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How a Leather Cover Crashes the Kindle

CmdrTaco posted more than 3 years ago | from the still-no-antennagate dept.

280

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!"

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Yikes! (1, Insightful)

Iphtashu Fitz (263795) | more than 3 years ago | (#34632840)

Wow. That's a pretty major design flaw.

Re:Yikes! (2, Informative)

yincrash (854885) | more than 3 years ago | (#34632908)

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.

Re:Yikes! (4, Insightful)

microcars (708223) | more than 3 years ago | (#34632976)

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.

Re:Yikes! (2)

MoonBuggy (611105) | more than 3 years ago | (#34633052)

I'm assuming it was done simply for price - the case with the light uses the hooks for power, so rather than having two entirely separate designs they just left out the light and painted over the conductive parts (and apparently didn't do a very good job of it...). Probably cheaper to mould 10,000 pairs of hooks out of metal and then paint over half than to make 5,000 out of metal and 5,000 out of plastic.

It's a problem with the case design, not the Kindle, as far as I can see.

Re:Yikes! (5, Insightful)

biryokumaru (822262) | more than 3 years ago | (#34633138)

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...

Re:Yikes! (2)

NoahsMyBro (569357) | more than 3 years ago | (#34633560)

I've got a Kindle and case from before the new version, with the possible lighted case, existed. Obviously I can't know whether or not the lighted version had been conceived when my case was designed.

But the hooks on my Kindle cover ARE metal, and ARE painted black. I assumed (& still believe) they were metal instead of plastic due to the increased strength of the metal hooks, and that they were coated/painted for esthetic reasons - the hooks feel more comfortable if you touch them, there is less chance they'll scratch the Kindle as you attach it to the cover, and they look more elegant, all perfectly reasonable reasons.

I don't think this is a case of anybody taking a shortcut somewhere to lessen the cost of anything.

Re:Yikes! (5, Interesting)

Sanat (702) | more than 3 years ago | (#34633840)

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

Re:Yikes! (1)

C_amiga_fan (1960858) | more than 3 years ago | (#34633594)

Classic case of Same design - slight variation.

The lighted version has metal hooks tied to the light, while the non-ligthed version is the same basic design plus some non-conductive paint. An elegant and easy solution, unless the paint chips off.

Re:Yikes! (1)

bws111 (1216812) | more than 3 years ago | (#34633814)

But that would be a completely different design. Not only would they have to put paint on the hooks, but they would intentionally have to tie the two hooks together with a piece of wire or something, which obviously is not done in the lighted version. That makes no sense.

Re:Yikes! (1)

harrkev (623093) | more than 3 years ago | (#34633502)

I am confused (being a Nook owner). Does the Kindle have contacts on the side, so that a light can leech power from the Kindle itself? If the case on the Kindle is simple, solid, unconductive plastic, this should NOT happen...

Re:Yikes! (1)

biryokumaru (822262) | more than 3 years ago | (#34633562)

Yes.

Re:Yikes! (4, Informative)

jgagnon (1663075) | more than 3 years ago | (#34633734)

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.

Re:Yikes! (1)

fucket (1256188) | more than 3 years ago | (#34633190)

On one version of the cover, they apparently are powering a lamp.

Re:Yikes! (1)

by (1706743) (1706744) | more than 3 years ago | (#34633022)

Seeing as the cover causes the Kindle to reboot (and not burst into flames), there's likely a current-limiter of some sort on the Kindle -- small current limiters are pretty simple to make. I suspect a shorted out Li-Ion could cause a lot more damage than a simple reboot...

2 ohm is not a ahort circuit. (2, Insightful)

MatanZ (4571) | more than 3 years ago | (#34633152)

If it connects directly to the battery at about 4V, it will only draw 2A, or 8W. This should be enough to warm the case, but not to make it or the device burst into flames.

