Laptop boots to blank screen

Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.

If I pull the power cable out, push it back in, then press the power button
the same thing happens,

However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but then
the laptop appears to cut the power (as if it is overheating) ... then 2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..

I did manage to boot as far as the windows logo by leaving the laptop in a
cold room for an hour and then trying.

So you see why it points to overheating .. but on the other hand when I feel
the heatsink with my finger it does not feel too hot at all! (I had another
laptop overheat, and it felt hot alright)

any ideas?

"someone_else" wrote in
message ...
Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.

If I pull the power cable out, push it back in, then press the power
button the same thing happens,

However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but
then the laptop appears to cut the power (as if it is overheating) ...
then 2 seconds later the fan whirrs on as if the laptop is rebooting.
Nothing appears on the screen ..

I did manage to boot as far as the windows logo by leaving the laptop in
a cold room for an hour and then trying.

So you see why it points to overheating .. but on the other hand when I
feel the heatsink with my finger it does not feel too hot at all! (I had
another laptop overheat, and it felt hot alright)

any ideas?

I should add I tried the laptop with the hard drive out, then with the
memory out, I also tested it with the battery and had the same results. ( I
had to remove it when the laptop would not shut down during the endless
rebooting)

Could it be a problem with the GPU heatsink? (I've only been looking at the
CPU heatsink) I'm not sure where on this thing the GPU heatsink is. (it's a
Packard bell Easynote)

The other thing I considered .. maybe there's a voltage problem on some
component . but I don't know where to start looking ..

"someone_else" wrote in
message ...

"someone_else" wrote in
message ...
Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.

If I pull the power cable out, push it back in, then press the power
button the same thing happens,

However if I power down by holding the power button for 7 seconds
(leaving the power cable attached); the fan whirrs for 2 seconds as
before, but then the laptop appears to cut the power (as if it is
overheating) ... then 2 seconds later the fan whirrs on as if the laptop
is rebooting. Nothing appears on the screen ..

I did manage to boot as far as the windows logo by leaving the laptop in
a cold room for an hour and then trying.

So you see why it points to overheating .. but on the other hand when I
feel the heatsink with my finger it does not feel too hot at all! (I had
another laptop overheat, and it felt hot alright)

any ideas?

I should add I tried the laptop with the hard drive out, then with the
memory out, I also tested it with the battery and had the same results.
( I had to remove it when the laptop would not shut down during the
endless rebooting)

Could it be a problem with the GPU heatsink? (I've only been looking at
the CPU heatsink) I'm not sure where on this thing the GPU heatsink is.
(it's a Packard bell Easynote)

The other thing I considered .. maybe there's a voltage problem on some
component . but I don't know where to start looking ..

It's cooling down in this room now, I connected the power cable, press the
power button and again it's got a far as the windows logo screen and has
stopped, the logo screen is just sitting there, no activity. I add this to
my report only to speculate that if the CPU or the GPU were overheating
surely they would overheat even in this halted state. The CPU fan is not
even blowing. So I therefore don't believe the laptop is overheating at all.

any ideas?

On Sun, 5 Apr 2009 02:13:57 +0100, "someone_else"
wrote:


"someone_else" wrote in
message ...

I should add I tried the laptop with the hard drive out, then with the
memory out, I also tested it with the battery and had the same results.
( I had to remove it when the laptop would not shut down during the
endless rebooting)

You won't be able to get it to do anything without the
memory installed. Next time you are able to get it to POST
and attempt to boot, boot to a Memtest86+ CDR and run
memtest86+ for a half hour noting whether it locks up or
produces any errors.


Could it be a problem with the GPU heatsink? (I've only been looking at
the CPU heatsink) I'm not sure where on this thing the GPU heatsink is.
(it's a Packard bell Easynote)


If it has integrated chipset video then the GPU is built
into the northbridge, which is often cooled by the same
heatpipe assembly that cools the CPU, so look around for
another smaller chip under the heatpipe.

A separate discrete GPU could also be under the same
heatsink, or if you see a 2nd heatsink that's more likely
where it would be if 2nd 'sink isn't southbridge. Seek a
service manual for it which may list component location, and
you might seek a similar model mainboard on ebay or a laptop
parts store online to see if you can find a picture of the
mainboard large enough to make out components on it.



