Resoldering the GPU? [was Re: [ltp] vertical lines error on the lcd screen]

[Hrvoje Ivanic]

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Oisin Feeley wrote:
> On 4/3/07, James Knott <james.knott@rogers.com> wrote:
>> Oisin Feeley wrote:
>> > On 4/3/07, Bill Andrus <languru@us.ibm.com> wrote:
>> >>  > (vertical lines, console mode text garbled...)
>> >>
>> >> Your System Board has failed.  The ATI display chips are on a PCB
>> >> carrier
>> >> that is soldered into the main PCB, and (usually due to flexing or
>> >> pressure
>> >> around the spacebar and trackpoint buttons) the internal soldering =
has
>> >> broken.  Problem in its earliest stages will be temperature and
>> pressure
>> >> sensitive, later it will become more pronounced with system
>> >> freeze-ups and
>> >> reboots.
>> >
>> > I've heard people talk about sending the board to have the solder
>> > "re-fluxed" to correct this problem.  Do you have any idea if this i=
s
>> > really possible?
>> >
>>
>> "Re-fluxing" wouldn't do much, as flux is only used during soldering.
>> Howver, problems can often be resolved by resoldering intermittent
>> connections.
>=20
> Sorry, I mean "re-flowing".
>=20
> So, what about reflowing the solder then?  Has anyone had success with
> doing that themselves or with sending it for repair somewhere (and if
> so what sort of price would it be?).
>=20
> In this link the poster talks about having a screen corruption issue
> similar to the OP which he fixed by resoldering the video chip himself
> http://www.thinkwiki.org/wiki/Problem_with_garbled_screen
>=20
> In this link the poster describes the problem which I have (similar to
> the OP's with the screen displaying gradually creeping downward
> horizontal lines, but the system becoming entirely unresponsive.  This
> is a T40 with an ATI Radeon Mobility M7 graphics chip.
>=20
> http://www.thinkwiki.org/wiki/Problem_with_video_related_system_lockup_=
II
>=20
> I've disassembled extensively and have concluded that the problem is
> probably due something like this (can't see any obvious cracks on the
> board but lightly flexing it in that area does cause lock ups.  I can
> use the machine for days on end without any symptoms if I just use a
> USB keyboard/mouse, but I'd like to have a portable laptop again ;)
>=20
> As you can tell, I don't know anything about soldering (I used to make
> crude electronics projects when I was a child, but that was a long
> time ago and I've forgotten any skill I had), so I'd rather not do it
> myself.  The laptop is no longer under warranty, so I'd need to pay
> whatever it takes and it's only a T40.  So, is it cost-effective to
> have a "board shop" (if I can find one in Canada) do this, or should I
> just go crazy and try it myself?
>=20
> Oisin


hello,

i had the same problem - typing, touching the nipple, adjusting the
screen, etc resulted in a black screen (i.e. backlight off/no ldc
signal), sonetimes a garbled one. sometimes a power cylce helped, at
other times some "bending" of the notebook (which is btw a t41, 2723
series).

this annoyed me so much that i disassambled the notebook and poked
around on the motherboard. i was able to reproduce the error by gently
lifting the gpu on the "north-east"-corner with my fingernail.

there, two types of errors appeared:
a)
the backlight/lcd signal vanishes and the notebbook had to be power cycle=
d

b)
just the backlight went off vs. sometimes a garbled screen, no power
cycle required.

it was obvious that the gpu was losing contact with the motherboard.

since the gpu is a BGA type chip (http://en.wikipedia.org/wiki/BGA) you
cannot solder much, even from the lower side of you motherboard.

now, BGAs are soldered in a oven or via infrared radiation so the
solution in my case was to apply heat to the gpu at this specific
position and to hope, pray, wave a dead chicken. you get the picture
(you can easily wreck a chip by literally over-cooking it).

a friend of my colleague is some sort of hardware guru who has
experience in repairing stuff; he had this "hot air tool" made
especially to work with ICs. it was not a standard hot air blower...
he applied head to the gpu for say one minute, let it cool and let me
assemble the notebook and try to reproduce the screen issue.
"lifting" the gpu with my fingernail produced no error anymore.

this was two weeks ago and i consider the notebook repaired.

i know i can consider myself lucky because
a) by applying heat you can easily destroy the gpu and
b) if the motherboard had a "crack" somewhere only a replacement could
have helped.


so, this error _may_ be repairable. risks are involved.

what one can do to avoid this error:

don=B4t lift the notebook solely by grabbing it on the pcmcia/hdd area. i=
t
flexes way too much; at least the t41 series has this drawback.

and yeah, cooking the gpu scared the shit out of me.


take care and good luck.



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