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  • EEVblog #135 – Kindle Case Mythbusting

    Posted on December 23rd, 2010 EEVblog 32 comments

    Dave investigates the Amazon Kindle 3 reset/lockup problem that countless people have been having with the leather case.
    Is it the metal tabs shorting something out, or something else?

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    • JoeDow

      Hi Dave,
      nice tests. Could the charging state of the battery have an effect? Perhaps it can’t deliver so much current if its emptier.
      Greetings and merry christmas,
      Joe

    • JRR

      There are still a lot of possibilities with the tab shorting which would be very difficult to test. What if it shorting out coincides with a 3G poll that stops interrupts, and that inhibits the firmware from current limiting it (if the firmware is what does the current limiting)? There are a lot of situations where specific events happening in some specific order could lead to something odd happening. It could even be that the tab shorting out the RX pin in a specific timing kicks it into some weird monitor mode or something. Who knows? I’m sure the Kindle engineers will have a time figuring this one out.

      • Bill

        If it were a shorting issue, wouldn’t the LED version being having a much higher rate of issues than the version with the painted tabs?

    • ac

      I guess the way to find out is to have a setup which resets then put some tape or re-paint the thing to prevent the shorts, if that DOES fix the issue then it’s pretty conclusive that it’s got something to do with those.

    • http://devrandom.pl XANi

      Just scrathed a bit of paint from my (unlit) cover, nope, no connection at all.

    • wayne

      I did froze my kindle 3 several times two weeks ago by static discharge onto the usb mini cable shield. It was cold and dry weather and my plastic jacket I was wearing at the time it happened.
      I note you haven’t hacked the screensavers pictures yet and also I can now load picture into a folder and step through them with the page switches.all the mods are found on the internet.

    • Jonathan

      I have had my Kindle 3 WiFi in standby mode in my winter jacket hidden pocket, with no covers, lock up after lots of ESD when removing my jacket. Would not come out of standby. Had to hold down power key for a good while. Upon the reset, it acted like it was going to start from scratch, but it reloaded all of my materials with no issues or network connection.

    • http://thexmoschallenge.wordpress.com/ Berni

      Yeah ESD is notorious for crashing stuff.

      I have a idea that the paint is actually causing this. It could be that the case charges up with ESD until it reaches a high enough voltage to zap trough the paint and give it a ESD discharge to one of the pins in there. Your case has no paint so with a constant connection to ground it cant built up any ESD or could just be made out of something that doesn’t generate static.

    • Derek

      Great work Dave!
      As I’ve said to you in an email – I “seem” to have fixed mine with a 2.2Mohm resistor and a 0.1 uF capacitor wired across the terminals.

      I’m also wondering if the right approach is to remove the paint and allow the tabs to make proper contact with the Kindle internal terminals. Then all metal parts would be at the same potential – no ESD. This is the opposite of what most people have been trying.

    • Kevin

      Could the paint be conductive, falling away inside and shorting something else?

    • Adrian

      Dave, could yo do a review or give me a mere opinion on the Atten products, specifically their DSOs ?

      Thank you!

      Regards

    • Gonnafail

      Im wondering if it is a capacitance effect. If the semi painted metal tabs are creating some sort of capacitance effect on the tx rx lines and these are a shared bus. This could effect rise and fall time and cause data corruption.

    • Derek

      Yesterday I took my trusty Dremel tool and (carefully) removed the paint from both terminals using a fine sandpaper disk. I know that I am making reliable contact because I see the 4v between the terminals.

      Although it is still early days, the Kindle has worked perfectly since! I’m really hopeful that this is the solution…

    • nik

      Could shorting out the ground and rx pin in the right circumstance cause a break signal?

      Would be interesting to hook the kindle up to a rs232 -> TTL adapter, and then send a break signal. It might cause the kernel to go into a debugger or something similar.

    • http://themezz.com theMezz

      Great video.. and love your blog. Thanks (I have this Kindle issue and shopping for a new case – amazon would only give me a $25 credit and not a full refund – they did however replace my 4 month old Kindle hoping that would help, but it doesn’t help )

    • Robin Commander

      Great video, glad I read this as I’ve just received a shiny new Kindle 3 for christmas and I was in the market for a case.

      In view of the problems I’ve gone for a “Tuff-Luv” leather case instead of the Amazon one.

