System Won't Turn Off
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From: Steve Giannoni on 9 Jun 2010 10:50 Thanks for responding. It never worked before. Can't follow your response discussion ... On Tue, 08 Jun 2010 16:46:31 -0400, Paul <nospam(a)needed.com> wrote: >Steve Giannoni wrote: >> P-IV running Windows XP Home. Windows appears to be shutting down as >> the screen goes dark, but the "turn off" has to be done manually. Any >> help will be greatly appreciated & thanks ... > >Was it working at one time ? > >There can be hardware or software reasons, and if it was all working >at one time, that might help eliminate the software reasons. > >******* > >The hardware looks like this. The front switch is momentary contact, >and the motherboard logic converts the pulse from that switch, into >a solid continuous level on PS_ON#. If PS_ON# is zero volts, that >means the supply should come on. IF PS_ON# is at a 5V level, then >the supply should go off. Because the main cable of the supply has >a pullup resistor on it, that holds off the supply when no motherboard >is connected to drive that signal. That's why the PSU won't run by >itself when its sitting on the bench (jamming PS_ON# to COM starts it). > > Front_Switch ------ Southbridge/SuperIO -----------------> ATX PSU > ^ PS_ON# | > | +5VSB | > +----------------------------------+ > >In terms of hardware, it could be a (motherboard) driving end problem. >Or, it could be a problem with the thresholding of the signal by >the ATX PSU. > >It's theoretically possible for a person to characterize the behavior >of both ends. You can check that the pulldown function of the motherboard >works. You can check that the pullup function on the PSU works. If >you don't know how to do that, you'd replace the motherboard and PSU >and test by substitution (which is a pretty expensive way to do things). >Since PSU failures are more common, you'd start with the PSU end. > >Sticking a multimeter on the PS_ON# line, and looking at the voltage >levels, would give you a hint. If the line is swinging from 0.4V to >close to 5V when the computer is "supposed" to be off, then that >would tell you the PSU is likely having a problem reading the signal >level (bad PSU). If the line swung from 0.4V to 1.4V, then you'd have more >trouble guessing at who is at fault. That would require more >characterization of either end of the line. The motherboard end >can only pull down on the line, since the signal is open collector. >But when you see only a 1.4V level, is the pullup weak, or is the >motherboard driver still tugging on it ? That is indeterminate. You would >then need to separate the motherboard and supply, and test them separately. > >These are ATX supply specs. I'll use the middle one, to discuss how >to use one of these. The third one is for 24 pin connectors. > >http://web.archive.org/web/20030424061333/http://www.formfactors.org/developer/specs/atx/ATX_ATX12V_PS_1_1.pdf > >http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf > >http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf > >On page 30 of ATX12V_1_3dg.pdf , you can find the main cable pinout. The >PS_ON# signal is green in color and on pin 14. The body of the main power >connector is open at the back, and you can jam the probe of your multimeter >in there, when the system is running. (That is easier to do, when the >system is removed from the computer case and sitting on your table.) >I connect the ground on my multimeter, to a screw on the back of the computer >in the I/O area. That way, I only need one hand to guide the red probe to >the main connector. That avoids shorting the meter tips together. >Setting my meter to the 20VDC range, allows me to measure 5V logic signals. > >On page 20 is shown the behavior of the input. Normally, for a TTL >level circuit, the driving end might manage a swing of 0.4V to 2.4V minimum, >while the input threshold is set at 0.8V and 2.0V. Since 2.4V is higher than >2.0V, the input says "that's a logic 1". When the 0.4V level is seen, that is >less than 0.8V, so the input says "that's a logic 0". Values between >0.8V and 2.0V (like if you saw a 1.4V level), will confuse the logic >and the input will either guess it is logic zero or one. In some cases, >this failure to swing properly, causes the less than normal behavior. > >I've even heard of cases, where a 1.4V level presented on PS_ON#, causes >the power supply to be "half on". The supply works, but won't meet full >load specs, and "falls over" easily. So the thresholding on PS_ON# on the >PSU end, isn't guaranteed to be "purely digital". In some instances, >the circuit on the end of the signal behaves in an analog way, so a half >way signal makes for a half-weak power supply. You're more likely to see >that on an older power supply. > > Paul
From: GlowingBlueMist on 9 Jun 2010 12:12 On 6/8/2010 12:44 PM, Steve Giannoni wrote: > P-IV running Windows XP Home. Windows appears to be shutting down as > the screen goes dark, but the "turn off" has to be done manually. Any > help will be greatly appreciated& thanks ... Like others have mentioned the problem could be hardware or software at this stage. I have had external USB devices, which had their own external power source, feed 5 volts back into the computer's USB port and causing similar shutdown problems. One was a cheap manufacturer who left out a protective blocking diode and another had a jumper that was to have been removed when using an external power supply. As for the software possibilities, I would boot a copy of one of the Live Linux distributions in order rule out that kind of problem. If the Linux OS boots properly and powers down the PC correctly then the problem has most definitely been identified as a software issue with your present installation. Live Linux software can downloaded at http://www.livecdlist.com/ You would need to burn it to a CD or DVD before using it. If your motherboard supports booting from USB you can use the freeware program UNetbootin and have it transfer a Live Linux distribution to a Flash drive. It is great for test booting a system when you suspect the CD/DVD drive may be defective, provided the motherboard supports booting from a USB port. The program will download the Linux distribution for you or it can use a Linux ISO you have already downloaded to load and make your Flash drive bootable. You can find the UNetbootin at: http://unetbootin.sourceforge.net/ and it is Freeware. For this I usually use Puppy Linux as it is a rather small download while still retaining the necessary software to recognize most systems. It has a graphic desktop that it boots into rather than just the command line that many other distributions might present. No need to know Linux commands to boot or shut it down. Last, I have seen a motherboard battery starting to fail that caused random hidden changes on the motherboard setup. As a last resort I'd try replacing your motherboards battery and reconfigure the BIOS settings, especially if the battery is 4 or 5 years old.
