help - troubleshooting a computer

[dodecahedron]

i'm trying to trouble-shoot my sister's computer, and would appreciate some help.

when powered up, the computer does not make any sound (beep) at all, and does not output any video to the monitor (not even the BIOS stuff).

the monitor appears to be OK, it displays the "no input signal" message and puts itself into standby mode.

the power supply appears to be OK, the LED on the case turns on, the case fan drawing air in at the fron is working, the fan on the cooling mechnism of the Pentium II slot is spinning. also the CDROM drive is powered and the tray opens and closes.

my suspicions:
1. the videocard is dead
(but on second thought, if that were the case then i should still hear the Beeps the mobo makes upon boot, no?)

2. the motherboard is (partially) dead. although it's at least partially working, since it's supplying power to the the cpu-slot cooler fan, to the CDROM drive, the LED.

3. CPU dead?
(haven't thougt about this option till just now - duh now it seems to me the most obvious possibility...)

i tried pulling the vid card out of its socket, wiping clean the contacts and re-installing, no help.

OK what do you guys think?
any suggestions as to what i should check next?
i can try to replace the videocard with another one (from my computer), but other than that i don't know what else i can try to diagnose the problem. (could that fry my vidcard???)
any tips?

thaks in advance.

[UALOneKPlus]

I had nearly the same problem:

http://www.cdrlabs.com/phpBB/viewtopic.php?t=12798

[Dartman]

I've had that happen 3 times here. One time the motherboard had a cable for the USB2.0 ports in the wrong spot one time the mother board just died for whatever reason, the last time it was a faulty voltage rail on my power supply. I think 5 volt was dead so the board wasn't hurt but couldn't boot either. I replaced the supply and everything worked OK again. Later I took the Antec 303 smart power apart and found a bunch of cracked/cold solder joints on the output side. I reflowed them all and it has replaced the other one and is still working well again. By the way all my fans and hard drives were still spinning up like everything was OK so that is a good possibility for yours as well. The other one I'm sure the board died as I could remove everything and never a beep and I tried a known good PS on it.

[CDRecorder]

It could be the RAM, too. BTW, did this problem just appear one day, or did something happen to the computer before this problem occurred?

[Han]

Check the capacitors around CPU slot. Some of them could be bad...

[dodecahedron]

Check the capacitors around CPU slot. Some of them could be bad...

how do i check them?
what should i look for?

and if some are bad, is there anything i can do to fix it (short fo replacing the mobo?)

[Han]

You can check them with a measuring device, but usually burst or leaked capacitors are the bad ones. Here are some shots of replacing burst capacitors with new ones on ABIT VA6 Slot1 motherboard, and here is a text about leaking capacitors mucking up motherboards...

Just about a month ago I had to replace three burst capacitors on a friend's ABIT BF6 mobo. The symptoms were exactly the same as yours are.

[CDRecorder]

and if some are bad, is there anything i can do to fix it (short fo replacing the mobo?)

If you're good at soldering or if you know someone else who is, you could replace the capacitors yourself. I have a friend who replaced the capacitors on several of his own boards, and the boards are running fine now, as far as I know.

[dodecahedron]

thanks for the info and pics.
this mobo is at least 4 years old (don't remember exactly) so that bad capacitor fiasko in your link Han is'nt relevant.
but when i'll get a chance i'll look at the capacitors on the mobo and see if any are bad.

i'm not experienced at soldering so i won't be fixing it myself (if that is indeed the case).