GTA02 C4110/1 replacement?

Al Johnson openmoko at
Sat Sep 13 11:49:22 CEST 2008

On Saturday 13 September 2008, Joerg Reisenweber wrote:
> Am Di  9. September 2008 schrieb Al Johnson:
> > On Monday 08 September 2008, you wrote:
> > > On Mon, 8 Sep 2008, Al Johnson wrote:
> > > > Some time ago Joerg (IIRC) suggested it might be possible for the
> > > > brave/foolhardy to replace the undersized caps in the headset output
> with
> > > > something more suitable, or even with audiophile esoterica like Black
> > > > Gates. Looking at the schematics I see these are C4110 and C4111
> > > > which appear to be located under the can that has the bluetooth
> > > > module stuck
> to
> > > > the top of it. So how easy is it to open and close this can without
> > > > breaking anything?
> > >
> > > Hi,
> > >
> > > I tried, just to see if I could do it, to add a capacitor in parallel
> > > to the VB_SYS one: this is the solution the OpenMoko-people were
> > > researching to get rid of the
> > > gta02-won't-boot-on-an-empty-battery-even-with-usb-connected-thing. My
> > > experience: Don't do it unless you have experience with soldering tiny
> > > SMD-stuff, and the tools to do it. It's almost trivial to destroy stuff
> > > if you don't have the experience.
> > >
> > > (btw, I made pics of my endeavour; if anyone wants to see them, just
> > > raise your hand and I'll upload them.)
> > >
> > > Jeroen
> >
> > I've done the odd bit of rework on tiny SMD stuff before, so that's not
> > so much of a worry. I'm more worried about breaking something while
> > lifting the lid, especially with the bluetooth module where it is.
> I lifted quite some can lids, by using a small knife or screwdriver (knife
> works better).
> There's no issue with BT on lifting the lid, you just need 10 minutes of
> calm repeating same effort until you finally succeed.
> Capacitors are the right ones (IIRC), you cam simply solder some wires to
> them, and route those to any place where you are able to position decent
> ones. You even might cut a small hole to the can for this purpose.

That was the plan, initially via the hole in the can close to the end of the 
bluetooth module. There should be space in the case for a pair of caps up 
there too, but it's perhaps too close to the bluetooth antenna. I guess it'll 
be trial and error time when I get round to it ;-)

> Or you just short them, and place the real good ones inside your headset
> jack outside of GTA02 ;-)

Tempting, but I'm not sure I want DC on the jack when things are getting 
plugged in, or if I forget one day and plug in a non-special headset.

> Please come up with a photo footage on your rework, as I fear I don't find
> the time soon to do that myself. :-)

I probably won't be doing it soon either, but if nobody else has done it by 
then I'll post photos. 

> You got schem and component placement. It should be easy ;-)

I know - that's one of the things I love about this project! 

> cheers
> ps: you also might want to short the 33R, they're useless as soon as you
> got decent C (needed for GSM-DL firmware flashing via hs-connector, if at
> all)

Is there any chance we'll get to flash the GSM firmware? I could always remove 
the short if needed I suppose.

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