Tea + Dell

[GT]

I would like to start this with "a friend of mine...", but I can't!

I have a 1 year old Dell Inspiron 6400 and decided to pour a full cup of
fresh, just boiled tea over it. Sounds silly to mention it, but no milk or
sugar, just a fresh slice of lemon. Before I could even whip the power cable
out of the back, the machine turned itself off instantly. I pulled the
battery after a moment to limit any further power related damage. The memory
compartment underneath seems to be dry. The hard disk seems to be dry -
removed that about 5 minutes after the event.

I have tried to remove the case to inspect for fluid, but there must be some
of those hidden plastic close once, never open, catches. I know from
experience that you have to prize them with a screwdriver, chewing the case
in the process, to open the case, so I have just wiped clean the outside of
the laptop and hair-dryered the keyboard and intend to leave it in the
airing cupboard for a few days before I go near it with power.

1. Yes I feel silly, but these things happen
2. Does anyone know if the keyboard is a sealed unit (isolated from the main
board area)?
3. Does anyone know if the mousepad is a sealed unit (isolated from the main
board area)?
4. Does anyone know how to open the back (bottom) of an Inspiron 6400?
5. Does anyone know if the Inspiron 6400 has a liquid sensor and shuts off
immediately (I hope so)?
6. Anyone have any other advice to maximise the posibility of my getting it
to work again?

TIA,
GT

 

[kony]

I would like to start this with "a friend of mine...", but I can't!

I have a 1 year old Dell Inspiron 6400 and decided to pour a full cup of
fresh, just boiled tea over it. Sounds silly to mention it, but no milk or
sugar, just a fresh slice of lemon. Before I could even whip the power cable
out of the back, the machine turned itself off instantly. I pulled the
battery after a moment to limit any further power related damage. The memory
compartment underneath seems to be dry. The hard disk seems to be dry -
removed that about 5 minutes after the event.

I have tried to remove the case to inspect for fluid, but there must be some
of those hidden plastic close once, never open, catches. I know from
experience that you have to prize them with a screwdriver, chewing the case
in the process, to open the case, so I have just wiped clean the outside of
the laptop and hair-dryered the keyboard and intend to leave it in the
airing cupboard for a few days before I go near it with power.

Don't power it up yet. Was it monster strength tea or just
garden variety weak stuff? Tea (+lemon) is variably acidic,
can etch metal into solution which should be completely
rinsed out. It would probably corrode the contacts and
keyboard first so all these should be unplugged while
rinsing what can be rinsed.

1. Yes I feel silly, but these things happen
2. Does anyone know if the keyboard is a sealed unit (isolated from the main
board area)?

Even if the keyboard were sealed, it's not going to keep the
liquid from leaking around it onto the other areas. That
is, unless you have a unit specifically advertised as
water-resistant (nearly water-proof). Obviously it made
it's way past the keyboard or it would have kept running and
you might've just had a keyboard malfunction.

I don't know what the melting point is of the plastic film
ribbon connectors but they might be suceptible to the heat.
The whole laptop needs disassembled and rinsed out, then
either forced-air or heat dried for quite a while (when it
looks dry there would still tend to be water wicked under
BGA/etc chips so it's better to give it an extra day next to
a fan than to rush it.

3. Does anyone know if the mousepad is a sealed unit (isolated from the main
board area)?

On that model, I don't know. In general, no, very little if
anything on a laptop has the gaskets and design needed to
repel water to this extent unless it was specifically
designed (marketed) for this. At most some areas might have
a fiberous dust gasket like on an optical drive door area
but this will soak up the tea and be another thing that
needs a more thorough cleaning (just rinsing should be
enough, though in this cleaning process I would use a bit of
detergent, not soap, before the final rinse cycle. An
artist's paintbrush is a good tool to agitate the tea and
other misc particules into solution before rinsing.

