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laptop power fault: compaq presario C300EA

T

tg

Jan 1, 1970
0
I have a Compaq laptop Model Presario, service tag C300EA that will not
start. It's this one: http://www.microdevices.lk/images/Laptop.jpg
the motherboard is an IBL30 LA-3324P and they retail for about £125.
ouch
The problem is when I plug a power supply into it and press the on/off
button the power led flashes rapidly for a few seconds and then cuts
out. I then have to wait about a minute before it will light up again.
I've tried three different power supplies, one of them coming from a
battery/voltage converter and all three power supplies produce the same
fault on the laptop so it's not the power supply. It acts the same with
or without a battery fitted. When the power supply is plugged in I did
notice the battery icon flickers all the time with no battery in.
I also connected an amp meter to the power supply and when the power
light does flicker there is virtually no current draw into the laptop.
I split the chassis to take a look and saw that the power socket wires
go straight onto the motherboard. There is no power board or
daughtercard as such..
does anyone have an idea if there's a known component that causes this
problem? or is it a case of new motherboard?
thanks for any pointers.
 
R

Rich Webb

Jan 1, 1970
0
I have a Compaq laptop Model Presario, service tag C300EA that will not
start. It's this one: http://www.microdevices.lk/images/Laptop.jpg
the motherboard is an IBL30 LA-3324P and they retail for about £125.
ouch
The problem is when I plug a power supply into it and press the on/off
button the power led flashes rapidly for a few seconds and then cuts
out. I then have to wait about a minute before it will light up again.
I've tried three different power supplies, one of them coming from a
battery/voltage converter and all three power supplies produce the same
fault on the laptop so it's not the power supply. It acts the same with
or without a battery fitted. When the power supply is plugged in I did
notice the battery icon flickers all the time with no battery in.
I also connected an amp meter to the power supply and when the power
light does flicker there is virtually no current draw into the laptop.
I split the chassis to take a look and saw that the power socket wires
go straight onto the motherboard. There is no power board or
daughtercard as such..
does anyone have an idea if there's a known component that causes this
problem? or is it a case of new motherboard?
thanks for any pointers.

Perhaps the plague? No, not THAT one, THIS one:
<http://en.wikipedia.org/wiki/Capacitor_plague>

Worth eyeballing since you already have the main board exposed.
 
I have a Compaq laptop Model Presario, service tag C300EA that will not
start. It's this one:http://www.microdevices.lk/images/Laptop.jpg
the motherboard is an IBL30 LA-3324P and they retail for about £125.
ouch
The problem is when I plug a power supply into it and press the on/off
button the power led flashes rapidly for a few seconds and then cuts
out. I then have to wait about a minute before it will light up again.
I've tried three different power supplies, one of them coming from a
battery/voltage converter and all three power supplies produce the same
fault on the laptop so it's not the power supply. It acts the same with
or without a battery fitted. When the power supply is plugged in I did
notice the battery icon flickers all the time with no battery in.
I also connected an amp meter to the power supply and when the power
light does flicker there is virtually no current draw into the laptop.
I split the chassis to take a look and saw that the power socket wires
go straight onto the motherboard. There is no power board or
daughtercard as such..
does anyone have an idea if there's a known component that causes this
problem? or is it a case of new motherboard?
thanks for any pointers.

The symptoms suggest a short on the mainboard, the PSU aren't able to
regulate so their protection circuits are cycling them off as best
they can (at the price-point of the design).

There isn't much you can do at this point except strip the mainboard
down as much as possible. Disconnect hard drive, optical, memory, CPU
(except if you take the heatsink off and it was heatsinking the
chipset, you must put that heatsink back on and ensure it makes good
contact with the chipset still), card reader, screen, inverter board.
See if it will then "seem" (since you have no screen, watch the power
LED(s)) to stay on. It may not, without a processor and memory. If
necessary put those back in and retry. If it stays on, reconnect
screen but not the backpanel lighting inverter yet. If it turns on
and stays on, see if there is output to the screen by shining a strong
flashlight on it.

