Getting PC to work again - need help

[mehere]

First sorry for cross posting I was not sure which NG would give me the
better response.

OK

I have a PC I am trying to rescue form my Parents. They had a mouse
infestation and they got into the PC and obviously the PC stopped working.

I have now cleaned out the PC and removed all the crap of all boards by
using a very similar process as at
http://www.badcaps.net/forum/showthread.php?s=e2aa99fffd27920b8f5e8511dc194a16&t=1463&page=2&pp=15
and all appears to be looking good.

I have reconnected everything and having no additional luck.

Symptom is that the MB appears to be gettng power (can see the LED's light
up) and when I push the power button the CPU fan and two other case fans
spin for a brief couple of seconds and then nothing.

So my question what could be the issue can you point me to what I should
look at first. I tought of a new case with a new Power supply, but thought
before I do that I'd ask here for some ideas.

BTW its an ASUS A7V8X MB with an Athlon 2.4Ghz CPU I think

Cheers

Greg

 

[Vanguard]

First sorry for cross posting I was not sure which NG would give me
the
better response.

OK

I have a PC I am trying to rescue form my Parents. They had a mouse
infestation and they got into the PC and obviously the PC stopped
working.

I have now cleaned out the PC and removed all the crap of all boards
by
using a very similar process as at
http://www.badcaps.net/forum/showthread.php?s=e2aa99fffd27920b8f5e8511dc194a16&t=1463&page=2&pp=15
and all appears to be looking good.

I have reconnected everything and having no additional luck.

Symptom is that the MB appears to be gettng power (can see the LED's
light
up) and when I push the power button the CPU fan and two other case
fans
spin for a brief couple of seconds and then nothing.

So my question what could be the issue can you point me to what I
should
look at first. I tought of a new case with a new Power supply, but
thought
before I do that I'd ask here for some ideas.

BTW its an ASUS A7V8X MB with an Athlon 2.4Ghz CPU I think

Cheers

Greg

Disconnect all drives (floppy, hard, CD/DVD, Zip, external, etc.).
Remove all daughtercards from the PCI slots. I assume this mobo has an
AGP slot for an AGP video card so leave that in; however, if the mobo
has onboard video, also remove the AGP video card. Remove all memory
sticks but one in the first slot. You should now have a barebones setup
with just the power supply unit (PSU), mobo, one RAM stick, and a video
card (or none if using onboard video). See if the box gets past the
POST (it won't boot because you have all the drives disconnected). If
not, try using a different memory stick (if there was more than one in
the original configuration), and repeat using one stick from the set of
memory sticks that are available. All of them could be bad but not
likely unless a surge burned them all out or you didn't take proper
anti-static precautions and are zapping every component inside the box.

Under that barebones configuration, you have a limited number of
components that could be bad if the box still doesn't POST. If it still
doesn't POST, get a PSU tester (I don't know your level of expertise;
see my posts in the Google Groups copy at http://snipurl.com/rcpd).
However, in your case, the fans do come on meaning the mains from the
PSU got enabled and are supplying power to the mobo. Because it shuts
down in a few seconds, could be the CPU fan is not connected or you have
it on backwards. The BIOS uses the 3rd wire (RPM sense) to see that the
CPU fan is spinning and will shutdown the PSU if it is not spinning or
not spinning fast enough to prevent the CPU from burning up. Intels
will throttle their duty cycle to run slower to reduce heat whereas the
AMDs will burn up unless external controls are used to power it down.

Could be the settings in the BIOS are screwed up, maybe because the CMOS
battery is too weak. Get a new CMOS battery and jumper the 2 header
pins used to reset the BIOS. Maybe then you can keep the unit powered
up long enough to go into the BIOS screens to set it up the way that you
want. Also, some mobos won't power up if the CMOS battery is missing.

 

[mehere]

Disconnect all drives (floppy, hard, CD/DVD, Zip, external, etc.). Remove
all daughtercards from the PCI slots. I assume this mobo has an AGP slot
for an AGP video card so leave that in; however, if the mobo has onboard
video, also remove the AGP video card. Remove all memory sticks but one
in the first slot. You should now have a barebones setup with just the
power supply unit (PSU), mobo, one RAM stick, and a video card (or none if
using onboard video). See if the box gets past the POST (it won't boot
because you have all the drives disconnected). If not, try using a
different memory stick (if there was more than one in the original
configuration), and repeat using one stick from the set of memory sticks
that are available. All of them could be bad but not likely unless a
surge burned them all out or you didn't take proper anti-static
precautions and are zapping every component inside the box.

