Vivotab Note 8 battery voltage drop, micro-USB broken, crack sound, help please..

Discussion in 'Asus' started by riukas, Apr 4, 2015.

  1. riukas

    riukas Pen Pal - Newbie

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    Hi guys, need your help ASAP with my two dying AVTN8s (one of them with quickly dying battery too) that I've recently bought (formally still with asus/amazon UK warranty, although they have already been opened by non-asus person, so does the warranty still hold? Seems there are no any kind of warranty seals in there?).

    First AVTN8 unit has started losing USB connection intermittently (it has started to work only after moving up/down the USB connector in the USB socket), and afterwards USB port got broken totally (the "5 pins" part of the MicroUSB connector has disconnected from PCB completely). I know there is a similar post there about replacing the whole MicroUSB PCB part, but it was too expensive and/or slow here where I am (new PCB shipping time 1-2 months, and I need the tablet working ASAP..). So some technical guy has tried to fix it for me by resoldering the new MicroUSB port. It didn't work, sadly; it was just too small and PCB contacts were missing at the soldering place on PCB surface. Also, MicroUSB board looks even worse now after this fix attempt, with some broken pins of it's connector to motherboard and so on (USB PCB board connector which connects to the mobo).
    Before trying to fix it, battery had some 18% left, and tablet was fully functional, except USB connection. There is little chance battery level could have dropped to 0% just before resoldering started. I'm pretty sure there was some battery left at that moment.
    The thing I'm nervous now is that here's what happened at the end of resoldering procedure:

    1) trying to power on the tablet: 4 or 5 blinks at the power button (this probably means battery is badly discharged? Or some other error?)

    2) checking battery voltage with voltmeter (while usb charger cable disconnected): voltmeter at the battery showing some value which is really too low, probably around 3V (I don't recall exact value), and the voltage is dropping*. After connecting charger via usb cable, the battery voltage is still dropping*, fast.
    *Voltage is dropping ~0.02V per minute or so. That guy told me, that normally when charging, voltage should go up.
    He measured the voltage near the place where it's soldered, and even though the charger is 5V, he could only find ~0.2V or ~2V (I don't recall it exactly) at the place where it was soldered. No good.
    At some moment pressing power on button has started not showing any signs: it doesn't even blink anymore.

    3) that person tried to resolder USB port again, but it looked desperate, this time solder was all over those 5 usb pins, and it was late evening; so he put it back into the tablet (as I understand, the pins were shortened by the solder!), and said he doesn't know what to do with this USB PCB.. I was scared about the fact that tablet is not even booting though this time, and the battery voltage dropping - probably motherboard and/or battery is dying/dead?.. :( :( I asked him to take that USB PCB out, because maybe it's shortened usb pins have also caused (or are still causing) damage to other parts of the tablet. So he took the USB PCB part out. He said "this tablet is malfunctioning probably because of some electrostatic discharge that could have happened [probably during this fix attempt] or something else, but surely not because of that shortening". Hm...

    4) afterwards the working USB PCB part from another AVTN8 (part number and modification/version exactly the same) has been put into this one for testing purposes, but sadly the symptoms were all the same: tablet not booting after pressing power on button, and not showing any blinks. Voltage is dropping constantly even with this normally working USB board or without any USB board - it has dropped 0.2V (from 2.6V to 2.4V) in two or three days (tablet is shut down fully and has been holding charge around 18% for several weeks unused before these fixes). Voltage now is probably around 2V or less as I write this message.
    Here is the scary part for me: If charger is connected via cable (using good working USB PCB part), there is a soft short cracking sound being heard, and the voltage is dropping much faster than disconnected from cable: dropping around 0.01V per 40 seconds, but after disconnecting it, the voltage returns to the previous value. This dropping (and returning to the previous value) is not normal, is it? If connected to the charger, there is no cracking sound in another properly working tablet, and the voltage is rising (going up) until it stops at 4.3V at it's battery while the led on the power button is constantly indicating the charging/charged status.
    It's been too scary to leave the first tablet charging longer than 2-3 minutes, because the voltage was dropping, and dropping fast. The person who tried resoldering that USB PCB told me that if battery voltage drops below 0.9V, it's very bad (probably irreversibly bad) for the battery..
    I think there was some warmth felt at the Windows button at the edge of the mobo while making these tests at least once, but not sure about this.
    So, now the first tablet is disconnected from charger, and voltage is dropping day by day, which I think means it's battery is already dead or will just die in a week or so... :( (getting replacement parts is very slow in where I live, even at the local Asus service center, it takes months to get anything for this tablet model). Also I'm afraid that the dying battery can damage the other parts in the tablet, namely motherboard and maybe other parts too?..

