Fixing Openmoko hardware bug #1024

December 30, 2009 in Openmoko | 4 comments

Stuff has bugs, both hardware and software. One of the hardware bugs in Openmoko phones has been bug number #1024 causing things to happen that prevent the GSM chip to go to ‘deep sleep’ mode to save power.

Someone came up with a fix: add a capacitor.

So we did.

Wiki page with instructions to detect if you’re hit by the bug: http://wiki.openmoko.org/wiki/1024
Bug report: http://docs.openmoko.org/trac/ticket/1024
Instructions to fix the bug: http://www.neofundas.blogspot.com/

After opening the case

After opening the case

Small, isn't it?

Small, isn't it?

One end soldered to the ground

One end soldered to the ground

Other end soldered to the old capacitor

Other end soldered to the old capacitor

Thanks Antti & open hardware!

Results

The suspend power consumption dropped to around 6000 µA from around 15-20000µA when I now allow the GSM modem (Calypso) to go to deep_sleep mode. The 1200mAh battery should now give up to 200 hours = 8 days of power. Of course this is theoretical – I also need to use the phone to make calls, let GPS show me my location etc etc – and as I move, the GSM needs to wake up ever now and then because of the changing base stations. So nowadays I recharge it every other night still being able to make calls and do other stuff with it. Nice improvement!

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  1. khiraly’s avatar

    khiraly on December 31, 2009 at 11:19 am

    Could you please write the exact type of the capacitor?
    Preferably with a mauser link…

  2. Risto H. Kurppa’s avatar

    Risto H. Kurppa on January 2, 2010 at 2:03 pm

    Hi Khiraly, long time no hear :)

    The capacitor was 0805, 10v, 10µF (or 16V, not sure..) – and I don’t think it was too difficult to do the fix, if one has any soldering experience, it should be doable. Go on and give it a try!