Hi,
When I came home today my step-sister told me that my pc wouldn't start anymore. She had been browsing the web a bit and then had left it on. About 3 hours later she heard a small 'pop' noise and the pc shut itself down. All that time no one had touched the PC.
At first I thought it was a cap that had exploded inside the power supply, so I took it out and tested it. Well, it worked just fine, so I put it back in.
When I press the power button, I can see the power supply start spinning for about 0.5 seconds and then it just shuts down and nothing happens anymore. I can press the power button as much as I want to, just nothing happens. When I remove the power chord and then plug it back in, it starts all over again: 0.5 seconds fan on, then everything shuts down again.
Does anybody has any idea what could be causing this? The pc was working just fine, well, except for one blue screen saying something about an error in the registry, but that can't have anything to do with it, since the pc now can't even get to the POST sequence.
Help!
When I came home today my step-sister told me that my pc wouldn't start anymore. She had been browsing the web a bit and then had left it on. About 3 hours later she heard a small 'pop' noise and the pc shut itself down. All that time no one had touched the PC.
At first I thought it was a cap that had exploded inside the power supply, so I took it out and tested it. Well, it worked just fine, so I put it back in.
When I press the power button, I can see the power supply start spinning for about 0.5 seconds and then it just shuts down and nothing happens anymore. I can press the power button as much as I want to, just nothing happens. When I remove the power chord and then plug it back in, it starts all over again: 0.5 seconds fan on, then everything shuts down again.
Does anybody has any idea what could be causing this? The pc was working just fine, well, except for one blue screen saying something about an error in the registry, but that can't have anything to do with it, since the pc now can't even get to the POST sequence.
Help!
Check the power supply capacitors on the motherboard, frequently they are to blame. If you can test the psu with another motherboard that would be helpful. Some computer stores (such as the one where I work) will test your powersupply for free.
Many pc power supplies when presented no or very little load will exhibit the 1/2 second fan spinning up then nothing.
70% chance it is your power supply, 29% chance it is power supply related but on your motherboard, 1% chance it is something else.
Many pc power supplies when presented no or very little load will exhibit the 1/2 second fan spinning up then nothing.
70% chance it is your power supply, 29% chance it is power supply related but on your motherboard, 1% chance it is something else.
About that no load thing, when I tested the power supply by shorting the green wire to ground on the big mobo connector, there wasn't any load on the power supply right? Yet it kept running.Ignite said:
Then, when I put it in the pc it shuts down instantly. I'll check for cap failures on the mobo. Any idea how I should to that (except for seeing if they look burned)?
Just in case...
If one of the components have blown (not on the motherboard), test it with a minimum config, even rip out the graphics card and memory.
If the psu doesn't shut down and the motherboard starts to beep, hopefully the motherboard is fine, and one of the other components have blown.
Otherwise, it pretty much has to be either the psu, motherboard or processor.
/Andreas
If one of the components have blown (not on the motherboard), test it with a minimum config, even rip out the graphics card and memory.
If the psu doesn't shut down and the motherboard starts to beep, hopefully the motherboard is fine, and one of the other components have blown.
Otherwise, it pretty much has to be either the psu, motherboard or processor.
/Andreas
If you feel like it, try warming the motherboard with a hairdryer, then booting. One of my PCs (which usually stays switched on 24/7) absolutely refuses to hard boot at room temp (PSU pulses like yours), but will do so quite happily if warmed a little.
I suppose I should track down the fault really, but a little heat is so reliable that I can't really be bothered!!
I suppose I should track down the fault really, but a little heat is so reliable that I can't really be bothered!!
While we're waiting for David H@ck's PC to come to live, I would like to post my version of the problem ....
I have a Pentium II PC which is about 6 to 7 years old. Recently it has develop a problem of not being able to boot up on first try. I'll describe more in detail below.
1) When I first turn on the computer, it will shut off after a few seconds.
2) I then press the power button a couple time and then the computer will start booting up again.
3) After a few seconds, it'll shut off again.
4) I then repeat step #2.
5) Sometime, it will boot up after a couple tries.
6) Sometime, it will boot up in safe mode where I have to reboot again so that it's in full boot mode.
7) Once it's booted up, the computer will stay on and operational.
8) If the computer is left on overnight, it will not function anymore on the next day (I guess this is what you call "computer freezed") although the computer does stay on.
9) I have visually inspected the power supply - I don't see anything unusual.
10) I also don't hear any "high pitch" sound from the power supply for sign of bad capacitors.
I would like to stress that if the computer does boot up, it'll stay on and operational except for one case that I mention above.
What could be the problem? Thanks.
I have a Pentium II PC which is about 6 to 7 years old. Recently it has develop a problem of not being able to boot up on first try. I'll describe more in detail below.
1) When I first turn on the computer, it will shut off after a few seconds.
2) I then press the power button a couple time and then the computer will start booting up again.
3) After a few seconds, it'll shut off again.
4) I then repeat step #2.
5) Sometime, it will boot up after a couple tries.
6) Sometime, it will boot up in safe mode where I have to reboot again so that it's in full boot mode.
7) Once it's booted up, the computer will stay on and operational.
8) If the computer is left on overnight, it will not function anymore on the next day (I guess this is what you call "computer freezed") although the computer does stay on.
9) I have visually inspected the power supply - I don't see anything unusual.
10) I also don't hear any "high pitch" sound from the power supply for sign of bad capacitors.
I would like to stress that if the computer does boot up, it'll stay on and operational except for one case that I mention above.
What could be the problem? Thanks.
No, I did not have the computer overclocked.
CMOS battery? Isn't that the battery on the motherboard for remembering the date and time? How is it that this will affect the booting of the computer? This is a question - I really don't know.