Re:2 ohm is not a ahort circuit. (1)

Anonymous Coward | more than 3 years ago | (#34633610)

Actually, I don't think it's a huge design flaw. There have been far bigger ones. Not realising that the insulation layer would be subjected to repeated abrasive events and then cause a current draw should leave an engineer sheepish, but given that it involves two independently engineered pieces of kit, I'll forgive it given that a) the result is pretty minor and b) Amazon are giving refunds quickly and c) not pulling a Jobs and suggesting that users are somehow at fault.

Re:Yikes! (1)

RollingThunder (88952) | more than 3 years ago | (#34633042)

Or they could just have the two hooks not part of the same piece of metal.

Get a sufficient air gap, and there's no circuit.

Re:Yikes! (1)

Ephemeriis (315124) | more than 3 years ago | (#34633060)

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.

That'd certainly be a more permanent and universal fix...

But I think something easier would simply be to require that manufacturers use plastic for those clips instead of metal.

Re:Yikes! (4, Insightful)

fuzzyfuzzyfungus (1223518) | more than 3 years ago | (#34633100)

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.

Re:Yikes! (2)

mikeee (137160) | more than 3 years ago | (#34633250)

But that case was designed for the Kindle 2, which (I think?) *doesn't* put power across those pins. If that's the case, this is mostly a Kindle 3 design flaw - they should have made the slot spacing different so you couldn't use a Kindle 2 case.

Re:Yikes! (1)

Cwix (1671282) | more than 3 years ago | (#34633308)

Instead of physically changing things, I wonder if they could use a software tweak to determine if there is a short, and just shut off the power to the connections if there was.

Re:Yikes! (1)

Jeff DeMaagd (2015) | more than 3 years ago | (#34633398)

I don't know if software can solve this problem if it pulls down the voltage rails so much that the CPU doesn't operate reliably, remember, it is causing stalls and reboots. They probably would have to change hardware to add more robust power protection to those connectors.

Re:Yikes! (1)

bws111 (1216812) | more than 3 years ago | (#34633592)

Looking at the closeup of the hook you can clearly see the leather cover under the hole, so it doesn't look like the two hooks are connected with anything at all.

Re:Yikes! (4, Interesting)

vlm (69642) | more than 3 years ago | (#34633300)

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! (1)

DreamArcher (1690064) | more than 3 years ago | (#34633590)

Good call, but it still indicates a problem and will certainly vary depending on the amount of paint scratched off. I assume he's using a cover that has not yet started causing problems.

Re:Yikes! (1)

jamesh (87723) | more than 3 years ago | (#34633674)

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?

You do have to look pretty closely (and RTFA in the first place of course :) but there's definitely an M there. That doesn't seem enough to induce any sort of fault in the thing, especially if it's a power output to drive a light where the resistance of the light bulb would be much less. Maybe scraping more paint off lowers the resistance significantly...

Re:Yikes! (1)

Dunbal (464142) | more than 3 years ago | (#34633334)

Yeah sure blame the cover maker - but someone had to approve it.

Re:Yikes! (1)

jgagnon (1663075) | more than 3 years ago | (#34633806)

Or... blame both?

Re:Yikes! (3, Informative)

Mr. Freeman (933986) | more than 3 years ago | (#34633466)

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.

Re:Yikes! (5, Funny)

skids (119237) | more than 3 years ago | (#34632910)

...Also a good reason why you shouldn't post a list of "57 Lamest Tech Moments of 2010" before 2010 is over.

Re:Yikes! (1)

The MAZZTer (911996) | more than 3 years ago | (#34633170)

No biggie, it's not like it's a round number so they can always up it to 58.

Re:Yikes! (1)

140Mandak262Jamuna (970587) | more than 3 years ago | (#34633302)

But it is actually 59. 58 th is the Kindle metal hooks. 59th is slashdot posting 57 lamest moments before the year is complete.

