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Help - pc not turning on



 
 
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  #1  
Old May 8th 18, 04:23 PM posted to alt.comp.hardware.pc-homebuilt
Yes[_2_]
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Posts: 105
Default 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  
Old May 8th 18, 04:35 PM posted to alt.comp.hardware.pc-homebuilt
Rene Lamontagne
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Posts: 187
Default 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  
Old May 8th 18, 04:43 PM posted to alt.comp.hardware.pc-homebuilt
rp
external usenet poster
 
Posts: 9
Default 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  
Old May 8th 18, 06:56 PM posted to alt.comp.hardware.pc-homebuilt
Shadow[_2_]
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Posts: 195
Default 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  
Old May 8th 18, 07:06 PM posted to alt.comp.hardware.pc-homebuilt
Paul[_28_]
external usenet poster
 
Posts: 1,467
Default 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  
Old May 8th 18, 07:57 PM posted to alt.comp.hardware.pc-homebuilt
mike
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Posts: 75
Default 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  
Old May 8th 18, 08:41 PM posted to alt.comp.hardware.pc-homebuilt
VanguardLH[_2_]
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Posts: 1,453
Default 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  
Old May 9th 18, 12:49 AM posted to alt.comp.hardware.pc-homebuilt
Flasherly[_2_]
external usenet poster
 
Posts: 2,407
Default 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  
Old May 9th 18, 02:57 AM posted to alt.comp.hardware.pc-homebuilt
Yes[_2_]
external usenet poster
 
Posts: 105
Default 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  
Old May 9th 18, 07:15 AM posted to alt.comp.hardware.pc-homebuilt
Flasherly[_2_]
external usenet poster
 
Posts: 2,407
Default 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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