Does anyone have component level repair experience on laptops?
I've got a Dell Inspiron 8500 notebook computer with a charging problem-
The computer will run fine from the batteries until they are dead.
When plugged into the AC adapter, the BIOS gives an error message stating
that it cannot recognize the AC adapter, but it will power the computer. It
will not charge the batteries with the AC adapter.
The AC adapter has been confirmed good in two ways: the AC adapter powers
another identical computer with no problem, and another adapter gives the
same symptom.
When I plug the AC adapter into a Port Replicator and the computer onto the
port replicator, the batteries will charge.
The adapter input jack on the motherboard has been replaced, and I've
inspected the board as well as possible for a bad connection or faulty
components, but without a schematic of the power/charging circuit it's
nearly impossible to search for a fault.
The obvious solution is to replace the motherboard - again (this is my third
mobo in 5 years). I don't wish to invest another $160 in parts for another
temporary repair on this flawed design.
Does anyone have a schematic (longshot) or experience on repairing this
mobo?

"Mike S" nospam wrote in :

Does anyone have component level repair experience on laptops?
I've got a Dell Inspiron 8500 notebook computer with a charging
problem- The computer will run fine from the batteries until they are
dead. When plugged into the AC adapter, the BIOS gives an error
message stating that it cannot recognize the AC adapter, but it will
power the computer. It will not charge the batteries with the AC
adapter. The AC adapter has been confirmed good in two ways: the AC
adapter powers another identical computer with no problem, and another
adapter gives the same symptom.
When I plug the AC adapter into a Port Replicator and the computer
onto the port replicator, the batteries will charge.
The adapter input jack on the motherboard has been replaced, and I've
inspected the board as well as possible for a bad connection or faulty
components, but without a schematic of the power/charging circuit it's
nearly impossible to search for a fault.
The obvious solution is to replace the motherboard - again (this is my
third mobo in 5 years). I don't wish to invest another $160 in parts
for another temporary repair on this flawed design.
Does anyone have a schematic (longshot) or experience on repairing
this mobo?


I suppose you could note down all the ICs in the area of the jack and
locate their spec sheets and find the one[s] that regulates the battery
charging.
The spec sheets usually have application notes with typical circuit
diagrams.

--
Jim Yanik
jyanik
at
kua.net

Mike S wrote:
Does anyone have component level repair experience on laptops?
I've got a Dell Inspiron 8500 notebook computer with a charging problem-
The computer will run fine from the batteries until they are dead.
When plugged into the AC adapter, the BIOS gives an error message stating
that it cannot recognize the AC adapter, but it will power the computer. It
will not charge the batteries with the AC adapter.
The AC adapter has been confirmed good in two ways: the AC adapter powers
another identical computer with no problem, and another adapter gives the
same symptom.
When I plug the AC adapter into a Port Replicator and the computer onto the
port replicator, the batteries will charge.
The adapter input jack on the motherboard has been replaced, and I've
inspected the board as well as possible for a bad connection or faulty
components, but without a schematic of the power/charging circuit it's
nearly impossible to search for a fault.
The obvious solution is to replace the motherboard - again (this is my third
mobo in 5 years). I don't wish to invest another $160 in parts for another
temporary repair on this flawed design.
Does anyone have a schematic (longshot) or experience on repairing this
mobo?


I'm guessing that the DC input jack repair was less than successful.

I think it's likely that one or more layers of the pc board are not
connected to the replaced jack. The charging circuitry appears to be
good, since the battery charges in the docking bay. I'd be surprised if
there was duplicate circuitry to recharge from that source, only a
different connection to the same part of the circuit that gets power
from the input jack.

Resoldering the DC jack might get it working again.

jak

On Sun, 6 Apr 2008 20:45:56 -0400, "Mike S" nospam wrote:

Does anyone have component level repair experience on laptops?

I've got a Dell Inspiron 8500 notebook computer with a charging problem-
The computer will run fine from the batteries until they are dead.
When plugged into the AC adapter, the BIOS gives an error message stating
that it cannot recognize the AC adapter, but it will power the computer. It
will not charge the batteries with the AC adapter.
The AC adapter has been confirmed good in two ways: the AC adapter powers
another identical computer with no problem, and another adapter gives the
same symptom.

Look carefully at the connector on the adapter plug. There is an
outside metal contact. That's the ground. There's a concentric metal
contact ring on the inside, which is the +19.5VDC. There's also a
tiny center pin. The tiny center pin supplies some kind of handshake
with the computer that informs the computah that it's the right power
supply. If the center pin is broken somewhere, the handshake never
happens, and the computer complains that it can't identify the power
supply.

The most common point to break the center pin is in the plug at the
end of the power cable. The center wire is tiny and breaks easily.
Shove the laptop against the wall, bending the cable at a right angle
to the connector, and you've got a broken center wire.

However, since you've gone through the exercise of substituting power
supplies and verifying that they're good on a different Insprion 8500,
methinks that it's not the adapter. That leaves the power jack on the
motherboard, and associated circuitry.

