It's retro laptop time - TI TravelMate 4000 WinSX

[rubber_jonnie]

Re: backlight. It's probably the cold cathode florescent tube gone bye-bye rather than anything else.

I did consider that if the machine was running off battery the backlight would be off, but all the info I've found suggests otherwise. The BIOS too suggests this isn't the case either.

I agree, it is likely the CCFT that's gone, it wouldn't be the first one I've had this happen on. Have been wondering if there's a way to replace with LED's.

[rubber_jonnie]

OK, so a little investigation and I can see something. Power is off:

IMG20251016111253.jpg (177.92 KiB) Viewed 107 times

And power is on:

IMG20251016111227.jpg (164.87 KiB) Viewed 107 times

So there is a little bit of light being generated by the tube, but clearly insufficient for the job at hand. Also, if I turn up the brightness that is reflected at the tube, but still not enough.

The inverter has a 10v supply. My assumption is that it's enough, however I'm wary of trying to measure the output of the inverter as we're looking at (As best I can tell) could be up to 600v AC.

My meter does supposedly support up to 600v, but I'm wary nonetheless.

So at present it could be:

1. The inverter can't generate the voltage required to fully illuminate the tube.
2. The tube is tired and won't fully light.
3. A combination of both.

I am leaning towards number 1 at the moment though, but you neve know with the tubes.

[rubber_jonnie]

Looking closer at the tube, I see it's quite dark at the top end:

IMG20251016125434.jpg (170.94 KiB) Viewed 101 times

So thinking it does look like the tube.