HP Pavilion a1000 doesnt post

[krismalicoat]

I've got another head scratcher I need a little assistance with. I have this HP pavilion a1000 in my shop. At first the computer wouldn't even turn on. I replaced the psu on it with one i know is good first and that made the fans come on but not the power led light. There was no video or beeps at this point. Next I tried to reset the bios. This computer has 2 jumpers? Is that normal? Anyway I moved both jumpers over to reset the bios and I also removed the cmos battery. Started the computer once, unplugged it to turn it off because the power button would not turn it off. Moved the jumpers back and replaced the cmos battery. Turned the machine back on and it had signs that it wanted to live. I got a memory error beep code which was one short beep followed by one long beep. I replaced the memory it had with memory i know is good and that took care of the beeps. Not only did that stop the beeping but now i have a power led and the cd drive is functional and I can turn off the computer by the power button. However, I still have no post or video at all. I thought the on board video may be bad. So i substituted a video card in that i know is good, but it did not change the video issue. I need a little help. What do I need to try next? Is is salvageable?
The motherboard looks clean, no flaws on it, a little dust here and there but i blew that off with canned air.
I would try a cpu swap but i dont have one to substitute. Is there another way to test the cpu?

 

[roy69]

The fact that you had to change the PSU tells me there may have been a major problem. If the memory is bad and he video may be bad, I would suggest that a power problem has fried the whole system. The only way around is to test every component. if you do not have a spare CPU do you have a spare mobo that the CPU will fit into?

 

[krismalicoat]

I do have a board it will fit into infact. I hadnt thought about this before because the board it will fit in is actually a working computer that has a cpu in it. I switched both the cpus. The cpu from the non-working board in my working computer did not power on, instead it just powered all the fans and drives but did not post, there was also no power led and i could not open the cd drive. However the working cpu in the board in question did not make the video come on either. The board in question had no change in behavior.
This is interesting though, while both these processors are amd, same socket and also both 64bit, when I put the good processor back in my working pc, it displayed the same behavior it had just a moment ago with the substituted cpu. I had to take the memory out except for 1 stick and reset the bios by the jumper to make it post and boot again.
The questioned board showed no different behavior when i reinstalled the cpu it had originally.
Im looking over these capacitors very carefully but i cant see any bulging or leaking from any of them. I feel this is a malfunctioning component on the board. I dont know how to test the capacitors though to see which ones may be bad or how to test other components. I only have a digital multimeter that doesnt have the uf setting so I dont think i can test them unless i get a proper meter for it can i?

 

[roy69]

I had thought this may be the case. It sounds as if the whole system has been fried. Motherboards are not designed to be fixed. Your best bet it to replace every item that has been fried. I suspect that the faulty cpu that you installed into your working system may have corrupted the bios, hence needing a bios reset.

 

[krismalicoat]

Im afraid that I wouldnt be able to get my working pc working again lol. But if the cpu is bad, then in theory if I swap the cpus again and reset the jumper on the questioned board then perhaps it will work? Unless there are components on the board that are bad in which case they may fry my good cpu, and i definitely do not what that. I think it may be time to visit the recycling center and rummage around for spare parts.
I just wish the problem with this board were more obvious, I cant see any damage to any parts on the board, If i could see it it may be easier to repair. Its truly disappointing to see a board in almost in working condition be thrown away for a small malfunctioning component.

By the way, I do have one more question I was gonna post but Il just ask it in this thread.
I have another motherboard that Ive had for a while now, it shorts out immediately when you turn the power on.
This is a fail safe in the board to protect components. I found that if i unplug the cpu power the board will turn on but no post of course because the cpu isnt running. But whenever the cpu power is plugged in on the board it always shorts out. Ive already bench tested this with the same results. Also there is no damage to the board as far as i can see. There is however some dust that has been caked onto the board and some components that i cannot remove with air, i dont wanna put any solvents on it to try to remove it in fear of damaging the board further.
Is this salvageable? Is there a way i can follow the cpu circuit and replace the components that relate to it? Or something? I dont quite understand how to tell what components on the board help or are for the cpu, memory, etc. If im going to attempt a repair I need an idea of this but i cannot seem to find useful information online. Every page and video i see is some one talking about replacing the capacitors. But which ones? and what if its not a capacitor causing the issue? How do i tell?
Also where would i buy replacement capacitors?

 

[roy69]

As far as I know, motherboards are not designed to be repaired. This is beyond my tech knowledge. A lot of electrical items can fail and not show any signs that they have failed. The only thing you can look for is bent pins and signs of scorching.