Depending on particular model popularity, it might range from easy to extra hard.

I am talking about a universal solution that can be modified per computer.

https://www.ebay.com/sch/i.html?_from=R40&_tr … t+kit&_osacat=0

It seems these can be cut to size, though my biggest worry would be fitting the controller board. I understand it could be very difficult in some / most cases. But that is also why I am seeing if anyone has attempted something like this already?

A lot of fuss and the result is so-so. This is if you change to LEDs.
The KIT they sell has a cheap controller and the LEDs are connected incorrectly.
In the factory version, they are all connected in series, in KIT - in groups of 3 LEDs and are powered by 12V (to put it simply).
As a result of uneven aging, the backlight is spotted.

PS.
Siemens 3816FA, just not so yellow, like my.
And then, I had to redo the native CCFL driver to drive the LEDs. For the one being sold - is a piece of garbage.

shevalier wrote on 2023-05-28, 15:28:

A lot of fuss and the result is so-so. This is if you change to LEDs. The KIT they sell has a cheap controller and the LEDs are […]
Show full quote

A lot of fuss and the result is so-so. This is if you change to LEDs.
The KIT they sell has a cheap controller and the LEDs are connected incorrectly.
In the factory version, they are all connected in series, in KIT - in groups of 3 LEDs and are powered by 12V (to put it simply).
As a result of uneven aging, the backlight is spotted.

Ok I think I understand. Are you saying that to trim it down, you have to cut in groups of three? I was also reading something about this as well, and that you have to change the resistor to compensate the power per every 3 leds removed. Definitely seems like a a good amount of work to get it right.

Nope, It`s a cut 2 times and it once touched with a soldering iron.
"it's a good amount of work"
- completely disassemble the monitor
- completely disassemble the matrix
- glued the LEDs string to the reflector
- assemble the matrix
- detect dust between the layers of the assembled matrix
- repeat disassembly/assembly
- disable CCFL driver
- find the connection points for control signals - enable and brightness
- screw the LED driver somewhere
- assemble the monitor
- detect LED driver flickering
- detect that the gamut has left (completely different colors)
- detect uneven glow of the screen surface
- detect that the brightness adjustment limits are very strange
-
-
- (non)profit
CCFl is better to change to CCFl, from my experience.

shevalier wrote on 2023-05-28, 16:12:

Nope, It`s a cut 2 times and it once touched with a soldering iron. "it's a good amount of work" - completely disassemble the mo […]
Show full quote

Nope, It`s a cut 2 times and it once touched with a soldering iron.
"it's a good amount of work"
- completely disassemble the monitor
- completely disassemble the matrix
- glued the LEDs string to the reflector
- assemble the matrix
- detect dust between the layers of the assembled matrix
- repeat disassembly/assembly
- disable CCFL driver
- find the connection points for control signals - enable and brightness
- screw the LED driver somewhere
- assemble the monitor
- detect LED driver flickering
- detect that the gamut has left (completely different colors)
- detect uneven glow of the screen surface
- detect that the brightness adjustment limits are very strange
-
-
- (non)profit
CCFl is better to change to CCFl, from my experience.

Ok that makes a lot of sense.

Changing the CCFL was also something I was curious about. I wasn't sure about matching sizes and such, but maybe it is not too difficult? It seems that would have a more even light balance and better compatibility?

Yes, you don't need to do anything with the driver.

But in my experience the lamps don't go out overnight. They lose their brightness for a long time and depressingly and shine with an increasingly pink light.
It looks more like the lamp driver died.

shevalier wrote on 2023-05-28, 16:51:

Yes, you don't need to do anything with the driver.

But in my experience the lamps don't go out overnight. They lose their brightness for a long time and depressingly and shine with an increasingly pink light.
It looks more like the lamp driver died.

Yes I was just thinking this same thing actually, or at least I thought it would be worth checking other parts first. I have seen something similar on a different laptop I had where I thought it could be backlights but changing the inverter board fixed the problem. It was a while ago though so I am having a hard time which laptop that was, or if it was even this same one?

