Slashdot Mirror
How a Leather Cover Crashes the Kindle
An anonymous reader writes "Amazon has started offering refunds to Kindle owners who own the unlit leather case who claim that it causes their Kindles to reboot, but are playing dumb on the cause: "our engineering team is looking into this." People have been wondering how a leather cover could possibly crash an electronic device, and why is Amazon offering money back if they don't think there's a problem? It seems that some of the folks over at Connectify have figured it out, and it's a doozy!"
Lest we forget:
http://ftp.sunet.se/jargon/html/magic-story.html
Palm trees and 8
Someone had to do it.
Maybe they can substitute the metal now connecting the hooks with extremely fine steel wool. Then everyone will remember it's the Kindle.
We constantly hear about needing to "program defensively" and test for "can't happen" conditions.
Here's one for defensive engineering.
not owning a Kindle I don't understand why there is even a need to have the two "hooks" connected in any way by a piece of conductive material.
They are not powering a lamp, they just keep the Kindle attached to the leather case.
I like microcars
a malfunction in a high tech device that actually can be fixed with duct tape
First, his meter's reading 2 Megaohms, not 2 Ohms. I guess he's not much of an "Electronics Person". Second, it would appear that he's measuring conductivity though his body to achieve that number. Both of his fingers are touching the probe tips.
The linked article at Connectify says they measured a resistance of 2 Ohm, but on the picture I read 2 MOhm!
Check yourself with the large version of the picture.
The flaw is certainly in the cover(using two physically separated hooks, rather than a single piece of metal, would not have been rocket surgery and would have provided dielectric strength high enough to resist pretty much any voltage that wouldn't also kill the user.) However, we really have no way of knowing whether the cover maker failed to follow amazon's orders, whether amazon failed to issue the correct orders, or who was responsible for considering the situation where the + hook and the - hook are not separated by an LED and current limiting resistor.
If amazon didn't think about it, or naively thought that a thin layer of cheap paint would do, they fucked up. If the cover maker looked at a design document that said "Connecting hooks must be electrically separate" and said "eh, one painted part is cheaper than two physically disconnected parts, paint'll do." then they fucked up.
If you RTFA, you'll see the hooks are totally different. You're in the right vein, though. The unlit case looks like it uses a single strip of cut metal for the attachment hooks, a pretty simple design, and much cheaper than making hooks that aren't shorts.
My guess is the only reason they're painted black is because they were aware of this problem and thought that would fix it good and cheap. Or the paint is simple corrosion prevention and they didn't know...
When you're afraid to download music illegally in your own home, then the terrorists have won!
It looks like a flaw on the part of the cover maker. Amazon could put some amperage limiting circuitry, but I imagine it would raise the cost.
Look closely at the dudes meter, its 2 megohms not 2 ohms. Lets guess its a single cell li-poly at 3.7 volts. Thats a smokin' current of 74 microamps. What, a quarter of a milliwatt, something like that?
Good luck building a 74 microamp fuse. I once built a microwave preamp in the 80s and static fried the active device, that probably was a 74 microamp fuse, in a weird sort of way.... Active current limiting at that level is kind of a mystery to me... I suppose you'd need a mosfet off resistance in the hundreds of megohms since the load impedance is in the single megohm range, but PC board leakage currents are going to be a problem at that level. Leakage currents thru the plastic kindle case would probably be in the microamp range?
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
You suppose wrong.
We used AA batteries in prison to light cigarettes when they took away access to the wall sockets.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Being a product manager, I would guess that whomever wrote the spec for the cover latch, specified dimensions, and what is required for it to be a sturdy fit. But that they forgot to specify that there was to be no electrical connection or conductivity between the tabs.
The Winning bidder probably chose to make the bracket out of brass (guess here) to ensure dimensional integrity, and because a plastic mold for a thermoplastic injected part would be a couple tens of thousands of dollars.
But, I would bet my last dollar that someone at QA at Amazon figured this out, and specified that the bracket had to be painted with a non-conductive paint as a band aid.
This is how trivial, serial bad decisions come back to bite you in the arse
Suppose you were an idiot and suppose you were a member of Congress
I got a Marware cover for my iPad and love it. One issue it had though, was that the iPad's compass simply never worked. It always gave me the Figure-8 Shake warning, and I eventually thought that perhaps my iPad was defective... Then one day I noticed that the flip out "foot" in the cover is held in place by two magnets. Whoops. Really only an issue if you use a compass app or if you want to figure out directions while not moving, but an interesting design issue none-the-less.
That's actually a terrible idea. Limiting the current through the hooks would still result in lots power being wasted, just not enough to crash the device. Over time this will cause the battery to discharge completely, which results in the owner charging it, which leads to greatly reduced battery lifetime.
If you run your batteries between 20% and 80% charge, you get orders of magnitude more life out of them compared to running them between 10% and 95% charge.
-1 disagree is not a modifier for a reason. -1 troll, flaimbait, redundant, overrated are NOT acceptable substitutes.
How exactly do you fry an ebook?
