MaverickUK wrote on 2024-08-12, 07:59:

I have a Toshiba Libretto 100CT that I've enjoyed for many years, but unfortunately the display has finally failed […]
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I have a Toshiba Libretto 100CT that I've enjoyed for many years, but unfortunately the display has finally failed

Although it's possible to find replacement Sharp LQ71Y03 panels still, such as from https://www.elecok.com/sharp-lq71y03-7-1-a-si … -lcd-panel.html I would rather replace it with something newer that will look better and hopefully last longer.

I've been trying to find information about the type of connection used on this laptop, but I couldn't find enough detail in the service manuals for it. The best I found were suggestions it could be Low-Voltage Differential Signaling (LVDS) or Parallel TTL (Transistor-Transistor Logic)

After watching https://www.youtube.com/watch?v=vvn2lBFhioQ I've decided to try a simular approach and tap into the VGA output on the expansion slot bus.

To experiment with I've ordered:

• A modern 7" LCD: https://www.aliexpress.com/item/1005005292813240.html
• A 50 PIN driver board that accepts a VGA signal: https://www.aliexpress.com/item/1005006164948575.html

At the moment my concerns are

• That it won't be possible to get a VGA signal from the expansion slot pins
• That the LCD panel won't fit in the case
• It might be tricky getting a suitable voltage for the controller
• Even if everything else works - that I'll be able to fit a suitable controller inside the laptop

So overall it feels like a bit of a moon shot, but hey... gotta try these things, right?

Very open to suggestions or advice from those with more knowledge in any of these areas

how has it died? im assuming you've got a black scrren, if thats case replacing the screen even for an original or new one wont guarantee to fix the problem, i used to work for a company that repaired electronics for Argos, i've fixed a shit load of lcd tv's, so have some experience with this.

if your getting funny colours or lines across the screen and jiggling the ribbon cable doesn't make a difference its beyond repair, if you've got a black screen, shine a torch or light on the lcd, if you can just make out an image its a backlight problem, sometimes the screen might light up for a second on powering up then go black or sometimes the backlight might flicker or pulse, this is usually caused by a faulty inverter board (board that powers the backlight) rarely is it the actual led strips in the screen, for the tv's we had replacement inverter boards we pulled from other sets with smashed screens, i actually own one of the models i used to repair which developed a backlight problem, but without replacement boards i had to replace capacitors, luckily they were screeching so it was easy to identify the caps at fault, i picked up some caps from rscomponents for about £10 and got it working.

the inverter board on yours is probably small and only has a few caps, replace them all and see if it fixes the problem, you could also hook some power up to the connector on the lcd to check the led strips are still working, tho if you dont know the exact voltage maybe dont do that, after that then look at upgrading the lcd. if you do let us know how it goes i've got a toshiba cdt330 with a watermarked screen that needs replacing.

I think laptops that age have a glass bulb for backlight and not an LED.

DudeFace wrote on 2024-08-13, 06:12:

the inverter board on yours is probably small and only has a few caps, replace them all and see if it fixes the problem, you could also hook some power up to the connector on the lcd to check the led strips are still working, tho if you dont know the exact voltage maybe dont do that, after that then look at upgrading the lcd. if you do let us know how it goes i've got a toshiba cdt330 with a watermarked screen that needs replacing.

I appreciate the benefit of your experience and advise. Unfortunately it seems that I've jumped to a conclusion as the problem may not be the screen.

With the dock attached I've connected the laptop to an external monitor via the VGA output, but when I turn it on nothing happens.

I have a vague memory of this occuring before and was due to the hard drive (replaced with a CF card) being loose which caused this behaviour. However after reseating the hard drive nothing changes, so I'm unsure of what the fault is.

When power it connects the expected LEDs light up at the top right of the screen and when the power button is pressed these change state as you'd expect when it's normally turned on. However nothing else happens beyond this.

Unknown_K wrote on 2024-08-13, 06:48:

I think laptops that age have a glass bulb for backlight and not an LED.

now that you mention it your right even by 2006-2007, lcd tv's were using long glass bulbs that would run either side of the screen, it was unusual for both to fail at once unless the inverter board was toast.

