[Gta04-owner] problems with battery loading

H. Nikolaus Schaller hns at goldelico.com
Sat Jun 4 16:47:00 CEST 2016


Hi,
did you have success yet?

We are currently running our OpenPhoenux hacking weekend and I have just observed
a strange thing with the USB charger:

if I unplug and replug the USB cable on the PC side the GTA04 (with 4.7-rc1 kernel)
does not recognise that event. But if I unplug the USB cable at the GTA04 end it is
recognised.

This looks a little similar to your issue report.

BR,
Nikolaus



> Am 27.05.2016 um 21:20 schrieb t.munker at gmx.net:
> 
> Hi,
> my guess was that i did some short circuit (maybe with some higher
> resistance) so that voltage is brought from VBUS to the charging
> detection pin. But since VBUS is used to charge, i don't know. maybe
> the cables impedance plays a role and acts as a small capacitor in
> combination to some resistances i introduced while soldering the new
> connector?
> 
> I've measured at the big usb-end of my charging cable and got following
> readings:
> left: 0 Volt  to shielding
> middle two pins: did't care much, something between 0.6 and 0.9 Volt
> right: 5,xx Volt
> 
> I can't see any suspicious in these measurements.
> 
> I am waiting to buy/lent me an hot air gun, before i open up the phone
> and maybe try to resolder again.
> 
> Is there any way to ensure that not the IC mentioned by Nikolaus
> is defect? 
> Any other thoughts?
> 
> kind regards,
> Thomas Munker
> 
> 
> 
> Am Fri, 27 May 2016 12:13:54 +0200
> schrieb "H. Nikolaus Schaller" <hns at goldelico.com>:
> 
>> Hi,
>> 
>>> Am 26.05.2016 um 23:33 schrieb <t.munker at gmx.net>
>>> <t.munker at gmx.net>:
>>> 
>>> Hi,
>>> 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...
>> 
>> That is really strange. Wake-up means that there is some power
>> detected on the VBUS line. But how connecting just a cable with open
>> other end can do this is strange.
>> 
>>> 
>>>> 
>>>>> 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.
>> 
>> Yes. Or no. Some cables have 0 Ohm to shielding others don't. But the
>> GTA04 should have 0 Ohm between both.
>> 
>>> 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).
>> 
>> Yes.
>> 
>>> The right outer pin then is the VBUS line and should measure 5V to
>>> GND.
>> 
>> Yes.
>> 
>>> 
>>> Is there something to say about the resistances between the lines on
>>> the phone? I want to check if i did some bad connections...
>> 
>> If you take an ohmmeter (with low voltage!) you can usually see some
>> values above kOhms.
>> 
>>> 
>>> I guess i have to measure voltages, while the gta04 is running?
>> 
>> Yes.
>> 
>>> 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)? 
>> 
>> Hm. It could also be a broken ESD chip. It has some diodes inside
>> which protect against overvoltage but are high resistance if voltages
>> are ok.
>> 
>> If these diodes allow reverse-current, a voltage on some data line
>> may rise VBUS to a level that is detected as a charger wakeup event.
>> 
>> On the other hand it still does not explain why it happens with a
>> cable not plugged to a power supply...
>> 
>> BR,
>> Nikolaus
>> 
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