4. Does anyone know how to open the back (bottom) of an Inspiron 6400?

You should check Dell's website, and if all else fails get
some little pieces of plastic film, like a credit card cut
into slits, so when you start prying around the edges with a
knife made of the softest material you have, you can slip
the pieces of plastic in to keep the shell parts cracked
open. Sometimes using masking tape to keep these plastic
pieces in place can help.

5. Does anyone know if the Inspiron 6400 has a liquid sensor and shuts off
immediately (I hope so)?

I've never heard of a non-waterproof laptop having a sensor
like this, and doubt it could be a comprehensive protection
since there would have to be such sensors scattered
everywhere just to cover all potential liquid entry points,
in order to shut it off before liquid reached some other
area first. I suspect it's more likely the liquid shorted
out a power supply rail in one way or other and the unit
shut off when it couldn't regulate the power properly
anymore. The remaining question would be if there was
another short to something more sensitive. You may have
some kind of failure, but it may not be a total loss.

6. Anyone have any other advice to maximise the posibility of my getting it
to work again?

Complete methodical disassembly and cleaning... but you
probably suspected as much already. As with other
combinations of questionable parts, you should try it with
only the bare minimum parts connected, for example leaving
HDD and optical, card reader/etc disconnected. That is the
ideal but since it could be a PITA to keep stripping laptop
down and reassembling it, you might instead make 100% sure
it's dry before trying it and leaving the battery out so if
it doesn't work or really, starts smoking, you can pull the
power cord.

While you have it open, inspect certain areas like fuses
(probably surface mount type)(but actually, inspect all
areas regardless of fuses and ensure all residue except
perhaps some meant-to-be permanent, no-clean solder flux (if
present) is removed). It is likely to have fuse(s) and
might have blown one or more. You might need to use a
multimeter to check continuity across them. Since it may be
difficult to get into the back areas the keyboard you might
need to soak in detergent solution and aggressively agitate
it while wiggling the keys. At least this was unsweatened
tea, since parts like the optical drive in particular
shouldn't be water-cleaned and so there is a better chance
it survived/working without a sticky residue remaining. I
would also be hesitant to get the top half, LCD panel wet
unless it later seems to be a problem or had obviously
gotten tea wicked up into it. I would probably try the
touchpad without rinsing it out yet... unless it was
obviously full of tea residue, in which case getting it wet
then dry again but with the residue removed and fully dried
should be at least better than it was before.

The other alternative is to drop it off at a laptop repair
center, but you never know what they're going to tell you,
some places tend to replace a whole board instead of finding
a blown fuse or other simple discrete repair... though if
you isolated a blown fuse and didn't feel you had the skill
to source and replace it, indicating what is needed with the
circuit board out could reduce the cost of repair at a
general electronics repair shop... probably little more than
minimal bench fee if you were fortunate enough that a
failure was only a fuse, which it could be and there's not
much diagnostics you can do to a laptop board until you spot
a problem or fix the blown fuse so the rest gets power.

 

[GT]

Don't power it up yet. Was it monster strength tea or just
garden variety weak stuff? Tea (+lemon) is variably acidic,
can etch metal into solution which should be completely
rinsed out. It would probably corrode the contacts and
keyboard first so all these should be unplugged while
rinsing what can be rinsed.


Even if the keyboard were sealed, it's not going to keep the
liquid from leaking around it onto the other areas. That
is, unless you have a unit specifically advertised as
water-resistant (nearly water-proof). Obviously it made
it's way past the keyboard or it would have kept running and
you might've just had a keyboard malfunction.

I don't know what the melting point is of the plastic film
ribbon connectors but they might be suceptible to the heat.
The whole laptop needs disassembled and rinsed out, then
either forced-air or heat dried for quite a while (when it
looks dry there would still tend to be water wicked under
BGA/etc chips so it's better to give it an extra day next to
a fan than to rush it.



