rework

Petr Vanek vanous at penguin.cz
Tue Mar 10 09:43:02 CET 2009


hi,

i was lucky enough to get someone to perform the gsm buzz rework.

i find the images used in the
http://people.openmoko.org/joerg/GSM_EMI_noise/big-C_rework_SOP_rc2.pdf
quite rather _small_ therefore please find some of my pictures done via
microscope here: http://vanous.penguin.cz/files/om/SOP/

Please feel free to use them to improve your manual.

Also, we found that placing the 100uF cap according to the manual is
rather strange and could cause problems in future - so we placed the
cap in a way that is will be soldered to the PCB on both ends, making
it hold really tight (that particular picture is somewhat blurry)

We didn't have 2k2 in 0402 size so we used 2x 80Ohm in series (we just
built a A shape with them).

The fix works - done on two units, one showed gsm buzz before and now
it's gone.

Some of the other pictures show D4301, D4302, as under the microscope we
found one of them damaged from manufacturing - placing the cover -
something om might watch for.

cheers
petr





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