GSM-noise "buzz" issue
angus.ainslie at gmail.com
Thu Oct 30 15:34:47 CET 2008
On Thu, Oct 30, 2008 at 7:30 AM, Joerg Reisenweber <joerg at openmoko.org>wrote:
> Attaching the bead is *not* the fix exactly, cutting the connection from
> JK4401:4 to coppertrace is considered the fix.
I cut the connection between pin 4 and its pad. The bead is now in series
between the pad and the spring that used to be JK4401:4.
> Anyway it seems you tried to achieve this by cutting the contact from
> (your first picture). Alas it's not clear if you correctly isolated
> on PCB, so to me it looks like you soldered the bead on the pin4-pad and
> maybe you just shorted the tiny gap between PCB-pad and the metal-stub
> you cut off pin4-contact on JK4401, while soldering the bead.
No there is no direct connection between pad 4 and the connector.
> Cutting the contact sure is a good thing, anyway I recommend to isolate
> PCB-pad by some plastic, so it is securely NC and in some distance to
> JK4401:4 metal spring. (see:
> Then do first test to find buzz is gone.
That's effectively what I did. I attached teflon tape to the bottom of the
connector to isolate it. The buzz is still present.
> Then place bead to pad of R4404 NC, or even piggyback it to C4405, and
> to upper golden contact of JK4401, above pin4. (Please note you need the
> only for hs mic function, which may still be broken when using it during
> RF activity)
Right now I what to get rid of the buzz ( I'm going to attempt the A7 bodge
) and have the connector reattached so I can try and dump the GSM firmware.
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