Computer won't power up

[CLC]

My wife's computer stopped working the other day. She would push the power
button and nothing would happen. I guessed ot was either the power button
or the power supply. I bought a new case but it didn't start up. Next
thought it was the motherboard, so I bought a new mother board. Still no
power. Any ideas?

 

[Dave]

My wife's computer stopped working the other day. She would push the power
button and nothing would happen. I guessed ot was either the power button
or the power supply. I bought a new case but it didn't start up. Next
thought it was the motherboard, so I bought a new mother board. Still no
power. Any ideas?

TWO bad power supplies.

Any power supply you get with a case is junk. NO exceptions. No, not even
Antec. There are some good Antec power supplies, but I've never seen one
sold as a set with a case. Now watch someone post their junk as "but this
one is good".

My best guess would be that the original power supply died, and the
replacement power supply is incompatible, or not connected right.

But we'd need more information to troubleshoot this. Does NOTHING happen
when you press the power button? Nothing AT ALL?

If so, that would point to a bad power supply (or two of them) or maybe the
first one died and the second one was not connected properly.

If you get fans spinning and LED lights on (but nothing else happens) when
you press power, that would be (again) bad power supply or possibly new
power supply not connected properly. BUT, in this second example, you might
instead have a bad motherboard (more likely) or bad CPU (less likely).

Always look at the power supply first in a system that won't power on. Yes,
there are other things that can cause this symptom, but the odds are so slim
that it will be something other than the power supply, that it's best to
start AT the power supply.

In short, you have not eliminated the power supply as a suspect, and that is
what your symptom is pointing to. -Dave

 

[jim evans]

Remove or completely unplug everything except the processor, RAM and
monitor then try to boot. Do it do anything? Does it beep? Does
anything display on the screen? I you see bios data on the screen
when you didn't before, one of the things you unplugged has failed.

If the answer is nothing happens, I agree with Dave. Looks like two
bad power supplies. Power supplies are a common thing to fail. Stock
boxes come with crap power supplies.

 

[w_tom]

My wife's computer stopped working the other day. She would push the power
button and nothing would happen. I guessed ot was either the power button
or thepower supply. ... Any ideas?

Wild speculation to fix something typically costs more money and
wastes time. "Follow the evidence" as said in CSI. Best way to
accomplish that is to spend only 30 seconds with a meter (as sold even
in K-mart) to first learn what exists. Your eyes cannot see what is
obvious. Numbers from the meter will either see the problem
immediately OR make possible posts here that are useful. An answer
based in speculation is wasted time and money.

Procedure was posted previously in "When your computer dies without
warning....." starting 6 Feb 2007 in the newsgroup alt.windows-xp
at:
http://tinyurl.com/yvf9vh
Connector chart to locate each color:
http://www.hardwarebook.net/connector/power/atxpower.html

In your case, important are numbers from the purple, gray, and green
wires both before and when power switch is applied. Less than 30
seconds. Do not complicate the problem by removing or disconnecting
anything. A part is replaced because the problem is obvious. Same
procedure then confirms a successful solution. Most are unaware that
a defective power supply can still boot a computer. Procedure can
also identify a defective new supply long before its warranty expires.

 

[Stephen]

My wife's computer stopped working the other day. She would push the power
button and nothing would happen. I guessed ot was either the power button
or the power supply. I bought a new case but it didn't start up. Next
thought it was the motherboard, so I bought a new mother board. Still no
power. Any ideas?

Plugged in with a good cord into an outlet with power?

 

[Jan Alter]

Wild speculation to fix something typically costs more money and
wastes time. "Follow the evidence" as said in CSI. Best way to
accomplish that is to spend only 30 seconds with a meter (as sold even
in K-mart) to first learn what exists. Your eyes cannot see what is
obvious. Numbers from the meter will either see the problem
immediately OR make possible posts here that are useful. An answer
based in speculation is wasted time and money.

