Power supply fried, replaced it, computer won't start

Yesterday morning, ten hours after I'd last powered my PC down, I turned
it on and noticed immediately a burning "electrical fire" smell.

Turned the computer off (using Windows shutdown first from the login
screen), disconnected all peripherals and the power, opened the case.
Attached the power cord only, started it, everything worked (hard drives
were cycling, CPU fan going, motherboard lights on, etc.), but I noticed
the smell again. I did some sniffing and it was definitely coming from
the power supply. Then the computer just stopped.

I am not a "hardware guy" but I did some research on the web, consulted
with the friend who helped me build the computer, and it seemed pretty
open and shut. The 350 watt supply that came with the case ($35 for
case and supply) was to blame.

So went to FactoryDirect today and picked up
http://www.factorydirect.ca/catalog/product_spec.php?pcode=PO0450
seemed to be a worthy "bang for the buck" 350-watt supply.

http://www.hardwaresecrets.com/article/362/ is the instructions I
followed.

Before disconnecting the old PSU, I carefully labelled every connection,
showing what it was connected to, and the orientation on the drive or
board. (The PSU had a 20-pin connection to the motherboard, the ATX12V
comnnector, and my computer has two hard drives, a DVD drive, and a 3.5"
floppy.)

Plugged the computer in, turned on the PSU, and nothing. Ultimately, I
tried a known good power cord and the new cord that came with the PSU, a
known working outlet, several permutations, nothing. The voltage
selector is correct (115 volts) on the back of the PSU. The green light on the
motherboard stays lit. But no drive lights come on, and no sign of any
activity. (not even fans)

The motherboard seems to show no abuse; the capacitors
all look shiny and intact.

Any help is appreciated, thanks.

 

if you have a volt meter you can test the output to make sure power is good yellow and black 12v I believe. Also make sure that the wires to the switch are still connected from the front panel to motherboard. Hope that helps

 

It is unfortunate, but occasionally when a PS fries like yours did, they take out the motherboard too by sending bad voltage/amperage down the line into the board. You could try removing all devices: any and all PCI cards (modem, NIC, etc), video card, disconnect all IDE drives, disconnect the floppy drive. Unplug the power cords to all the drives too. Try to power up the PC with everything removed/disconnected. If it powers up, then it's just a process of elimination to find the faulty device. I've seen bad floppy drives prevent PC's from starting up, so it could be anything, hopefully it's not the motherboard. Try to power it up with the memory sticks removed. If it does power up, it should beep all crazy because there's no RAM installed. You could also try popping a new CMOS battery in..... good luck! Be sure to post your progress.

hd2k

BTW- be sure to leave the main power cord from the PC to wall unplugged whilst in the case, removing and disconnecting cards and such. Many motherboards will stay 'hot' if plugged in, even with the power shut off... so be careful!