PSU? If it is the power supply unit, why is that the computer WILL STAY ON & OPERATIONAL once it's booted up?
CMOS battery? Isn't that the battery on the motherboard for remembering the date and time? How is it that this will affect the booting of the computer? This is a question - I really don't know.
PSU? If it is the power supply unit, why is that the computer WILL STAY ON & OPERATIONAL once it's booted up?
Fcel:
This sounds like a tough nut to crack...
Try with a minimal config, just mobo, graphics card, one stick of memory (if there are more than one) and harddrive.
Maybe skip the harddrive and boot of a floppy or cd (with a known good floppy or cd drive).
Also reseat all connectors and cards, there could be a bad connection/oxide somewhere.
Polimorphs suggestions are good too.
If you know how, try to go into the bios and reset it to "safe defaults", maybe try to underclock the processor if that's possible.
If the minimal config works, put the other stuff in one by one, and see what part is causing the trouble.
/Andreas
This sounds like a tough nut to crack...
Try with a minimal config, just mobo, graphics card, one stick of memory (if there are more than one) and harddrive.
Maybe skip the harddrive and boot of a floppy or cd (with a known good floppy or cd drive).
Also reseat all connectors and cards, there could be a bad connection/oxide somewhere.
Polimorphs suggestions are good too.
If you know how, try to go into the bios and reset it to "safe defaults", maybe try to underclock the processor if that's possible.
If the minimal config works, put the other stuff in one by one, and see what part is causing the trouble.
/Andreas
Devil_H@ck !
If you did what Nuppe suggested and it still not working,
presumably there is a short circuit on the motherboard, or the
CPU itself, because the PSU has got short circuit protection, so it
shuts down immediately. The pop sound could be an IC or the CPU which is burned out.
Best regards:
Gyuri
If you did what Nuppe suggested and it still not working,
presumably there is a short circuit on the motherboard, or the
CPU itself, because the PSU has got short circuit protection, so it
shuts down immediately. The pop sound could be an IC or the CPU which is burned out.
Best regards:
Gyuri
fcel:
You posted while i was typing...
The psu could be delivering flaky voltages and then stabilize after some time in operation (this is a guess, i'm not very good at electronics, correct me if i'm wrong).
Even if you didn't have the computer overclocked, a reset to default settings in the bios would overwrite corrupted data in the cmos settings (if there are any).
/Andreas
You posted while i was typing...
The psu could be delivering flaky voltages and then stabilize after some time in operation (this is a guess, i'm not very good at electronics, correct me if i'm wrong).
Even if you didn't have the computer overclocked, a reset to default settings in the bios would overwrite corrupted data in the cmos settings (if there are any).
/Andreas
Bill,
Thanks for your CMOS link. I've read it. It certainly could explain the reason why the computer would freeze up after leaving it on overnight. The thing is ... the computer will boot up after several tries without me inputing any of the CMOS setting manually .... which tells me that the CMOS setting is NOT lost .... which means the battery is doing it's job of storing the setting.
I certainly will open up the computer and see if I can get a replacement CMOS battery from Radio Shack and try it out. I'll report my findings.
nuppe/All,
I should also mention that the power supply fan has been making loud noise & I think it went dead completely. I have since replaced the power supply fan. Could it be that the damage is done already even before I replaced the fan? Damage in terms of intermediate damage - may be once those componebts on the power supply module got heated up, it'll work again?
1) Yes, I could consider the option of replacing the PSU.
2 )Are these PSU still readily available in the market? This is a 6-3) 7 year old computer.
4) I believe the newer PSU are getting fancier .... are they "backward compatible"?
5) How much money are we talkiing about?
Thanks for your CMOS link. I've read it. It certainly could explain the reason why the computer would freeze up after leaving it on overnight. The thing is ... the computer will boot up after several tries without me inputing any of the CMOS setting manually .... which tells me that the CMOS setting is NOT lost .... which means the battery is doing it's job of storing the setting.
I certainly will open up the computer and see if I can get a replacement CMOS battery from Radio Shack and try it out. I'll report my findings.
nuppe/All,
I should also mention that the power supply fan has been making loud noise & I think it went dead completely. I have since replaced the power supply fan. Could it be that the damage is done already even before I replaced the fan? Damage in terms of intermediate damage - may be once those componebts on the power supply module got heated up, it'll work again?
1) Yes, I could consider the option of replacing the PSU.
2 )Are these PSU still readily available in the market? This is a 6-3) 7 year old computer.
4) I believe the newer PSU are getting fancier .... are they "backward compatible"?
5) How much money are we talkiing about?
With all respect for DIY, I used to repair PSU’s in the early days.
I succeeded to fix 1 of the two that came in. The fixed ones were used but came back usually within two or three months.
They were all less then one year old.
So I quit fixing them. Compared with the price of the whole PC, a decent power supply is rather cheap.
And you’re more or less sure it will keep working for a longer period.
A refurbished PSU that is say five or more years old is simply not reliable anymore.
Too much caps are worn out, the board itself has become overheated, bad solderings everywhere, fans making noise…
Just my 0.2 €’s
/Hugo
I succeeded to fix 1 of the two that came in. The fixed ones were used but came back usually within two or three months.
They were all less then one year old.
So I quit fixing them. Compared with the price of the whole PC, a decent power supply is rather cheap.
And you’re more or less sure it will keep working for a longer period.
A refurbished PSU that is say five or more years old is simply not reliable anymore.
Too much caps are worn out, the board itself has become overheated, bad solderings everywhere, fans making noise…
Just my 0.2 €’s
/Hugo
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