[Gta04-owner] GPS fix? Fixed.

[Dr. H. Nikolaus Schaller]

Am 23.11.2011 um 15:53 schrieb Christoph Mair:

> On Wed, Nov 23, 2011 at 3:15 PM, Neil Jerram <neil at ossau.homelinux.net> wrote:
>> On 22.11.2011 08:07, Dr. H. Nikolaus Schaller wrote:
>> 
>>> A first estimate means that the traces must be cut. Or the chip must
>>> be
>>> removed, two pins must be bent upwards, and the chip resoldered.
>>> 
>>> Then a 2mm and a 5mm long tiny wire must be soldered. IMHO quite
>>> difficile if you don't have a stereo microscope.
>> 
>> I wonder if there could be a simpler fix, if one assumes that one will never
>> want to use an external antenna?
>> 
>> (Even though I won my ebay auction, and now have an external antenna ready
>> to try out, I don't really want to use one as part of my normal Phoenux
>> usage, if we can get GPS working without it.)
>> 
>> Even better if the fix could be a reversible one - so that I could try it
>> and then reverse it if not successful.
> 
> I added the crossing wires after the coupling caps C1205 and C1206. If
> you bend one side of them side- or upwards (with your soldering iron
> of course, everything else might destroy the caps and the traces on
> the board) you have a free pad (where the cap was sitting before) and
> a free end of the cap. Both are are a good place to connect wires to
> them. It is _much_ easier that reworking the IC. You can do it without
> microscope but a magnifying glass can be useful.
> I might post pictures when I'm at home again.

So what Christoph is indicating is that we may have a solution: crossing
over the signals by wires. It is a little tricky to remove and rotate the
capacitors and solder two tiny wires. But it is possible.

Here is a photo (through a microscope - bottom is the SD card reader, top is the GPS module):


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After applying this hardware patch, GPS works fine. And I have
the impression that it even works a little better than a GTA02
sitting near it (but this is not an objective measurement).

For all those on preorders for the GTA04A4 boards:

we will either add these wires to the board in the factory. Or we use
a replacement chip that appears to have the switch control signal
inverted. Christoph just has found one and we are evaluating if
it is indeed 100% compatible in all other parameters.

So you don't have to care about this GPS discussion...

BR,
Nikolaus