Under that barebones configuration, you have a limited number of
components that could be bad if the box still doesn't POST. If it still
doesn't POST, get a PSU tester (I don't know your level of expertise; see
my posts in the Google Groups copy at http://snipurl.com/rcpd). However,
in your case, the fans do come on meaning the mains from the PSU got
enabled and are supplying power to the mobo. Because it shuts down in a
few seconds, could be the CPU fan is not connected or you have it on
backwards. The BIOS uses the 3rd wire (RPM sense) to see that the CPU fan
is spinning and will shutdown the PSU if it is not spinning or not
spinning fast enough to prevent the CPU from burning up. Intels will
throttle their duty cycle to run slower to reduce heat whereas the AMDs
will burn up unless external controls are used to power it down.

Could be the settings in the BIOS are screwed up, maybe because the CMOS
battery is too weak. Get a new CMOS battery and jumper the 2 header pins
used to reset the BIOS. Maybe then you can keep the unit powered up long
enough to go into the BIOS screens to set it up the way that you want.
Also, some mobos won't power up if the CMOS battery is missing.

I'll try what you have suggested.

Just one thing I had to remove the CMOS battery to clean the board, never
done that before - it is back in - could this be the issue - do I need to
reset pins or something?

Expertise (me) is average but willing to leanr

Cheers

Greg

 

[mehere]

Disconnect all drives (floppy, hard, CD/DVD, Zip, external, etc.). Remove
all daughtercards from the PCI slots. I assume this mobo has an AGP slot
for an AGP video card so leave that in; however, if the mobo has onboard
video, also remove the AGP video card. Remove all memory sticks but one
in the first slot. You should now have a barebones setup with just the
power supply unit (PSU), mobo, one RAM stick, and a video card (or none if
using onboard video). See if the box gets past the POST (it won't boot
because you have all the drives disconnected). If not, try using a
different memory stick (if there was more than one in the original
configuration), and repeat using one stick from the set of memory sticks
that are available. All of them could be bad but not likely unless a
surge burned them all out or you didn't take proper anti-static
precautions and are zapping every component inside the box.

Under that barebones configuration, you have a limited number of
components that could be bad if the box still doesn't POST. If it still
doesn't POST, get a PSU tester (I don't know your level of expertise; see
my posts in the Google Groups copy at http://snipurl.com/rcpd). However,
in your case, the fans do come on meaning the mains from the PSU got
enabled and are supplying power to the mobo. Because it shuts down in a
few seconds, could be the CPU fan is not connected or you have it on
backwards. The BIOS uses the 3rd wire (RPM sense) to see that the CPU fan
is spinning and will shutdown the PSU if it is not spinning or not
spinning fast enough to prevent the CPU from burning up. Intels will
throttle their duty cycle to run slower to reduce heat whereas the AMDs
will burn up unless external controls are used to power it down.

Could be the settings in the BIOS are screwed up, maybe because the CMOS
battery is too weak. Get a new CMOS battery and jumper the 2 header pins
used to reset the BIOS. Maybe then you can keep the unit powered up long
enough to go into the BIOS screens to set it up the way that you want.
Also, some mobos won't power up if the CMOS battery is missing.

Hmm no nothing, no sound beeps or anything - sounds like its cactus.

and yes i have static protection etc

Have not tested the PSU though I think that may be the main issue as teh PSU
fan does not come on or does that only come on when the PSU reaches a
certain temp? Not willing to play around with power supplies not knowing
what and how too risky being power

I'll have to try and source another PSU to test - what Wattage do I need,
must it be 400W

Cheers

Greg

 

[mehere]

It was the PSU

 

[Vanguard]

Just one thing I had to remove the CMOS battery to clean the board,
never done that before - it is back in - could this be the issue - do
I need to reset pins or something?

If you left the battery out for more than minute, could be the CMOS
settings have faded so it is dubious as to their values. Usually this
results in a CMOS checksum error but not always. You should reinsert
the battery (you already did that) and then short the 2-pin header with
a jumper for about 5 seconds to clear the CMOS table copy of the BIOS
settings that were saved to it. This forces a reload of the BIOS
settings but those will be the default values, not those that you
modified, so you will need to go back into the BIOS to check that all
the settings are as you need or want them.

make sure you put the battery in correctly. It is possible that it can
be slid in upside down. Probably won't hurt anything but definitely
won't supply the *positive* 3.3VDC needed to keep the CMOS table intact.
Don't buy a lithium wafer battery more than 3 years old. Even if it is
new, it may say that it has a shelf life until 2007 but it was
manufactured 5 years ago so it is already 3 years old. Get a battery
that has its shelf life listed far enough out to ensure you are getting
a fresh one. Replacing a weak battery with another weak battery doesn't
solve any problems. Those wafer batteries cost maybe around $4 (and is
probably the common CR-2032 available lots of places), so just go get a
new one rather than trying to use the old one (you didn't mention how
old is the computer).