On that model, I don't know. In general, no, very little if
anything on a laptop has the gaskets and design needed to
repel water to this extent unless it was specifically
designed (marketed) for this. At most some areas might have
a fiberous dust gasket like on an optical drive door area
but this will soak up the tea and be another thing that
needs a more thorough cleaning (just rinsing should be
enough, though in this cleaning process I would use a bit of
detergent, not soap, before the final rinse cycle. An
artist's paintbrush is a good tool to agitate the tea and
other misc particules into solution before rinsing.



You should check Dell's website, and if all else fails get
some little pieces of plastic film, like a credit card cut
into slits, so when you start prying around the edges with a
knife made of the softest material you have, you can slip
the pieces of plastic in to keep the shell parts cracked
open. Sometimes using masking tape to keep these plastic
pieces in place can help.



I've never heard of a non-waterproof laptop having a sensor
like this, and doubt it could be a comprehensive protection
since there would have to be such sensors scattered
everywhere just to cover all potential liquid entry points,
in order to shut it off before liquid reached some other
area first. I suspect it's more likely the liquid shorted
out a power supply rail in one way or other and the unit
shut off when it couldn't regulate the power properly
anymore. The remaining question would be if there was
another short to something more sensitive. You may have
some kind of failure, but it may not be a total loss.




Complete methodical disassembly and cleaning... but you
probably suspected as much already. As with other
combinations of questionable parts, you should try it with
only the bare minimum parts connected, for example leaving
HDD and optical, card reader/etc disconnected. That is the
ideal but since it could be a PITA to keep stripping laptop
down and reassembling it, you might instead make 100% sure
it's dry before trying it and leaving the battery out so if
it doesn't work or really, starts smoking, you can pull the
power cord.

While you have it open, inspect certain areas like fuses
(probably surface mount type)(but actually, inspect all
areas regardless of fuses and ensure all residue except
perhaps some meant-to-be permanent, no-clean solder flux (if
present) is removed). It is likely to have fuse(s) and
might have blown one or more. You might need to use a
multimeter to check continuity across them. Since it may be
difficult to get into the back areas the keyboard you might
need to soak in detergent solution and aggressively agitate
it while wiggling the keys. At least this was unsweatened
tea, since parts like the optical drive in particular
shouldn't be water-cleaned and so there is a better chance
it survived/working without a sticky residue remaining. I
would also be hesitant to get the top half, LCD panel wet
unless it later seems to be a problem or had obviously
gotten tea wicked up into it. I would probably try the
touchpad without rinsing it out yet... unless it was
obviously full of tea residue, in which case getting it wet
then dry again but with the residue removed and fully dried
should be at least better than it was before.

The other alternative is to drop it off at a laptop repair
center, but you never know what they're going to tell you,
some places tend to replace a whole board instead of finding
a blown fuse or other simple discrete repair... though if
you isolated a blown fuse and didn't feel you had the skill
to source and replace it, indicating what is needed with the
circuit board out could reduce the cost of repair at a
general electronics repair shop... probably little more than
minimal bench fee if you were fortunate enough that a
failure was only a fuse, which it could be and there's not
much diagnostics you can do to a laptop board until you spot
a problem or fix the blown fuse so the rest gets power.

Thanks buddy. One day, someone here will ask a question that you can't
answer!

I'll attack it with a screwdriver tonight and see if I can prise the case
off. I have spent many a happy hour inside desktop PCs, but never dismantled
a laptop base unit - I've only fixed hinges and broken plastic in
screens/lids. Looking at a few pictures online, it would appear that the
keyboard can be removed, providing access to most of the innards, without
opening the bottom of the case - any hints or tips here?

 

[GT]

Thanks buddy. One day, someone here will ask a question that you can't
answer!

I'll attack it with a screwdriver tonight and see if I can prise the case
off. I have spent many a happy hour inside desktop PCs, but never
dismantled a laptop base unit - I've only fixed hinges and broken plastic
in screens/lids. Looking at a few pictures online, it would appear that
the keyboard can be removed, providing access to most of the innards,
without opening the bottom of the case - any hints or tips here?