A demonstration for you:
1) Purchase Kindle
2) Purchase and download 1000 ebooks to Kindle
3) Throw kindle into incinerator
4) Purchase new Kindle and click "Sync"
5) 1000 ebooks "magically" appear on new kindle and more remarkable show no signs of fire damage.
Plastic has the virtue of being non-conductive, but my guess is that such a tiny part made in plastic could be problematic in terms of strength.
A work that expires before its copyright never enters the public domain and thus enjoys eternal copyright protection.
Fahrenheit 404?
-- I'm not a pessimist, I'm a realist. It's not my fault that life sucks so much. --
Breakdown: The lighted case gets its power from the connectors that hold the Kindle in the case. The unlit case has these two connectors physically connected even though there is no light. Putting the Kindle into the unlit case where the metal contacts are clean causes a short between the two connectors.
The ability to get power through those connector points was by design in the Kindle or the lighted case never would have been able to be designed the way it was.
It sounds to me like the engineer(s) involved with the unlit case did not communicate well with the Kindle engineers or vise versa.
Remember to maintain your supply of
His fingers appear to be touching both metal probes of the meter so 2 meg-ohms seems about right for his internal resistance.
And in the end, the love you take is equal to the love you make
I used to work on an old IBM AS400 which provided about 150 terminals (5250) to a bank. At random times, all of the terminals would lose connection to the AS400 which was located in the datacenter which was located in the floor below where everyone sat. The connections would only drop during the daytime, we could hook up all sorts of diagnostic equipment at night and almost never saw a drop.
After about 2 weeks of troubleshooting we determined that every time the elevator passed the cable infrastructure which was run down the elevator shaft, it would cause the terminal sessions to drop...
Imagine everytime you left the building at 2am after not being able to find a problem; to have someone call you and say "just as you were leaving the terminals reset..."
So all you have to do is scrape the paint, and wire in a little LED and resistor, and you have a free lit case? Thanks Amazon !
I want to delete my account but Slashdot doesn't allow it.
Jeff Bezos: "You're reading it wrong."
:)
Everybody gets what the majority deserves.
1000 minus, of course, the number of those ebooks that Amazon has decided can no longer be downloaded since the time they were downloaded into the old Kindle. Now, depending on how your tastes in ebooks line up with Amazon's whims in maintaining their public interest, that difference might be zero, or 1000, or anywhere in between.
IBM 4341 mainframe in our data-center that would just shut down regularly every Friday night, around the same time ... shutdown coincided with the approach of the USS Lexington ... Apparently the radar from the ship was strong enough to ... trigger a shutdown.
Another IBM radar story (Third hand: CE involved -> my brother -> me.)
Shortly after the "Foreign Attachments" suit required IBM to allow other companies' equipment to be directly connected, there were a number of multivendor projects, of which this was one.
Each component worked fine in the respective labs. But the first integration of the whole system took place at the final site. (Why rent some space, hook it all up, get it running, tear it down, move it, and hook it up again, when you can do it once at the final site?) So they hooked it up and nothing worked right.
Several weeks of hair-tearing and finger-pointing by exasperated CEs from several companies ensued. At one point my brother's buddy had time on his hands and decided to fix the really annoying flickering fluorescent tube. He turned off the lights - and the tube kept flickering. WTF?
He called the other CEs over and demonstrated this. Then they all took a quick look around the environment to see what might be causing it. It was a short look: The wooden building was right next to the antenna for the airport's search radar.
Lined the room with conductive material. Everything started working just fine. Handshakes all around, exit stage left.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
As already mentioned above, the multimeter in the picture is reading 2.164 megaohms which is quite a high resistance and would make no difference at all to the operation of the Kindle.
It seems that the blog owner has realised their mistake and replaced their blog entry with the content of another, but not before it made it's way into Google Cache
For those interesting in seeing the high-resolution "Oopsie" image, it is here.
Some things are best left to Google ("What's the capital of Assyria" etc), but turning that into "anything should just be Googled" is pretty counter-productive.
I've never disagreed with a sentiment so much before online. The internet is an incredibly vast wealth of knowledge and I feel that any time you have any question, it should be used accordingly.
It's amazing how much information you have access to, it is not difficult to self teach yourself computer programming, car mechanics, advanced physics, art techniques, or almost anything else using just internet information sources, and supplies at home to get you started. Obviously if you want to do car repair you should have a car and the tools necessary for the job, but understanding what to do and whats needed can easily be found online, with step by step guides!
The simple question "How does one do something" is the BEST kind of question the internet handles. There is even a popular site dedicated to it, howto.com - and Youtube will have tons of videos on topics like that.
The problem is that handy did not ask for backgruond information on where it comes from, he did not ask how to acquire those materials in prison, he did not ask about smuggling or manufacturing equipment - he merely asked how to light a cigarette with batteries. The video addresses that.
If, perhaps, he's interested on how to Smuggle items into prison - he should google "How to smuggle items into prison" and he can see the news reports on how people have tried to smuggle things in before.
I'm on the Connectify blog and I don't see anything about leather cases or flaws. When I search the page for "leather" I only see the tag and nothing else.
Darryl L. Pierce "What do you care what people think, Mr. Feynman?"