One of my kids dropped their Kindle when plugged in. The USB jack became loose, and the Kindle no longer wanted to charge. Specifically, gymnastics involving propping the kindle up, twisting the plug and standing on one foot were required to make it briefly charge until you walked away, and being out of warranty this was a terminal condition for the little tablet. Before going wireless, we’d previously taken the Kindle WAY apart, tried to resolder the USB socket and after 2 hours of stressful work on tiny components we had a fix that lasted 4 days.
I had 3 Palm phone “slip on back’s” each with a wireless charging receiver circuit and a spare palm touchstone charger in my junk bin. I also had some beer in the fridge and free time on a snowy Saturday.
First we used a spudger to open the Kindle, separating the back cover from all the circuitry in the main case. Google “spudger”, buy one if you like doing this kind of thing.
The Kindle back cover had a stainless steel liner. Presumably this was for RFI compliance or a blast shield for LiPo over-exuberance. Invariably, this would not have played nice with an inductive coupling so we pulled it off and insulated the coppery-clad back with packing tape at the “X” marking the center of the back:
This “X” is where we would tape the inductive power receiver that we carefully peeled off of a Palm back. The “power receiving” coil is really thin wire, and it loves to break if you are rough with it. Don’t be rough with it.
We put the power receiver onto the plugged-in touchstone, noted and marked which of the two terminals was “+5.5ish” volts. Once marked, we soldered a couple of thin wire leads to the charge receiver terminals, and prepared to locate where the Kindle took in 5V and Gnd:
We plugged in a regular USB plug to the dodgy socket, and while one kid wiggled it around, I probed to identify where 5V occasionally came out on the backside. Ground is easy to find, as most of the big fat “filler traces” that screws contact are ground. The +5v is the one on the left below, GND is the ugly solder joint on the right:
Well, that was about it- we snapped the back in place, crossed our fingers and put the Kindle on the junky old Touchstone base:
The charge indicator on the side turned Orange, and the Kindle started charging. Now, the thicker back makes the Kindle sensitive to the exact location of the external Touchstone with respect to the charging coil so we marked a “put charger here” circle on the back with a silver sharpie. When located correctly the Kindle charges as fast as it did with the factory-provided charger!
Junk parts + broken Kindle + beer + dad = happy kids and a rejuvenated Kindle!
Palm Touchstone inductive charger: http://www.amazon.com/Palm-Touchstone-Charging-separate-Charger/dp/B002CMEIWK
Palm Inductive charging back: http://www.amazon.com/Palm-Computing-Div-Touchstone-Cover/dp/B002UNKGMC
Recommended beer: http://www.sierranevada.com/beer/year-round/torpedo-extra-ipa
This worked surprisingly well, and while not all USB-charged products may like being fed by a (less regulated?) touchstone power receiver it may work great. The Touchstone is FANTASTIC, charging your phone by just putting it onto a little charging tombstone is super convenient and avoids the USB jack damage that our Kindle suffered. This would probably work for many other tablets, phones, and other USB charged thingamabobs that have room for the (very thin) Palm touchstone receiving circuit. If you have an incapacitated USB jack, or if you are looking for a way to pass 5V without wires/via/breaching a plastic case then give this a try for $14.
The Kindle has been happily recharged daily with this hack for the last two weeks, and so far so good.
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