[Gta04-owner] problems with battery loading

t.munker at gmx.net t.munker at gmx.net
Thu May 26 23:33:21 CEST 2016

thanks for your answer so far!
I still have some questions:

Am Thu, 26 May 2016 23:07:29 +0200
schrieb "H. Nikolaus Schaller" <hns at goldelico.com>:

> Hi,
> > Am 26.05.2016 um 20:14 schrieb <t.munker at gmx.net>
> > <t.munker at gmx.net>:
> > 
> > Hi,
> > i've got some problem with loading my battery.
> > 
> > Symptoms are:
> > When plugging usb line in at the phone, phone wakes up and starts
> > loading, if there is power.  
> Even without the cable connected on the other end?

The phone even wakes up without the other cable end connected. But does
not start loading, since there is no power...

> > Plugging in at the other end of the usb line is not detected (when
> > first plugged in at phone, phone wakes up, but can't load since
> > there is no power and goes sleeping again)
> > After some seconds (mostly) (sometimes even about half an hour) it
> > stops loading, even when battery capacity is still critical.  
> Hm. Looks like broken cable.

Since i used different cables, i would suspect the connector.

> > 
> > Old openmoko power adapter doesn't seem to work at all.
> > 
> > To get the phone usable i need to watch it closely, and unplug and
> > replug it, if it stops loading.
> > 
> > 
> > Environment:
> > I use QTMoko. Since this has some lag until plugging is detected, i
> > use neocontrol to view power status.
> > I resoldered my usb-port, maybe something went wrong there. But
> > right after resoldering it, it was working good and now got slowly
> > worse... Also the sd-card got already corrupted at some point, i
> > will reinstall next days to exclude a software error
> > 
> > 
> > Where i need help:
> > Is there some way to determine why the phone stops loading?  
> I don't know about tools but latest QtMoko still uses the old 3.7
> kernel which does not have a good charger driver. The main problem is
> that it simply stops charging as soon as the USB voltage inside the
> GTA04 drops below 4.5V. And does not restart unless you unplug +
> replug the cable.
> This may have a reason in a weak cable or weak power supply,
> especially with almost empty battery when the charging current going
> through the cable (in parallel to operating the GTA04) is highest.
> This may be ~800 mA...
> > 
> > When i want to check my usb-port, is this possible with a simple
> > ohm-/volt-/ampere-meter? What are the readings that i should expect
> > between the usb-pins when connected correctly to the board?  
> A common source of trouble is if the GND or the shield is not really
> connected. This may happen during repair. So you should check if you
> have 0V on GND
> 3.3V on data lines (may be there only for a very short test cycle so
> you can't notice) ca. 1V on the ID line
> 5V on the VBUS line
> For charging, the data lines are not used. Therefore having a good 5V
> input is most important.

i don't have a clue about the usb-standard, so i describe here what i
hopefully understood:
When i look at the big connector side of my usb
cable (other side connected to the phone), i guess the left of the outer
pins should be GND and have 0V (and 0Ohm) to the shielding.
The two inner pins are the data lines, of which one should have 3.3V
for some micro seconds and the other is the ID Line and should have 1V
(both against the GND, and shield).
The right outer pin then is the VBUS line and should measure 5V to GND.

Is there something to say about the resistances between the lines on
the phone? I want to check if i did some bad connections...

I guess i have to measure voltages, while the gta04 is running? If this
should be measured while gta04 is off and connected to some power
source, how can i measure them (where should i point my measure tip)? 

Kind regards,
Thomas Munker

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