Bug #1024 (oscillating re-camping), a possible solution.
nils.faerber at kernelconcepts.de
Wed Jun 10 19:25:19 CEST 2009
Daniel Willmann schrieb:
> On Wed, 10 Jun 2009 10:32:59 -0300
> Werner Almesberger <werner at openmoko.org> wrote:
>> Nils Faerber wrote:
>> My first try was the "single iron, lots of solder" attack.
>> To my great dismay, the cap didn't budge. I then went through
>> all my electronics torture chamber has to offer, hot tweezers,
>> etc., with pretty much the same lack of result. In the end, I
>> reduced the problem to a simple mechanical one that could be
>> solved with a dremel.
> Okay, harsh measures...
> I've since reworked about 6 or so (all various GTA02 versions - A5/A6,
> MP and prototypes) and I managed to get the cap off on all of them. I
> have to admit that it's not too easy, though.
For the first device I used a Dremel to almost completely remove
("scratch off") the old an was thus able to confirm the glue underneath
it - brownish stuff, sticks like hell to the parts (PCB and cap) and
does not at all get less sticky when getting hot. Well, that's what it
is good for during production ;)
> Be aware that the right side of the cap is connected to the
> groundplane, so you need quite some energy in order to get it to heat
> up enough. There could also be glue in the mix, but I'm not sure how I
> could check that.
> I usually heat up both sides with two soldering irons wait a little and
> then try to move it around a little on the board until it's loose. Then
> I gently lift it off while holding it between my two soldering irons.
Hmm... then in GTA02 the cap is not glued anymore, I guess. Because in
GTA01 you would definitely not be able to get rid of the cap this way,
the glue will keep it in place.
My GTA01 now works again - yippie!
I had to solder the new one twice to the board because the first time I
managed to create a short-circuit underneath the new cap. I can now
confirm that the regulator feeding the Calypso is pretty short
resistant! The second time I used the two iron approach to remove it again.
Next I will do the same to my GTA02 - hopefully there is really no glue
in GTA02 and the two iron approach works again.
Many thanks for sharing your experience!
> Daniel Willmann
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