Found Dell support manuals detailing how to remove everything. I should be
fine with this info:
http://tinyurl.com/39f7lz

 

[kony]

Found Dell support manuals detailing how to remove everything. I should be
fine with this info:
http://tinyurl.com/39f7lz

Take your time and use a good screwdriver of proper size as
some of the screws may be in pretty tight with threadlock on
them. It would be better to buy a new screwdriver if unsure
than to strip a screw.

 

[GT]

Take your time and use a good screwdriver of proper size as
some of the screws may be in pretty tight with threadlock on
them. It would be better to buy a new screwdriver if unsure
than to strip a screw.

I have a new set of minature 1-3.5mm flat, cross and start screw drivers.
Laptop is now in many pieces!.

Its not as bad as I thought.

Screen wasn't touched. Mainboard (rear 2/3 of casing) looks like nothing
touched it anywhere - clean as a whistle. Looks like the touchpad mouse and
the keyboard took most of the tea. The rest has poured forward through the 2
lid latch holes at the front and around the speakers and some round the
battery casing and just touched the connections, which I assume caused the
short and immediate power down. I think I may have inadvertantly saved the
machine as almost before the cup had even landed, I picked up the laptop and
tipped it forward and the tea all poured out through the speaker
perforations/holes, which is the only part of the inside that has no
electrics (of importance - just speaker wiring). I think this is also how it
arrived in the battery compartment - also at the front.

So, nothing inside looks like it needs a clean, which is good news. The
battery works just fine - it has a test button. I have cleaned the casing
and battery compartment, so the only parts that may be damaged are the
keyboard and mousepad. I think the keyboard will be OK - cleaned up OK and
none of the keys are sticky. However the mousepad has some residue on the
underside, so may be shot, but I'll leave it overnight and see what happens
tomorrow. For once, I can actually say that there is no data on the machine
that isn't backed up, so its not the end of the world!

I'll leave it all in the airing cupboard over night and put it together
again in the morning. I'll keep you posted. Thanks for the advice Kony.

 

[GT]

I would like to start this with "a friend of mine...", but I can't!

I have a 1 year old Dell Inspiron 6400 and decided to pour a full cup of
fresh, just boiled tea over it. Sounds silly to mention it, but no milk or
sugar, just a fresh slice of lemon. Before I could even whip the power
cable out of the back, the machine turned itself off instantly. I pulled
the battery after a moment to limit any further power related damage. The
memory compartment underneath seems to be dry. The hard disk seems to be
dry - removed that about 5 minutes after the event.

Completely overhauled the box, inspecting and drynig as I went. The only tea
damaged parts are the keyboard, mousepad and battery compartment. Some
liquid must have reached the battery connector as the power went off
immediately following the tea incident. I have dried all the parts and left
it all over night. No circuitry has been touched by the liquid, other than
whatever is under the keyboard keys and under the mousepad and buttons.

However, it is dead. Power from battery or mains gives nothing. No fan
noise, no lights, nothing. I strongly suspect that damage was done when the
tea hit the battery contacts, but don't know where to begin in diagnosing
the problem. Will probably just phone Dell, explain and see what they
recommend. Its only just over 1 year old (1 year warranty!), but a repair
might be more costly than a new machine!

 

[kony]

Completely overhauled the box, inspecting and drynig as I went. The only tea
damaged parts are the keyboard, mousepad and battery compartment. Some
liquid must have reached the battery connector as the power went off
immediately following the tea incident. I have dried all the parts and left
it all over night. No circuitry has been touched by the liquid, other than
whatever is under the keyboard keys and under the mousepad and buttons.

However, it is dead. Power from battery or mains gives nothing. No fan
noise, no lights, nothing. I strongly suspect that damage was done when the
tea hit the battery contacts, but don't know where to begin in diagnosing
the problem. Will probably just phone Dell, explain and see what they
recommend. Its only just over 1 year old (1 year warranty!), but a repair
might be more costly than a new machine!

Do you have a mulltimeter? If not, now is a good excuse
to get one. Even some cheap $20 generic is a very useful
tool for many purposes, it need not be a $200 Fluke.

