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Is it the keyboard or the motherboard?

Posted on 2007-03-21
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Last Modified: 2013-12-09
A friend spilled coffee all over her Dell Inspiron 300m notebook computer. It appeared that the thing was hosed. She sent it back to Dell and they said they fixed it by putting in a new keyboard. When she got it back, it had the same problem. Some keys on keyboard did not work at all, some spewed out triple letters. She got her money back from Dell and I volunteered to take a look at it for her.

I pretty much concluded that the keyboard was still the one that the coffee got spilled onto. Close exam with a magnifying glass showed crud on it, and it seemed to me that the "a" key stuck a bit. Also the space bar "didn't feel right".
When I turned on the computer, it beeped furiously. The "alt" key on the left of the spacebar stopped the beeping. Trying to type into Microsoft Word gave very strange results, mostly, as stated for the original problem, triple chars when one key was hit and other keys not working at all.

I managed to run AdAware, SpyBot, SpyWareBlaster and AVG. No problems were found but the definitions are several months old. I couldn't connect the pc up to my wireless net because I couldn't type in the key!

Since I had nothing to lose, I removed the keyboard and soaked it in hot water to remove the crud. I let it dry for several days. Now all keys have an consistent touch and feel so I think the crud was removed.

I put the keyboard back in and turned the pc on: no beep beep beep at startup anymore. But the keys still don't work. Different symptoms though: lots more keys don't work at all. A few do work. Others spew out two chars. But nothing is consistent.

What is very puzzling is that the keys behave differently depending upon what app I'm using (Notepad, Word, Excel). Why would this be?

I did order a replacement keyboard, hoping that that really was the problem. I just put it in, and turned the pc on. I get the beep beep beeeeeeeeeeeeeeeeeeeeeep at startup. And NONE of the keys work.
Of course, it could be that this "refurbished" part is also bad! But how would I know?

I don't have a USB keyboard to plug in to the notebook. All my keyboards are PS/2!

The touchpad does work.

I know it's possible that something shorted out on the motherboard. Do I have enough conclusive evidence to suggest this? And that the keyboard is not the faulty part? Or it's not a virus or something else?

Thanks!
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Question by:alicia1234
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LVL 39

Expert Comment

by:PUNKY
ID: 18767042
Last time I did on similar is pull out the keyboard, do a good inspection on cable, connector (connection between keyboard and motherboard), then drying up the motherboard a bit. It works. Not sure about your case, might be circuit shorted due to contamination still there? but it is good to take a look.
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Author Comment

by:alicia1234
ID: 18767069
Connector is good. This happened months ago so motherboard is dry. I don't know where/how to look for a short on the motherboard.
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LVL 39

Expert Comment

by:PUNKY
ID: 18767166
Try this:

http://www.experts-exchange.com/Hardware/Misc/Q_21797028.html

Even few months ago, but if residue are still there that would cause issue. Specially at soldered pins or leads.
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Author Comment

by:alicia1234
ID: 18767200
Sorry ... don't understand why you referred to that link? It's about changing a harddrive and getting the BIOS to recognize it??
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LVL 39

Expert Comment

by:PUNKY
ID: 18767245
Reset bios and more things else. It should help fix some issue there as well. Try it, and it is no harm at all.
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Author Comment

by:alicia1234
ID: 18767270
Well, since the keyboard does not work, I would not be able to enter any of those codes to get in to the BIOS to reset it! ;-(
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LVL 39

Expert Comment

by:PUNKY
ID: 18767341
My bad! forgot that keyboard no work :)

Can you hook up PS/2 keyboard? I think it should have 1 port for mouse/keyboard on this system.
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Author Comment

by:alicia1234
ID: 18767384
My initial post mentions that I do not have a USB keyboard ... only PS/2, unfortunately, and there is no PS/2 connector. I may go out and find a converter but not today.
But the original question really was this: the fact that two keyboards didn't work ... would that indicate conclusively that it is indeed the keyboard and not the motherboard?
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Accepted Solution

by:
willcomp earned 250 total points
ID: 18767619
The way to be 100% sure is to connect a USB keyboard.  Should be able to purchase one for under $10.00 or borrow one for testing.

What about touchpad (mouse)?  Will apps open and close normally?  If so, chances are good that it's either keyboard or keyboard connector.  Those ribbon cables are tricky, so ensure that cable is properly seated in motherboard connector.
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Author Comment

by:alicia1234
ID: 18767696
willcomp: I will try to get a USB kb to test.
The touchpad does work (as mentioned in my initial post). Apps open and close ok. Anything I can control totally with the touchpad works fine.
I have tried two notepad keyboards and I have securely connected the cables to the motherboard. One is the kb in question; the other is supposedly a brand new one. Neither one works but each one shows different symptoms.
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Author Comment

by:alicia1234
ID: 18845491
I was able to borrow a USB keyboard to test and it DID work.
So a summary of the situation is this:
1) External USB keyboard works so that must mean it's not the motherboard per se
2) Two different internal keyboards (one brand new) do NOT work, but each exhibits different symptoms.

So I'm leaning now towards a problem with the keyboard connector that is on the motherboard. Is all hope lost? Or is there something I can do to fix this? There are no visual signs of damage.
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LVL 39

Assisted Solution

by:PUNKY
PUNKY earned 250 total points
ID: 18845529
There must be something there, even you dont see any damaged. It is good to take a look again, re-insert cable in connector and lock it down good. Also, inspect see if any contamination on gold fingers of cable terminal, connectors.
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LVL 32

Expert Comment

by:willcomp
ID: 18845630
If it were the keyboard connector, I would expect repetitive symptoms and not different ones.
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Author Comment

by:alicia1234
ID: 18845771
willcomp: do you have any other ideas?
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LVL 32

Expert Comment

by:willcomp
ID: 18845806
I'd contact Dell and request a warranty repair on their repair.  Could just be a faulty keyboard which is not unusual for replacement notebook keyboards.  Was the other notebook keyboard you tried an identical keyboard?
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Author Comment

by:alicia1234
ID: 18845921
The other notebook keyboard was exactly the same. Same part number and everything. That's what's so strange to me: why would two keyboards behave differently?
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LVL 32

Expert Comment

by:willcomp
ID: 18846044
That's a question I wish I had an answer for.  It defies logic.
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LVL 39

Expert Comment

by:PUNKY
ID: 18846058
Because as said above, one is defective and other is good :)
Restart computer and press F12, then choose diagnostic see if system would fail the keyboard?
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Author Comment

by:alicia1234
ID: 18846088
punky: I can't press F12 ... it doesn't work on either of the internal keyboards.
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Expert Comment

by:willcomp
ID: 18846169
Just to be sure --> when you change keyboards, are you releasing the latch (pull up on plastic bar on top of keyboard connector) and pressing down on bar to relatch after inserting ribbon cable?
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LVL 39

Expert Comment

by:PUNKY
ID: 18846496
If you have Dell dianostic cd, use it is same with F12.
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Author Comment

by:alicia1234
ID: 18968608
Sorry ... it's not abandoned. I have not been able to get back to it but I will. Please give me a few more days. Thanks. ;-)
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Author Comment

by:alicia1234
ID: 18994089
Bottom line is that I never solved the problem. I am thinking that it must be the connector, and so I am awarding points based on that. Thanks.
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