X230 Backlight fuse

[Grarea]

Evening all.
I have been suggested to come here with my problem.
I hope that is ok.

Short version:
Like a numpty, I plugged my screen back in without removing the battery.
On the plus side, I think I fixed the issue I was trying to fix.
I just can't really see the screen any more.
I have been trying to find which fuse the backlight fuse is for the X230 and really struggling.
Either I am typing the wrong things in or it is all secret squirrel info.
I have been told it is F7 near the screen connector. The F7 I can find is near the VGA socket.

I would appreciate a hand. Thanks.

Background. (Long version)
I picked up this X230 a few months ago knowing that it had a screen issue.
It was a replacement for an old Dell that would try and set fire to my desk.
It was cheaper and way better.

The X230 gave those odd lines and was intermittent.
Changed the cable. Substantially better.
Still pretty frustrating when it goes off though.
Looked at the board under the screen. Looking made it worse
Decided I had nothing to lose and the 'cold solder joint' theory seemed like a possibility here.
So I heated the board in the hopes of reflowing something.
I actually think it might have worked.

Unfortunately, I completely forgot (in my excitement) to remove the battery when doing the screen.
What a wally.

My 230 will not get massive use currently, but it is great to have a working laptop around.
(They get used a lot more when they work and don't try to self ignite don't they )
I am keen to be playing with some Linux distros on it.

I shall be reading up on the possible upgrades as well.

[RealBlackStuff]

Check fuse F2 (3A/32V, marked P) near the LCD-connector.
Piggyback solder a new one on top of it.

[Grarea]

Ok, nice one, thanks loads.

I have another question.
I seem to have continuity between everything and everything.
Doesn't seem to matter what I touch.
Is that right?

To my little mind, touching f2 for example and anything else shouldn't beep.
It is just a fuse for the backlight circuit, right?
Which is unplugged and therefore not a complete circuit.
Does that mean I have a short somewhere?

[RealBlackStuff]

I suggest you read up on how to test something for continuity!
You only touch both ends of a fuse, nothing else.
If it beeps, it's OK, if not, it's blown.

[Grarea]

Yes, I did that. It beeped.
But then, if I then touch something else while touching that fuse it also beeps.
Makes me wonder if something has shorted somewhere else.

[Grarea]

where I was told it was F7, I had a look for it.
It was near vga.
Out of curiosity, I looked a bit closer.

It doesn't look great to me. What do you reckon?
https://imgur.com/a/QSw33O1

[RealBlackStuff]

F2 supplies power to the backlight.

F7 (5A/6V, very fast) supplies power to the CRT.
It is not known to blow, but check it anyway.

[Grarea]

OK, thanks.
I have tested continuity on both of those, plus every fuse I can find so far. All beep.
Pretty sure I haven't found them all yet though.

[Grarea]

Tested for continuity.
Y = beeps. N= no beep. ? = not found yet.

f1 y
f2 y
f3 y
f4 y
f5 y
f6 y
f7 y
f8 y
f9 ?
f10 ?
f11 y
f12 y
f13 y
f14 y
f15 ?
f16 y
f17 y
f18 y
f19 y
f20 y
f21 y
f22 y
f23 ?

I shall have another hunt when I have uncrossed my eyes a bit.

[RealBlackStuff]

Does an external monitor still work?
If you remove all RAM and then try to boot, does it beep 1-3-3-1?
If not, you'll most likely need a new mobo.

[Grarea]

I shall need to put it all back together to test that.
The mobo is separate currently.

What could it be that makes it need a new mobo?
Last time I switched it on, it was working, you could see it with a torch.

[RealBlackStuff]

No need to assemble first.
Just put in fan, 1 RAM, DC-in, keyboard and external monitor.
Make sure KB does not short the motherboard anywhere.
Then plug in AC and see if it can boot to BIOS.

[Grarea]

Thanks for this.

No need to assemble first.
Just put in fan, 1 RAM, DC-in, keyboard and external monitor.
Make sure KB does not short the motherboard anywhere.
Then plug in AC and see if it can boot to BIOS.

Yup, it boots to bios (need to press F1 as it beeps twice (which i have read up to mean the code error (which is 0271 which is real time clock error (undid cmos battery))))
Boots to Bios with battery and ac (with battery in)

Does an external monitor still work?
If you remove all RAM and then try to boot, does it beep 1-3-3-1?
If not, you'll most likely need a new mobo.

Yes, removed RAM and get 1-3-3-1
and external monitor works via vga.

(phew)

[Grarea]

Does it absolutely have to be a backlight issue?
Could it be down to the screen board at all?

I have kind of assumed not as they are two different circuits (or so it appears).
But it was the board under the screen that I was fiddling about with.

[RealBlackStuff]

Maybe you damaged the LCD-cable?
Everything else seems to work.
Can you try that screen in another X220/X230?

[Grarea]

Unfortunately not, no.

So, what could still be wrong?

The backlight cable.
The backlight itself? (where actually is the backlight? I have searched online and get loads of stuff about backlit keyboards)
Could it be something to do with the board under the screen itself? Would that need to send a signal or something?
LCD cable. Are you thinking that if that is damaged, it won't send the right signal? I recently replaced it, but who knows what I have done now.

[Grarea]

Oh, wait, is the backlight in the actual screen itself or separate?
I was thinking it was a separate thing. But now I don't know.

Is the backlight powered through the same cable as the screen?
Is it then controlled by the board under the screen itself?

[RealBlackStuff]

Backlight-LEDs are inside the LCD along the bottom.
They are controlled by the small PCB along the bottom.
I've never heard of the LEDs or the PCB going wrong on such screens.
My main suspicion still rests with the LCD-cable.

[Grarea]

OK, pretty sure I have found it.
Thank you so much for your help.
It seems to work fine. I shall put it back together and see if it stays working.
Also to se if I have fixed the original problem.

A little bit frustratingly, the ribbon cable on the back of the monitor attached to the screen board wasn't attached properly.
I have reseated it properly I think.
I don't remember undoing it. (Don't take it for gospel whether I did or not though)

Sorry to have used up all of that time of yours.
I have learned loads though, so thank you so much for your patience.

[Grarea]

Oh, gutted.
After all that, I haven't solved my initial issue.

When the backlight wasn't working, the screen seemed to work all day (unless I didn't notice it go off).

Now the backlight is working again, but i lose the screen.
It didn't stay on for long.
Just enough to tease me into thinking all was well.

The cold solder joint theory seems like a good one.
A poor connection somewhere.

It is like when it warms up it goes off.
Whereas before it would come on when it warmed up then go off again.
(Or something)