Keep the battery out, plug the AC adapter in and trace the
power from the onboard (or occasionally separate power
board) section. Basically you would take meter probes and
follow the power path, from input all the way to some
chips.

As I vaguely mentioned previously, I would check all fuses'
continuity first.

Unplug all hardware non-essential to post and then see if it
runs. Essentially it has same troubleshooting as a desktop,
just more integrated and more fiddly connectors.

 

[GlowingBlueMist]

Do you have a mulltimeter? If not, now is a good excuse
to get one. Even some cheap $20 generic is a very useful
tool for many purposes, it need not be a $200 Fluke.

Keep the battery out, plug the AC adapter in and trace the
power from the onboard (or occasionally separate power
board) section. Basically you would take meter probes and
follow the power path, from input all the way to some
chips.

As I vaguely mentioned previously, I would check all fuses'
continuity first.

Unplug all hardware non-essential to post and then see if it
runs. Essentially it has same troubleshooting as a desktop,
just more integrated and more fiddly connectors.

I don't know if your model has a way of powering it back on with out using
the keyboard but it might be worth a try of doing that with the keyboard
totally removed from the unit. If it looks like it is trying to power up
you might try flushing out the keyboard with 180% alcohol, or what you can
get that is stronger than the cheap rubbing alcohol they sell at the grocery
store, while it is still removed from the chassis. Then keeping the temp in
mind either use a hair dryer to blow dry the alcohol or leave it on
something warm, like a TV or other thing to air dry for a day or two. It
might just get the keyboard working again.

 

[Noozer]

I have a 1 year old Dell Inspiron 6400 and decided to pour a full cup
You'll need to let it dry for SEVERAL days... If liquid got into any nooks
and crannies it will take a while to dry.

I'd open it up and pull the drive(s) out, keyboard, etc... Basically
anything that isn't difficult to remove and might trap moisture. Once apart,
point a fan blowing across it to speed drying. Leave it for several days.

It might help to rinse in warm distilled water or possibly 90% isoproyl
alcohol... but that would depend on how much tea got into the machine.

A lack of sugar or milk is a very good thing... Shouldn't gum anything up.

 

[GT]

Do you have a mulltimeter? If not, now is a good excuse
to get one. Even some cheap $20 generic is a very useful
tool for many purposes, it need not be a $200 Fluke.

Keep the battery out, plug the AC adapter in and trace the
power from the onboard (or occasionally separate power
board) section. Basically you would take meter probes and
follow the power path, from input all the way to some
chips.

Odd... Plugged in the power adapter and the light comes on (on the adaptor).
Plug that into the laptop and the power light dies on the power adaptor and
the laptop does nothing. There is no power available (instantly) to trace
through the laptop! Sticking the multimeter into the end of the power
adapter wire shows the correct 19.5v, but 0 amps. Seems like the power
adapter is shot! We have another inspiron 6400 at work, so I will figure out
if the adapter is shot by using it on the working PC on Monday. What I am
reluctant to do is try the working power adapter in the broken laptop, as it
might blow the working adapter!

What it feels like is that the laptop 'trips' the power adapter when it is
connected to the laptop, but of course this doesn't explain the 0 amps
readout, unless my multimeter is broken. This is possible as it has
different connections for current and voltage testing.

The laptop battery is fully charged and the laptop doesn't work from that
either, so there is still definitely a problem in the laptop, however, I
rarely use (and could live without) the battery.

 

[Paul]

Odd... Plugged in the power adapter and the light comes on (on the adaptor).
Plug that into the laptop and the power light dies on the power adaptor and
the laptop does nothing. There is no power available (instantly) to trace
through the laptop! Sticking the multimeter into the end of the power
adapter wire shows the correct 19.5v, but 0 amps. Seems like the power
adapter is shot! We have another inspiron 6400 at work, so I will figure out
if the adapter is shot by using it on the working PC on Monday. What I am
reluctant to do is try the working power adapter in the broken laptop, as it
might blow the working adapter!

