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| omen666 2003-10-06, 10:43 am |
| I have a Vaio Laptop which misses out letters when you type i've tried another keyboard and also an external keyboard that i know both work fine but i still have the same problem. I've also done a clean reinstall (Win XP Home).
Any Ideas
Thanx | |
| azimuth40 2003-10-06, 4:50 pm |
| quote:
Originally posted by omen666
I have a Vaio Laptop which misses out letters when you type i've tried another keyboard and also an external keyboard that i know both work fine but i still have the same problem. I've also done a clean reinstall (Win XP Home).
Any Ideas
Thanx
More definition needed on what misses out letters means. Is it continous, random, sometimes, most of the time? Since it happens with an external keyboard also then we are looking for a common junction point.
It could be the motherboard keyboard controller. It could be a bad buffer driver; cracked resister, open or shorted signal line. If a letter appears but it is not the right one then check for bit affinity by typing the alphabet and compare the ascii bit pattern of each letter looking of a stuck true or stuck false bit. | |
| omen666 2003-10-07, 12:29 pm |
| Thanx for that but you lost me at More
All i can tell you is that it is intermitent and when you press a key it will sometimes misses that letter altogether so you have to press it again.
It never types the wrong letter just misses them out.
Hope this helps! | |
| azimuth40 2003-10-07, 2:43 pm |
| quote:
Originally posted by omen666
Thanx for that but you lost me at More
All i can tell you is that it is intermitent and when you press a key it will sometimes misses that letter altogether so you have to press it again.
It never types the wrong letter just misses them out.
Hope this helps!
Ooops that is not good then is it.  History lesson. What do you do with old CPU that have paid for themselfs? You turn then into pennies to make controllers. The core of the 8080 with started it all for Intel has some rom some prom and some ram added to it and is renamed a 8042 UPI (Universal Peripheral Interface) used for anything that you need a 8 bit processor for. The 8042 on the IBMPC was called a keyboard controller. You have a similar chip or chip function in the keyboard. They talk to each other on a serial interface (your keyboard cable).
The one in the laptop normally eliminates part of that and uses a ribbon cable and absorbed logic to do a parallel to serial function (make and break on the switches). Once you are past that then it ties into the external connector like normal. So you could have a broken ribbon or a bad clock signal which would affect both internal and external keyboards. Check the PS2 connector pinout in any book and then trace it back. Which of the things to check depend on the design of the laptop.
There is not many standards in laptop design past the CPU and Northbridge. That is why most hate working on them. However since you say it is intermittant even on an external keyboard, it may just be the clock or serial data line.
You could disconnect the internal keyboard and see if it works OK with just an external keyboard. If it does then look for a bad connector somewhere. You could also have a fractured etch on the motherboard. Sometimes even the disk seeking, or CD spinning up will cause an intermittant in a hot laptop. You will probably have to replace the motherboard unless you have time to spend flexing things until you find it.
You have a crappy problem to find. I assume it is off warranty already. | |
| omen666 2003-10-07, 3:57 pm |
| Yes it only just off waranty which is a bit of a pig.
Ill try everything you've suggested and hopefuly strick it lucky.
Thanx for your help and time its much appreciated. |
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