Hey guys, I have an Clevo mobinote m521n notebook that I am trying to repair for someone. The laptop has supposedly have had water damage and that the motherboard needs to be replaced but I would like to be sure. The problem with it is certain keys produce a series of characters as opposed to just one character. Some letters end of moving the cursor up etc. As it is a laptop I think that the keyboard controller resides on the motherboard itself and am just wondering if the problem is likely to be the keyboard or the motherboard. The erroneous keys produce strings that are repetitive in that if the keyboard were at fault I was thinking that the strings produced may vary a bit. The rest of the laptop functions perfectly and indeed trying an external USB keyboard works perfectly. Note also that this has nothing to do with regional settings as they have all been carefully scrutinized. At present I am trying the laptop out using ubuntu 10.04 on a USB memory disk as the OS installed on the HDD is not functional. Any ideas? Thanks

 

If anything, moisture may have gotten to the keyboard connector right under it, Have you removed the keyboard and make sure it is completely dry? there may be moisture between the pieces of plastic membrane that are used as the buttons... and this could be causing a short to adjacent keys when others are pressed....

My .02
B. Morse

 

Well the laptop has been like this for over 6 months at this stage so its doubtful to be moisture unless some kind of liquid was spilt on it like coke. I have removed the keyboard and tried reinsterting the connector a few times but the same result occurs. At this stage all i want to know if its the keyboard or the motherboard although it looks just as difficult to obtain either! I was thinking of trying a couple laptop keyboards from other laptops but the connectors are not standard. Also, as mentioned, the problem is repetitive, affecting the same keys.

 

<snip> the problem is repetitive, affecting the same keys.

This could mean that you have some kind of sticky residue of some sort causing the buttons to "stay pressed"..... try changing the keypress speed in the BIOS (Typematic Rate and Typematic Delay) to see if this solves your issue..... and also while in the BIOS try typing with the same keys that are giving you an issue to see if this issue is not related to the windows drivers..... if it is try uninstalling the generic keyboard driver if it is the Microsoft MCIR 109 Keyboard driver, and see if this solves the issue (Although as soon as you restart windows will reinstall this same driver unless you can find an updated driver for your systems keyboard)


B. Morse

 

Ok i took a look in the bios and didnt see any places that would let me even try the keyboard properly in it. As it happens I have only tried linux on the laptop but when I get a chance I will try a version of windows. I managed to get into the shell on the HDD linux OS. when trying the keyboard, it is the same problem. Note also that the other version of linux that I have tried was a fresh install onto a USB drive that I have verified works on a different pc. I would say that you are most likely right about the keyboard being sticky.

In your opinion though, do you reckon there could be any physical damage to the motherboard? some keys on the keyboard do work.

Thanks

 

Most likely it is just the keyboard that is causing the problem, those plastic membranes sometimes form a sticky fluid in between them (from moisture or other fluids being spilled or dripped on it) and if you can actually take the actual keyboard apart, and wipe down in between the plastic membrane, this may solve your issue.... or you could try swapping out the keyboard with a new one, this would be the cheapest way to try and fix it without sinking too much money on a new motherboard (Hoping it is not the motherboard, if it was I believe you would have more issues than just a few sticky keys).... sometimes you can buy damaged or non working devices off of ebay, and you can try and use that for parts to try and fix the one you have...

B. Morse

 

I'll try giving it a good cleaning and I have also applied for a quote for a replacement. Thanks for your help

 

One last thought that I forgot to mention. Some of the keys would produce the likes of /.ngh: for example and when trying each corresponding key individually like the letter n in the preceeding string, it works perfectly. So if it were the case that the keyboard were sticky or there were some kind of shorting going on to to residue etc wouldnt that mean that the affected keys would no longer work? Does this rule out the keyboard from being the cause of the problem?

 

It sounds like you have a short in the keyboard and or connector.

If it IS waiting for a keypress input, that means that the keypad is ok(ish) If a key was stuck, It would just "beepbeepbeepbeepbeepbeepbeepbeepbeepbeepbeepbeepbeepbeep"

from the key buffer over-filling. And when you got to a prompt, it would "type by itself"

I would check under the plastic/rubber keypad sheet. Look for crystals, odd sheen, syrups ect. Give it a good cleaning. CHECK YOUR CONNECTORS.

If the keyboard controller was bad, you would likely have a "Keyboard Not Installed" error from bios.