What it feels like is that the laptop 'trips' the power adapter when it is
connected to the laptop, but of course this doesn't explain the 0 amps
readout, unless my multimeter is broken. This is possible as it has
different connections for current and voltage testing.

The laptop battery is fully charged and the laptop doesn't work from that
either, so there is still definitely a problem in the laptop, however, I
rarely use (and could live without) the battery.

You make a current measurement, in series with one rail, like this:

A.C.
Adapter ----------------x <--- multimeter_current_setup ---> x-------> laptop
D.C. input
Output -------------------------------------------------------------> connector

To make a current measurement, normally you'd have to hack into the
cable, break one wire, and insert the multimeter on the current
range, to measure the current in the wire. Currents, you measure
in series - voltage you measure in parallel.

Don't even go near the current measurement function, unless you know
how it works. The current measurement terminals on the multimeter, are
a "dead short". If you shove the multimeter, set on current, and wires
plugged to the "current holes" on the meter, into a power adapter,
that shorts out the adapter, and potentially blows the protection
fuse inside the multimeter, or the fuse inside the device being
tortured.

This is why the "current measurement holes" on the multimeter, are
separate from the "voltage/ohms" holes. It is to prevent accidents.

As a result of these details, I hardly ever use the current ranges
on my digital multimeter.

I have a "clamp-on" DC ammeter, but even that requires physical
separation of the conductors, to get a reading. If you clamp one
of those meters, around the pair of wires in the adapter cable
shown above, the reading would be zero. If the jaws are clamped
around just one of the two wires, you get a valid current reading.

Measuring current is tricky, and you have to know what you're doing.
Otherwise, you'll be replacing the fuse inside the multimeter, a lot

Paul

 

[Andy]

Odd... Plugged in the power adapter and the light comes on (on the adaptor).
Plug that into the laptop and the power light dies on the power adaptor and
the laptop does nothing. There is no power available (instantly) to trace
through the laptop! Sticking the multimeter into the end of the power
adapter wire shows the correct 19.5v, but 0 amps. Seems like the power
adapter is shot! We have another inspiron 6400 at work, so I will figure out
if the adapter is shot by using it on the working PC on Monday. What I am
reluctant to do is try the working power adapter in the broken laptop, as it
might blow the working adapter!

What it feels like is that the laptop 'trips' the power adapter when it is
connected to the laptop, but of course this doesn't explain the 0 amps
readout, unless my multimeter is broken. This is possible as it has
different connections for current and voltage testing.

The laptop battery is fully charged and the laptop doesn't work from that
either, so there is still definitely a problem in the laptop, however, I
rarely use (and could live without) the battery.

To measure current you have to place the ammeter in series with the
load.

 

[kony]

Odd... Plugged in the power adapter and the light comes on (on the adaptor).
Plug that into the laptop and the power light dies on the power adaptor and
the laptop does nothing. There is no power available (instantly) to trace
through the laptop!

Take your meter and measure continuity (and then resistance)
across the PSU input jack contacts. If you can't get the
meter probes into the jack you will have to trace it back on
the PCB. The goal is to determine if the PSU is shot or
just being pulled down to a shorted output.

Another test you could do is (assuming PSU still seems
operational when not plugged into laptop) leave PSU
disconnected from laptop and load it somehow, the load
depending on it's voltage rating. If the PSU light no
longer lights up when disconnected from AC, disconnected
from laptop for a few minutes, then plugged back into AC, it
would seem either the PSU was dying or this new short
condition has done it in, but maybe it's fine so I write the
next paragraph about it...

Supposing it's a 14.4V supply that might allow connecting a
car headlight to it, though much higher voltage and you
wouldn't expect the car headlight to last for long so some
power resistors might be used, the goal being to put at
least a fair load on the PSU, say half of it's rated output
give or take. Something like 4 parallel series of 2, 22
Ohm, 10W power resistors would be in the ballpark as a rough
guess but do the math to be sure I didn't brain fart. Maybe
5 parallel series if the PSU is fairly low voltage relative
to most laptop PSU.