From: Steve Giannoni on 9 Jun 2010 14:48 Thanks for responding. How do I "boot a copy of one of the Live Linux distributions"? Which item do I download? I am a novice at stuff at this level, etc. ... On Wed, 09 Jun 2010 11:12:53 -0500, GlowingBlueMist <glowingbluemist(a)truely.invalid> wrote: >On 6/8/2010 12:44 PM, Steve Giannoni wrote: >> P-IV running Windows XP Home. Windows appears to be shutting down as >> the screen goes dark, but the "turn off" has to be done manually. Any >> help will be greatly appreciated& thanks ... > >Like others have mentioned the problem could be hardware or software at >this stage. > >I have had external USB devices, which had their own external power >source, feed 5 volts back into the computer's USB port and causing >similar shutdown problems. One was a cheap manufacturer who left out a >protective blocking diode and another had a jumper that was to have been >removed when using an external power supply. > >As for the software possibilities, I would boot a copy of one of the >Live Linux distributions in order rule out that kind of problem. If the >Linux OS boots properly and powers down the PC correctly then the >problem has most definitely been identified as a software issue with >your present installation. > >Live Linux software can downloaded at http://www.livecdlist.com/ You >would need to burn it to a CD or DVD before using it. > >If your motherboard supports booting from USB you can use the freeware >program UNetbootin and have it transfer a Live Linux distribution to a >Flash drive. It is great for test booting a system when you suspect the >CD/DVD drive may be defective, provided the motherboard supports booting >from a USB port. The program will download the Linux distribution for >you or it can use a Linux ISO you have already downloaded to load and >make your Flash drive bootable. > >You can find the UNetbootin at: http://unetbootin.sourceforge.net/ and >it is Freeware. > >For this I usually use Puppy Linux as it is a rather small download >while still retaining the necessary software to recognize most systems. > It has a graphic desktop that it boots into rather than just the >command line that many other distributions might present. No need to >know Linux commands to boot or shut it down. > >Last, I have seen a motherboard battery starting to fail that caused >random hidden changes on the motherboard setup. As a last resort I'd >try replacing your motherboards battery and reconfigure the BIOS >settings, especially if the battery is 4 or 5 years old.
From: Paul on 9 Jun 2010 15:30 Steve Giannoni wrote: > Thanks for responding. It never worked before. > > Can't follow your response discussion ... > Check Device Manager. Look at the "Computer" entry. Does it say "ACPI Multiprocessor" or "ACPI Uniprocessor" ? Those support all the power control features. I suspect your problem is hardware related. If you didn't have working soft power control in the OS, then you would have seen a Win98 style "it is now safe to turn off your computer" screen image by now. Since you're seeing a black screen, the OS thinks it has turned off the power. And in that case, there is a hardware problem with respect to the interpretation of the PS_ON# signal on the main power cable. There is a purported picture of the WinXP shutdown screen here. This is what you'd see, if the OS knew it could not turn off the power, and was relying on the user to do it manually. When you see the image in this picture, it means caches have been flushed to disk, and removal of power won't corrupt any file systems. http://www.gearhack.com/Forums/DisplayComments.php?file=Computer/Windows/Shutdown_through_remote_desktop. Paul
From: Steve Giannoni on 9 Jun 2010 16:23
Device manager says Uniprocessor. I am a novice at this level and can't follow your comments ... On Wed, 09 Jun 2010 15:30:58 -0400, Paul <nospam(a)needed.com> wrote: >Steve Giannoni wrote: >> Thanks for responding. It never worked before. >> >> Can't follow your response discussion ... >> > >Check Device Manager. Look at the "Computer" entry. >Does it say "ACPI Multiprocessor" or "ACPI Uniprocessor" ? >Those support all the power control features. > >I suspect your problem is hardware related. > >If you didn't have working soft power control in the OS, >then you would have seen a Win98 style "it is now safe to >turn off your computer" screen image by now. Since >you're seeing a black screen, the OS thinks it has >turned off the power. And in that case, there is a >hardware problem with respect to the interpretation >of the PS_ON# signal on the main power cable. > >There is a purported picture of the WinXP shutdown >screen here. This is what you'd see, if the OS knew >it could not turn off the power, and was relying >on the user to do it manually. When you see the >image in this picture, it means caches have been >flushed to disk, and removal of power won't corrupt >any file systems. > >http://www.gearhack.com/Forums/DisplayComments.php?file=Computer/Windows/Shutdown_through_remote_desktop. > > Paul |