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#1
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Help - pc not turning on
While troubleshooting a new HD, I just ran into a new problem of which
I'm not sure where the problem is. When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. When I turn off power completely (using the on/off button on the PSU), wait awhile, turn back on the PSU power button, and then turn on the pc using the on/off button on the front of the pc, I get the same problem described above - pc lights up but immediately stops. The problem occurred while I was troubleshooting a problem with a new HD. My testing of the HD involved frequently turning the pc on and off in order to switch the power cords and SATA cords among the HDDs. My first thought was that the switch on the front of the pc broke, but that doesn't seem likely because the pc will power up however briefly when I press the switch. Second thought is that there's a "fuse" ?? needing to be reset. Third thought was wondering if the CMOS battery needs replacing. Fourth thought was worrying if I need to replace my mobo. Fifth thought was same question but about my PSU. Sixth thought is wondering if I corrupted BIOS somehow. I would enter BIOS to check if the new HD was listed in the SATA info, so I was always entering and exiting BIOS and resuming booting up. My notes about the pc are not handy. The mobo is an ASUS AMD mobo about 4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/ CD device and graphics card are the same age. The HDDs vary in age, all SATA. I have four. IIRC, the PSU is rated to handle 600W. Thanks, John |
#2
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Help - pc not turning on
On 05/08/2018 10:23 AM, Yes wrote:
While troubleshooting a new HD, I just ran into a new problem of which I'm not sure where the problem is. When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. When I turn off power completely (using the on/off button on the PSU), wait awhile, turn back on the PSU power button, and then turn on the pc using the on/off button on the front of the pc, I get the same problem described above - pc lights up but immediately stops. The problem occurred while I was troubleshooting a problem with a new HD. My testing of the HD involved frequently turning the pc on and off in order to switch the power cords and SATA cords among the HDDs. My first thought was that the switch on the front of the pc broke, but that doesn't seem likely because the pc will power up however briefly when I press the switch. Second thought is that there's a "fuse" ?? needing to be reset. Third thought was wondering if the CMOS battery needs replacing. Fourth thought was worrying if I need to replace my mobo. Fifth thought was same question but about my PSU. Sixth thought is wondering if I corrupted BIOS somehow. I would enter BIOS to check if the new HD was listed in the SATA info, so I was always entering and exiting BIOS and resuming booting up. My notes about the pc are not handy. The mobo is an ASUS AMD mobo about 4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/ CD device and graphics card are the same age. The HDDs vary in age, all SATA. I have four. IIRC, the PSU is rated to handle 600W. Thanks, John My first thought is that you might have killed the PSU with a too quick turn off turn on cycle, Again I say might Rene |
#3
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Help - pc not turning on
On Tue, 8 May 2018 15:23:42 -0000 (UTC), Yes wrote:
When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. Disconnect everything you can, apart from the motherboard. If the PSU still doesn't keep the fans running remove any video cards and try again. If it's still failing it's likely to be the PSU. It's showing signs of shutting off due to an overload and it could be the PSU that's failed. Good luck. -- Regards - Rodney Pont The from address exists but is mostly dumped, please send any emails to the address below e-mail rpont (at) gmail (dot) com |
#4
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Help - pc not turning on
On Tue, 8 May 2018 15:23:42 -0000 (UTC), Yes
wrote: While troubleshooting a new HD, I just ran into a new problem of which I'm not sure where the problem is. When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. When I turn off power completely (using the on/off button on the PSU), wait awhile, turn back on the PSU power button, and then turn on the pc using the on/off button on the front of the pc, I get the same problem described above - pc lights up but immediately stops. The problem occurred while I was troubleshooting a problem with a new HD. My testing of the HD involved frequently turning the pc on and off in order to switch the power cords and SATA cords among the HDDs. My first thought was that the switch on the front of the pc broke, but that doesn't seem likely because the pc will power up however briefly when I press the switch. Second thought is that there's a "fuse" ?? needing to be reset. Third thought was wondering if the CMOS battery needs replacing. Fourth thought was worrying if I need to replace my mobo. Fifth thought was same question but about my PSU. Sixth thought is wondering if I corrupted BIOS somehow. I would enter BIOS to check if the new HD was listed in the SATA info, so I was always entering and exiting BIOS and resuming booting up. My notes about the pc are not handy. The mobo is an ASUS AMD mobo about 4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/ CD device and graphics card are the same age. The HDDs vary in age, all SATA. I have four. IIRC, the PSU is rated to handle 600W. Thanks, John I had exactly the same problem, posted in another forum. Strangely enough, a ASUS AMD board, only mine was 13 years old. Started after I did some frequent rebooting from Windows to Linux and back. I found if I unplugged it from the mains for an hour or so it would boot normally (yes, just shutting down did not work). In the end it became so annoying I just bought a new MB, power supply, memory etc ... IOW a new PC (minus the HD, keyboard, mouse and DVD Writer). I'd try a borrowed PSU. If it still does not work, can't help you. I never did figure out what the problem was. Things I tried - swapping the PSU, removing the graphics card and using the onboard, unplugging the DVD Writer and HD, re-seating the RAM and putting in a new, tested CMOS battery. The only constant was the MB itself. []'s -- Don't be evil - Google 2004 We have a new policy - Google 2012 |