I would wonder if there is still some water or tea in the
laptop somewhere, and with it pulling enough current to shut
off the PSU (if the PSU were still good), I'd be doubly sure
to check the laptop fuses at some point as such a short
condition seems like it ought to burn a fuse else why would
they be there at all... maybe just overrated or the short
was before a fuse in the path.

Sticking the multimeter into the end of the power
adapter wire shows the correct 19.5v, but 0 amps. Seems like the power
adapter is shot!

I'm not sure exactly how you're taking this reading but as
Paul and Andy mentioned the multimeter would have to be in
series with the power, either positive or negative lead is
broken and the meter leads are placed in series so the
current flows through the meter.

At this point, IF I understand what you are describing in
that you had the meter probes in the current measuring
jacks, you had the PSU unplugged from the laptop, you put
one meter probe on the PSU positive contact (probably a DC
barrel connector?) and one meter probe on the negative PSU
contact, then you have probably almost instantly blown a
fuse in the meter (or worse, if it was a really dirt cheap
meter they might have left out the fuse entirely but I
though there was some UL requirement for a fuse(?).

Regardless, if your meter no longer seems able to measure
the current of anything the fuse is probably blown. A
random guess is it has around 500mA rating as when there's
another fuse it is usually closer to 10A or more and I doubt
the laptop PSU can generate over 10A.

We have another inspiron 6400 at work, so I will figure out
if the adapter is shot by using it on the working PC on Monday. What I am
reluctant to do is try the working power adapter in the broken laptop, as it
might blow the working adapter!

That's why I suggest trying questionable adapter by itself,
and measure for continuity/resistance at the laptop power
jack, while the PSU is not connected to it (nor the
battery).

If you plug the PSU in and the light comes on, I would tend
to guess the adapter is ok and the laptop is shorting it out
but this is just a first impression.

What it feels like is that the laptop 'trips' the power adapter when it is
connected to the laptop, but of course this doesn't explain the 0 amps
readout, unless my multimeter is broken. This is possible as it has
different connections for current and voltage testing.

I suspect Andy, Paul and I have covered the current issue.
It's an aggravation to have to replace a fuse but most of
the tests you could do don't necessarily require current
checking so for now it's not a problem per se, you can still
measure whether the incoming voltage remains near the spec'd
level and the continuity of the input + - contacts... which
of course should have a very high resistance reading between
them if any.

The laptop battery is fully charged and the laptop doesn't work from that
either, so there is still definitely a problem in the laptop, however, I
rarely use (and could live without) the battery.

If you're unsure if it's dry then point a fan at it while
open for a couple days, or it may be time to either take it
apart and agitate the board in warm detergent water then
rinse and dry for a few more days, or before that perhaps
unplug all non-essential things in case some integrated
peripheral is shorting out. By nonessential I mean only
goal is to get laptop to turn on and post, nevermind being
able to use it so even the touchpad should be disconnected
until it shows signs of life again.

 

[GT]

You make a current measurement, in series with one rail, like this:

A.C.
Adapter ----------------x <--- multimeter_current_setup --->
x-------> laptop
D.C.
input

Output ------------------------------------------------------------->
connector

To make a current measurement, normally you'd have to hack into the
cable, break one wire, and insert the multimeter on the current
range, to measure the current in the wire. Currents, you measure
in series - voltage you measure in parallel.

Don't even go near the current measurement function, unless you know
how it works. The current measurement terminals on the multimeter, are
a "dead short". If you shove the multimeter, set on current, and wires
plugged to the "current holes" on the meter, into a power adapter,
that shorts out the adapter, and potentially blows the protection
fuse inside the multimeter, or the fuse inside the device being
tortured.

Exactly what I have done! I heard a spark/click and wondered what I had
done, now the multimetre measures no current! Oops - it was only cheap!

Power supply seems fine and strangely, the laptop powers on today, but only
for a second. Will leave it to dry for another day!