Another factor is that I recently switched its OEM 1066Mhz CPU with a 1200Mhz I recently acquired. I had intended to monitor the heat to make sure it wouldn't cause any issues so it may be another factor in my mistake. However, if it is just a matter of replacing some caps or resistors then I don't mind taking the time.

I have some experience with upgrading a few of my 1995 to 2001-ish computers to LED backlighting. It's worth doing on some older ones but getting the right voltages and determining the signals that run the backlight can be tough - my older Toshibas run the backlight circuit at 5 volts and the generic LED backlight drivers run at 12 to 19 volts I believe. Then you have to find the Enable signal if it has one, and the adjust signal.
The generic driver wants a 0 to 5v voltage to determine brightness (0v brightest) and that's much more standardised on later 14"+ laptops but on my Toshiba Portege 3010CT it used 3 digital signals to count 1-8 for brightness and I had to implement an attiny to read that and convert it to a voltage via PWM.
A lot of this can be determined while the laptop is running by adjusting the backlight and measuring voltage on each backlight pin where it's done digitally, but one wrong move while it's running and the circuitry can be damaged so beware.
The generic backlight strips can usually be cut down in blocks of 3, but it should say in the listing. The driver board I have experience with is a green PCB of the unboosty blue which is a generic LED driver board that has the backlight adjust signal support. There are even more cut down versions out there that don't even support brightness adjustment with just a 3-pin header instead of the 4-pin header. The brightness can flicker a bit at lower brightness settings but I've found that can be mitigated a bit with some extra capacitance added in.

Shevalier has a point though, on the 2000s-era 14"+ laptops where the bezels were suddenly far smaller, switching to LED backlighting has a lot less room and the CCFLs are much thinner. I had to add some extra diffuser sheets into the 10.4" LCD of my Thinkpad 240 to get the LED lights to diffuse properly as they'd otherwise show up as a bunch of little spotlights.
There are quite a lot of parts still available for that era of laptops though, your Gateway 9550 looks like it's a close relative of the Dell C600 series and the 14" screens for those should still be available for cheap. That can be somewhat easier than doing an LED retrofit in a laptop with limited working space.

Also I recently thought that the backlight was bad on my Compaq N600C since it was so dim, but that turned out to be the drivers werent installed and once the correct drivers were all installed, I could put the brightness up properly and it's not super-bright but at least usable now. Looks like your one doesn't need drivers to set the brightness though.

Thermalwrong wrote on 2023-05-28, 18:27:

I have some experience with upgrading a few of my 1995 to 2001-ish computers to LED backlighting. It's worth doing on some older […]
Show full quote

I have some experience with upgrading a few of my 1995 to 2001-ish computers to LED backlighting. It's worth doing on some older ones but getting the right voltages and determining the signals that run the backlight can be tough - my older Toshibas run the backlight circuit at 5 volts and the generic LED backlight drivers run at 12 to 19 volts I believe. Then you have to find the Enable signal if it has one, and the adjust signal.
The generic driver wants a 0 to 5v voltage to determine brightness (0v brightest) and that's much more standardised on later 14"+ laptops but on my Toshiba Portege 3010CT it used 3 digital signals to count 1-8 for brightness and I had to implement an attiny to read that and convert it to a voltage via PWM.
A lot of this can be determined while the laptop is running by adjusting the backlight and measuring voltage on each backlight pin where it's done digitally, but one wrong move while it's running and the circuitry can be damaged so beware.
The generic backlight strips can usually be cut down in blocks of 3, but it should say in the listing. The driver board I have experience with is a green PCB of the unboosty blue which is a generic LED driver board that has the backlight adjust signal support. There are even more cut down versions out there that don't even support brightness adjustment with just a 3-pin header instead of the 4-pin header. The brightness can flicker a bit at lower brightness settings but I've found that can be mitigated a bit with some extra capacitance added in.

