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    #1

    ASUS X93S: specific keyboard keys are not working randomly

    Hello, i got an issue with my Asus X93S laptop. The integrated keyboard has keys that randomly not working. The important thing is this:
    The keys that are not working, when they dont, are always the same keys. Which are:
    "S", "3","7","=","0","-","c","²",F5,F10, Delete, Caps lock.
    I found the schematics here:
    http://www.s-manuals.com/notebook/asus_x93sv
    I've measure the voltage on the JKB connector (the keyboard connector with 24 pins), page 44 in the schematics pdf.
    When the keys are not working, i've measured wether 0v or 3.3v on every pin. The pin9 was at 0v when the key "s" was not working and 3.3v when the key suddenly back working. (i was measuring pins when the voltage switched from 0v to 3.3v). So i'm suspecting something related to pin KSI4, there is C338, but not sure where it is. First anyone can tell me if you have ever seen this problem? It's hard because its random.
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    #2
    Re: ASUS X93S: specific keyboard keys are not working randomly

    Hi, sorry for my poor English. In my experience all keyboard problems % 90 or 95 liquid or even a little drop damage the keyboards conductive layers , rest of the esd caps, KBC EC controller or bios problem. In your case not "C338" please look closely, "KSI4" connect to "C342". you must be remove this cap or change temporarily the other caps then test for a while.Are you examine when the KSI4 go down to "0" you try removing keyboard and measure at same time this point? Maybe keyboard have a some leak to gnd or other traces.

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      #3
      Re: ASUS X93S: specific keyboard keys are not working randomly

      Originally posted by relax79 View Post
      Hi, sorry for my poor English. In my experience all keyboard problems % 90 or 95 liquid or even a little drop damage the keyboards conductive layers , rest of the esd caps, KBC EC controller or bios problem. In your case not "C338" please look closely, "KSI4" connect to "C342". you must be remove this cap or change temporarily the other caps then test for a while.Are you examine when the KSI4 go down to "0" you try removing keyboard and measure at same time this point? Maybe keyboard have a some leak to gnd or other traces.
      I forgot to mention the most important thing, i replaced the keyboard by a new one and that didnt solve the problem.
      You are right, this is C342 that is connected to KSI4.
      You suggest to try with C342 removed? or replaced by another similar cap? I'll try to do a bridge to bypass the C342 cap.
      You said:
      "In my experience all keyboard problems % 90 or 95 liquid or even a little drop damage the keyboards conductive layers , rest of the esd caps, KBC EC controller or bios problem."
      Not sure i full understand. You say 90% of the keyboards issues are coming from a little drop damage? What do you mean? I replaced the keyboard by new one it's the same issue. It's not coming from the keyboard itself. An issue with the EC chip could be a potential cause, yes. In my case, it is UE1, "KB930QF".
      It is a Keyboard Controller, is it the same chip that we call the EC chip?
      I could measure directly on the pin 59 on UE1, if this voltage is 0v, then i can conclude that the UE1 chip is faulty, right?
      Last edited by int0x13; 10-10-2016, 05:29 AM.

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        #4
        Re: ASUS X93S: specific keyboard keys are not working randomly

        You are two options, remove the cap or install new , this is not so critical part, keyboard works without this cap. You do not bridge cap, just remove the cap and leave that pads empty. If you bridge this point go "0" again. You able to install 100p new cap if you want later.
        Last edited by relax79; 10-10-2016, 10:03 AM.

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          #5
          Re: ASUS X93S: specific keyboard keys are not working randomly

          Originally posted by int0x13 View Post
          I could measure directly on the pin 59 on UE1, if this voltage is 0v, then i can conclude that the UE1 chip is faulty, right?
          When you remove the cap and point still show "0" volt then yes maybe your KBC EC controller faulty or controller pin solder not good some reason (solder crack pin to solder pad)
          You must be careful because controller pins pitch very low. Sorry for my poor English.

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            #6
            Re: ASUS X93S: specific keyboard keys are not working randomly

            Originally posted by int0x13 View Post
            a little drop damage? What do you mean?
            my English poor, sorry, I mean any liquid (water, coffee,cola) an even a water drop harm the keyboards inner conductive paint layers and yes your problem not coming from keyboard , I am understand now. I say replace options earlier for the understanding is the cap really failure or not. For examle if you change the c338 to c342 , is the c342 cap have a problem this time must be "KSI3" go to "0"

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              #7
              Re: ASUS X93S: specific keyboard keys are not working randomly

              the "s" key doesnt work anymore for some hours now. I've measure the voltage on pin KSI4 (pin9), it's moving between 0.7v-1v. (not 0v now, dont know why).
              I've measure the caps resistance and it's the same with JKB pin9 capacitor and pin10 capacitor. It's hard to work with such a small cap. It's really tiny. You can remove one without removing all the near one, with hot air? It's so tiny.

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                #8
                Re: ASUS X93S: specific keyboard keys are not working randomly

                I am use generaly two soldering iron for this situation but if you have not you must be find sticky aluminum foil tape (generaly using for bga rework stuff) to covering near caps
                https://www.aliexpress.com/item/Heat...0-f2a2c808e299

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