Am So 5. April 2009 schrieb Rask Ingemann Lambertsen: > On Fri, Mar 27, 2009 at 03:34:00AM +0100, Joerg Reisenweber wrote: > > > Regarding your low volume: did you check R4303? (It's the one below the two NC > > pads and right side to C4303, the one you borked and replaced. It's clearly > > mentioned in my SOP paper) R4303 is not mentioned in your story if I didn't > > miss anything. Usually it's 0R and it's amazing you get *any* signal at all > > from mic if you haven't replaced it by a ~2k2k (probably anything between > > 400Ohms and 3k will do, though I learnt by your report even a 0R will do at > > least partially :D ). > > Joerg, could you clarify the significance of R4303 a bit? For example, > how would I tell if it has 2.2 kOhms or 0 Ohms without measuring it (on a > device without the buzz fix as well as with the buzz fix)?
Probing is the *only* way you can tell afaik. We are basically grounding upper end of mic with a huge capacitor (AC), so we need some R >>0Ohms on the lower end of mic to get some signal at all. > > The 100 uF capacitor is just the C4306 which isn't installed by default, > right? Without checking for correctness of #4306 basically yes. > > MICBIAS is also supplied to the headset mic (location 44xx). Would it do > any good to add a 100 uF capacitor somewhere in that area too? Nope, for a number of reasons it won't work, just break function of hs-mic completely. See explanation some lines above. HS-Mic is singlen-ended (lower pin connected to GND) /j
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