Hardware mod for starting GTA02v5 without battery? (Was: Need battery help in DC area)

Rask Ingemann Lambertsen rask at sygehus.dk
Sun May 10 20:51:39 CEST 2009

On Sat, May 09, 2009 at 10:36:19PM -0400, Paul Buede wrote:

> Also, does anyone have instruction on how to fix my Freerunner so it can 
> boot off USB or wall charger?  Is it a hardware mod or firmwae upgrade 
> or something?

   It's a hardware mod. It's capacitor C1767, page four of the schematics[1]
at the bottom. There's a (rather poor) picture of a reworked A5 here:


   Better picture (of the whole A5 PCB without the rework):

   Electrically, the rework is simple enough: Just connect a larger
capacitor in parallel to the existing one. But it sits under the main can,
so making it fit isn't easy. The picture of the reworked device isn't very
good, but it looks like a capacitor has been connected to the VB_SYS side of
R1768 and to the GND side of C1722.

   See <URL:http://people.openmoko.org/werner/gta02-chg/> for an explanation
of the problems GTA02v5 has starting without battery power.

   Btw, where is C1767 itself? I can't find it on either the assembly
silkscreen[2] or the component placement drawing[3]. At 47 uF on the A6, it
ought to be easy to spot.

[1] http://people.openmoko.org/joerg/schematics/GTA02/Schematics_Freerunner-GTA02_A5-A7cumulative_public_RC0.pdf
[2] http://people.openmoko.org/joerg/schematics/GTA02/GTA02-MB-A6(50-71481-00)_assembly%20silkscreen.pdf
[3] http://people.openmoko.org/joerg/schematics/GTA02/Component-placement_Freerunner-GTA02-MB-A6.pdf

Rask Ingemann Lambertsen
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