P.S.
Please learn to snip when replying. Don't quote the entire parent post
unless it is so short, like just a few lines, that snipping doesn't save
much. Users don't want to have to scroll though a long post that
contains gobs of quoted posted in their entirety. I'm verbose so it is
even more important that you snip the quoted content.

 

[Vanguard]

Hmm no nothing, no sound beeps or anything - sounds like its cactus.

and yes i have static protection etc

Have not tested the PSU though I think that may be the main issue as
teh PSU fan does not come on or does that only come on when the PSU
reaches a certain temp? Not willing to play around with power
supplies not knowing what and how too risky being power

I'll have to try and source another PSU to test - what Wattage do I
need, must it be 400W

Cheers

Greg

If the fan in the PSU doesn't spin, it could be because:

- There are 2 fans inside the PSU: a constant RPM fan (at the backside)
and a thermally-controlled fan (on the bottom). This reduces fan noise
by having just the constant RPM fan running and using the
thermally-controlled fan when temperatures increase beyond some
threshold. It also provides cooling redundancy: if the constant RPM fan
fails then the thermally-controlled fan will spin up (or should spin up
even if temps aren't high enough to trigger the thermistor circuit), or
if the thermal-controlled fan dies then the constant RPM fan is still
there pumping out some heat.

- The PSU has overheated, has a fault, detects a short (i.e., too many
amps going out its mains to the external taps), or other problem so it
shuts down.

- If the PSU has a circuit breaker, maybe it blew (but then it did so
for a reason). Does it have one and have you tried resetting it? Some
have a fuse but those rarely now have a fuseholder that lets you easily
remove the fuse from the outside of the PSU case and instead you have to
open up the PSU case and unsolder the burnt out fuse and solder a new
one in.

- A fault in the motherboard is preventing the PSU from powering up.
Although power is "off", +5VDC is still supplied from the PSU to the
mobo for the power-on circuitry. I've already mentioned in my other how
the power circuit works in the post to which I provided a link. The PSU
won't come up unless the mobo lets it but the mobo can't use that
circuitry unless it the 5VSB line is good to the mobo and the PS-On line
is brought low on the 20-pin mobo/PSU connector. That's why in the
other post I mention that you may need to disconnect the PSU from
everything and use a tester (which you can build yourself with just a
power resistor and DVM or buy one but be sure it puts a load on the PSU,
like 10 to 25 watts).

- The PSU fan is jammed with mouse turds or was defective and wore out.
You might have to replace that fan if you have the guts or expertise to
try or just get a new PSU.

You could either get another PSU and see if your system powers up or get
a PSU tester to do the check (and may still end up buying another PSU).
PSU testers aren't super great for testing a power supply. They only
give indication of the voltages coming out of the PSU. Most that I've
seen also have a power resistor inside to provide some load on the PSU
as unloaded taps may not be accurate when measuring their voltage (i.e.,
they look good when unloaded but drop drastically when loaded so the PSU
cannot regulate the voltage to maintain it at the required levels). A
PSU tester will probably run you around $15. If you have a DVM (digital
voltmeter), you could simply leave the PSU hooked up in the barebones
configuration already mentioned and then check the voltage outputs under
load.

If the PSU fan doesn't even jiggle when you hit the Power button, could
be a defective PSU (not supplying the 5VSB to the mobo, blown fuse, or
internal fault) or a defective mobo (that won't let the PSU come on).
Sounds like you are the point that the PSU needs to be disconnected and
tested alone. You mentioned that some LEDs are lit on the mobo which
pretty much means the 5VSB is okay from the PSU to the mobo. I don't
know if a blown fuse would also kill the 5VSB output (depends if the
fuse protects the input side of the PSU or the mains inside the PSU).
So it could be a bad mobo that won't let the PSU come on, bent pins on
the 20-pin header to which the PSU connects to the mobo, or a fault back
in the PSU (with the mains - which the fan also runs off of - and not
with the 5VSB output).

 

[mehere]

sry for not snipping

Got it working it was the PSU

 

[mehere]

Was the PSU

 

[Lee]

First sorry for cross posting I was not sure which NG would give me the
better response.

OK

I have a PC I am trying to rescue form my Parents. They had a mouse
infestation and they got into the PC and obviously the PC stopped working.

Greg

Greg... mouse urine is highly concentrated and therefore highly corrosive.

I've serviced many such machines over the years and got best results by
stripping down the system completely and washing the motherboard, cards,
cables, and case in warm water with dish washing liquid! Rinse with
more warm water.

Do NOT do this with drives.

Allow to dry for a day minimum and then re-assemble.

Even after this, you still may have to replace components.
Good luck
Regards
Lee in Toronto



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