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!"

Comments

Not unprecedented

[betterunixthanunix]

Lest we forget:

http://ftp.sunet.se/jargon/html/magic-story.html

Re:Not unprecedented

[mswhippingboy]

Reminds me of an incident I encountered back in the late '70s in Pensacola, Fl. We had an IBM 4341 mainframe in our data-center that would just shut down regularly every Friday night, around the same time. We had IBM SEs come in and pour over the logs, week after week, but they could find nothing wrong and no indication of why it was shutting down. They installed monitors to check for power surges - nothing. They replaced parts - still nothing. We were in discussions with IBM to have the entire machine removed and replaced with a new machine - something IBM said they had never had to do before. After months of pulling our hair out, we discovered (not sure who made the connection - but it seemed to be a long shot at the time) the shutdown coincided with the approach of the USS Lexington (aircraft carrier) coming into port (some 10 miles or so away) from it's regular training missions. Apparently the radar from the ship was strong enough to play havoc with the circuitry causing it to trigger a shutdown. The SE installed RF shields within the box and the problem occurred no more.

So much for magic.

Re:Yikes!

[vlm]

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?

Re:Yikes!

[Khyber]

You suppose wrong.

We used AA batteries in prison to light cigarettes when they took away access to the wall sockets.

Re:He's got it all wrong

[blair1q]

Reminds me of the Garmin Edge reboot and USB connectivity problems. They didn't use a flex to connect the rear case electronics to the front case electronics, they used a riser with flexible fingers. Fair enough, but they integrated this riser with the mini-USB port jack, and because of that surrounded the case opening with a thick gasket of stiff rubber. See what's coming? When the case is closed, the gasket puts a high spring force between the two circuit boards right where the fingers are mounted, reducing the spring force the fingers can apply to their mating contacts. When using the unit in a vibrating situation (you know, like on a bike, especially an MTB in typical MTB terrain), intermittent loss of contact results in power-bus glitches, which results in inadvertent power-cycling. And these things boot slower than a netbook running Windows Vista, so not only is it wearing on your data-gathering sensibilities, it's fracking boring waiting for the thing to come back to usable state so you can sweat while you wonder if it'll blow itself out again.

Also, repeated insertion and removal of the USB connector leads to loose USB connectivity, and reboots while plugged into the computer.

It took Garmin nearly a year to "figure it out", while everyone online who knew what the insides looked like knew within seconds what was going on. And Garmin's solution was to introduce the next model (at 3X the price). People owning the buggy model were offered a chance to mail in the device for a fix, but most were out of warranty, and the fix was not reputed to be a sure one.

Moral: Never -- ever -- trust a corporation when the potential for money flow is negative to them.

Re:KaWow

[anUnhandledException]

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.

Re:Yikes!

[Sanat]

His fingers appear to be touching both metal probes of the meter so 2 meg-ohms seems about right for his internal resistance.

The old AS400 and the Elevator

[HockeyPuck]

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..."

Another IBM/Radar story.

[Ungrounded Lightning]

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.