Spilt soda on Laptop Keybord - any suggestions on fixing theKeyboard? [Home Built PC]

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From: Mike Easter on 5 May 2010 14:57

Ron Cliborn wrote:
> I spit some soda on my the KB of my laptop.

If we are going to talk about how to disassemble a LT keyboard, we
should be talking about which brand and modelno LT it is.

The 'generic' concept is that you disassemble it properly, clean it
properly - which might likely be done with water - and reassemble it
properly after you have dried it - all appropriate subparts - completely.

Specifics would depend on the specific LT.

> When I turned it off, cleaned it up & rebooted I had problems with my
> Keyboard.

You shouldn't have done all of that with a wet conductive device.

When you spill conductive liquids into electronics, you are not supposed
to be allowing live improper conduction/contacts to take place.

You should have ceased all operation prior to the disassembly, cleaning,
and drying process.

> I think the last time I priced a replacement Laptop KB, it was around
> $100.

It is possible that you should be pricing a replacement *LT* now, not
just a keyboard.

> Is this a problem that can be fixed by disassembling the laptop and
> doing an extensive cleaning or has something
> actually broken it the laptop, like maybe a keyboard controller?

You won't know the answer to that until you do it right in the first place.

--
Mike Easter

From: Paul on 5 May 2010 15:36

Ron Cliborn wrote:
> I spit some soda on my the KB of my laptop.
> When I turned it off, cleaned it up & rebooted I had problems with my
> Keyboard.
> Only some of the keys worked.
> The keys that worked were all spread out so it wasn't like just a
> small area of keys had quit.
>
> I think the last time I priced a replacement Laptop KB, it was around
> $100.
>
> My question is this:
> Is this a problem that can be fixed by disassembling the laptop and
> doing an extensive cleaning or has something
> actually broken it the laptop, like maybe a keyboard controller?
>
> I'm very comfortable taking my DESKTOP system apart and rebuilding and
> replacing components as needed.
> The laptop is something I've never opened before except to upgrade
> HD's and Ram.
>
> I'm not sure if the problem can be diagnosed by my brief description
> but if anyone is willing to help me with this, I"I'll answer any
> additional questions and be grateful as hell.
>
> Incidentally, computer makes a noise as if a key is stuck, but tapping
> on each and every key does nothing to make it stop which leads me to
> believe that something is broken.
>
> I figured if all else fails I'll just buy a cheap external KB and use
> it, but I"d like a try at fixing it first.
>
> The injured laptop is a Toshiba.
> I also have another Toshiba laptop that doesn't work.
> The keyboard is different is it would fix the "cut out" area.
> Not sure if it would help or not, just figured I'd mention it.
>
>
> I'd be very appreciative of any help, suggestions or even flames on
> this matter.
> I cannot begin to tell you the grief I'm catching from the wife on
> this one.
>
> So if you can assist me.....
>
>
> Ron

1) All foreign residue should be removed. The keyboard is relatively
safe to wash. Remove all power from the computer. On some laptops,
you lift the bezel above the top edge of the keyboard, to gain access.
There may be screws hiding under there, that hold down the keyboard.
Remove the keyboard and wash it. Since your beverage involves sugar,
it is imperative to wash it immediately. Run cold water over the
assembly, in your sink.

2) If the keyboard can be disassembled, do so, so that the drying can
be more thorough. I have a membrane keyboard (the one I'm typing on),
and the layers of the membrane come apart. I propped the three layers
apart, so all layers could dry. The design is clever, in that the
membranes are "welded" at hinge points, so you can hold them apart,
but later, they still maintain precision alignment.

3) Place the keyboard parts next to an electric fan. Leave a flow of air
over and around the assembly, for a couple days.

4) Some keyboards tend to trap water inside the key assembly. There are
many different key assembly types, some drying easier than others.
When I dried my keyboard, giving it a shake two days later, was still
causing water to fall out of the key caps. I have one other, relatively
expensive keyboard, which had steel rivets in it, and couldn't get it
apart for cleaning. My cheap keyboard that I'm typing on, cleaned up
easy. And still works.

5) If you did a good washing job, none of your keys will stick. I wasn't
so lucky, and ended up with three sticky keys on the expensive keyboard.
The spring mechanism was not sufficient to overcome the sticky sugar residue.
Once the sugar is in there, no amount of water is really going to make it
clean again (unless you can take everything apart).