Re:Yikes! (1)

petes_PoV (912422) | more than 3 years ago | (#34633206)

Then it would have to be 58 lamest tech moments

Re:Yikes! (1)

PIBM (588930) | more than 3 years ago | (#34632928)

Well, it`s not the cover which is at fault, but rather the jumper between the power and ground when putting it on ;)

Re:Yikes! (0)

Anonymous Coward | more than 3 years ago | (#34633478)

THIS IS WHY SCIENCE FOUND US INSULATORS.

(yes I'm meant to be yelling slashdot proofreader)

Re:Yikes! (5, Funny)

flaming error (1041742) | more than 3 years ago | (#34632950)

Maybe they can substitute the metal now connecting the hooks with extremely fine steel wool. Then everyone will remember it's the Kindle.

Re:Yikes! (1)

commodore64_love (1445365) | more than 3 years ago | (#34633058)

Yeah they're lucky the leather didn't catch on fire, but I suppose 12(?) volts isn't enough to make the metal hooks/jumper heat up to ignition point.

Re:Yikes! (2)

wed128 (722152) | more than 3 years ago | (#34633122)

1 volt is enough if you can source enough current....

remember folks, VOLTAGE != POWER

Re:Yikes! (0)

Anonymous Coward | more than 3 years ago | (#34633358)

RTFA. This accidental circuit was measured to have 2 ohms of resistance. 1 volt or 12 volts is definitely not enough to start a fire with 2 ohms of resistance. 240 volts probably is.

Re:Yikes! (2)

pclminion (145572) | more than 3 years ago | (#34633780)

"If you can source enough current..." as if you have any control over the current. It's a simple damn equation, people. V = I*R. For a given conductor, if you put one volt across it, a current V/R will flow through it. No, you can't magically wish for a higher current at the same voltage. Nor could you achieve an arbitrary voltage at a given current. If you can control both current and voltage, then BY DEFINITION you are changing the resistance.

Another one of my least favorites: "It's the current that kills, not the voltage." Actually, it's the stoppage of your heart that kills you, along with possibly the boiling and cooking of your internal organs. People take these sorts of sayings and end up making stupid decisions.

Re:Yikes! (1)

mangu (126918) | more than 3 years ago | (#34633282)

Steel wool will catch fire with any battery. When I was a kid I used to do it with 9 volts because the terminals are both on the same side, but I experimented with a 1.5 V C cell and a bit of wire and it worked.

Re:Yikes! (5, Interesting)

Khyber (864651) | more than 3 years ago | (#34633346)

You suppose wrong.

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

Re:Yikes! (0)

Anonymous Coward | more than 3 years ago | (#34633582)

You'd be surprised. I've seen electrical connectors with burn marks due to +12v

Re:Yikes! (1)

camperslo (704715) | more than 3 years ago | (#34633040)

Wow. That's a pretty major design flaw.

Yeah. At least it doesn't start a fire? Hopefully there's something between the battery and the terminals to limit the current to a safe value. I wonder if people could cut the strap or whatever is connecting the two hooks? I suppose then they might fall out or something. At least an external cover is easily replaced and they're willing to do it.
I suppose later some may complain that the occasional shorting of the power shortened the battery life so it should be replaced for free...

Queue the people ready to flame on other vendors' hardware.

Re:Yikes! (1)

tgatliff (311583) | more than 3 years ago | (#34633272)

I think Amazon (or the vendor) is realizing now that a $0.02 resistor is cheaper than using paint as a resistor.

I am biased I admit, but this also might be what you get when you engineer products using the lowest paid bidder. I mean by the time you get thru all of the layers of middlemen down to the designer, it ends up being a kid just out of college saying "oops.... Sorry about that boss. I never thought about what would happen if the paint came off"...

Re:Yikes! (1)

morari (1080535) | more than 3 years ago | (#34633416)

Ha, my Nook just keeps looking better and better! :P

Wifi on iphone broken with a rubber cover (0)

h00manist (800926) | more than 3 years ago | (#34632846)

Wifi broke on my iphone 3G. I believe it was heat-related. It stopped working in front of me, when I was making a large file transfer over wifi. It was sitting on top of a laptop, which was a bit hot, and with a common cover around it, which holds heat in a bit more than usual.

