Power switch problem of my Dell 600m laptop

[antonyliu2002]

Hi, guys,

Last August, I asked here about a power switch problem of my Dell 600m
laptop, which I got in June 2003.

Here is the link and thank you guys' diagnosis.

http://groups.google.com/group/alt....onyliu2002+600m&rnum=1&hl=en#787f77f33ff0f5cd

At that time, I said that I could not tell when the laptop will power
on when I push the power button.

I have noticed a pattern of the power function behavior recently.

I notice that it is impossible to power on this laptop shortly (say,
within 30 minutes or so) after it is powered off. It seems that I have
to let the entire laptop cool down to room temperature before I can
power it on the second time.

For example, quite often I have to shut down this laptop at home, put
it in my backpack, and then drive to my school library. This takes
around 10 minutes. At the library, I will have to wait 20 minutes or
so before I can power on this laptop.

I've noticed that this behavior has been pretty consistent. What do
you guys think might be wrong with this laptop? Why does it behave
like this?

Thanks.

 

[kony]

Hi, guys,

Last August, I asked here about a power switch problem of my Dell 600m
laptop, which I got in June 2003.

Here is the link and thank you guys' diagnosis.

http://groups.google.com/group/alt....onyliu2002+600m&rnum=1&hl=en#787f77f33ff0f5cd

At that time, I said that I could not tell when the laptop will power
on when I push the power button.

I have noticed a pattern of the power function behavior recently.

I notice that it is impossible to power on this laptop shortly (say,
within 30 minutes or so) after it is powered off. It seems that I have
to let the entire laptop cool down to room temperature before I can
power it on the second time.

For example, quite often I have to shut down this laptop at home, put
it in my backpack, and then drive to my school library. This takes
around 10 minutes. At the library, I will have to wait 20 minutes or
so before I can power on this laptop.

I've noticed that this behavior has been pretty consistent. What do
you guys think might be wrong with this laptop? Why does it behave
like this?

Thanks.

Is the battery fairly good or you're using an AC adapter
(like the original supply with it) or not? If the battery
were going bad I'd wonder if running it caused a voltage
depression which was too low to handle the initial surge at
a power-on event. It doesn't seem likely, but one other
thought was that perhaps the heating up was causing an
intermittent connection internally, but I would've thought
that would also interfere with proper operation while it was
running, not only after being turned off and then (attempt
to) turn on again.

In this period of time between power off & on again, have
you tried leaving the AC adapter in so it's charging the
battery? Do you have a 2nd battery you might take along
and swap in, knowing it's fresh from being recharged to see
if that makes a difference? Failing anything else, I'd
probably disassemble it, looking for any obviuos signs of
problems and try to push in, "jiggle" the ribbon connectors
in their sockets a little to try to ensure a good seating
and connection.

 

[antonyliu2002]

Is the battery fairly good or you're using an AC adapter

(like the original supply with it) or not? If the battery
were going bad I'd wonder if running it caused a voltage
depression which was too low to handle the initial surge at
a power-on event. It doesn't seem likely, but one other
thought was that perhaps the heating up was causing an
intermittent connection internally, but I would've thought
that would also interfere with proper operation while it was
running, not only after being turned off and then (attempt
to) turn on again.

In this period of time between power off & on again, have
you tried leaving the AC adapter in so it's charging the
battery? Do you have a 2nd battery you might take along
and swap in, knowing it's fresh from being recharged to see
if that makes a difference? Failing anything else, I'd
probably disassemble it, looking for any obviuos signs of
problems and try to push in, "jiggle" the ribbon connectors
in their sockets a little to try to ensure a good seating
and connection.

I always use my laptop with the AC hooked up. I have no idea if the
battery is dying. However, the problem I am talking about does not
seem to be related with the battery, because the same problem exists
even if I take out the battery and use the AC only. Given this, I
doubt it will help to test with a new battery.