    5) After above testing the working USB part was taken back into original (2nd) tablet, but by accidently bending the usb cable, USB started to work intermittently for this tablet too.. :( :( The connector has to be moved up/down to work properly too.

    I've ordered several units of this USB PCB part (will have to wait 1 or 2 months), but I'm totally confused especially with what to do with the first tablet (battery dying or dead, not charging even with working PCB part, I have a feeling that mobo could be damaged too, which is, well, just a feeling at this point.. but I need a working tablet ASAP, and really don't know what to do...)
    And also, what can be done with the second tablet now? (usb port started malfunctioning)
    Bring the malfunctioning USB PCB to yet another tech guy so he fixes it? (there are probably more chances to be fixed at this moment rather than when usb port breaks completely?)

    Please help..

    P.S. I put this post separately from USB PCB post and battery posts, because it's a "USB PCB plus battery" mixed problem (and probably "plus mobo related" too..), but I'll try to link these posts.
     
  2. yuki

    yuki Scribbler - Standard Member

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    Ouch, that sounds terrible.

    My tabs work perfectly - but my housecat decided to kill one of the asus vivotab note 8s: while charging on the shelf, she decided that the power-cord was attack-worthy, pulled the vivotab from its position ad it fell 1,5 meters.... landing DIRECTLY on the USB port with attached cable and breaking it. The usb port certainly disconnected from the mainboard - one could shuffle around the port with cable.

    i tried warranty anyhow - and asus did a free repair (replacing both boards according to the protocol).

    However if someone SOLDERED unsucessfully inside of the vivotab, i suppose asus will - for good reason, sadly -refuse any warranty claims.
     
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  3. riukas

    riukas Pen Pal - Newbie

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    What would you do in my situation?.. Especially with the first unit? I'm really afraid to try charging it. On the other hand if I don't charge it, it's losing voltage too. What happens to the tablet, motherboard, etc. if battery is fully discharged? Maybe it's worth to at least disconnect the battery from mobo now?.. Any other ideas?
    I need some simple, quick, full solution to all this mess.. (and hopefully not as pricey as just buying another replacement tablet..) :S
     
  4. Bronsky

    Bronsky Wait and Hope. Senior Member

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    The unit that has not been soldered, I would return to Asus to be repaired. I would pull the card with he USB port. The battery is probably discharging through the port connections that are shorted with the solder. You will need a new card for that one
     
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  5. riukas

    riukas Pen Pal - Newbie

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    Thanks for reply, Bronsky.
    "The battery is probably discharging through the port connections that are shorted with the solder."
    You see, voltage is dropping even when the usb pcb card is changed to the working one which is not soldered (see OP)..:
    "If charger is connected via cable (using good working USB PCB part) [...]"
     
    Last edited: Apr 5, 2015
  6. Bronsky

    Bronsky Wait and Hope. Senior Member

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    I've done a fair amount of soldering around motherboards and USB cards. http://forum.notebookreview.com/thr...cklit-keyboard-mod.491169/page-2#post-6504731 I can assure you that soldering a live board is risky. I always like disconnecting power before working on any components. I can also tell you from personal experience that you can do a lot of damage to any number of the main board components by crossing the wrong leads or grounding power to the wrong part of the chassis or frame. The heat of the soldering iron can do a lot of damage as well. Were you electrostatically grounded when you were doing that work? I don't really buy the electrostatic explanation. I ascribe to Occam's Razor.

    You have one perfectly good AVN8 ... right? The damage to the other tablet sounds serious. Even though they could deny a claim, I would send it in under the accidental damage warranty anyway. Maybe they'll just replace it instead of trying to fix it.
     