Procedure was posted previously in "When your computer dies without
warning....." starting 6 Feb 2007 in the newsgroup alt.windows-xp
at:
http://tinyurl.com/yvf9vh
Connector chart to locate each color:
http://www.hardwarebook.net/connector/power/atxpower.html

In your case, important are numbers from the purple, gray, and green
wires both before and when power switch is applied. Less than 30
seconds. Do not complicate the problem by removing or disconnecting
anything. A part is replaced because the problem is obvious. Same
procedure then confirms a successful solution. Most are unaware that
a defective power supply can still boot a computer. Procedure can
also identify a defective new supply long before its warranty expires.

No question that you'll get more information about the PS if a multimeter is
used to get the voltages. For one who is used to using one, checking
voltages, putting probes on connectors and knowing the safety skills that
are necessary to do testing this becomes trivial. For one who is a complete
novice, who only knows that they plugged the thing in and it didn't work,
all you have to do is mention 'voltage' and they think they are speaking a
forbidden language.
I AGREE, everyone should know how to use a multimeter, as well as using a
jack on a car to change a flat. It is a life skill, along with so many other
things, such as cutting a piece of wood with a handsaw. Reality is though,
that most people can't or don't know how to change a flat tire, and even
less people know how to use a multimeter and are even less reluctant to
learn because of the misbeliefed fear of 'immediate electricution' should
they attempt using one.
That said, I would urge the OP first to check the obvious; that the
outlet has electricity, that the power cord is good and plugged all the way
into the PS, that the power supply switch has not been inadvertantlly
switched from 110 to 220. If all that has been checked I would go to the
store and get the multimeter (everyone should have one. They are not only
invaluable, but they will impress the hell out of most of the population
when one knows how to use it) and really take the effort to check the
voltages as w_tom proposed in the first place. Play with it using a small
battery, such as a D or C cell until satisfied that it will not harm them
and actually does provide information. Then do the PS voltage check on the
power supply.
I would take the trouble to remove the PS from the computer first, so
accidents do not happen in the computer case and to simplify the diagnostic
effort. Put the PS on the table and attach a spare hard drive to it (as a
load) to make the voltage checks.
There are many good web pages available to go through the test process, and
(here's where I'm getting myself into trouble) it is quite straight forward
and easy, after one has practiced and feels at home with the multimeter.
For most they would see this dead computer as a problem. For a few they
would see it as an opportunity to learn something as they fix the dead
computer.

 

[John Doe]

No question that you'll get more information about the PS if a
multimeter is used to get the voltages.

If you are using a modern mainboard, you might actually get better
readings from the BIOS or from within Windows with a utility. That's
similar to using a utility that checks system temperatures. Make more
sense to test voltages and temperatures under a full load.

For one who is used to using one, checking voltages, putting
probes on connectors and knowing the safety skills that are
necessary to do testing this becomes trivial. For one who is a
complete novice, who only knows that they plugged the thing in and
it didn't work,

Safety is one concern. Trying to avoid destroying your hardware is
another concern. And if you're checking voltage, you better be sure
to avoid having the probe plugged into the current jack. Otherwise,
then you learn how to replace the fuse.

I AGREE, everyone should know how to use a multimeter,

Since I stoped doing electronics, I occasionally use mine for
checking battery voltages. But there are battery voltage checkers
for that.

 

[John Doe]

TWO bad power supplies.

Any power supply you get with a case is junk. NO exceptions. No,
not even Antec. There are some good Antec power supplies, but
I've never seen one sold as a set with a case. Now watch someone
post their junk as "but this one is good".

Someone question your opinion? I had no problems with the Antec
SmartPower 350 W supply that came with a case. In fact, it's still
working fine in my backup system.

 

[w_tom]

If you are using a modern mainboard, you might actually get better
readings from the BIOS or from within Windows with a utility. That's
similar to using a utility that checks system temperatures. Make more
sense to test voltages and temperatures under a full load.

Procedure using the multimeter also requires orange, red, yellow,
and purple wires measured under a full load. That missing load is why
power supply testers are so ineffective. That is also why the meter
would identify other problems such as a defective power cord,
excessively low AC voltage, or a defective power switch. All verified
in the same 'less than two minute' procedure posted above.

Some motherboards already include a multimeter inside its
semiconductors. But a 3.5 digit multimeter is necessary to calibrate
those BIOS hardware numbers. Any Windows utility that would read
voltages only uses the same hardware that must still be calibrated
with the meter.