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Need help troubleshooting, dead rk3066 tablet

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By mrnjau, Junior Member on 18th December 2013, 11:44 AM
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Hello,

I need help with my new tablet.

Model is Allfine Fine10 Yoy.

Specs:
  • Rockchip RK3066, 1.6GHz, Cortex A9 dual core; GPU: Mali 400 MP4
  • Android 4.1
  • 1GB (DDR3)
  • 16GB Nand Flash
  • 10.1 Inch / IPS
  • Battery: 7800mAh


It is not so old, about 5 months. Few days ago I have left it to charge overnight (it usually takes 4-5 hours to charge so I always charge it overnight) and in the morning it could not turn on. It is dead, no signs of life. I checked maybe it did not charge, so I changed power socket and tried again.
I can not charge it via USB so I can't test that.

There is not sign of life when connected to PC, adb list's no devices.
There is no sign of life after holding power/lock button for a long time and there is not signs after holding restart button.

It came factory rooted, I've never updated/flashed or anything.

I have not noticed any troubles so far, no lags, no freezing, no overheating.

Are you familiar with debug method for this kind of tablet?
What should I do, what test to make?

Can you help me debug this, please.

Thank you.
 
 
18th December 2013, 11:22 PM |#2  
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cheap china tablets are easy to open up. just pry the back cover off carefully and put a volt meter on the battery. its probably dead.

check your power supply first, it might have croaked too.
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21st December 2013, 11:05 AM |#3  
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Would it be possible to run tablet with removed battery, straight off adapter to check is it working?
21st December 2013, 01:54 PM |#4  
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Quote:
Originally Posted by mrnjau

Would it be possible to run tablet with removed battery, straight off adapter to check is it working?

Possibly, at least some part of startup.
Most device processors will start up if they notice power coming from somewhere.
At some point try will try to access the state and source of power.
If they notices that the battery is really dead (that is, the power is only from USB) they will shut down and go into charge-only mode.

It may be more likely that your battery is charged and the processor got wedged somehow.
Disconnect from USB, open the back, disconnect the battery and reconnect it.
21st December 2013, 07:37 PM |#5  
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Quote:
Originally Posted by Renate NST

Possibly, at least some part of startup.
Most device processors will start up if they notice power coming from somewhere.
At some point try will try to access the state and source of power.
If they notices that the battery is really dead (that is, the power is only from USB) they will shut down and go into charge-only mode.

It may be more likely that your battery is charged and the processor got wedged somehow.
Disconnect from USB, open the back, disconnect the battery and reconnect it.

Thank you for your reply,

I've precedeed as you sugested.

Solder is pretty hard on battery connection, so I unsoldered just one (negative wire, red one) and pluged it to charger and try to start it. I undsolderd just one because I don't want heat to ruin something and I guessed it should be enough to try this.
It still shows no signs of life.

However I've noticed something, when re-soldering red wire I have noticed that there is a spark when wire is near the solder point. So, there is some power in battery.

Any idea how to proceed? I still don't have multimeter to test battery voltage so that will have to wait.

Thanks once again.
22nd December 2013, 04:26 AM |#6  
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Oh, sorry, I thought that the battery was on a connector.
That makes life easier than soldering.

The red wire(s) are always the positive.
The black wire(s) are always the negative (ground).
Any other color wires on a battery are thermistor, id sense or communication.

Yes, finding/borrowing a voltmeter is the next step.
3rd March 2014, 01:27 PM |#7  
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Quote:
Originally Posted by Renate NST

Oh, sorry, I thought that the battery was on a connector.
That makes life easier than soldering.

The red wire(s) are always the positive.
The black wire(s) are always the negative (ground).
Any other color wires on a battery are thermistor, id sense or communication.

Yes, finding/borrowing a voltmeter is the next step.

Renate, I hope you still follow this topic.
I'm sorry for 2 months without updates, I've waited for some time for parts from China.

So, what have I done so far...

1) Get multimeter.

2) Test battery.

Battery is designated as 3.7V, however output is 4.15 - 4.16 V.
I've presumed this is fine.

3) Test the charger.

Charger is designated on 5V and 3A. I've tested voltage, it is fine. However ampers dance between 0.5A and 3.5A. I've presumed that charger is faulty, so I've ordered new one. Generic 5V, 3A charger.

4) Put it back together, re-solder the battery and connect charger. Test again.

Voltage on battery connectory is same as before - 4.15V.

After 20min there is no change in battery temperature (source: my fingers), however power jack where new charger is connected is getting warm, but not too warm.

Tried to power it on, no signs of life. Tried holding restart button for forewer, no sign of life.


I'm out of ideas.
3rd March 2014, 02:58 PM |#8  
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3 Amps is a heck of a charger.
Where did that come from? Is it stock?
You have a little round coaxial connector for the charging input on the tablet?
There's no reason that it should be drawing 3 amps or anything getting warm.

The battery is fully charged.
There could be a high resistance in the battery protection module so that it looks charged but can't actually supply any current when called upon.

There's a USB connector on this too?
And nothing appears when you connect a USB cable to it?
I wouldn't expect ADB, but maybe a bootloader.
Run devmgmt.msc when plugging it in and see if anything at all shows up.
3rd March 2014, 03:33 PM |#9  
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Quote:
Originally Posted by Renate NST

3 Amps is a heck of a charger.
Where did that come from? Is it stock?
You have a little round coaxial connector for the charging input on the tablet?
There's no reason that it should be drawing 3 amps or anything getting warm.

The battery is fully charged.
There could be a high resistance in the battery protection module so that it looks charged but can't actually supply any current when called upon.

There's a USB connector on this too?
And nothing appears when you connect a USB cable to it?
I wouldn't expect ADB, but maybe a bootloader.
Run devmgmt.msc when plugging it in and see if anything at all shows up.

Stock charger is 3A, so I bought with indetical specs. My research showed that a lot of chinese tabs use 3A chargers (Ainol Hero, etc..)
Yes, charger connector is 2.5mm "needle".

Some 30min after I posted this area around connector and speaker on motherboard got very very hot, I almost injured myself by touching it. So I've disconnected it.

No, nothing on USB. I've mentioned it in my first post, there are no signs of life on adb. Or "dmesg", which should list something even if device was bricked.
3rd March 2014, 04:30 PM |#10  
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Um, are you sure that the polarity of the supply is correct?
For coaxial plugs the center is usually positive.

If it got that hot you probably have blown something.
3rd March 2014, 04:42 PM |#11  
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Quote:
Originally Posted by Renate NST

Um, are you sure that the polarity of the supply is correct?
For coaxial plugs the center is usually positive.

If it got that hot you probably have blown something.


http://www.amazon.com/2000mah-Adapte...5XRX7QS8JJ91Y9


This is that kind of power connector, 2.5mm. Are we talking about the same thing? Is is possible for this kind of connectors to have non-standard polarity.

Maybe nothing is blown, I would smell that. Maybe there just hi resistance somewhere along the line.
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