If it works this far, an inverter failure is a common cause. If it
didn't work at all up to this point, mainboard probably needs
replaced. If it works up to some point in the middle, suspect the part
(s) you added at that point. These days such a problem is typically
handled by replacing the mainboard at a repair shop, then if that
doesn't work they replace the next part and so on, till it's fixed or
the customer refuses to pay for their diagnosed problem since often
the laptop cost little more than the total repair cost.
 
H

hr(bob) [email protected]

Jan 1, 1970
0
Didn't think laptops used electrolytic capacitors...

--
Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

What did you think they used for capacitors in the power supply?
 
J

jakdedert

Jan 1, 1970
0
Conor said:
Didn't think laptops used electrolytic capacitors...
They're surface mount, so you might not recognize them. Google is your
friend....
 
What did you think they used for capacitors in the power supply?

In the external AC-DC brick/wart, yes there are certainly
electrolytics.

In the interior of the notebook, only a cost-cutting design would have
any, so yes it is possible but no better notebook would have any.
 
Conor said:
They're surface mount, so you might not recognize them.  Google is your
friend....

Yes, but, although surface mount caps can be electrolytic, in a
notebook (none at all if it's a good design), very few caps are
electrolytic, if any, except in the external brick AC-DC PSU.
 
C

Conor

Jan 1, 1970
0
What did you think they used for capacitors in the power supply?

Grasping at straws.

That's not remotely related to the problem is it?
 
C

Conor

Jan 1, 1970
0
jakdedert said:
They're surface mount, so you might not recognize them. Google is your
friend....

I wouldn't buy any laptop using electrolytics other than in an external
power brick.
 
R

Rich Webb

Jan 1, 1970
0
I wouldn't buy any laptop using electrolytics other than in an external
power brick.

The battery (or external supply) sources one voltage. The main board and
peripheral components require multiple, regulated voltages. Therefore,
somewhere there are several DC-DC converters to supply those voltages.
Those regulators will likely use tants or low ESR aluminum
electrolytics.

The OP is having problems with a "laptop power fault," therefore
*something* is likely wrong in a power stage.

Capacitors in the power stages are rather more likely to fail than
inductors or (properly rated) semiconductors, therefore it's worth
examining them for no other reason than crossing them off the list.
 
I have a Compaq laptop Model Presario, service tag C300EA that will not
start. It's this one: http://www.microdevices.lk/images/Laptop.jpg
the motherboard is an IBL30 LA-3324P and they retail for about £125.
ouch
The problem is when I plug a power supply into it and press the on/off
button the power led flashes rapidly for a few seconds and then cuts
out. I then have to wait about a minute before it will light up again.
I've tried three different power supplies, one of them coming from a
battery/voltage converter and all three power supplies produce the same
fault on the laptop so it's not the power supply. It acts the same with
or without a battery fitted. When the power supply is plugged in I did
notice the battery icon flickers all the time with no battery in.
I also connected an amp meter to the power supply and when the power
light does flicker there is virtually no current draw into the laptop.
I split the chassis to take a look and saw that the power socket wires
go straight onto the motherboard. There is no power board or
daughtercard as such..
does anyone have an idea if there's a known component that causes this
problem? or is it a case of new motherboard?
thanks for any pointers.

Check that it's not the Compaq model that used RAM for BIOS and dies
when the backup battery gets low.
 
J

Jerry Peters

Jan 1, 1970
0
In said:
Yes, but, although surface mount caps can be electrolytic, in a
notebook (none at all if it's a good design), very few caps are
electrolytic, if any, except in the external brick AC-DC PSU.

That's complete nonsense, of course a laptop uses electrolytics, and
lots of them to filter power throughout the unit. As jakedart said
they're surface mount units. Take one apart sometime & look.