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  7. riukas

    riukas Pen Pal - Newbie

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    It's great to meet here experienced people like you, Bronsky. Yes, surely the usb pcb card was disconnected from mobo before soldering. Then the soldering of usb pcb card took place (separately from mobo which had battery connected to it). All this was done by another tech person who had soldering tools, not me. Yes, I also thought that shortening or crossing can make damage, even if done for a short time. He was confident he did the soldering well several times, but each time it didn't work, and testing it with voltmeter/ohmmeter when connected back to the mobo, it appeared that something's wrong with shortening/crossing (also, the battery voltage was going down). I feel this was bad, at this point already damage to other components (such as mobo and/or battery) already could have happened. The last time he tried to resolder usb port to that small pcb board he just left it kinda all 5 pins shortened (feeling that it's too hard to fix this pcb board and not wanting to split the big drop of solder which has shortened all 5 pins, because it was late, and probably because of tiredness), including again the bad part - he put it back into the tablet. I asked him to take it out then, so after several minutes this "usb pcb board" was taken out from the tablet.
    The problem is, when I have connected the good usb pcb card (from another working tablet) and then tried to charge via usb, it didn't charge. What I think now about the other parts of this first AVN8 unit (by having connected the good usb pcb card and leaving the "soldered pcb part" away, because it looks really bad with connector pins broken, etc.):
    - Maybe the battery is simply discharged too deep (it showed around 2.6V back then, now will probably be ~2V), and when someone tries to charge the battery which is discharged this deep, the voltage normally(?) goes down at first, but it would still charge at the end? which would mean that the tablet is not malfunctioning, but it's just trying to charge this baly dischaged battery? (after I disconnect the charger, battery voltage returned back to 2.6V then) What do you think? But I highly doubt it could be so (and that tech guy said that battery voltage shouldn't go down - it should go down only when there is some load, connected to battery). So most probably when I connect the charger, the battery is actually being discharged. I'm also afraid to damage battery (and/or other tablet parts) even more if the tablet is actually malfunctioning or the battery is discharged below some safe level. Are my fears logical here? What could happen then?
    - Maybe the battery is simply discharged too deep (maybe irreversibly, although he said it is still safe until it hasn't reached 0.9V), and other parts like mobo are still working.
    - Maybe there is already damage made to other or several components, like mobo, etc.

    BTW, what did you mean by ascribing to Occam's Razor in my situation?

    I have one "good" AVN8 (2nd unit), which works ok, but has a usb port which functions only when I bend usb cable up/down until it makes the contact*. It has started disconnecting just recently/now, when I put it's usb pcb board back after swapping components (for testing in the first AVN8) and then probably after I have bent usb cable near connector, therefore it has lose contact somewhere. So this unit has a usb port problem, but otherwise it's good.

    * there is something wrong with the contact between cable and usb port, and/or between usb port and that small pcb board, maybe because I bent the cable connector accidentally when it was connected (the same could have happened to the first AVN8 at the beginning too, because it also was losing contact, and then the "5 pins" part of the usb port disconnected completely from the pcb board)
     
  8. Bronsky

    Bronsky Wait and Hope. Senior Member

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    The simplest explanation is probably the right one. The most obvious cause is probably the cause. The soldering job is at the core of your problem. The failure of the unit to boot, even with the good board, is troubling. You should be able to charge with the good USB in place. That tells me that there is likely damage to a component on the main from hooking up the shorted USB board. If it as me, I would swap the functioning board in the broken unit and send it in for accidental warranty or repair. Order a new USB board for the functioning unit and throw out the one shorted by the solder.
     
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  9. Bronsky

    Bronsky Wait and Hope. Senior Member

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    I'm curious. What did you decide to do?
     
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  10. riukas

    riukas Pen Pal - Newbie

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    Many thanks for your ideas and a follow-up! Still thinking, rather complicated situation, because delivery times are very long here.. Probably I'd go your route. But I also need a working unit ASAP. On the other hand buying another new one is pricey. And also I see that amazon UK prices for 64GB model have increased considerably since December.. :/ £316.45 instead of this one for £214.73.., which makes me doubt even much more.
     
    Last edited: Apr 10, 2015
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