#5
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Help - pc not turning on
Yes wrote:
While troubleshooting a new HD, I just ran into a new problem of which I'm not sure where the problem is. When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. When I turn off power completely (using the on/off button on the PSU), wait awhile, turn back on the PSU power button, and then turn on the pc using the on/off button on the front of the pc, I get the same problem described above - pc lights up but immediately stops. The problem occurred while I was troubleshooting a problem with a new HD. My testing of the HD involved frequently turning the pc on and off in order to switch the power cords and SATA cords among the HDDs. My first thought was that the switch on the front of the pc broke, but that doesn't seem likely because the pc will power up however briefly when I press the switch. Second thought is that there's a "fuse" ?? needing to be reset. Third thought was wondering if the CMOS battery needs replacing. Fourth thought was worrying if I need to replace my mobo. Fifth thought was same question but about my PSU. Sixth thought is wondering if I corrupted BIOS somehow. I would enter BIOS to check if the new HD was listed in the SATA info, so I was always entering and exiting BIOS and resuming booting up. My notes about the pc are not handy. The mobo is an ASUS AMD mobo about 4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/ CD device and graphics card are the same age. The HDDs vary in age, all SATA. I have four. IIRC, the PSU is rated to handle 600W. Thanks, John There is a protective fuse, but it's a slow blow. If it was gone, the supply sections wouldn't come on at all. In particular, with the fuse open, the +5VSB would not be present before you push the button on the front. The fuse F1 is on the upper left of the schematic below. You have sufficient +5VSB, that it is powering the motherboard supervisor circuitry and when you push the front button, it asserts (grounds) the open-collector PS_ON# signal. A secondary way to operate a supply, is to ground PS_ON# yourself. This is what we do when making home-made power supply testers, is use a switch to ground PS_ON#. I don't recommend leaving hard drives you don't have backups of, on the SATA portion while messing around. If you want to jiggle PS_ON# your own self, boot with a floppy or CD. At most then, you could blow up a $20 DVD drive. After PS_ON# is asserted, the power supply has the internal overcurrent detection disabled for the first 35 milliseconds. This gives time for the output stage capacitors on the PSU to charge up. (C30, upper right and so on). http://www.pavouk.org/hw/en_atxps.html After the 35 millisecond interval, the PSU starts checking for overload. If something on the motherboard draws too much current, the PSU shuts off. It uses +5VSB power to "record" the failure internally, inside the PSU. Attempts to push the button on the front at this point, are likely to fail. As soon as you turn off the power at the back, and turn it on again, that resets the recording of an overcurrent, and you can then try the front button again. Some old supplies, can become "weak" and produce hardly any output at all (I have one here that will run a 12V 100mA fan, but if you add a second fan, it causes the PSU to croak). It's not clear why the overcurrent isn't working properly in that case. The power supply can be "weak", if the primary side switching wasn't working properly. Q1 and Q2 alternate applying 300VDC to the primary side of T3, and all the outputs are tied via turns ratio, to producing some output values. The diodes on the output side of T3, rectify the AC waveform coming from transformer T3. The large output caps (like C30) filter the ripple from the rectification action, making DC voltages (12V, 5V, 3.3V and so on). The PSU design uses "isolation" and transformers or optoisolators, to isolate sections of the PSU for safety. The drive signals to run the switching transistors, are transformer isolated. The idea is to leave fewer paths that can electrocute the user (a noble objective). So what we know at the moment, is the motherboard did manage to activate PS_ON#. We don't know if it's a good solid logic low. The PS_ON# driver on the motherboard is notorious for fouling up, even though the input spec on the PSU only requires a couple milliamps of ground sinking to work. Some of the motherboards from the year 2000 era were using 74F series logic with 48mA drive for some reason, "as if the motherboard makers knew something". You see, the power supply maker couldn't give a damn about making a "logic gate" to analyze PS_ON# and they use various discrete circuits to check the logic level. And there must be some failure conditions, that takes it out on the motherboard PS_ON# driving chip. I would agree with the previous posters, to swap in a spare supply and re-test for symptoms. If you had a power supply tester (one where you could put a decent load on each output), then you could get some idea how healthy the PSU is. Instead of that, simply buying another supply and testing, is a step you can carry out. If you have a multimeter and know how to use it, you can check the logic level on PS_ON#. Before pushing the front button on the PC, PS_ON# should be the same voltage as +5VSB (i.e. 5.0 volts). Once you press the front button, you want a good solid logic low to be seen on PS_ON#. Since your supply only stays on for 35 milliseconds, it's going to be pretty difficult to get that reading :-/ Only a digital storage scope would work for a job like that. ******* Here are the three generations of ATX PSU specs I know of. If your supply has a 20 pin connector, then the middle spec is the one you want. If the supply has a 24 pin (I have a supply now with a solid 24 pin and it isn't even split any more into 20+4 sections), then you want the bottom spec. The first spec is just to prove that at one time (~year 2000) there was a -5V on the supply. The bottom two specs removed -5V, and the motherboard only needs -12V if it has an RS232 serial port on the motherboard (something a TI 75232 uses). Spec 1.1 has -5V on it. 20 pin connector. http://web.archive.org/web/200304240...12V_PS_1_1.pdf Spec 1.3 has -5V removed. 20 pin connector. http://www.formfactors.org/developer...X12V_1_3dg.pdf Spec 2.2 introduces... 24 pin connector. http://www.formfactors.org/developer...public_br2.pdf Some of the information in there, helps explain how the interface works. Power_Good for example, is a way for the PSU to tell the motherboard that the rails are stable, and the motherboard can come out of reset. You're not there yet, as at 35 milliseconds, the supply winks out, and is never going to deliver Power_Good logic 1 level. During the 35 millisecond interval, the power supply isn't yet ready to assert Power Good. That comes a bit later. There is a timing diagram in the spec that might illustrate the details of that. While the motherboard VCore can latch off, when it detects a failure, the fans would still be spinning. And I think your computer case cooling fans are only "twitching" a bit before they go off and stay off. So it's not a motherboard VCore problem. Swap in a spare PSU and retest. Good luck, Paul |
#6
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Help - pc not turning on
On 5/8/2018 8:23 AM, Yes wrote:
While troubleshooting a new HD, I just ran into a new problem of which I'm not sure where the problem is. When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. When I turn off power completely (using the on/off button on the PSU), wait awhile, turn back on the PSU power button, and then turn on the pc using the on/off button on the front of the pc, I get the same problem described above - pc lights up but immediately stops. The problem occurred while I was troubleshooting a problem with a new HD. My testing of the HD involved frequently turning the pc on and off in order to switch the power cords and SATA cords among the HDDs. My first thought was that the switch on the front of the pc broke, but that doesn't seem likely because the pc will power up however briefly when I press the switch. Second thought is that there's a "fuse" ?? needing to be reset. Third thought was wondering if the CMOS battery needs replacing. Measure it. I've had strange issues when the battery dropped too low. How low is too low "depends". Anything below 2.9V is on its way out, replace it anyway. Fourth thought was worrying if I need to replace my mobo. Fifth thought was same question but about my PSU. I've had several power supplies fail to produce reliable 5VSB. The capacitor goes high ESR. The 5VSB supply has huge spikes on it. Voltmeter reads the average voltage and says you have 5V. Put a scope on it and there are huge spikes. But put a load on it and it drops, or the spikes cause the board to malfunction. Replacing the cap fixed 'em. Sixth thought is wondering if I corrupted BIOS somehow. I would enter BIOS to check if the new HD was listed in the SATA info, so I was always entering and exiting BIOS and resuming booting up. My notes about the pc are not handy. The mobo is an ASUS AMD mobo about 4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/ CD device and graphics card are the same age. The HDDs vary in age, all SATA. I have four. IIRC, the PSU is rated to handle 600W. I've had issues with UEFI. Win8.1 install killed my system. It acts just like yours. Never found a way to recover it. Thanks, John |
#7
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Help - pc not turning on
Yes wrote:
When I press the on/off button for the pc on the front of the case, I see it start to light up but within a fraction of a second, it shuts down is the best way I can describe it - does not continue to boot up. When I press the on/off button again, nothing happens. Take off the side panel from the case. When you press the Power button to turn on, does the CPU fan spin? If not, the BIOS will see it has zero RPM (no speed) and immediately shutdown to protect the CPU from burning up (and possibly taking out regulators and other parts on the mobo next to the CPU). If you removed the CPU fan's cable from the mobo and put it back on, make sure you got it aligned properly. There is a polarizing tab but it's just a plastic flange that can bend out, so it is still possible to misalign the cable on the connector. If the RPM (sense) wire is broken, the BIOS will also see no RPM for the CPU fan. If the CPU fan doesn't spin, maybe it's bad and needs to be replaced. Make sure something isn't obstructing its fins, like a wire or cable hitting the fan and slowing it down or stopping its rotation altogether. If you see the CPU fan start to spin after pressing the Power button but it immediately stops along with the computer shutting down, the fan is probably okay - but the PSU may not be. Since you were digging around inside the computer, make sure all connectors are fully seated, the CPU and GPU fans spin up (even if momentarily), the memory is fully seated (although you usually hear a beep for bad memory unless there is no speaker or it is disconnected or has failed). "ASUS AMD mobo" is insufficient to tell anyone just WHAT you actually have. Give a model number. Some of those have diagnostic LED displays on the mobo that will show an error code. |
