Dave, my main power switch / breaker (on rear of PC) is poping when he PC is left on for 1-2 days. Turning it OFF then back ON and then pressing the power button on the front panel returns the system to full functionality. There is no scan disk etc to indicate an improper shutdown. Any suggestions appreciated!
To answer this question, I went straight to the source, to Jerrold Foutz of Power Supply Design Tips and a generally superb chap. Here’s his best shot at answering your question:
I don’t answer questions about PC power supplies because as a power supply
circuit designer I need a schematic and a meaningful parts list as a
starting point. Schematics for PC’s, and especially their power supplies,
are almost impossible to come by (it is highly competitive and no one
wants their competitor to have this information), and if you get one, the
parts list is mostly proprietary part numbers and there is no way to find
data on the part and learn its characteristics.
Having said that, here are a few observations, which may or may not be
valid. Take them for what they are worth, partially informed opinion.
Circuit breakers are usually of the magnetic or thermal sensing type, with
thermal sensors being the cheapest, hence that is what is probably used in
your PC.
They are triggered by higher than normal current heating up a non-linear
resistive element that at a certain temperature (related to current) will
open the breaker. You have to add the ambient heat to the self heating, so
the breaker may open sooner in a warm room, or when air flow is
restricted, such loose papers blocking a vent, etc. They are also
mechanical devices. This means they are often not as reliable as
electronic components and they can be more subject to shock and vibration.
A breaker about ready to open might be triggered if the computer is
bumped. If your power supply is operating at its limit, a random bump
could explain what is happening to you, as unlikely as it seems.
The thing that bothers me is that the opening of the breaker does not
trigger the response to a non-controlled shutdown. If the computer is in a
sleep mode, loss of power might not trigger it. However, I’m just guessing
here.
If something goes wrong in either the computer start-up or shut-down
sequence, the standard fix is to turn off the power, wait 30 seconds for
internal capacitors to discharge and then turn it back on. This is
probably one of the most controlled sequences your computer goes through
and almost always works. It seems to be working in your case.
One exception can be the sleep mode. Here, there is a low power drain to
keep some control circuits alive and this may interfere with recovery. In
this case, the time honored fix is to remove the plug from the wall, wait
the mandatory 30 seconds, plug it in, and then turn it on. For laptops,
you have to remove the power cord and battery, wait 30 seconds, then put them back in.
If this does not work, you usually have to send the computer in to a
qualified technician for the product for repair or replacement.
You may be able to get some help on forums that cater to the PC hobbiest,
but it is the exception to get a good answer. My batting average is less
than one hit in 25 tries.
Although it only contains a line or two related to your problem, you might
want to read Notes on the Troubleshooting and Repair of Small Switchmode Power Supplies, which is one of the links at RepairFAQ.
I know this did not answer your question, but hopefully it gives you some
insight into what may be happening.
the orange light at the side of the power cable is on, but laptop not powering up. Any other suggestions? I feel I probably need to take it to someone.
OK, I yanked it out (gripping my laptop very firmly). After several attempts because it’s still very stiff, the power came back on! Thanks so much.
Given how they’re connected, I can’t imagine anything bad would happen if you give it a really good pull. Just make sure your laptop doesn’t fly across the room! Good luck.
I cannot get the power cord out of my Powerbook G4. It’s been stuck in there for a long time and I occasionally have to wiggle it to get the power to come on. It’s never really bothered me because the computer is more or less kept in one place, but suddenly it’s not powering up the Mac and my battery has run down. I don’t want to pull too hard in case I break anything, but I think it’s knackered anyway. Do you know if it’s possible to do anything about this…whether I can replace that broken part, or will I have to take it in for repair? Thanks. By the way, this is a great website.
Hi, Dave I have a XP PC 5 years old that has taken to shutting off in the middle of something. About 30 minutes of work and just go to black !
Could this be a power supply problem or is it in power management software ?
I have an EMachine computer. After being on for 1/2 hour it just shuts down. To turn it back on I have to unplug it from the wall, plug it back on, and then I can push the power button and it will come on. Do I need a new power supply? It’s clean of dust and I have actually taken the casing off in case it was getting too hot, which it’s not.
Please help.
my computer will not go into standby or the hibernate mode. have tried to correct in power options and am told that the UPS is not is not configured correctly. I don’t know how to fix it. any suggestions for a novice
ok u get strait to stuff that might be not the issue
there is always a strait chance to be the ups failure
but i had this same problem with
belkin gold ups it was all couse of program called
bulgard that came with ups as drivers it sets pc to turn off after some time by itself just uninstall the program if u have and setup windows to take care of ups power and etc
Is Windows xp pro corporate edition the same as windows xp pro vlk
or would windows xp pro oem be the same or neither
Thanks a lot for your prompt and comprehensive reply to my question!
The possible solution might amuse you. I had a WyFi router sitting on the top of the computer (inches away from the power switch). The rubber feet were hanging over the side so the hot base rested on the computer case.I now believe this excess heat caused the switch/breaker to pop.
Again, thanks for the assist!
I had the same problem – the cause was evident when I had a good look around the exhaust fan for the power supply. �It was filled with dust – cleaning it up, as well as the power supply components and the computer innards (where does all that dust come from?) fixed the problem completely.
Mechanical (and electrical) parts DO go bad – I replace the ON/OFF switches (from the rear of power supplies) and cooling fans on a regular basis. If you were a technician, etc. those parts are easy to replace. (NEVER open a supply unless you’re qualified.) If not, the simplest solution is to replace the supply. (It’s only held in place with 4 screws; the electrical connections all unplug inside the computer.) (Engineer, including power supplies, 22 years!)
Sure sounds like a bad power supply to me. Of course I’m not a power supply enginneer, but there look to be two credible sources for the guy’s problem: either the wall circuit is sending surges through the wall plug that trigger a shutdown in the pc’s power supply or the supply is going bad. I find the first to be unlikely, since he probably would have noticed other things going flaky along with the pc.
The power supply is certainly the most likely culprit, and since they’re relatively inexpensive these days, it makes little sense to avoid replacing this one. In fact, I wouldn’t waste any time. Left alone, this thing could easily fry the entire system.
That said, if the problem continues AFTER replacing the psu, then there is more than likely a bad motherboard at the heart of it.