As for how the keyboard works, it uses "matrix" technology. Imagine the
following scenario. Eight wires work as "senders". Eight wires work as
"receivers". The wires are laid out in a grid, and each "cross point"
has a key located on top of it, to close the connection between the
two wires. The "sender" wires have a pulse pattern sent through them.
The "receivers" are checked, to see if a pulse is present. The matrix
is "scanned" many times a second. When a key press is detected, there
is a "debounce" interval. The key closure must exist for some number
of milliseconds, for the key to be considered closed. That kind of
digital filtering compensates for the springy contact bounce as
the key contact closes.

OK, so the basic concept is a matrix. But, when you look at the wiring
plan on the keyboard, it is pure chaos. The matrix wires are *not*
laid out the same way as the keys on the keyboard, in neat rows.
A sender wire "snakes" through the keys. When you see weird patterns
of non-functional keys, they could well all be on the same matrix wire.

Some of the keys have "private" wires. The modifier keys, like shift,
control, alt, might have their own private wires.

The "receiver" wires, at least on the keyboard I built as a hobbyist,
are high impedance inputs. That means, they may pick up stray currents
relatively easy. If you were to leave a conductive residue on the
keyboard printed circuit board, that may be sufficient to upset
a receiver wire. In some cases, people see multiple key presses,
keys appearing in "pairs" and so on. These could all be artifacts
of the matrix scheme, capacitance or resistance where it shouldn't
be in the matrix and so on.

A few tips on laptops:

1) Try to find a "disassembly" web site with pictures. It will
save you a world of grief taking the laptop apart. In some cases,
you're required to pry out the bezel above the keyboard. You could
do cosmetic damage while doing that. For some of them, there
is a trick, while for others, damage is more likely.

2) Be methodical when handling screws and fasteners. If there are
forty screws scattered about your table, all different sizes, you'll
never get them back in the correct holes. You could make a drawing
of the bottom of the laptop, and tape each screw to its relative location.
Or use whatever scheme works for you. One of the reason they charge a
couple hours labor for laptops, is the time it takes to take all those
screws out and not lose them.

3) Virtually *every* connector inside the laptop is delicate. Cable
assemblies may be packed into the unit in the most devious ways.
If this is the first laptop you've worked on, you could easily damage
a ribbon cable while disassembling the thing. Everything inside a laptop
is smaller than in a desktop computer, and more delicate.

Some parts of a computer, should not be washed. I wouldn't wash an optical
drive (because you can get the optical lenses dirty). A hard drive has a
breather hole, and it should not be immersed in liquids. Some of the
holes on hard drives, are only covered by a sticker (like the servo writer
port, used at the factory). The motherboard should be relatively safe to wash.
The keyboard should be safe to wash (as long as you can get it thoroughly dry,
before applying power again).

With desktops, if you get liquid in them, there is 120 or 220 VAC inside
the chassis. If the liquid bridges from the alternating current, to the
computer parts, damage could occur. In a laptop, by comparison, there is
low voltage DC (say 19 volts). But if that bridges to a sensitive circuit,
it could still blow something. There are some CMOS signals on logic chips, that
don't have full protection against electrical insults. So you really
should remove all power from the device, once the liquid has entered.
Pop the main battery. Unplug the adapter. When it is all dry again,
power up.

Due to the sugar, there is no such thing as a trivial spill. If you ignore
a spill involving sugar, a couple of days later, when you find a key
sticking, you'll wish you'd taken care of it. The sugar doesn't come out
nearly as easy, once it has dried.

Good luck,
Paul

From: kayef on 5 May 2010 18:31

From: Conor on 6 May 2010 04:43

On 05/05/2010 19:46, Ron Cliborn wrote:

> I'd be very appreciative of any help, suggestions or even flames on
> this matter.
> I cannot begin to tell you the grief I'm catching from the wife on
> this one.
>
> So if you can assist me.....
>

Go on Ebay and buy a complete replacement. Used ones in the UK around
around �15-�20. There are plenty of "how to" guides on the internet.

--
Conor I'm not prejudiced. I hate everyone equally.

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