Mic volume extremely soft after buzz fix with SHR unstable

Jan Girlich vollkorn at cryptobitch.de
Mon Feb 22 19:45:39 CET 2010


Am Montag, den 22.02.2010, 17:25 +0000 schrieb Al Johnson:
> It can be hard to tell whether the joint is electrically good just by looking 
> at it, and solder connections on those components are tiny. You really need to 
> use a meter to test it, and I expect this was done by whoever did the fix for 
> you, so it probably isn't the problem. If you are competent to test this, or 
> know someone who is, the schematics and fix SOP are both available:
> 
> http://people.openmoko.org/joerg/GSM_EMI_noise/big-C_rework_SOP_rc2.pdf

Okay, the joint I suspected to be broken seems fine. It's the one on the
left of the two red arrows in the above description. That's where my
capacitor is connected to and I just checked the the resistance from the
capacitor to the pad where the right red arrow points at. No measurable
resistance, so the joint should be electrically good.

> > > Controls 48 and 12 are on maximum, while control 5 has 12 steps
> > > remaining. You still have scope to make the mic a fair bit louder if you
> > > need to. 3, 5 and 121 would give the same volume level with less chance
> > > of distortion.
> > 
> > Tried it. Still so soft that you have to yell really loud at the phone
> > and only hardly can hear anything on the other end. I'm usually testing
> > with my stereo, turning it on and putting the phone on the speaker. But
> > I have to turn my stereo to levels it's getting uncomfortably loud just
> > to hear a faint noise over the phone.
> 
> So 3, 7, 127 is still too quiet? In that case something may be wrong. Check 
> the buzz fix, and also that the hole in the case isn't blocked.

Checked it, the hole is free.
Jan
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