|
Posted by - Bobb - on August 17, 2007, 6:04 pm
Please log in for more thread options Have you tried an EXTERNAL keyboard ? Cost $10 (CompUSA, Best Buy) and if
IT fails too then you are SURE it's not a physical issue - rather a logic
problem. Especially since you say that it gets worse the longer you use
it - sounds heat related rather than keys sticking.
If external works, is that acceptable ? Can still use as desktop PC.
Beats tossing it in the trash.
>P wrote:
>> Hi, I have a Dell Latitude CPx notebook with a keyboard problem:
>>
>> It has worked well for many years, but some months ago, it started
>> typing more than one letter
>>
>> for each key pressure. This problem has become worse, now it's boring
>> to write something, I
>>
>> musst always stay there do delete duplicate characters.
>> I obviously checked the related windows options in the control panel,
>> but this seems to be an
>>
>> hardware problem.
>> I also noticed that now CTRL and Shift keys work only if I press them
>> very hard .
>> When the laptop is turned on for many hours, it is still worse.
>>
>> so I replaced the keyboard, but the problem came again after a couple
>> of days.
>>
>> I tried to disassemble and reassemble the notebook many and many times,
>> tried both the old and
>>
>> the new keyboard but nothing has changed. The keyboard's connector are
>> in good state.
>>
>> I don't know what to do, I start thinking that this could be a
>> mainboard fault, what could I do?
>>
>> Thanks for the answers.
>>
>>
> If the symptoms are identical, it's likely that your keyboard is ok.
> If they're just similar, you might have two bad keyboards.
>
> I had a similar problem with a cpxj keyboard. Replacing keyboard fixed
> it so I never went further with the diagnosis.
>
> This is often caused by some high resistance between the interconnect
> pins. I've seen bad scanner chips with internal shorts.
> I've seen dirty connectors with gunk in the connector.
> I've seen what looked like pencil marks on the flexible cable shorting
> traces.
> I've seen gunk in the keyboard shorting traces under the keys.
>
> Not much can be done about the bad chips...except cleaning the board if
> it's external to the chip. If you look at the signals on the receiver
> pins as you press keys, you can see if two signals are present and
> where. I once put a pullup on a chip pin to counteract a
> high-resistance
> short. Worked for a while, but broke again.
>
> You can clean ribbon sockets with some paper dipped in alcohol. Use the
> heavy bond high-cotton paper cut to the right width. Don't wanna leave
> paper fibers in there.
>
> You can clean the flexible cable, but have to be careful not to wipe off
> the needed part of the carbon conductors. Conversely, if the conductors
> are "weak", you can sometimes build them up with a pencil.
>
> I once fixed a bad keyboard with a stun-gun. Let it arc between
> conductors and it burned out whatever was shorting. Obviously won't
> work if there's any electonics in there.
>
> Most keyboards come apart rather easily. You can clean between the
> layers, let it dry and reassemble. Reassembly is VERY difficult without
> the proper press...keyboard construction varies widely. YMMV.
>
> Sometimes a thorough cleaning of the motherboard fixes all manner of
> ills. But it's a last resort.
> mike
>
> --
> Return address is VALID!
| 
XML Sitemap