      Fingers crossed this will be trouble free as it doesn’t use the side slots to hold the Kindle…

    • AdeBe

      How big is resistance of this black paint?
      My theory is that when this paint on contacts wears off, it’s pieces “travel” inside the Kindle case, which occasionally can connect some pins inside.

    • Spencer

      So let me get this straight, you’re attempting to bust the “myth” that the unlighted Kindle case is causing problems for Kindle 3 owners…but you don’t even TOUCH one of the cases in question during your demonstration? Congratulations. You’ve busted the myth that you have any clue what you’re talking about.

      • http://www.eevblog.com EEVblog

        No, I was trying to bust the myth that many people thought it was the paint wearing off the metal contacts and shorting out something internally in the Kindle.
        It is perfectly valid to try and do this without the actual case in question. If you don’t understand why that is, then you have no clue what you are talking about.

    • f4eru

      Hello

      Definitively a problem linked to the paint.
      The ESD theory is valid, but could also be that the paint makes a resistance which reinjects TX to RX, creating an echo which could potentially make a buffer overflow, etc…

      i had on a system of mine recently a big problem due to a floating RX pin which remained active after the debug adapter was removed. After power on, everything was OK, but after an hour or so, the pin reached the switching voltage, sending many random characters to the uart, sometimes even simulating a “valid” debug frame, crashing the micro. Not easy to debug !!

    • Glenn Holt

      I have a Kindle 3 with a leather case from TrendyDigital. I too see a lot of lockups, but am hesitant to place blame on the case.

      Why is firmware not being considered as a culprit here? There are many stories of Kindle lockup issues from day 1, most, I would assume, were “case free.”

      • http://www.eevblog.com EEVblog

        The firmware could very well be the culprit. But there are just too many reports of lockups when used with that particular case that magically disappear when out of the case, so it sounds like there is some form of external influence as the trigger.

    • Peter

      Can you please stop your exaggerated look and voice. Terrible.

      • http://www.eevblog.com EEVblog

        Can you please go and do your own blog instead of bitching about other people’s content?
        Terrible.

    • n

      nice work. really appreciate you taking your kindle apart. ignore the critics and trolls. good work.

    • http://www.doommeister.com DoomMeister

      Nice post. Just to add my tuppence, In addition to the lock-up condition I also noticed that there was a significant drop in battery level judging by the battery indicator (i haven’t torn down my kindle so cannot measure the battery directly). This loss was in the order of 50% within a night of charging.

      Would ESD cause this battery drain? Or conceivably just perhaps put the processor into an error loop causing the battery drain.

      • http://www.eevblog.com EEVblog

        ESD can cause excess battery drain due to SCR lockup. I’ve done a tutorial on this.

    • LightedCase

      Just to throw another 2 cents… I have the same resetting / locking up issue on my Kindle 3 and I am using the Lighted Amazon Case. The Amazon forums are a fury with these issues. I plan on switching to a neoprene slip case to see if the issue is magically resolved.

      • Ian

        I have a neoprene slip case and have never had any problems with my kindle – apart from when I sat on it and broke it :) Fortunately Amazon replaced it even though I told them how I broke it! kudos to Amazon.

        P.S. DONT change your style mate, ignore the haters :)

    • LCM

      Hello dave,

      I manage in the past to jam several device by sending garbage signal/noise through the RX pin.
      Maybe the painted tabs are shorting the RX, locking the a polling tread listening the serial connection?
      I have no Kindle so I can’t check this myself

      Best regards,

    • Marcel

      I have a Nokia 6110 navigator which continuously locks up when I put it in my belt carrier with magnet locks

      The magnets itself proved to do weird things inside the phone.
      Does the kindle softcover have any magnet locks?

      Just an idea.

    • babao

      I had the freeze/instant reboot problem with my kindle when using the unlighted cover, and it would happen couple of times a week, especially when going outside. I called customer support, and they suggested not using the cover. It worked for a while, but I am still getting the occasional instant reboot (no freeze though), when I take the kindle outside (like when going to work). My conclusion, based just on what I read, is that there is something related to static charge, and it is exacerbated by using the cover.
      The thing that annoys me the most is that when the instant reboot happens I lose the mark in the book I was reading, and that is something that could easily be fixed by software.