Re:Wifi on iphone broken with a rubber cover (0)

Anonymous Coward | more than 3 years ago | (#34633236)

Wow. That has nothing to do with anything. Congratulations.

Not unprecedented (4, Interesting)

betterunixthanunix (980855) | more than 3 years ago | (#34632890)

Re:Not unprecedented (2)

spun (1352) | more than 3 years ago | (#34632902)

That really was "magic" compared to this, though. This is just a plain old short circuit.

Re:Not unprecedented (1)

Anonymous Coward | more than 3 years ago | (#34632994)

That really was "magic" compared to this, though. This is just a plain old short circuit.

That story isn't all special either. The switch was there to discharge static buildup on the case. Something inside the computer wasn't properly grounded and flipping the switch made the connection to ground complete, thereby discharging any static. This would also cause the computer to crash given a large enough potential difference, and where the static buildup was.

This would make sense had it been a fault of the power supply.

Re:Not unprecedented (1)

nomadic (141991) | more than 3 years ago | (#34632914)

WHOA the ftp.sunet.se server is still around? I haven't seen that in years...

Re:Not unprecedented (1)

tacktick (1866274) | more than 3 years ago | (#34633054)

Did you have a "Get off mah lawn!" moment?

Re:Not unprecedented (5, Interesting)

mswhippingboy (754599) | more than 3 years ago | (#34633318)

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:Not unprecedented (5, Funny)

mangu (126918) | more than 3 years ago | (#34633470)

I have a similar experience when we were installing some computers in a hydro power station control center. The old control system used electromechanical relays, so it was quite robust, but the digital computers kept crashing. There were some 500 kV lines right going over the control center, so it was assumed they were causing enough interference to crash the computers.

After months of studies, it was decided that shielding the control center was the only solution. However there was a problem, the large glass window to the observation hall. Someone mentioned that there existed a transparent conductive paint, so they called a paint supplier:

-"Hello, I'm looking for some invisible paint, to paint glass"

They hung up without an answer at the other side...

Re:Not unprecedented (1)

Red Flayer (890720) | more than 3 years ago | (#34633490)

We had IBM SEs come in and pour over the logs

Well there's your problem. They must have spilled some of the liquid they were pouring over the mainframe.

The RF shielding obviously had the side effect of waterproofing the circuitry case.

Something we need more of (3, Insightful)

QuantumBeep (748940) | more than 3 years ago | (#34632952)

We constantly hear about needing to "program defensively" and test for "can't happen" conditions.

Here's one for defensive engineering.

Re:Something we need more of (1)

fuzzyfuzzyfungus (1223518) | more than 3 years ago | (#34633180)

I would hope, for any remotely adequate mechanical engineer or industrial designer, (or heck, even an interior designer) "potential wear, degradation, and derating of the surface coatings on parts in mechanical contact" wouldn't even fall into the category of "reacting to a 'can't happen' condition; but simply count as standard diligence.

Now, I can imagine the organizational dysfunction where the guy speccing finishes might be told "low cost, attractive, applies to metal and aesthetically compatible with leather", without being told that his finish really has to be dielectrically stable for the lifetime of the product, while, at the same time, the guy who knows that the hooks must not short the device has no say in the finish selection...

Re:Something we need more of (1)

MBCook (132727) | more than 3 years ago | (#34633640)

Shouldn't there be something (like a current limiting resister) so that even if a mistake like this DID happen, it couldn't draw too much current and cause these kind of problems? Surely you could detect how much current is being drawn and shut it off if it's too much. Other devices do that.

Also, if the brownouts are the problem, why doesn't the Kindle notice the voltage getting low and complain? At this point, why would any electronic device be able to get to such a low voltage point where it can't continue to guarantee it's operation without warning the user.

more tags (1)

Anonymous Coward | more than 3 years ago | (#34632956)

facepalm

Metal hooks? (1)

93 Escort Wagon (326346) | more than 3 years ago | (#34632964)

It seems to me the design flaw is with the cover rather than the Kindle. Who in their right mind would put a metal hook into an electrically "live" slot unless they intended to draw electricity? Polycarbonate would do the job, or even hard rubber.