Jerry
 
J

Jerry Peters

Jan 1, 1970
0
In said:
The symptoms suggest a short on the mainboard, the PSU aren't able to
regulate so their protection circuits are cycling them off as best
they can (at the price-point of the design).

There isn't much you can do at this point except strip the mainboard
down as much as possible. Disconnect hard drive, optical, memory, CPU
(except if you take the heatsink off and it was heatsinking the
chipset, you must put that heatsink back on and ensure it makes good
contact with the chipset still), card reader, screen, inverter board.
See if it will then "seem" (since you have no screen, watch the power
LED(s)) to stay on. It may not, without a processor and memory. If
necessary put those back in and retry. If it stays on, reconnect
screen but not the backpanel lighting inverter yet. If it turns on
and stays on, see if there is output to the screen by shining a strong
flashlight on it.

If it works this far, an inverter failure is a common cause. If it
didn't work at all up to this point, mainboard probably needs
replaced. If it works up to some point in the middle, suspect the part
(s) you added at that point. These days such a problem is typically
handled by replacing the mainboard at a repair shop, then if that
doesn't work they replace the next part and so on, till it's fixed or
the customer refuses to pay for their diagnosed problem since often
the laptop cost little more than the total repair cost.

Had a problem like that with an old Dell laptop. Measuring the
resistance across the power input jack showed a direct short. After
disassembling the unit I found an electrolytic across the power lines,
after the rf filter & fuse that was shorted. Removed it and the laptop
now works fine (so much for no electrolytics in laptops).

Jerry
 
In said:
Conor wrote:



That's complete nonsense, of course a laptop uses electrolytics, and
lots of them to filter power throughout the unit. As jakedart said
they're surface mount units. Take one apart sometime & look.

        Jerry

I have, several times. They use mostly if not entirely solid,
(usually chip) caps, and ceramics with good reason. Electrolytics
wear out too fast inside modern laptops because of the elevated temps,
not to mention their height being a problem when engineering something
as thin as reasonably possible.

Here's a picture of both sides of a quite typical HP laptop mainboard,
under two years old and quite similar to what they're still using.
Point out the electrolytic caps on it and BTW, this is the whole thing
there is no separate power board:

http://img242.imageshack.us/img242/5075/topsmfz3.jpg
http://img243.imageshack.us/img243/961/bottomsmsf5.jpg

The solid caps are black, and yellow. The ceramics of course are tan.
There are plenty more pictures from 3rd parties available with a
google search if you can't accept the above pics are typical:
http://images.google.com/images?q=laptop+mainboard
 
... BTW, this is the whole thing
there is no separate power board:

By that I meant no internal power converter board that's separate, it
does have a separate input jack board (also without caps, it's only a
strip big enough to hold a couple jacks), and the brick AC-DC adapter
separate as with practically all laptops in the last several years.
 
Had a problem like that with an old Dell laptop. Measuring the
resistance across the power input jack showed a direct short. After
disassembling the unit I found an electrolytic across the power lines,
after the rf filter & fuse that was shorted. Removed it and the laptop
now works fine (so much for no electrolytics in laptops).

        Jerry

Now you know one of the reasons why they don't typically put
electrolytics in laptops anymore. I never suggested no old laptop
ever had any, but this is a pretty modern laptop not some ancient Dell.
 
B

bz

Jan 1, 1970
0
[email protected] wrote in [email protected]:

Two light tan, near left bottom corner, ~1/4 distance to top edge and ~1/8
distance to right edge, with brown polarity bands, opposite polarity, bands
out.

There are almost certainly others but resolution insufficient.

I see at least 3 on the bottom view, one near the top edge center and two
near the bottom edge center, partially hidden by a wiring bundle.

Any cap over 10 uF will probably be electrolytic.




--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap
 
C

Conor

Jan 1, 1970
0
I guess you'll never own one then ....

There speaks someone who knows **** all about electronics. If you did,
you'd know why electrolytic caps in a laptop is generally considered "A
Bad Idea".
 
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