Did you measure the capacitor on other "normal" phones? If on the phones without the problem capacitor measures around 10uF as supposed than we have our solution :)
Leonti On Wed, May 6, 2009 at 5:48 PM, Dieter Spaar <[email protected]> wrote: > Hello, > > I spent quite a lot of time to modify and patch > various settings in the GSM firmware trying to change > the behavior of the two phones which show the extreme > "Deep Sleep" problems (immediate PCH reception error > if the phone enters "Deep Sleep"). > > Those modifications did not remove the problems and > also did not cause any problems for the working > phones I have. So till now it seems that there is > no software workaround which can solve this problem. > > However on one phone I was able to solve the problem > by replacing a capacitor which buffers one of the > power supply lines of the Calypso chip (the power > comes from an LDO in one of the other GSM chips). > This capacitor is supposed to be 10uF, however > I measured 7.6uF. I don't have SMD parts here so > I replaced it with a standard 10uF electrolytic > capacitor (I measured 10uF). After this > modification the "Deep Sleep" problems are gone > and the phone works as good as the other good ones. > > Its still too early to conclude anything from > the above. I have ordered a few SMD capacitors > and will try the same with the other problematic > phone. Additionally its necessary to test if this > modification just moves the problem to lower > temperatures (remember, the problems also go > away if I warm up the phones by a few degree). > > Best regards, > Dieter > > > _______________________________________________ > hardware mailing list > [email protected] > http://lists.openmoko.org/mailman/listinfo/hardware >
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