But I have to admit I had never even noticed those side slots on my Kindle 3 - until I read this story.

Re:Metal hooks? (3, Interesting)

gander666 (723553) | more than 3 years ago | (#34633372)

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

Re:Metal hooks? (1)

MBCook (132727) | more than 3 years ago | (#34633680)

Or, you could design the product not to have connections to it's battery exposed like that. How about a simple physical switch (not unlike those in headphone jacks) that prevents power from going through the latch slots unless a little switch is pressed in.

That way, if the latches are full you could have the current on, and if they had a little cutout slot in them or a notch, the power could be off. Then you could use a piece of metal, even without paint, and it wouldn't cause this problem so long as it has the right notch.

EE101 (1)

TheL0ser (1955440) | more than 3 years ago | (#34632988)

Apparently the designers of the cover skipped the lesson on not putting short circuits into a device.

Re:EE101 (1)

kbielefe (606566) | more than 3 years ago | (#34633210)

Probably because they never took that class. I can imagine management saying, "This one doesn't have a light, so we don't need electrical engineering to approve the design, only mechanical." That sort of thing happens at my work more often than I would expect, going both ways.

Wow (5, Funny)

RightwingNutjob (1302813) | more than 3 years ago | (#34633006)

a malfunction in a high tech device that actually can be fixed with duct tape

Re:Wow (0)

Anonymous Coward | more than 3 years ago | (#34633102)

Duct tape is conductive in some cases. I learned this when I needed to hold a battery on the board of a 486. Electrical tape is the preferred method. /now that was fun //needing a new board, not so fun

He's got it all wrong (5, Informative)

specialperson (1963158) | more than 3 years ago | (#34633034)

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.

Re:He's got it all wrong (1)

bruce_the_loon (856617) | more than 3 years ago | (#34633110)

With a multimeter with only one ohm setting, no frequency, HFE or cap tester, he's just a glorified plug-tester.

Now, can someone with a Kindle cover and a proper meter please test for us to settle it.

Re:He's got it all wrong (4, Informative)

Khyber (864651) | more than 3 years ago | (#34633420)

It's the hooks. I just took my fiance's mother's Kindle and pulled her non-lit leather cover off.

Paint worn to SHIT, metal exposed. Metal is brass.

I didn't even use a multimeter, I just used some new equipment from Nichia's yesterday visit to see if it would actually work as a full conductor.

Lit the LED up without any problem.

Quite conductive.

Re:He's got it all wrong (1)

bruce_the_loon (856617) | more than 3 years ago | (#34633608)

Thanks for the confirmation. Glad I didn't buy one with my Kindle.

Now, did he stumble onto the real problem or was he just recreating the scene for the pics?

Re:He's got it all wrong (1, Interesting)

Anonymous Coward | more than 3 years ago | (#34633628)

Ahh Khyber, you still around? Mods Khyber is a troll, who claims crazy stuff, please see his previous posts before modding him up!

Re:He's got it all wrong (0)

Anonymous Coward | more than 3 years ago | (#34633506)

No. If I scrape the paint off, then I'll have the short...

Every other person who commented is dumb (2, Informative)

jeffmeden (135043) | more than 3 years ago | (#34633124)

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.

That was the first thing I thought of when seeing the picture as well... Thank goodness he posted the full res version of that so we can very clearly see the M on the meter. What a maroon.

Re:Every other person who commented is dumb (0)

Anonymous Coward | more than 3 years ago | (#34633406)

What a maroon.
 
Good ol' Bugs Bunny. Where has he gone?

Re:He's got it all wrong (1)

vlm (69642) | more than 3 years ago | (#34633146)

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.

He would get about the same resistance if he skipped the whole leather cover thing and just held the meter probes. You'd think they'd notice something like that.

