_out. Trace from In side to the rectifier. Check for short I find a lot of these are shorted. If it checks OK then ohm out the rest of the output Rectifiers to see if any are shorted. If they check Ok come back on line and we will move on to next area.