GSM-noise "buzz" issue

Joerg Reisenweber joerg at
Fri Oct 31 21:26:25 CET 2008

Am Fr  31. Oktober 2008 schrieb Angus Ainslie:
> On Fri, Oct 31, 2008 at 1:45 PM, Joerg Reisenweber 
<joerg at>wrote:
> > You HAVE to replace R4303 0R with a 2k2 !! (check R from mic housing
> > MIC4301:2
> > to GND! Has to be 2k2, will read 0R usually)
> > Otherwise this cap fix CAN NOT work. Refer to schematics, please.
> >
> >
> Your original instructions said R4403, they also said that R4403 wasn't on
> any schematic so I didn't try to look for it. Where should it be in the
> schematic ? I didn't mention it but I did do that part as well. Well almost,
> the closest value I had was 2k
> Should it be R4303 ?

Sorry for any faults or ambiguities! Once again:

change R4303 (oh-three) [0R, MIC4301:2 to GND] to 2k2 

R4304 (oh-four) is not in the published schem [any more], it's obviously been 
replaced in schematics by C4306 [NC, MIC4301:1 to GND]. However you may find 
R4304 in component placement diagram (you won't find C4306 there!). It's the 
two empty pads left side of the component array left to mic. Symmetric to 

If you want to retrofit C4306 with a huge capacitor, you could use the empty 
pads of R4304 to connect it. You also *have* to make the R4303 0->2k2 change, 
otherwise mic signal is shorted by this capacitor and you won't see decent 
signal on mixer input.

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