And Connectify earns their spot on "57 Lamest Tech Moments of 2010"

seriously though pretty much any tightly fitting leather case will probably put the device under some continuous strain, probably leading to something internal flexing, then a reboot. With those nice strong metal clamps gripping the case tightly, I could imagine it.

Re:He's got it all wrong (1)

makomk (752139) | more than 3 years ago | (#34633484)

He would get about the same resistance if he skipped the whole leather cover thing and just held the meter probes.

He may well effectively be doing just that. Given how difficult it is to make reliable electrical contact with a small area of metal using standard multimeter probes, together with the general level of competence displayed, I wouldn't be surprised to find the probes aren't in contact with the metal at all.

Re:He's got it all wrong (4, Interesting)

blair1q (305137) | more than 3 years ago | (#34633586)

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:He's got it all wrong (1)

pz (113803) | more than 3 years ago | (#34633260)

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.

And unless the metal we assume exists between the hooks were exceedingly thin, or the spots where the paint was rubbed off exceedingly small, 2 ohms would not be a reasonable resistance for a wire of that length. If the spots where the paint was rubbed off were small enough that the contact resistance was 2 ohms, then they would be difficult to find with the probes. Metal at macroscopic sizes conducts quite well. A quick check with my handy Fluke 179 shows that a clip lead, roughly the same length as the distance between the two hooks in the Kindle cover, has a resistance that is below the threshold of measurability on the meter (0.1 Ohm).

While this fellow might have discovered the actual problem, the photo and text from the linked article do not suggest he's done it the way he thinks he has.

Re:He's got it all wrong (1)

vlm (69642) | more than 3 years ago | (#34633512)

If the spots where the paint was rubbed off were small enough that the contact resistance was 2 ohms, then they would be difficult to find with the probes. Metal at macroscopic sizes conducts quite well. A quick check with my handy Fluke 179 shows that a clip lead, roughly the same length as the distance between the two hooks in the Kindle cover, has a resistance that is below the threshold of measurability on the meter (0.1 Ohm).

http://en.wikipedia.org/wiki/American_wire_gauge [wikipedia.org]

Lets assume the metal wire in the kindle case is copper and a foot long (makes it simpler), you'd need a wire gauge quite a bit below 40 AWG to get 2 ohms in a foot. seeing as thats about as small as commercially available, yet is till way too big, and yet is only 3 thousandths of an inch across... doing some reasonable extrapolation thats a piece of copper about a thousandth of an inch in diameter. That will snap before it falls off the assembly line.

I suppose if the Chinese used nichrome or stainless steel its not so bad, but its still .. unrealistic.

Re:He's got it all wrong (1)

BlitzTech (1386589) | more than 3 years ago | (#34633354)

His left finger looks like it's touching, but I'm not entirely convinced the right one is.

Regardless of that nitpick, it is still showing 2 MOhms, which shouldn't draw nearly enough power to do anything he thinks it's doing.

Purely speculation, but does it look like the black probe is even touching the metal...?

Re:He's got it all wrong (3, Informative)

mrjatsun (543322) | more than 3 years ago | (#34633492)

My son's Kindle has this problem... I removed the cover the other day and it has not had it sense. I just broke
out the multimeter, I was unable to get an electrical path even when scraping the paint on the hooks.

Three words. (1)

OmniGeek (72743) | more than 3 years ago | (#34633044)

Phaser on overload. (Depending on the short-circuit current capacity of the Kindle's battery and the resistance of the shorting bar,that is.)

2 Ohm or 2 Megaohm? (5, Informative)

Danh (79528) | more than 3 years ago | (#34633062)

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.

Re:2 Ohm or 2 Megaohm? (2)

RightwingNutjob (1302813) | more than 3 years ago | (#34633344)

Careful inspection of the picture leads me to conclude that the air gap between the negative probe and the hook probably does have a 2 MOhm resistance

The upside (2, Funny)

willoughby (1367773) | more than 3 years ago | (#34633068)

Well, as long as it's rebooting that gives you at least a few moments while Amazon cannot delete your files...