The other thing I considered .. maybe there's a voltage problem on some
component . but I don't know where to start looking ..

If there is a voltage problem that is not due to
malfunctioning AC adapter, it seems beyond your ability to
find and fix a mainboard problem so that would suggest
needing a new mainboard. Memory, like mainboard can have
bad solder joints that break open when they get warm so if
you have different memory or another system to test the
memory in, that might rule it out.


It's cooling down in this room now, I connected the power cable, press the
power button and again it's got a far as the windows logo screen and has
stopped, the logo screen is just sitting there, no activity. I add this to
my report only to speculate that if the CPU or the GPU were overheating
surely they would overheat even in this halted state. The CPU fan is not
even blowing. So I therefore don't believe the laptop is overheating at all.

any ideas?

Usually if/when a fan fails, it's due to the bearing being
shot. Push on the fan blades, use something long and thin
like a straw or small paint brush if it's hard to access the
fan, and see if the fan spins freely when you give it a
little nudge, or if it seems stiff like the bearing has
failed. However, this seems unlikely as you previously
reported it was spinning, but some fans become problematic
when they get warmer causing different tolerance in the
bearing... I'm just trying to rule a few things out since
only you can see the laptop and I don't know if it is
designed to totally turn the fan off when it's not very hot
or only spin it at low RPM.

Best guess failing any further evidence from comments above
is that the mainboard has failed. You could pull it out and
inspect it in case anything is visually obvious, but
otherwise you are left deciding what whole laptop would be
worth if it worked again and weighing that against
replacement mainboard cost if it's no longer under warranty.

someone_else wrote:
Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.

If I pull the power cable out, push it back in, then press the power button
the same thing happens,

However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but then
the laptop appears to cut the power (as if it is overheating) ... then 2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..

I did manage to boot as far as the windows logo by leaving the laptop in a
cold room for an hour and then trying.

So you see why it points to overheating .. but on the other hand when I feel
the heatsink with my finger it does not feel too hot at all! (I had another
laptop overheat, and it felt hot alright)

any ideas?


A heatsink can be cold for two reasons.

1) It can be so well cooled, for the level of power being dissipated,
that it ends up having a low temperature.

2) If the heatsink is not making contact with the hot object, then
the heatsink will remain cold. That is my suspicion in your case.

When a heatsink is attached to a processor, usually a thermal interface
material (TIM) of some sort, is applied between the heatsink and the processor,
to promote good heat conduction. On my current computer for example,
the heatsink and the top of the CPU are not flat, so there isn't contact
over the entire area. I use thermal paste, to bridge the gap. Only
a little is needed, a thin film, enough to fill surface irregularities
- if you apply too much, it gushes out and gets into the processor socket.
Which can upset the electrical connections.

I usually "calibrate" by first applying a very small dot of paste (half
a rice grain). Then squish it into place with the heatsink. Now, take
it apart, and estimate how much larger the next application would have
to be, for the paste to reach the edge of the mating surfaces. Add a
little more, because you want the gap to be "wet" and be showing
some paste. But not so much, that it drips down on stuff.

Between applications, you clean off all the loose material, before
applying fresh paste. I use isopropyl alcohol, which isn't really
the correct solvent. There is a kit, which does a better job if you
want something that really dissolves the paste. After cleaning, you
want to allow the thing to dry, before applying the paste. Any material
which dilutes the paste, even fibers from a cleaning rag, can
reduce the cooling efficiency a bit.

(Cleaner, for rich people)
http://www.newegg.com/Product/Produc...82E16835100010

(Ceramique - a thermal paste)
http://www.newegg.com/Product/Produc...82E16835100009

There are other materials besides paste. There are thermal pads
of various sorts. There are phase change materials, which
are sometimes screen-printed onto the surfaces, by the
manufacturer. But paste is the thing which consumers have
the easiest time buying. That doesn't mean it is the
best, from the end user point of view, because paste
occasionally needs to be reapplied (it can dry out or
squeeze out, of the gap).

I still have my original tube of AS3, and that stuff lasts
a long time. Mine has actually started to separate in the
tube. That is how old it is.

Everything inside a laptop, breaks easily. Take care.

Good luck,
Paul

On Apr 4, 9:49*pm, Paul wrote:
someone_else wrote:
Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.

