Tablet Won't Power On

Discussion in 'WonderMedia Based' started by Iskuri, Apr 17, 2012.

  1. Iskuri
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    Iskuri Junior Member

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    Hi, I bought this wondermedia based tablet off ebay, sold as faulty, to see if I could get it working. I have taken it apart and cannot see any problems that could occur from the hardware. If I plug it in the charge light comes on and everything but if I try to turn it on, plugged in or not, nothing happens, no light or anything. Any ideas? Thanks.
  2. J515OP
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    J515OP Super Moderator Staff Member

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    Test the actual battery and see if it has any charge. See if you can unplug it where it connects to the device and see if it has any juice with a multi-meter.
  3. Iskuri
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    Iskuri Junior Member

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    I tested it with my makeshift multimeter, and you're right, nothing is coming through. Surely though, if it's plugged in it should still power on? What can I do now I know the battery doesn't work?
  4. J515OP
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    J515OP Super Moderator Staff Member

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    Not necessarily. It sounds like you need to find where the circuit is broken. Check the leads coming into the battery from the device with the device plugged in to see if the power is coming through. Not sure how the charge light works but that doesn't mean the device is getting power when plugged in, just that the light is.
  5. Iskuri
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    Iskuri Junior Member

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    Good point! I tested it while it was plugged in and there was indeed no power being transferred to the battery, anything I can do about that?
  6. J515OP
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    J515OP Super Moderator Staff Member

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    My next step would be to carefully examine the port where the charging cable connects to the device. See if there are any noticeably loose connections right where the power is supposed to be coming in. It is not uncommon for the micro usb ports to break since that is a weak point in most tablets. Maybe you can find a simple disconnection that can be soldered or repaired.
  7. Iskuri
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    Iskuri Junior Member

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    I'll have a look, it's very odd to me that the light comes on but the battery isn't charged. It's making me tempted to just patch the led's power straight into the battery haha.
  8. J515OP
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    J515OP Super Moderator Staff Member

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    Strange yes. I wouldn't be surprised though if the led draws directly or nearly so from the port. Particularly if it is located near it. It would be simple to tie into the power directly rather than pulling it someplace else off the board.
  9. Iskuri
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    Iskuri Junior Member

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    Are you saying there's a way to make the tablet draw power from the mains itself? Because that'd be really useful! I'm going to have to find out why there's no power going to the battery.
  10. J515OP
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    J515OP Super Moderator Staff Member

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    No, just that the charging led indicator may work that way. For example inserting the hot charging cable into the micro usb simply creates a physical connection that both completes the circuit to the led indicator and powers it. While examining the micro usb you might be able to see how the led charge indicator is powered.

    Powering the actual device is another issue. It would interesting to know if it would run if the battery had power even though the battery can't get power from the charger to recharge. Since it won't run being plugged in though I suspect the power isn't making it very far beyond the micro usb connector. It might be toast unless you are able to find an easy disconnect that can be repaired or are a hardware expert.
  11. Iskuri
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    Iskuri Junior Member

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    I'm quite good with hardware, so I'll take a look. This one is charged with a regular jack, and the usb plug is this weird proprietary thing, I'd attempt to charge through usb if there was a way to access the damn thing.
  12. J515OP
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    J515OP Super Moderator Staff Member

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    Something like one of these? http://www.androidtablets.net/forum...dermedia-wm8505-android-tablets.html#post3103

    So I see a a few possibilities to look at.

    1. Track the power input inward and see if you can detect a bad connection preventing power from getting in.
    2. Work from the battery leads back to see if you can detect a bad connection preventing power from getting in.
    3. If you can find the power leads coming in from the proprietary thing you should be able to wire those to a standard usb port. Just take a female usb cable and cut the wire and attach usb wires to the power pins of the proprietary port. That way you can at least attach to a regular usb cable and see if you can get power that way. (OR you can try the easy way and find the proper cable for the port and see if it will power/charge the device. Sounds like you don't have this cable though.)
  13. Iskuri
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    Iskuri Junior Member

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    No, it's not got an Apple port (I have a wm8505 with one of those and this is definitely not one of those. I'll see if I can do one of those things you suggested. It's very interesting to me that the CPU can be removed easily, what would happen if I replaced my wm8505 one with it?
  14. Iskuri
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    Iskuri Junior Member

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    It turns out I was wrong, and there is actually power going to the connectors going to the battery, is there anything else I can check?
  15. J515OP
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    J515OP Super Moderator Staff Member

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    And how about double checking the battery? Is it charging?
  16. Iskuri
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    Iskuri Junior Member

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    I check the multimeter with it having been on charge for a while and no charge is going through. But if it is plugged in then there is some charge going through.

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