System Won't Turn Off
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From: Steve Giannoni on 8 Jun 2010 13:44 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 ...
From: Steve Giannoni on 8 Jun 2010 16:12 Just Googled this and found many things that could cause this; hopeless !... On Tue, 08 Jun 2010 13:44:02 -0400, Steve Giannoni <casagiannoni(a)optonline.net> 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 ...
From: Paul on 8 Jun 2010 16:46 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: Man-wai Chang to The Door (33600bps) on 9 Jun 2010 01:45 On 6/9/2010 01:44, 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 ... Did you try these registry hacks? http://www.mytechsupport.ca/forums/index.php?topic=11974.0 -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.34 ^ ^ 13:40:01 up 21 days 16:51 2 users load average: 1.01 1.05 1.18 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
From: Steve Giannoni on 9 Jun 2010 10:38
Thanks for responding. Unfortunately the registry hacks didn't cure the problem ... On Wed, 09 Jun 2010 13:45:50 +0800, "Man-wai Chang to The Door (33600bps)" <toylet.toylet(a)gmail.com> wrote: >On 6/9/2010 01:44, 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 ... > >Did you try these registry hacks? >http://www.mytechsupport.ca/forums/index.php?topic=11974.0 |