When I plug the AC adapter into a Port Replicator and the computer onto the
port replicator, the batteries will charge.
The adapter input jack on the motherboard has been replaced, and I've
inspected the board as well as possible for a bad connection or faulty
components, but without a schematic of the power/charging circuit it's
nearly impossible to search for a fault.

Well, if it's not the jack or the connection, then there's a broken
trace somewhere. No schematic, no easy fix. Sorry.

The obvious solution is to replace the motherboard - again (this is my third
mobo in 5 years). I don't wish to invest another $160 in parts for another
temporary repair on this flawed design.
Does anyone have a schematic (longshot) or experience on repairing this
mobo?

3 boards in 5 years implies that you're doing something wrong with
this laptop. My guess(tm) is that it has something to do with the
docking station. I've had problems with those in the past. Perhaps
the order and sequence that power is applied or removed. Perhaps a
ground gets disconnected before the power. Dunno, just guessing.
http://geekswithblogs.net/jjulian/archive/2004/12/09/17171.aspx
(Note the docking station comments).

If you still have one of the old mother boards, you can possibly trace
out where the wire to the center pin ends.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
On Sun, 6 Apr 2008 20:45:56 -0400, "Mike S" nospam wrote:

Does anyone have component level repair experience on laptops?

I've got a Dell Inspiron 8500 notebook computer with a charging problem-
The computer will run fine from the batteries until they are dead.
When plugged into the AC adapter, the BIOS gives an error message stating
that it cannot recognize the AC adapter, but it will power the computer.
It
will not charge the batteries with the AC adapter.
The AC adapter has been confirmed good in two ways: the AC adapter powers
another identical computer with no problem, and another adapter gives the
same symptom.

Look carefully at the connector on the adapter plug. There is an
outside metal contact. That's the ground. There's a concentric metal
contact ring on the inside, which is the +19.5VDC. There's also a
tiny center pin. The tiny center pin supplies some kind of handshake
with the computer that informs the computah that it's the right power
supply. If the center pin is broken somewhere, the handshake never
happens, and the computer complains that it can't identify the power
supply.

The most common point to break the center pin is in the plug at the
end of the power cable. The center wire is tiny and breaks easily.
Shove the laptop against the wall, bending the cable at a right angle
to the connector, and you've got a broken center wire.

However, since you've gone through the exercise of substituting power
supplies and verifying that they're good on a different Insprion 8500,
methinks that it's not the adapter. That leaves the power jack on the
motherboard, and associated circuitry.

When I plug the AC adapter into a Port Replicator and the computer onto
the
port replicator, the batteries will charge.
The adapter input jack on the motherboard has been replaced, and I've
inspected the board as well as possible for a bad connection or faulty
components, but without a schematic of the power/charging circuit it's
nearly impossible to search for a fault.

Well, if it's not the jack or the connection, then there's a broken
trace somewhere. No schematic, no easy fix. Sorry.

The obvious solution is to replace the motherboard - again (this is my
third
mobo in 5 years). I don't wish to invest another $160 in parts for
another
temporary repair on this flawed design.
Does anyone have a schematic (longshot) or experience on repairing this
mobo?

3 boards in 5 years implies that you're doing something wrong with
this laptop. My guess(tm) is that it has something to do with the
docking station. I've had problems with those in the past. Perhaps
the order and sequence that power is applied or removed. Perhaps a
ground gets disconnected before the power. Dunno, just guessing.
http://geekswithblogs.net/jjulian/archive/2004/12/09/17171.aspx
(Note the docking station comments).

If you still have one of the old mother boards, you can possibly trace
out where the wire to the center pin ends.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


Thank you all for your replies.
The other motherboards suffered different failutres (bad design) so I have
several full sets of power supply components to work with.
I don't think the problem is related to use of the port replicator because I
just started using it to charge the notebook now. Never used it with the
previous motherboards. The pinout of the adapter is helpful.

On Mon, 7 Apr 2008 16:03:57 -0400, "Mike S" nospam wrote:

The other motherboards suffered different failutres (bad design) so I have
several full sets of power supply components to work with.
I don't think the problem is related to use of the port replicator because I
just started using it to charge the notebook now. Never used it with the
previous motherboards. The pinout of the adapter is helpful.

The plot thickens...

Sitting in my "get around to it" pile of dead laptops is an Inspiron
8600. It uses the same power connector as the 8500. The laptop is
seriously intermittent. The problem (I've been told) is that the
motherboard uses BGA (ball grid array) chips. These are ceramic
chips, with solder bumps on one side. They are reflow soldered to
matching pads on the motherboard. Bend the motherboard even slighly,
and the solder connection breaks. My guess(tm) is that my junk pile
has about 5 machines (mostly HP laptops) that have similar problems.