#8
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Help - pc not turning on
On Tue, 8 May 2018 15:23:42 -0000 (UTC), Yes
wrote: When I turn off power completely (using the on/off button on the PSU), wait awhile, turn back on the PSU power button, and then turn on the pc using the on/off button on the front of the pc, I get the same problem described above - pc lights up but immediately stops. The problem occurred while I was troubleshooting a problem with a new HD. My testing of the HD involved frequently turning the pc on and off in order to switch the power cords and SATA cords among the HDDs. My first thought was that the switch on the front of the pc broke, but that doesn't seem likely because the pc will power up however briefly when I press the switch. Second thought is that there's a "fuse" ?? needing to be reset. Third thought was wondering if the CMOS battery needs replacing. Fourth thought was worrying if I need to replace my mobo. Fifth thought was same question but about my PSU. Sixth thought is wondering if I corrupted BIOS somehow. I would enter BIOS to check if the new HD was listed in the SATA info, so I was always entering and exiting BIOS and resuming booting up. My notes about the pc are not handy. The mobo is an ASUS AMD mobo about 4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/ CD device and graphics card are the same age. The HDDs vary in age, all SATA. I have four. IIRC, the PSU is rated to handle 600W. Thanks, John Another -- I didn't check if this is already mentioned -- is when putting together a new build. First, though, I breadboard them, conceptually rather loosely and partially assembled on a table, for that contingency; ... maybe a piece of cardboard under the MB between the case, the PS propped up somewhere and such. Could then be any number of problems, although all after the obvious: 1a, always pinjumper a BIOS reset, 1b) monitor & keyboard, 2) barebone case to MB connections, 3) correct PS connections -- least and last, to lack a BIOS post. And so, once, it did so happen. I pulled the MB, out and insulated from the case, and it powered up. Then I reinstalled the MB with extra care to every case standoff: insulation grommets placed topside to the male screw, and beneath, to the tapped female column post. Fixed, although not every MB/case combo will act up like that. On the subject of swapping a PS. They would seem to be something along auto tires: A good idea have a spare, and easy enough, in case a computer doesn't roll, periodically, even if for good measure, to put one on and give it a push. Watching -- I just bought two spare PS units, this past couple weeks, on sale promotions. Both new: one for $12 and another $25. They're probably back up and together around $100. Beateruppers. |
#9
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Help - pc not turning on
The consensus is that my problem is most likely the PSU. I'll give RP's
suggestion to disconnect power cables a try first to see if there's any life signs. If not, looks like I'll be in the market to buy a new PSU. Thanks for all the comments and suggestions. John |
#10
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Help - pc not turning on
On Tue, 08 May 2018 14:56:54 -0300, Shadow wrote:
The only constant was the MB itself. - My last, or near, ASUS became intermittent though functional. After 5 or so years I started to feed it power supplies. Every year or so I'd give it a PS. It seemed to like them. Good enough, I figured, for nursing it along. Eventually too much of good things get old, maybe when the MB had 8-years' usage, when it bit my hand. I had an usual PS: Fortron or Sparkle, strictly server grade. Pick up that Sparkle and it wasn't like other power supplies. Somewhat compact and smaller than usual, it was its weight -- heavy as literally a brick. Not to mention quality, but class was written all over it. I plugged it into the ASUS one day and it got killed and died horribly. Stank like nothing else I'd run into for just a little wisp of accompanying smoke. I eventually switched over to Gigabyte MBs. I also used to talk with someone in realtime online MIRC chat forum. He carried a grudge against ASUS after working for them: Age-discrimination, he thought their revolving workforce for skewed younger people unfair. He also told me he had watched QC and overall engineering implementation decline. A conversation some years before I bought that board...ah, here it is: K8N-E+(Deluxe) using an AMD 754 3000 with 5-PCI slots for "back in the day." Half price, though, for a $100US MB sold by a once reputable distributor: Someone's return on, I presumed, all-thumbs when it comes to hardware assembly. That same distributor wouldn't now think twice about cutting a throat with known trashed hardware, for nowhere near the same discounts, nor will offer any provision for honoring reversed charges on return shipping for discrepancies with merchandise promoted "as new". These days there's only one plan to have: the best cut-&-dried kind. |
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