I get another toy for this week.It is working great, exept it is not charging the batteries.
Teardown time!
Diagnosing the problem allways starting with visual expection. You can clearly see what is wrong here
The problem is clear, but how to replace a part that never existed in a good condition that is to say, you never seen it, just as a burned piece of silicon.Googling based on the PCB silkscreen get some hits but nothing usefull at all. I dig myself into the device power section, specialy in the charger circuits an I think this is some kind of regulator or protection circuit. Now time to thinking...
How this tablets are made? Every manufacturer design his own pcb from scratch? Not of course.Semiconductors like RockChip are popular in this segment.Lot of manufacturer use these kinds of SoC and exist somethink called "solution".A full solution for tablets,smartphones,TVboxs and others.
You don't need to searching too hard to find a reference design for the RK3188 or a similar RK SoC.
In the right schematic you can shortly find the blowed part.This was a PolyFuse, ZEN056 familly.This is a Polymer Protected Zener Diode and this means someone applyed wrong voltage on DCIN connector.Now you can order one.
After I replaced the burned fuse I see the ZEN056 can save the rest of the board from overvoltage.Nice engineering not least!
More picture
Teardown time!
Diagnosing the problem allways starting with visual expection. You can clearly see what is wrong here
 |
| Something blown up and burned hard |
The problem is clear, but how to replace a part that never existed in a good condition that is to say, you never seen it, just as a burned piece of silicon.Googling based on the PCB silkscreen get some hits but nothing usefull at all. I dig myself into the device power section, specialy in the charger circuits an I think this is some kind of regulator or protection circuit. Now time to thinking...
How this tablets are made? Every manufacturer design his own pcb from scratch? Not of course.Semiconductors like RockChip are popular in this segment.Lot of manufacturer use these kinds of SoC and exist somethink called "solution".A full solution for tablets,smartphones,TVboxs and others.
You don't need to searching too hard to find a reference design for the RK3188 or a similar RK SoC.
In the right schematic you can shortly find the blowed part.This was a PolyFuse, ZEN056 familly.This is a Polymer Protected Zener Diode and this means someone applyed wrong voltage on DCIN connector.Now you can order one.
After I replaced the burned fuse I see the ZEN056 can save the rest of the board from overvoltage.Nice engineering not least!
More picture
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