Re: Dell Laptop component level repair
- From: Jeff Liebermann <jeffl@xxxxxxxxxx>
- Date: Sun, 06 Apr 2008 23:34:41 -0700
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 jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.
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