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How to replace the damaged charging circuit, for tablets with a deador blown charging-circuit!
A simple workaround for Dropad A8 (and similar) users, that were so clever to void their warranty.
Disclaimer:I'm not responsible for any dama e, that is caused by followin this uide.If you drop some solder on your main board, it's your own bad luck.Dama ed !ithium cells can be dan erous. "here are enou h stories on the internet, thatshow you burnt cars, tables, toys etc. #ost of those batteries were bi er than the one inthe Dropad, but even the small cell in the dropad has enou h power, to let a wire melt ifyou cause a short. $o please take care, work in a safe environment (no colors, asoline,paper or other stuff, that easily catches fire around you).
"his workaround uses this char er from %Deal& tremehttp **www.deale treme.com*p*replacement+ + mm+-+ mm+dc+8+/v+ a+power+adapter+supply+ 00+-/0v+-+flat+pin+plu +1118/If D2 chan es their website and the link doesn't work, search at D2 for %$34.1118/
It will work for devices with a blown or dead char in circuit. It does not repair a dama ed(dead or blown) battery cell or a bad protection board. "he char er will not be able tochar e a bad cell.
I tested this on a Dropad A8, with a perfectly working char er circuit, and there are someproblemsas lon as the connection from the power plu to the (workin 5) char in circuit e ists, thebattery tries to char e itself5"he tablet will still work, but even when the tablet is shut down, it still drains the battery(pretty fast5).This simple solution should work, if the charging circuit inside the Dropad is blownup, and it might work if the circuit only works on low powerIf your tablet only char es very slow, try out this solution first, before you try the second orthird uide. I tested it on my Dropad, and nothin was dama ed...6har in the battery with the Deal& treme+char er, while the tablet is runnin , did notwork for my tablet5 I was able to char e my battery, with the D2+char er connected to thebattery directly. 4sin the tablets power plu only worked when the tablet was shut down,but that mi ht be, because my char in circuit did the 7ob.If your circuit is dead or blown, the char er will be able to power the tablet, but you will notsee the %char in status in Android. ou will see the battery volta e risin , but the system
will have no connection to the char er.
"he uide was written for a Dropad A8, but should also work for any of those china tabletswith a %9,/: battery .
I bou ht the D2+char er to cure my curiousity. I wanted to know, if it really is a !iIon+char er for a -+cell+pack, because I didn't find any of those char ers on other websites..
http://www.dealextreme.com/p/replacement-5-5mm-2-1mm-dc-8-4v-1a-power-adapter-supply-100-240v-2-flat-pin-plug-66684http://www.dealextreme.com/p/replacement-5-5mm-2-1mm-dc-8-4v-1a-power-adapter-supply-100-240v-2-flat-pin-plug-66684http://www.dealextreme.com/p/replacement-5-5mm-2-1mm-dc-8-4v-1a-power-adapter-supply-100-240v-2-flat-pin-plug-66684http://www.dealextreme.com/p/replacement-5-5mm-2-1mm-dc-8-4v-1a-power-adapter-supply-100-240v-2-flat-pin-plug-666848/13/2019 Charger Repair Guide 1
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ou"ll need:
."he D2 char erhttp **www.deale treme.com*p*replacement+ + mm+-+ mm+dc+8+/v+ a+power+adapter+supply+ 00+-/0v+-+flat+pin+plu +1118/
"his char er has a %4$ wall connector, but your ori inal power supply for the tablet usesthat two, so you mi ht have the ri ht adaptor you need for your wall outlet.
-.a solderin iron with a ood, clean tip;.solder wire
"he followin is not absolutely necessary, but recommended/. a multimeter, to check volta es and polarities (very recommended55)
. a %helpin hand , like this
It doesn't need to be from D2, but it helps holdin small pieces, while you need your bothhands, to solder a wire to a small board (for e ample the char er board).