If I pull the power cable out, push it back in, then press the power button
the same thing happens,

However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but then
the laptop appears to cut the power (as if it is overheating) ... then 2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..

I did manage to boot as far as the windows logo by leaving the laptop in *a
cold room for an hour and then trying.

So you see why it points to overheating .. but on the other hand when I feel
the heatsink with my finger it does not feel too hot at all! (I had another
laptop overheat, and it felt hot alright)

any ideas?

A heatsink can be cold for two reasons.

1) It can be so well cooled, for the level of power being dissipated,
* * that it ends up having a low temperature.

2) If the heatsink is not making contact with the hot object, then
* * the heatsink will remain cold. That is my suspicion in your case.


Thanks for replying!

If the heatsink is not making contact would it not shut down in all
cases?
At the moment, the laptop does remain powered up, (but only after I
disconnect and reconnect the power), and with a blank screen.
Yesterday it got as far as the windows logo screen before it froze. If
it was overheating would it not shut down in that case?

I really need to try thermal paste in any case, there is nothing to
lose.

cheers!

wrote:
On Apr 4, 9:49 pm, Paul wrote:
someone_else wrote:
Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.
When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.
If I pull the power cable out, push it back in, then press the power button
the same thing happens,
However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but then
the laptop appears to cut the power (as if it is overheating) ... then 2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..
I did manage to boot as far as the windows logo by leaving the laptop in a
cold room for an hour and then trying.
So you see why it points to overheating .. but on the other hand when I feel
the heatsink with my finger it does not feel too hot at all! (I had another
laptop overheat, and it felt hot alright)
any ideas?
A heatsink can be cold for two reasons.

1) It can be so well cooled, for the level of power being dissipated,
that it ends up having a low temperature.

2) If the heatsink is not making contact with the hot object, then
the heatsink will remain cold. That is my suspicion in your case.


Thanks for replying!

If the heatsink is not making contact would it not shut down in all
cases?
At the moment, the laptop does remain powered up, (but only after I
disconnect and reconnect the power), and with a blank screen.
Yesterday it got as far as the windows logo screen before it froze. If
it was overheating would it not shut down in that case?

I really need to try thermal paste in any case, there is nothing to
lose.

cheers!


So then maybe it is just freezing. If the power remains
running, but the screen won't update, then it could be
a freeze. It could even be just the display that is
frozen. (If the computer is networked with other
computers, you can try "ping" from another computer,
to see if it'll answer a ping request. If it answers,
then the processor on the laptop would still be
running.)

Freezing problems aren't that easy to debug - it could be
motherboard, CPU, RAM that is involved. Only in a few cases,
does it involve something like a bad driver. (Years ago, there
was a Marvell Ethernet driver that caused freezing.) But your
freezes are early in the boot process, so the drivers aren't
even running at that point. When the Windows desktop appears,
the drivers should all have run their initialization code
at that point. The fact that there is a time component
(runs longer when cold), suggests there is a thermal
component to it, but it still doesn't tell you what part
inside the thing, is at fault.

Tools you could try

1) Memtest86+ from floppy or CD (memtest.org)
2) Linux LiveCD from CD.
3) Booting DOS from a floppy or CD (there is at least one
CD image of a DOS floppy available out there)

My reason for recommending memtest86+, is not for the memory
test part. It is to see if a really tiny program can load and
run without freezing. Then, see how long the machine can run
with that test running. If it works, then you know that
memtest86+ doesn't use all the hardware in the computer.
It won't be trying to run the network interface, Wifi,
stuff like that.

DOS would be for similar issues - it might use a subset of
the hardware.

Linux would try to use everything, and I doubt you'd get
any further than Windows would. I only use that test case,
because I already have a number of CDs. I like older versions
of Knoppix (several of the 5 series), since they tend to write
text on the screen while they're starting up. When a computer
is unstable, the error messages printed in text during the
boot, gives you plenty of evidence to look at. Linux LiveCDs
that are silent during boot, are less useful.