The line starts there (1)

Duradin (1261418) | more than 3 years ago | (#34633074)

The line starts over there to bash on Amazon and/or the Kindle.

Don't worry, you don't need a valid or even sensible reason to get your chance. Just be frothing mad and they'll let you in.

Re:The line starts there (1)

jeffmeden (135043) | more than 3 years ago | (#34633244)

Where is the line for bashing the "expert" at Connectify who in the same sentence derides anyone who doesn't know what an ohm is, and demonstrates that he doesn't know how to use a multimeter... That's the line *I* want!

Re:The line starts there (1)

Duradin (1261418) | more than 3 years ago | (#34633542)

Next door over and there appears to be no waiting.

KaWow (1)

Charliemopps (1157495) | more than 3 years ago | (#34633120)

Whomever designed the case should be fired with extreme prejudice. They're lucky they didn't fry a significant number of very expensive ebooks with something this stupid. If I were a victim of this I'd demand a replacement kindle while I was at it... no telling what long term affect this had on the device.

Re:KaWow (1)

vlm (69642) | more than 3 years ago | (#34633386)

Whomever designed the case should be fired with extreme prejudice. They're lucky they didn't fry a significant number of very expensive ebooks with something this stupid. If I were a victim of this I'd demand a replacement kindle while I was at it... no telling what long term affect this had on the device.

The article pic shows about 2 megs not 2 ohms of resistance. Thats not too unlikely for a persons dry skin. If you think about what leather is made out of, it makes sense that a human body and a leather case would have about the same resistance. I think it would be safe to assume the kindle engineers designed it to survive dry skin contact, so the case designers building their case out of dry animal skin is not exactly the dumbest intersection of the fashion designer and electronics world I have ever seen.

Re:KaWow (5, Interesting)

anUnhandledException (1900222) | more than 3 years ago | (#34633588)

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:KaWow (4, Funny)

Jtheletter (686279) | more than 3 years ago | (#34633688)

Fahrenheit 404?

Dumb Design (1)

bylo (1211278) | more than 3 years ago | (#34633148)

What an incredibly dumb design. A pair of plastic hooks would likely be cheaper and work better.

And also break off. (4, Insightful)

maillemaker (924053) | more than 3 years ago | (#34633668)

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.

They're lucky it ONLY crashes (1)

petes_PoV (912422) | more than 3 years ago | (#34633188)

This arrangement effectively shorts the power supply - the users are lucky that it doesn't destroy their devices. They're even luckier that the problem seems to go away once the shorted power supply has crashed the Kindle, and presumably turned the power supply off. A shorted battery with all its power flowing through a nice, flammable animal product would be even worse - either for the leather or the battery.

Disclaimer: not a Kindle owner, just sowing a bit of FUD.

Re:They're lucky it ONLY crashes (1)

RightwingNutjob (1302813) | more than 3 years ago | (#34633380)

It's probably not the power bus directly. Most battery packs and I would assume these devices with exposed leads have built-in current limiters that shut down on an overcurrent condition. I recall seeing a news story a while back about knock-off cell phone batteries that didn't have this circuitry being a fire/safety hazard.

Now tell me . . . (0)

Anonymous Coward | more than 3 years ago | (#34633370)

Why does it take a team of Amazon engineers to figure this out? :P

Had an interesting issue with my iPad cover (3, Interesting)

wfolta (603698) | more than 3 years ago | (#34633422)

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.

Reminds me of my PowerBook G4 (0)

Anonymous Coward | more than 3 years ago | (#34633642)

My old PowerBook G4 (with the titanium case) had a small current running through the case. It was most noticeable if I brushed my fingertip across the palm rest slowly, and would only occur when the laptop was plugged into an AC outlet. I called Apple on it and they said it was my imagination, but I recently noticed the same thing on my aluminum unibody MacBook Pro. Anyone else experience this?

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