MaverickUK wrote on 2024-08-17, 08:02:

I appreciate the benefit of your experience and advise. Unfortunately it seems that I've jumped to a conclusion as the problem m […]
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DudeFace wrote on 2024-08-13, 06:12:

the inverter board on yours is probably small and only has a few caps, replace them all and see if it fixes the problem, you could also hook some power up to the connector on the lcd to check the led strips are still working, tho if you dont know the exact voltage maybe dont do that, after that then look at upgrading the lcd. if you do let us know how it goes i've got a toshiba cdt330 with a watermarked screen that needs replacing.

I appreciate the benefit of your experience and advise. Unfortunately it seems that I've jumped to a conclusion as the problem may not be the screen.

With the dock attached I've connected the laptop to an external monitor via the VGA output, but when I turn it on nothing happens.

I have a vague memory of this occuring before and was due to the hard drive (replaced with a CF card) being loose which caused this behaviour. However after reseating the hard drive nothing changes, so I'm unsure of what the fault is.

When power it connects the expected LEDs light up at the top right of the screen and when the power button is pressed these change state as you'd expect when it's normally turned on. However nothing else happens beyond this.

usually laptops dont output external vga automatically, you have to press a hotkey, on my toshiba 330cdt i have to hold the "Fn" key and press F5, i looked at a model released after yours and it uses the same combo, so its probably the same for most if not all toshibas of this era, not sure if it works on post it may only work from within windows, try this if it works then your lcd problem is down to your inverter board if it doesn't work check your ram.

MaverickUK wrote on 2024-08-17, 08:02:

I appreciate the benefit of your experience and advise. Unfortunately it seems that I've jumped to a conclusion as the problem m […]
Show full quote

DudeFace wrote on 2024-08-13, 06:12:

the inverter board on yours is probably small and only has a few caps, replace them all and see if it fixes the problem, you could also hook some power up to the connector on the lcd to check the led strips are still working, tho if you dont know the exact voltage maybe dont do that, after that then look at upgrading the lcd. if you do let us know how it goes i've got a toshiba cdt330 with a watermarked screen that needs replacing.

I appreciate the benefit of your experience and advise. Unfortunately it seems that I've jumped to a conclusion as the problem may not be the screen.

With the dock attached I've connected the laptop to an external monitor via the VGA output, but when I turn it on nothing happens.

I have a vague memory of this occuring before and was due to the hard drive (replaced with a CF card) being loose which caused this behaviour. However after reseating the hard drive nothing changes, so I'm unsure of what the fault is.

When power it connects the expected LEDs light up at the top right of the screen and when the power button is pressed these change state as you'd expect when it's normally turned on. However nothing else happens beyond this.

Try with another hard drive to see if that helps but you may have another issue.

I have actually done what you're suggesting but in a far roomier laptop: Re: What retro activity did you get up to today?
It was kinda worth it but you wouldn't be able to do that with a Libretto. Also it's a bit late but the LQ71Y03 screen itself can be had for ~£60 online.

There are other checks you can do first though since there's another possible fault in that perhaps the laptop is unable to fully start and therefore is not driving the screen. Your testing with the VGA output on the dock follows this and it's why I suggest trying another hard drive. Toshiba Librettos for whatever reason won't start the screen if there's no hard drive able to be detected.
But that's not all, sadly - these Toshibas all contain a Nickel Metal Hydride (NiMH) RTC battery which are mostly all leaking after 25 years of service - see the last picture on the following link for an idea of the damage that can do nearby circuits, though ignore the orange stuff, that's flux and I wasn't good about cleaning up flux back then: Re: What retro activity did you get up to today?
Since then I've found that those round test pads in the picture are the weak-spot, I've got two Toshibas back from the dead by repairing traces broken on the test pads. And 2x Libretto 50CT that had test pads for the keyboard connector near to the RTC battery connector.

You can check that without taking the laptop apart though, get yourself a parallel port POST code reader which costs about a fiver and that through the parallel port on the dock / port expander will show you where it's getting to when trying to boot. I used to use a home made reader with LEDs that shows the binary but this cheap little dongle shows the hex codes and it's far more useful. See what I mean here: Re: Toshiba 460CDT - POST/Flash codes?
Compare those codes with those in the "l100mm.pdf" maintenance manual on page 54