This power-on problem exists in any one of the following situations:

1. With AC only, that is, the battery is taken out.
2. With the battery only, that is, the AC is not connected.
3. With both AC and battery at the same time.
4. With neither AC nor battery, that is, no power supply at all.

 

[w_tom]

Imagine a capacitor that issues a reset to every computer IC only
when capacitor is discharged. Then stops outputting that reset signal
when charged. This is how master resets would be done. So that the
capacitor would discharge when computer was turned off, a diode was
also connected to that capacitor. Now let's say that diode has
failed or become disconnected. Now instead of discharging immediately,
the capacitor would take maybe ten minutes to discharge. Since the
capacitor never discharges, then the computer never gets the master
reset. A reset being necessary to tell that computer which program
instruction to execute first.

So the diode is missing or failed. Of course this is only
speculation - as will be most of your answers - due to insufficient
information. Best one can do is put is possibilities such as this.
Then what will you do? Replace motherboard no matter what is
suggested.

Your problem requires analysis at the component level. Your summary
is not even at the board level. It is at the system level. No where
near enough information to solicit anything but speculation. To
confirm the above is a problem, you would have to find that capacitor,
short it out, and then see if computer starts right up. It's just
not going to happen.

However your problem is typical of a 'power up' master reset that
does not happen. Without that master reset, a computer cannot know
what firmware instruction to execute first; appears non-functional
while computer acutally executes jibberish..

 

[CBFalconer]

.... snip ...

Your problem requires analysis at the component level. Your
summary is not even at the board level. It is at the system
level. No where near enough information to solicit anything but
speculation. To confirm the above is a problem, you would have
to find that capacitor, short it out, and then see if computer
starts right up. It's just not going to happen.

However your problem is typical of a 'power up' master reset that
does not happen. Without that master reset, a computer cannot
know what firmware instruction to execute first; appears
non-functional while computer acutally executes jibberish..

There are at least two things everyone should insist on in a
computer. A reset switch, and ECC memory.

 

[antonyliu2002]

Hey, Tom,

Given the scarcity of the information I provided, I think your analysis
really sounds convincing to me, although I do not know much about
hardware. I am almost sure that this is it, because your explanation
of possible capacitor/diode problems really matches the power on/off
behavior of this laptop.

So, suppose this is the problem, and suppose that I want to fix it, I
have no choice except changing the motherboard or getting another
laptop without this problem or stop using any laptop?

 

[w_tom]

Posted previously was this very important point:

Your problem requires analysis at the component level. Your
summary is not even at the board level. It is at the system level.
No where near enough information to solicit anything but
speculation.

Speculation. Number of problems that could also create your problem
is large. A problem made even worse because your analysis is too
distant - at system level.

The point of my post was how something - one of so many possibilities
- could have created your problem - and you still could not do
anything. Meanwhile, another fact. If the product is properly
designed, then it no longer uses the capacitor, resistor, diode timing
circuit. I only provided enough information to demonstrate at what
level your analysis must be done and did not mention the
capacitor/diode/etc circuit should have been long obsoleted by a better
semiconductor solution. The post was to demonstrate a point - not
possible to solve it using your system level analysis.

The scarcity of information is more a function of too many computer
assemblers who don't even know how electricity works. They swap parts,
something works, and therefore they know what failed. Not really.
They never learned about simple electrical functions found in computers
such as how a master reset line works or what it does.

Still this does not solve your problem. I know of no hardware
diagnostic that can even try to locate your problem. You don't even
have an oscilloscope (I speculate) so you are not going to see what the
master reset line does. In short, you are down to sending the laptop
into the shop for new motherboard or power supply control board - where
ever that master reset is generated. And this assumes this problem is
due to a master reset problem. Remember, this is only one of so many
possibilities.

Ask yourself why - if the number of reasons for your problem is large
- then why so few replies? Sparse responses because so many who are
computer repairmen don't even know how the master reset circuit works
OR (in some cases) what it does. My response only demonstrates one
example of wild speculation due to analysis at the system level - not
at board or component level.