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#irst some theory:ou may ask =>hy do I need a special char er?%
Answer >hile char in , !ithium batteries, both !i+Ion and !i+@o, behave very different toi6d or i#h batteries. "herefor it's not possible to char e them with a usual char er or
even a power supply, it will dama e them. At
http **batteryuniversity.com*learn*article*char in BlithiumBionBbatteriesyou find more information about it.If you compare their %
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After that the char er switches to CcvC+state it holds the char in volta e %constant , andthe current will o down, until the battery is fully char ed ( 8,;:). It did this until thecurrent had dropped to 90mA. "he capacity ratin says, the char in current should odown to 0,0;6, here it is 0, 00mA, so / mA would be better, but also take another
-0 minutes. At
http **batteryuniversity.com*learn*article*char in BlithiumBionBbatteries%"able - you can see, that you loose some battery capacity, if you don't char e up to /,-:."he problem with our battery is, the cells are connected in series. Fecause of thebehaviour of lithium cells, you can not simply char e a - cells pack to 8,/:5 If the cells aresli htly different, 8,/: mi ht cause one cell to be at only /, : and the other already at/,;: (overchar ed5), or even worse. "his will not instantly dama e that cell, but at least itmi ht cause a shorter cell lifetime."herefor the battery has a protection circuit built in, that will shut down the char in , if acell volta e reaches /,;:. Also it seems, the manufacturer took a lower (safer) volta e of8,;:, to call it Cfully char edC, and stop the char in process.
The Deal$%treme charger:$ince 9 th Guly -0 , D2 has this %power supply , the one we will use herehttp **www.deale treme.com*p*replacement+ + mm+-+ mm+dc+8+/v+ a+power+adapter+supply+ 00+-/0v+-+flat+pin+plu +1118/
>hen I first read the %8,/: , I wondered, and had a closer look. It says %!i+Ion char er onit's sticker5I ordered it and testedthis really is a char er, with all needed built in circuits, to correctly char e a - cell !ithiumbattery pack5 I tested it's char in behaviour, and it's a perfect replacement for a dama edcircuit in the tablets, it does the %66*6: char in ."he %66*6: switchin point is at 8,0:, this is nice, because it will char e a bit %softer thanthe ori inal circuit, but it will take a little bit lon er (maybe 0 minutes, not much more5).
As it's not able to detect the sin le cells volta e, it will need a workin protection circuit inthe battery pack, to protect the sin le cells from overchar in (7ust like the ori inal circuit5)."he plu on this char er does not fit the tablets plu , so we will e chan e it with theori inal connector.
http://batteryuniversity.com/learn/article/charging_lithium_ion_batterieshttp://www.dealextreme.com/p/replacement-5-5mm-2-1mm-dc-8-4v-1a-power-adapter-supply-100-240v-2-flat-pin-plug-66684http://batteryuniversity.com/learn/article/charging_lithium_ion_batterieshttp://www.dealextreme.com/p/replacement-5-5mm-2-1mm-dc-8-4v-1a-power-adapter-supply-100-240v-2-flat-pin-plug-666848/13/2019 Charger Repair Guide 1
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Hne last thin , about the =battery status%
In this chart you can see, how my dropad displays the battery status, compared to the
battery volta e, it was taken after a %battery calibration (useless, didn't chan e anythin 5)."he +a is is the time it took to dischar e the battery until dropad shut off,it was runnin for9 hours.I did this with the display, wifi and the battery app runnin the whole time. !ike this, thecurrent drawn from the battery should be nearly constant. "he char e of the battery will odown from 00 to 0 over the time, 7ust like the black dotted dia onal line. Fut thebattery app displays the char e like the blue curve, very hi h all the time. At C;00 minsC isa point, where the app says 0 , but in reality the battery only has ;0 runtime left, thisis a 19 error5
ou can also see, the - cell battery volta e is not oin down strai ht from ma to min, it's
also a curve. orst point is the 9,; :*;0 status at ;E0 minutes, there was only E runtime left.
A battery status of ;0 is an empty battery, not more. 4sually, in K*6 toys, the lithiumbatteries are only dischar ed to 9,/: (;,9: per cell), the nominal volta e of the pack.Dischar in it to a lower state stresses the cell and causes shorter battery lifetime.
!ater, when char in your battery, you may use this chart as a %reference for your char estatus.
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The mod begins, e%change the connecting wire&plug:
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After completely opened, you can see the two output wires, connected to the board."he ne t picture shows my Dropad's power supply, so be aware, different tablets mayhave a different board layout."he Dropad's power supply has one wire marked with a white line alon the wire. "hat isthe %ne ative wire, that oes to the outer sleeve of the plu .
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Hn this picture you can see a markin for the two wire connectionson the left it says %+D6 oin to the outer plu 's sleeve, ri ht is %LD6
Also If you later want to reassemble this power supply, have a look at the small wire loopin the middle of the board5 ou need to put the wire back to the small ap in the board,otherwise the board will not fit to the housin 5 Desolder the two wires from the boardIf your wires don't have the %ne ative markin , look at the board to find out, witch wire is%+ and mark it. If you have a multimeter, you may also check the ne ative wire afterdesolderin .