Paul

"Paul" wrote in message
...
wrote:
On Apr 4, 9:49 pm, Paul wrote:
someone_else wrote:
Hi all,
I received a laptop to fix today .. It behaves like it is overheating
but
I'm not sure.
When the power button is pressed the laptop fan whirs for about 2
seconds
and then nothing happens the screen is left blank, no further activity.
If I pull the power cable out, push it back in, then press the power
button
the same thing happens,
However if I power down by holding the power button for 7 seconds
(leaving
the power cable attached); the fan whirrs for 2 seconds as before, but
then
the laptop appears to cut the power (as if it is overheating) ... then
2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..
I did manage to boot as far as the windows logo by leaving the laptop
in a
cold room for an hour and then trying.
So you see why it points to overheating .. but on the other hand when I
feel
the heatsink with my finger it does not feel too hot at all! (I had
another
laptop overheat, and it felt hot alright)
any ideas?
A heatsink can be cold for two reasons.

1) It can be so well cooled, for the level of power being dissipated,
that it ends up having a low temperature.

2) If the heatsink is not making contact with the hot object, then
the heatsink will remain cold. That is my suspicion in your case.


Thanks for replying!

If the heatsink is not making contact would it not shut down in all
cases?
At the moment, the laptop does remain powered up, (but only after I
disconnect and reconnect the power), and with a blank screen.
Yesterday it got as far as the windows logo screen before it froze. If
it was overheating would it not shut down in that case?

I really need to try thermal paste in any case, there is nothing to
lose.

cheers!


So then maybe it is just freezing. If the power remains
running, but the screen won't update, then it could be
a freeze. It could even be just the display that is
frozen. (If the computer is networked with other
computers, you can try "ping" from another computer,
to see if it'll answer a ping request. If it answers,
then the processor on the laptop would still be
running.)

Freezing problems aren't that easy to debug - it could be
motherboard, CPU, RAM that is involved. Only in a few cases,
does it involve something like a bad driver. (Years ago, there
was a Marvell Ethernet driver that caused freezing.) But your
freezes are early in the boot process, so the drivers aren't
even running at that point. When the Windows desktop appears,
the drivers should all have run their initialization code
at that point. The fact that there is a time component
(runs longer when cold), suggests there is a thermal
component to it, but it still doesn't tell you what part
inside the thing, is at fault.

Tools you could try

1) Memtest86+ from floppy or CD (memtest.org)
2) Linux LiveCD from CD.
3) Booting DOS from a floppy or CD (there is at least one
CD image of a DOS floppy available out there)

My reason for recommending memtest86+, is not for the memory
test part. It is to see if a really tiny program can load and
run without freezing. Then, see how long the machine can run
with that test running. If it works, then you know that
memtest86+ doesn't use all the hardware in the computer.
It won't be trying to run the network interface, Wifi,
stuff like that.

DOS would be for similar issues - it might use a subset of
the hardware.

Linux would try to use everything, and I doubt you'd get
any further than Windows would. I only use that test case,
because I already have a number of CDs. I like older versions
of Knoppix (several of the 5 series), since they tend to write
text on the screen while they're starting up. When a computer
is unstable, the error messages printed in text during the
boot, gives you plenty of evidence to look at. Linux LiveCDs
that are silent during boot, are less useful.

Paul

I tried Memtest boot disk, Knoppix live cd and Windows XP install disk.
Nothing appeared on screen, they all spun in the drive for a second but
nothing seemed to happen after that. I tried pressing a key or two (return
for example) to see if any seeks were initiated but no joy, no noises from
the CD drive.

Any ideas on why the laptop no longer makes it to the windows logo screen,
when a couple of days ago it made it into windows, once, and then froze?

Here's a theory: Maybe there was a loose wire/connection to the GPU/LCD,
maybe it came loose (er) and caused a short, causing the laptop to refuse to
continue the POST.

Think I'll take it apart again, this time I'll look at the connections to
the LCD, they are not easy to follow unless it's completely disassembled.

someone_else wrote:


I tried Memtest boot disk, Knoppix live cd and Windows XP install disk.
Nothing appeared on screen, they all spun in the drive for a second but
nothing seemed to happen after that. I tried pressing a key or two (return
for example) to see if any seeks were initiated but no joy, no noises from
the CD drive.

Any ideas on why the laptop no longer makes it to the windows logo screen,
when a couple of days ago it made it into windows, once, and then froze?

Here's a theory: Maybe there was a loose wire/connection to the GPU/LCD,
maybe it came loose (er) and caused a short, causing the laptop to refuse to
continue the POST.

