GSM-noise "buzz" issue

[Joerg Reisenweber]

We found it's pin4 of JK4401 and only this pin that causes GSM-EMI-noise 
issue.
We placed a ferrite bead to this pin, and it stops noise. Alas this isn't a 
viable rework, as it is extremely fragile and doesn't fit into case.
See 
<http://people.openmoko.org/joerg/GSM_EMI_noise/noise_stopped_by_athena_rework/>

We tried to find another way to place a bead in this rail, first result 
(without bead yet), see
<http://people.openmoko.org/joerg/GSM_EMI_noise/noise_stopped_by_cut_pin4/>
This rework at least stops noise and should fit into case. It breaks function 
of headset mic and hold-button, but keeps function of headphones.
We try to find a way to restore function of mic and button, based on this 
rework.

I will keep you updated.
Please note all this IS NO RECOMMENDATION FOR A REWORK, and we can't answer 
any questions yet beyond what I've reported above.

cheers
jOERG


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