Video summary
The video features a teardown and repair attempt of a cheap, low-quality LCD slate designed for children, which the host describes as broken from the start despite having a functional battery. The device operates on a simple principle where a sharp stylus changes the state of liquid crystal material sandwiched between two plastic layers, allowing light to reflect off an underlying layer or pass through to create black marks. Although the original battery was dead and replaced, the slate failed to reset properly because the internal connections were poorly made with heat-stapled pads that did not make reliable electrical contact. Upon disassembly, the host discovered a tiny circuit board containing a switch and a transistor, but found that the device's performance was severely hampered by air bubbles trapped between the layers and faulty wiring that required external power to function even partially.
To fix the electrical issues, the creator experimented with various methods to secure the loose connections, eventually resorting to bending metal clips from another broken device and applying conductive paint to ensure proper contact between the terminals and the circuit board. After securing these components with hot glue and reassembling the unit, the host addressed the visual defects caused by air bubbles trapped in the LCD layers. He attempted to pop these bubbles using a rubber eraser and later a heat gun, noting that while applying pressure or heat could temporarily improve visibility, it often resulted in discoloration or smeared patterns on the screen. The process highlighted the fragility of the device, as pushing too hard risked squeezing out the liquid crystal material necessary for the display to work correctly.
Despite several attempts to restore functionality, including using a heat gun at increasing temperatures and manually pressing out imperfections, the slate remained largely unusable with persistent visual artifacts and unreliable operation. The host concludes that the device is fundamentally flawed due to its poor manufacturing quality, noting that even when it worked, the experience was subpar compared to drawing on paper. Ultimately, after exhausting repair options and confirming that the internal components were too damaged to be salvaged economically or effectively, he decides to discard the slate as electronic waste. The video serves as a demonstration of how inexpensive consumer electronics often lack durability and proper engineering, leading to the conclusion that such products are better avoided in favor of traditional alternatives like paper and pen.
Read the full video transcript
Quick video time. I have one of these
LCD slates. It's cheap, it's nasty, and
it doesn't work. Let's rip the lid off,
see how it works, and see if I can fix
it.
So, what this is is a drawing tablet for
small children. It's a simple slab of
liquid crystal material. No pixels. It's
just a continuous sandwich of the stuff.
You draw on it with a sharp stylus. This
causes the liquid crystal to change
state, which means that it becomes
transparent to the reflective layer
underneath. When you're done with it,
you're supposed to be able to push this
button
and it resets and all goes blank.
Except, as you can tell, it does not
work.
It resets itself by applying a voltage
across the liquid crystal produced by
this battery here, which I have in fact
replaced. So, I know this works.
See, 3.3 volts. This battery works. The
thing itself is a super cheap slab of
mass-produced plastic. There are no
screws other than the one that holds the
battery compartment in. [snorts] There
is an onoff switch here marked lock and
unlock, which makes me think that
there's a tiny PCB here, which has the
operation button on the other side of
it. And other than that, it is glued
together. Normally, I'd try hitting this
with some hot air to try and soften the
glue, but I think that's not going to do
the LCD material much good. So, let's
just start spudging and see what
happens.
I have seen someone take one of these
apart before,
but it did destroy the liquid crystal.
So,
well, that was straightforward enough.
Oops. That bending the LCD. At least
there's no glass, so there's nothing to
break. It's all just
cheaper plastic.
Well, there is a tiny PCB which I think
is broken now.
That was surprisingly straightforward.
Now
I H
Oh dear.
This is
I believe this is fried. Okay. So,
what's going on here?
Well, I can already see one thing that's
wrong. The battery is upside down. This
is the same way up than it was when I
got it. So, I suspect somebody has just
assembled this incorrectly.
The battery that came with it, by the
way, was completely flat.
So that should be like that. You see
there's one terminal there and one
terminal there.
And then we've got these two pads that
are supposed to make electrical contact
with these terminals.
And I think they've been heat stapled.
So if I do this,
nothing is happening.
Well, that's doing something when I push
the button.
I wonder if there's any electronics on
the other side of this.
And the answer is yes. There is one very
small chip here. Here is the power
switch. And
that looks like a transistor.
And that's got a D next to it. So, it
could be a diode.
Does the chip have a number on it?
I think that's a no. And also I need to
start finding myself a much better
microscope.
So there are two layers of plastic here
and they will have the liquid crystal
material sandwiched between them. So can
actually see this
coming apart.
The liquid crystal twists the
polarization of the light and the top
sheet will be a polarizing filter. The
way liquid crystal works is let's get
rid of that bubble. The light comes
through the top filter, gets polarized
in one direction, reflects off the
bottom layer, and then comes back out
through the polarizing filter. If the
liquid crystal twists the light in such
a way that the light can't make it out
through the top filter again, you get
black. If it doesn't, you get
transparent. And by applying a small
voltage across the liquid crystal, you
can change the state of it. And
presumably
when you squeeze the liquid crystal,
this also somehow changes the state of
the stuff.
So, this is actually still working.
Uh,
no, not very well, actually. I suspect
it's ruined,
but it never worked anyway. So, it
should go from black to transparent when
you press it.
So, this should really be black now.
So, let's give it a bit of power from
the bench power supply.
That one's positive.
That one's negative. Power on.
It is drawing nothing as you might
expect.
Hold this together. Push the button.
