GSM-noise "buzz" issue
joerg at openmoko.org
Fri Oct 31 20:54:03 CET 2008
Am Do 30. Oktober 2008 schrieb Angus Ainslie:
> 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
> > JK4401
> > (your first picture). Alas it's not clear if you correctly isolated
> > pin4-pad
> > 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
> > where
> > 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
> > pin4
> > 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.
Even without the bead attached?
> > Then place bead to pad of R4404 NC, or even piggyback it to C4405, and
> > connect
> > to upper golden contact of JK4401, above pin4. (Please note you need the
> > bead
> > only for hs mic function, which may still be broken when using it during
> > GSM
> > RF activity)
> Right now I what to get rid of the buzz ( I'm going to attempt the A7 bodge
Great rework shown in your other mail.
> and have the connector reattached so I can try and dump the GSM firmware.
Sorry I don't understand this. Isn't the connector attached yet? Why would you
want to dump GSM FW and why would you need the connector for that?
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