No POST, No BOOT Power Supply?

[seasection]

I've got a 500mhz AMD Duron tower that my friend's uncle put together for
him, all from parts that were "laying around".

I had installed a modem for him about a month ago. During the last couple
of weeks, he hasn't really used the computer much, but it has had problems
booting. Right now, there is no POST or Hard Drive grinding on boot. You
get the poweron green light, and that's it. No beeps. No monitor flicker.
Nothing. I opened the beast up, and reseated everything, memory, CPU/heatsink,
all cables. Nothing. I pulled out all PCI/ISA cards, except the video card.
Nothing. I reseated the CMOS battery. Nothing. Won't boot from a boot
floppy, or CDROM. The CPU Fan, Power Supply Fan, and Case Fan all are
working normally. The computer will not power off by use of the power button,
and will not reset with the reset button. I've disconnected the CDROM, HardDrive,
Floppy. Nothing.

My conclusion is that it must be a problem with one, or more, of the following three
components: Power Supply, CPU, or Motherboard.

The last thing I noticed before giving up is that the Power Supply was set to 230,
instead of the normal 115, I switched this too, but this too had no effect. I have
a feeling that the 230 has fried the motherboard.

Should I try and replace the power supply first? I have a feeling that it's probably
a bad Power Supply and a resulting fried Motherboard, which I will need to replace.
I don't have much experience with troubleshooting a power supply. I always assumed
that a bad power supply wouldn't power up at all.

Any suggestions?

Thanks,
Scott

[pzs22]

Hey, the same EXACT thing happened to me with my dads old computer. Turned it on, got the green power light, but nothing happened. I changed the mother board, and it worked perfect. To this day it still has the same powersupply, so I don't know if you need to change it. You might just want to if you have an extra just to be safe.

[seasection]

pzs22- thanks for your input.

I replaced the power supply on my lunch break from work,
and it works perfectly now. Whew....

I actually was kinda looking forward to putting an AthlonXP
combo in to see what all the hype is about. Hell, I still might.
For under $200, it'd be 3 times as quick.

Here again, I've learned something new.

Thanks,
Scott

[seasection]

Welp, I had the power supply working beautifully. I was still having
trouble installing a PCI DSI 56K modem. It says it's plug and play.
Windows kept wanting to assign it to COM5. I kept making registry
hacks to make it on COM4, then to COM3, and even COM2. None
of these worked. I used HyperTerminal to run an offline modem test.
It kept saying that it couldn't find any of the ports. I pulled the DSI
modem out and plugged it into another PCI slot. NO POST!!! I tried
another open PCI slot. NO POST!!! I tried removing the modem
card from the system. NO POST!!! I put the modem back into the
original PCI slot, and it would finally POST. I got sick of the DSI modem.
I pulled a Diamond Modem out of another computer and put it into
the working PCI slot. Drivers loaded on first boot. Device Manager
looked sweet. I went to run an offline test from HyperTerminal.
BLUE SCREEN!!!!!!!!! Rebooted. Started in safe mode. Reinstalled
drivers. Rebooted. Locked up when booting into Windows. Repeated
with the same results. I decided to run a fresh copy of Windows98SE.
Changed BIOS to boot from Floppy. FDISK, FORMAT. BIOS set
to boot from CDROM. CDROM churned and churned on my stupid
WINDOWS98 disk. I will now pull a CDROM out of another computer,
and try to install this way.

FedUP,
Scott