Oh, interesting. That worked.
It's even working up here or the very
badly.
So, either the battery terminals aren't
working properly and it wasn't
connecting to the battery or something
is wrong with these connections.
It is interesting that it started
working as soon as I hooked up the bench
power supply. And I was pushing this
down onto the
pad and pressing the button before
and it wasn't working and it now is. The
problem is that while these connections
are obviously completely trash, fixing
them is quite hard because this is
really soft thermoplastic and the
instant I touch a soldering iron to this
piece of metal mesh, this is going to
come loose. It's probably going to come
loose anyway. just from, you know,
looking at it. So, how can I fasten
these down to the pad that's
mechanically solid but also makes
electrical contact?
Trashy DIY mechanical clips.
These are made from one of these that's
been bent by me in my fingers. So, this
may, if I can figure out how to do this
without breaking anything else,
these may push onto the PCB
and
hold the connections together. Is that
actually working?
Maybe. Maybe.
Except I've forgotten there are actually
components on the other side of this.
So,
that's not necessarily going to work.
I suppose one advantage of this thing
being terrible is it doesn't really
matter if I break it. But, I've attached
a crocodile clip that holds this thing
on, and it does make electrical contact.
If I make a mark and push the button,
stuff disappears.
I then have
some of this.
This is conductive paint. It's a copper
or possibly silver particle in solvent
emulsion stuff. So [snorts] if I dab it
on here,
that should make electrical contact.
I'll just make sure this thing still
works.
Yes, it does. The solvent's now all
evaporated, leaving the copper behind.
You can see it's gone all shiny. So,
that should be making an electrical
connection. So, now we need hot glue.
And this should hopefully make a
mechanical connection and prevent
everything from falling apart again.
A lot of hot glue.
And now we kind of want to smear it
down.
And that's probably way too much and
it's not going to work.
And of course, it doesn't work.
One thing I have noticed is that
whatever's happening on the electrical
side keeps going for a little bit after
you press the button. So you can see it
just refuses to write until
until
something's not right there.
Yeah. Until a certain amount of time
passes.
I've reinstalled the board and done the
screws up. So all you need to do now is
put the battery in like so.
Scribble something and push the button.
And nothing happened. If I press here.
Yeah,
that hasn't worked.
Beginning to wonder if hot glue really
is capable of fixing anything or whether
that is in fact not true.
What happens now? No.
Yes. Okay. It doesn't need much pressure
to actually make it work. So, I think
we're good.
So, another dab of hot glue.
Try and hold that into position.
That should all be
That's about it. But actually, [snorts]
I expect that the plastic bezel is going
to hold this down sufficiently. Just
want to make that a little bit
mechanically
robust.
and in fact
does actually appear to work.
Okay, the next step is to add some
double-sided sticky tape underneath this
thing to hold it approximately in place
while I work on it.
Okay. And hopefully this thing still
works and I haven't bent it too much.
Put that about here.
Stick down.
H some rather big bubbles. Push button.
Right,
that brings us to the second thing,
which is to try and get all this stuff
working again.
So, these are bubbles between the two
layers, and I need to push them out. And
I'm going to try using this rubber.
Although, as Americans tend to giggle
when I say that, perhaps I should call
it an eraser. This should hopefully be
soft enough, but firm enough to be able
to push things out.
You see the pressure is causing the LCD
to discolor. So I pushed the button
again.
Well, as you can see by the result, it
looks like trash. I got the bubbles out,
but it's left these circular patterns.
So, I'm going to do something really
stupid. This thing is broken. Anyway,
I'm going to use a heat gun and see
I'm going to use a heat gun just to see
what will happen. So, this is set to
100. So, what's it going to do?
The answer is it's not doing anything.
So, let's crank it up a bit to 120.
No, it's having no effect whatsoever.
140
Oh, I'm seeing the color change.
Push button.
Uh,
nah, it's not doing anything useful at
all. You may even have a few more
bubbles there. I'm not sure I remember
there being that many.
Now, this is interesting. Pushing with a
hard object does actually seem to work
better than using the rubber.
So, let's just try going over this and
see if I can push
all the bubbles out.
Well, that is better, though it's not
good. And I suspect that if I push too
hard, I'll squeeze the liquid crystal
material out and I'll end up with more
smears simply because there isn't enough
material to polarize the light. So, I
think that's about as good as it'll get.
So,
let's stick the really sticky
mask back on, which is already going
hairy.
Ah, it sticks to my fingers everywhere.
And it's perfect.
I was actually planning on using this as
a on camera prop for just drawing stuff,
but even when it worked, it was pretty
trash. And now it is completely broken.
This bubble here is caused by the sticky
bevel
uh going over the hot glue lump, which
is about there, and it's pulling the
screen up. So, that's not brilliant.
And I suppose that is that. Before
anyone asks, yes, this thing is going
straight into the e-waste bin. I don't
think I'll get another one. Honestly, I
think I'm better off just drawing on
paper.
Anyway, be interesting to look through
the inards of this. One thing it would
be interesting to do is actually to peel
the two layers apart and get to the
liquid crystal stuff directly, but I
have a feeling that that's not actually
anything you want to get on your skin.
So, I'm not going to.
Yes, beautiful. And I think perfectly
suited to demonstrate the quality of
this drawing pad.
Anyway, quick video over.