However, all is not lost if you're not afraid to do something radical.
You can reflow solder the BGA chips by placing a metal can on top of
the chip, filling it with alcohol and cotton, and setting fire to it.
A heat gun is sometimes used to pre-heat and post-heat to slow down
the too rapid temperature rise and fall. I use an optical IR
thermometer to monitor the temperature. It's really easy to
overshoot.

http://gizmodo.com/gadgets/laptops/screw-geek-squad-just-use-fire-to-fix-the-ibook-225760.php
http://www.youtube.com/watch?v=W4Coozv2DdE
Lots more under "iBook repair"

I really like this one, but haven't tried the blow torch method:
http://www.youtube.com/watch?v=eT_xuSI-gDw

I've done this with several BGA devices with about 50% success rate.
It's not fool proof, but it's better than a dead or intermittent
laptop. No guts, no warranty, no gain.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"Jeff Liebermann" wrote in message
news
On Mon, 7 Apr 2008 16:03:57 -0400, "Mike S" nospam wrote:

The other motherboards suffered different failutres (bad design) so I have
several full sets of power supply components to work with.
I don't think the problem is related to use of the port replicator because
I
just started using it to charge the notebook now. Never used it with the
previous motherboards. The pinout of the adapter is helpful.

The plot thickens...

Sitting in my "get around to it" pile of dead laptops is an Inspiron
8600. It uses the same power connector as the 8500. The laptop is
seriously intermittent. The problem (I've been told) is that the
motherboard uses BGA (ball grid array) chips. These are ceramic
chips, with solder bumps on one side. They are reflow soldered to
matching pads on the motherboard. Bend the motherboard even slighly,
and the solder connection breaks. My guess(tm) is that my junk pile
has about 5 machines (mostly HP laptops) that have similar problems.

However, all is not lost if you're not afraid to do something radical.
You can reflow solder the BGA chips by placing a metal can on top of
the chip, filling it with alcohol and cotton, and setting fire to it.
A heat gun is sometimes used to pre-heat and post-heat to slow down
the too rapid temperature rise and fall. I use an optical IR
thermometer to monitor the temperature. It's really easy to
overshoot.

http://gizmodo.com/gadgets/laptops/screw-geek-squad-just-use-fire-to-fix-the-ibook-225760.php
http://www.youtube.com/watch?v=W4Coozv2DdE
Lots more under "iBook repair"

I really like this one, but haven't tried the blow torch method:
http://www.youtube.com/watch?v=eT_xuSI-gDw

I've done this with several BGA devices with about 50% success rate.
It's not fool proof, but it's better than a dead or intermittent
laptop. No guts, no warranty, no gain.



Thats a cool trick. Sounds better than blasting it with a heat gun and
blowing other componenents off the board. Have to try it on some junk boards
and see how it works.

Mike

"Michael Kennedy" wrote in
:

.....

Thats a cool trick. Sounds better than blasting it with a heat gun and
blowing other componenents off the board. Have to try it on some junk
boards and see how it works.

Build a dam around the component with paper. You can use a hot air gun to
remove or solder just one component, if you do things right.








--
bz 73 de N5BZ k

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

remove ch100-5 to avoid spam trap

On Tue, 8 Apr 2008 05:59:50 -0400, "Michael Kennedy"
wrote:

Thats a cool trick. Sounds better than blasting it with a heat gun and
blowing other componenents off the board. Have to try it on some junk boards
and see how it works.

Mike

http://www.youtube.com/watch?v=eT_xuSI-gDw

I found it really easy to overshoot. However, the failure is not
melting components or torching the board. It's having the BGA "drift"
or move sufficiently to short between connections. Some BGA chips are
also designed to have some air gap under the chip. If I over compress
this air gap to zero, I get more shorts caused by squeezing the solder
bumps into each other.

That's the problem with the C-clamp method. It localizes the heat,
but potentially squashes the solder bumps. The trick is apparently
not to over tighten the C-clamp. (I haven't tried this yet).

I did my best by first injecting some "no clean" liquid rosin flux
under the BGA before applying heat. The flux provided the necessary
oxidation protection, but also provided some protection against
shorting between pads.

Another trick I used it cut out the bottom of a somewhat larger
diameter tin can to use as a heat shield. I place it around the
burning cat food can. That fit inside the aluminum foil heat shield.
The problem wasn't burning components. It was melting the plastic
case because I was too lazy to remove ALL the plastic parts.

A few more tricks.

I had one success using a block of scrap aluminum on top of the chip
and a propane torch. It was a fairly small diameter BGA array, where
the cat food can was too large. Applying the heat about 1/2" above
the chip was very useful to prevent torching the board.

I put a heavy steel bolt or two as a weight at the bottom of the
burning can in order to keep it from moving around. Don't use a
painted can. Try to find a can with a flat bottom to maximize the
contact area surface. Use alcohol, not kerosene as some articles have
suggested, unless you enjoy the diesel stench.

I tried using some silicon grease, which had an interesting advantage.
When heated, whatever solvent is used to make it flow, gets
evaporated. The remaining silicon is more of a powder than a liquid,
which acts something like a glue. This kept the cat food can from
moving around. I cleaned off the mess afterwards with alcohol.

I'll try to remember to do a video next time.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558