need access to dell inspiron keyboard circuit

Posted on 2004-08-22
Last Modified: 2012-06-27
I have a Dell Inspiron 2650 laptop onto which, alas, I spilled some coffee. Some of the keys now double up... typing "1234567890" gives "q1w2e3r4tyu7i8o9p0" ("t" and "y" are unaffected), hitting the "[" key usually would give an indeterminate number of "[[[[[[[[[[[[..." and the curson arrow keys respond erractically. I popped the key tops off and q-tipped around there with alcohol which seems to have solved the "[[[[[[[[[..." problem but the other keys are still malfunctioning. Can anyone supply instructions (directions to a diagram?) on how to dig a little deeper into the laptop to access the keyboard circuitry where I might be able to clean up this mess?
Question by:BobArnett
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Accepted Solution

rid earned 250 total points
ID: 11865322
A new KB is indicated.

Since the component is (very probably) a loss anyway, you could try the drastic method of washing it with water.

1) Remove KB from the computer.
2) Get a sufficient quantity of distilled or deionized water.
3) Immerse KB for some time (say 30 minutes or so), lift up and re-immerse a few times.
4) Repeat with new water.
5) Hang up to drip, then provide moderate heat and some air circulation (let an ordinary incandescent lamp shine on it from a suitably short distance and aim a desk fan at it).
6) Leave like this for at least 48 hours.

The theory is that distilled water is more or less inert and the KB is powerless - no electrolysis or spontaneous corrosion in a short term perspective. Coffee components should be soluble in water. Drying out is key, as moisture will disturb signals inside the KB. Some heat (very moderate; no morer than 40 -50 C) and air flow will help a lot here.

Don't bother with this if you can't get an external KB to work OK - you may have problems below the KB, too, unfortunately.

Author Comment

ID: 11872126
OK, thanks for the tip. After checking an external keyboard, I'll try that out.

Author Comment

ID: 11872802
Is there some place I can get a diagram of how this thing is put together so I can get to the keyboard or should I just start taking out screws until it opens up?
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LVL 31

Expert Comment

ID: 11877286
There are screws undeneath the laptop. Those that are under the KB should be loosened and the KB can then be lifted out. Careful with the flat cables running to the Motherboard. They can be pulled out of their sockets easily once the clamping sleeves on the connectors are lifted a little.

Expert Comment

ID: 11888805
I had a dead keyboard that did soemthing simliar.  The problem is that the way the keyboards are made.  They are made with 3 layers of plastic, the top and bottom layers have the contacts and the middle layer is sort of a buffer layer with holes where each key is.  When you push down on a key, it will push the top layer down and pushes it enough so that it touchs the bottom contact shorting a circuit hence giving you a key.

Well what happened is that the soda is now creating new paths for the current to flow.  Now for sake of argument, your A key when pressed now types a \A instead of just the A, that doesn't mean that the problem is necessarly with the A key, it might be with someting else causing the A key to fail.  Keyboards are designed in a matrix and the soda is distrubing the matrix.

First thing I would do would be to go ahead and clean as much of the keyboard as possible using deionized water and/or rubbing alchol.  Pay attention to the edges of the keyboard in particular.  Once that is done test, if it still fails,you can try to take a hypo needle (the kind that diabetics use) and poke holes near where the drink was spilled and then rinse it off hoping that the water/alchol will penatrate the pinholes and breakdown the soda.  Then let dry (try using a hot hair dryer on it for an extended period of time).  The hot hair dryer hopefully will then evaporate liquids and your keyboard will work again.

If all that doesn't work, then try to buy a new keyboard for 10-30 dollars on ebay and call it good.

Author Comment

ID: 11917932
Thanks for the tips. After doing the whole laundry thingy, I found you were right; "A new KB is indicated"... so I've now got one on the way.
LVL 31

Expert Comment

ID: 11919515
I was afraid it might end like that...

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