Think I'll take it apart again, this time I'll look at the connections to
the LCD, they are not easy to follow unless it's completely disassembled.

On a desktop, I'd use a "beep test" as a test case.

Removing the RAM on a desktop, causes the processor to beep the
PC speaker. It proves two things. The computer realizes it doesn't
have any RAM. But the beep sound is made under program control,
and when you hear the "beep", you know the processor went down
through the Northbrdge and Southbridge, and read code from the
BIOS EEPROM. So it executed some BIOS code, in order to know
how to beep.

Sometimes, bad RAM will cause the BIOS program to get stuck, and
it cannot beep even though the RAM is bad. If removing the RAM,
gives a beep, then you'd suspect bad RAM was holding it
hostage.

You need to concentrate on some lower level tests, and
give up on Windows for now.

Simplify the setup. Disconnect the hard drive and optical
drive cabling. Experiment with removing the memory.

A laptop may have an LCD display, but it also has a VGA
or DVI connector on the back. You can try plugging a monitor
in there, if you suspect the LCD is no longer working.

The most likely cause of a "black" LCD screen, is a
backlight failure. There is a CCFL tube behind the
screen, that provides the light. The tube is driven
by a small board called an inverter. It converts 12VDC
to 1000 VAC at low current. That is what causes the CCFL
gas filled tube to light up. The CCFL draws about 3 watts
of power, so is not a strong light source. The "LCD"
part of the display is more reliable than the light
source.

But just as easily, a failure to execute BIOS code, will also
cause a black screen (GPU not programmed etc). So you cannot
for certain, associate a black screen, with a bad backlight.
It could be black for other reasons.

I see no reason to play with the LCD at the moment. If you
know your laptop beeps at startup, work with that to start
with. And if you really think the display is busted, use
an external LCD monitor and a VGA cable.

There is probably some key you press, to get into the BIOS.
On the machines here, the two different keys they use, are
the Delete key and F2. Different brands of computers choose
to use a different key, so check the user manual to know
for sure. "Fn F5" might change the display, to use the
external VGA, but that would only work if some software
is there to intercept the key press. As far as I know,
switching to the VGA connector is not a direct hardware
type feature.

Getting into the BIOS is an even lower level check than
trying to run Windows. Seeing the name of the hard drive
and of the optical drive, in the BIOS, would be proof
of a little bit of communications working with them.

The inside of the laptop contains power conversion circuits.
They convert battery voltage, into lower voltages that run
the logic. Your symptoms are also consistent with a failure
in those circuits. Even bad capacitors could do it (give
variable startup results, run for a short period of time and
so on). It isn't necessarily a logic failure - it could be
related to how things are powered internally.

Good luck,
Paul

On Sun, 5 Apr 2009 01:48:08 +0100, "someone_else"
wrote:

Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

It's always good to start out mentioning the specific make,
model, spec of the hardware.



When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.

But the laptop remains powered, LEDs lit at least?



If I pull the power cable out, push it back in, then press the power button
the same thing happens,

However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but then
the laptop appears to cut the power (as if it is overheating) ... then 2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..


You mean when you try to turn it on again after holding down
the power button for 7 seconds, or that it tries to start on
it's own without your having pressed the button?

Is the battery still installed at this point or you have no
battery or it won't hold a charge, or ??



I did manage to boot as far as the windows logo by leaving the laptop in a
cold room for an hour and then trying.

So you see why it points to overheating .. but on the other hand when I feel
the heatsink with my finger it does not feel too hot at all! (I had another
laptop overheat, and it felt hot alright)

Not necessarily overheating, it might be or it could be a
bad solder joint or crack elsewhere on the PCB, especially
considering laptops are subject to a lot more stress than a
desktop.

What is the history of the system? Has anyone else mucked
around inside it? Generally speaking the heatsink interface
won't go bad all by itself, it would require someone to take
the 'sink off and try to reuse the thermal interface
material again if it's a phase-change waxy pad instead of a
silicone rubber pad.

When it feels cool, is this always when it shows no response
on-screen or does it also feel cool when you are able to get
it to start booting windows? If it has had the battery
installed all this time, try it without the battery, and
vice-versa, if you'd been using the AC adapter try charging
the battery and using only battery power.