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Xperia Arc S - battery drain in OFF state - suspect hardware

23rd January 2014, 11:23 AM   |  #1  
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Hi there,

my problem is as shortly described in the topic.
The device drains between 50-190mA in an OFF state depending on the voltage applied.
I used a lab power supply to check it.

The procedure to measure it is:
0) perform repair using PC Companion - the device is completely clean
Model: LT18i
Android version: 4.0.4
Kernel: 2.6.32.9-perf
Build: 4.1.B.0.587
It has been upgraded from its factory version quite some time ago.
The drain problem started long after the upgrade.
1) Installed (just for formality): Battery Widget, Battery Stats Plus, OsmAnd, GPS Test, Total Commander
- the rest is usual bloatware that installs itself
1) switch off all possible functions (plane mode, WiFi OFF, BT OFF, ...)
- no alarms, no calendar notifications
2) power down the phone
3) take out battery, SIM card and SD card
4) connect power supply directly to battery connectors on the phone
5) no other cables connected (neither the battery)
6) apply voltage 4.2V (190mA) -> 3.0V (33mA) in 0.1V steps

Let me stress it again - the phone is in OFF state - no power button pressed, no attempt to boot it.
At this state I would consider 10mA normal, but definitaly not 200mA.

I have done a bit more measurements, but I don't think it is of use now.

As I mentioned above, the problem started suddenly, long after I upgraded to a newer OS version.
I noticed it since the phone started heating, which I could feel in the pocket.

Now, a bit about the heating. It seems that the source of it is a chip that I have identified as a Flash memory.
It sits around the top left under a metal shield when looking from the back of the phone,
after unscrewing the plastic mid-part. It is worm even in OFF state (no charger, just battery).
It gets very warm when the phone is ON and "unpleasantly" warm when there is some activity
(I actually played with the camera).

Otherwise the phone is fine. I haven't noticed any problems with it.
I use it as a navigation, SD card and SIM inserted, but no service (I mean the SIM card is inactive).

Now the actual question - is there a SW way (I mean without desoldering anything) to possibly
correct this problem? Unfortunately my suspicion is that some power management component
must have failed and it keeps delivering power.

Any help will be appreciated. It is still quite a nice device.

Marcin
24th January 2014, 12:20 PM   |  #2  
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I had this problem with my device as well (not as specific as yours, i didnt do any diagnostics just noticed the battery was draining even when off and the same part remained warm) which was the main reason I upgraded to an N5. Brought it to a service centre they said motherboard damage (apparently caused by water but i can't think of any instant i exposed my phone to water unless its from the humid climate here). It's not the battery because i have 2 batteries and both has the same problem, and definitely can't be fixed with software.. From 1 month trying different ROMs kernels and mods trying to fix it.

Sent from my Nexus 5 using Tapatalk
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27th January 2014, 03:29 PM   |  #3  
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Thanks tangosierra_, I have heard a lot of bad things about "authorised" service centers (of any kind).
I heard and read a lot of users complain about their lack of competence. They would always make sure
to void your warranty by showing you mechanical damage. If there is no damage, they would say
it was caused by water - why not? Everybody sweats - right?

Looking for some info about the flash chip (it is micron nw238) I came across this blog:
theelectronicfreak.blogspot.com/2011/08/sony-ericsson-xperia-arc-teardown-and.html
It seems to have a lot of interesting info in it.

For the moment I give up. It doesn't have to be this chip and I don't have enough experience
with such small devices. Resoldering a BGA of this size is beyond my capablities
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