Troubleshooting a computer that will not boot.

[lagdawg]

I have a friends computer which I was orignally going to install Linux onto. However, before I was able to install Linux it has acquired a fatal error. It will not boot up. When I turn on the power the screen turns on, then almost as fast turns off into standby mode (yellow light, instead of green). During this time the fans inside the computer run and the cd rom tray will open and close. However, there are no hd spinning noises or any beeps. I need to find out whats wrong with it so I can fix it. My first thought is the video card may be bad, but that doesn't explain the harddrive and such not running. (I do have an extra video card laying around I can test with, and I know the monitor is good.) I'm currently at work and the computer is at home, but I would like some advice on what I can do to find out what is wrong with the system. My first thought is to clear the CMOS when I get home and see if it works. If not should I try detaching everything from the motherboard and see if I can elicit a response in the form of beep codes? These are the only things I can think of to do, are there any other things I can do to get to the bottom of this? By the way this is an old compaq computer, I don't know what MB or Bios it has or even what CPU it has. Any ideas are appreciated.

[JohnT]

What you describe, if accurate, then its either a faulty PSU or MB.

[happybunny]

or memory?

I would strip it down to bare minimum...start with PS and mobo and cpu, then add memory, video, hd, etc, booting with each new item.

[Daedrus]

It also helps if you have an internal speaker plugged in. That way you will hear BIOS error codes if they exist. Bad video is usually one long beep and 2 - 3 short. Memory is constant beeping.

If you have a multimeter present, make sure that the correct voltages are going out to the hard drives, etc, 5V on red, 12V on yellow.

[lagdawg]

Thanks JohnT, I didn't even think about the PSU being faulty.


When I get home I will try to locate a spare PSU, I think I have one laying around somewhere. Is there some way to tell if it is the MB or the PSU with out a spare PSU (if I can't find one)?

[JohnT]

Originally posted by lagdawg
Thanks JohnT, I didn't even think about the PSU being faulty.


When I get home I will try to locate a spare PSU, I think I have one laying around somewhere. Is there some way to tell if it is the MB or the PSU with out a spare PSU (if I can't find one)? Check your voltages as suggested above.

[knute]

Originally posted by lagdawg
Thanks JohnT, I didn't even think about the PSU being faulty.


When I get home I will try to locate a spare PSU, I think I have one laying around somewhere. Is there some way to tell if it is the MB or the PSU with out a spare PSU (if I can't find one)?

Yeah. Pull the video card and turn it on. You should get some sort of beep code that means that it can't find the video card. If you get the beeps it's not the MB. If you don't get the beeps, it is the mb.

HTH

[Icarus]

I'm having a very simular problem with a system I jst put together also...power on, no beeps no post, nothing.

I know it's not the PSU on mine, it's brand new. Crazy thing is, I got a complete Gentoo install and when I rebooted, nothing.

I've been suggested to check the BIOS battery, at this point it's worth a shot as I don't have any other MBs to use.

[knute]

Reseat! Reseat, for the land of mb is fickle and finicky!

If you have more than one dimm, try them separatly. Also make sure that your mbd is set up to use the right kind of dimm. I had jumpers that I had to change depending upon whether I was using sdram or ddr.

[lagdawg]

I just opened the case. Checked the PSU first and got proper voltages +5v and +12v. While removing HD, Floppy, and CD-ROM cables a cover from a capacitor or something fell out. Looking at the motherboard it has a capaictor (not sure exactly, but I think that's what it is) which has no cover and looks like it may be burnt. Looks like I have to find a new MB. Anybody know where I can get a cheap Socket 7 MB for a K6 500 mhz processor?

Thanks for all the help.

[x]

Hmmmm... Well I have that mobo, with a 500Mhz CPU. Had planned on using it myself, but if you don't find anything get back to me. No promises, but maybe I could use one of my P166 instead.

As for the problem: well, your is solved but just FIY:
I get no picture on the monitor when I use a monitor with powersaving. Computer boots, I checked it by logging in blindly and issue 'halt'. But no picture.
Using 14" monitor w/o powersave=no problem.
Booting without picture, and then plugging in that 14"-monitor=no picture...

I think monitor goes into 'sleep' too fast, BIOS or videocard cuts the connection when no monitor is found.
I have no solution, just adding to the problems-list.

---------
Edit: this never happened with older computers, though, only with new ASUS N7S AMD 1,4GHz + GeForce440MX

[lagdawg]

Well, I found the exact board I am replacing for 30 + 15 s&h on Ebay. Is this a reasonable price? I still need to talk to the owner to see if he would rather upgrade or not, or just get rid of the computer and not fix it (I hope this option) as he has had a few problems with it and it is a secondary computer anyway.