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'pen the D(-charger:
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)ull out the board from the housing
Hn this picture you see the two solder connections to the output wire."he top left connection is the =ne ative% and oes to the outer sleeve of the plu ,
the bottom ri ht is =positive% and oes to the inner sleeve of the plu .
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>hen I first opened my D2+char er, the two wires were not connected to the board5 "hewires were stuck to the holes, and there were solder blobs at the end of the wires, but theywere not connected to the board5
Also, at the ri ht side of the picture, you can see a bi solder blob. "here was a shortpiece of wire in it, and it nearly touched the solder point on it's ri ht site.
It seems, these char ers really passed the =chinese M6%, they only for ot, to put the =M6%sticker on it ...!H!
Nave a look at your boards solderin , compare it with my picture. If anythin looks stran e,and you are not sure, if it's ok, take a picture and post it at slatedroid. I will try to help.
Desolder the wires from the D(-charger *use the +acuum pump to remo+e thesolder , and solder the wires of the tablets charger plug like this:
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)ut the board back to the housing of the D(-charger ."ake care to place the board between the two uide rails on each side of the housin ,otherwise the !&D will not fit to it's hole...
6lose the housin like you opened it, put the screw in it's place.
ou should check your work with a multimeter *if possible :after you put the charger to a wall outlet, you should measure ,.- ,/0 on the plug,outer slee+e of the plug has to be negati+e!
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1onnections inside the tablet:
"hese photos are taken from a Dropad's inner life, but I think the layout will be like this onefor most of the chinese tablets.#irst, desolder the battery connection, and23)'4T56T7: insulate both battery wires!2t is recommended, to take the battery out of the tablet!
In the upper ri ht corner you see the microphone, below is the power connector.
"he two silver surfces are connected to the outer sleeve of the plu (ne ative, round), thevery small piece of metal (small picture, left arrow), is connected to the inner sleeve(positive).>e need to connect these two to the battery connection.
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I found two places, where solderin a wire is very easyOround (ne ative, outer sleeve of plu )) is found at the solder point between the yellow %!shaped surface and the %$dcard holder,positive (inner sleeve of plu ) is connected to the first three 7oints in the strai ht row of themain board connector (if you solder the wire to the first 7oint only, you don't risk to solder tothe number /).
"he other ends of the wires are soldered directly to the battery connection.
"he wires I used are a bit too thick, the wires to the battery have the ri ht siPe. Also, don't place the wires on top of the main board like in my picture (this was only for thepicture5). !ike this, you will not be able to close the tablet's back without sQueePin thewires5
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3y Dropad connected to the D(-charger
Nere you see my Dropad connected to the D2+char er.Fecause my char er circuit inside the tablet still works, I have a %red and reen !&D atthe same time."he tablet works, and char in is possible when the tablet is shut down.
2f your charger circuit inside the tablet is completely dead, you should see a greenlight and the battery +oltage rising!
2f you tried this simple7 solution, you also ha+e a green and red7 9$D, and youwant to use the original power connector, you will need to disable the connectionfrom the power plug to the main board! That solution will be discribed in the secondguide! 2t is much more difficult and not recommended etter wait for the third partof the guide, that uses a secondary plug for the charger connection
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1onclusion:
I hope, everythin is workin as e pected? If not, wait for the ne t two uides...
>hen you did all this and the char in works, there still will be some thin s to keep inmind
.)"he D2+char er has an indicator !&D on it's topit shows %red while the char in volta e is below 8./:, and red when the volta e is morethan 8,/:."he ma imum volta e for a !ithium battery should not be more than 8,/:, sodisconnecting the charger when the light turns green is recommended3y char er didn't stop char in , the volta e rised to 8, : and more, this is bad for thebattery5-.)If the protection kicks in because the battery volta e is more than 8,/: (tablet switches offor doesn't start), it can be resetted by disconnectin the char er, wait some time, andreconnect it for a short momentIf it doesn't work, you may have to wait some hours , and try a ain.
;.)Don't trust chinese electronics5>hen you connect your char er to the battery, don't leave it unattended. All char ermanuals tell you this, because, if they fail, you're in trouble. Don't leave the batteryconnected to the char er, when char in is done. Don't leave the house, when the batteryis connected to the char er. If you have to o away, disconnect the char er.>e all had our bad e periences with the chinese stuff, so you know, chinese crap isune pensive, but mi ht be a trap...
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;ust to let you know, who you are going to trust
that"s me:
>ell, no comment, e cept
)rost!
!H!