Shevalier has a point though, on the 2000s-era 14"+ laptops where the bezels were suddenly far smaller, switching to LED backlighting has a lot less room and the CCFLs are much thinner. I had to add some extra diffuser sheets into the 10.4" LCD of my Thinkpad 240 to get the LED lights to diffuse properly as they'd otherwise show up as a bunch of little spotlights.
There are quite a lot of parts still available for that era of laptops though, your Gateway 9550 looks like it's a close relative of the Dell C600 series and the 14" screens for those should still be available for cheap. That can be somewhat easier than doing an LED retrofit in a laptop with limited working space.

Also I recently thought that the backlight was bad on my Compaq N600C since it was so dim, but that turned out to be the drivers werent installed and once the correct drivers were all installed, I could put the brightness up properly and it's not super-bright but at least usable now. Looks like your one doesn't need drivers to set the brightness though.

This is great information, and funnily enough that you mention the Dell C600 as it is another favorite PIII laptop that I own and I just had it out to play around with as well. This one has a very bright screen and I think I will have better match for some DOS / Win98 gaming once I get proper storage put in it.

Back to the Gateway 9550 though, I am going to get it in the bench pile so I can fully disassemble it soon so I can check all the parts. I think if I do a CCFL replacement I might try to replace with CCFL bulbs first before attempting the LED replacement. It is good to know that there is some experience with the LED replacement because I couldn't find much about it elsewhere.

I also had wondered if it was partly software related, or part of the connections that trigger the dimming on the driver. Mostly because I was noticing inconsistencies with it dimming for a while as sometimes it would start up so dim I would have to squint, then later switch on to more brightness. There are auto dimming functions in the bios as well. When I closed the lid last night, I actually made sure that the screen was latching the button to turn off. So my first impressions is it was not coming out of it dim mode. But restarting / pulling the cmos battery doesn't do anything at all. Shining a flashlight on it is the only thing that will display its image and it is non responsive to any of the brightness controls.

If it starts up really dim and isn't looking especially pink or red then the CCFL might be okay and it could be like shevalier says and just be the inverter or its power supply perhaps.

Replacing the CCFL itself on a 14" LCD with thin bezels is tough and delicate work, the CCFL itself is quite thin and you have to separate that glass tube from the backlight fresnel sheets and things. Sometimes replacing the whole LCD is cheaper since there's little demand for them but lots of laptops from that era were stripped for parts.

What I Can recommend is bypass the laptop's backlight power circuitry entirely. I have a couple of generic backlight CCFL testers (the blue box one is good to start with) which runs from 12v and powers the CCFL - with that you can see how well the CCFL itself is working and determine whether it's the LCD panel's CCFL or another problem with the inverter.

Thermalwrong wrote on 2023-05-28, 21:47:

If it starts up really dim and isn't looking especially pink or red then the CCFL might be okay and it could be like shevalier says and just be the inverter or its power supply perhaps.

Replacing the CCFL itself on a 14" LCD with thin bezels is tough and delicate work, the CCFL itself is quite thin and you have to separate that glass tube from the backlight fresnel sheets and things. Sometimes replacing the whole LCD is cheaper since there's little demand for them but lots of laptops from that era were stripped for parts.

What I Can recommend is bypass the laptop's backlight power circuitry entirely. I have a couple of generic backlight CCFL testers (the blue box one is good to start with) which runs from 12v and powers the CCFL - with that you can see how well the CCFL itself is working and determine whether it's the LCD panel's CCFL or another problem with the inverter.

The more I look into this the more I have realized how difficult this process will be. Hoping to get the Solo 9550 on the bench soon to do some more diagnostics. Testing the backlight independently sounds like a good idea.

Yep, it's a tight space in the LCD area and it's part of an embedded system so a few parts to consider 😀

Since the backlighting is a full system on its own there's the CCFL, its inverter power supply, the controller for that. Sometimes the problems are not what you'd think, I just did a panel swap on my Sony Z600TEK and thought the CCFL was bad because it would turn on, flicker for a couple of seconds and then turn off. Nope, looks like the cable was pinched or the CCFL's connector was dirty, since re-seating it and clearing space for its cables the backlight is working properly after all.

I'm actually interested in this myself as I have a few neat old laptops with very dim backlights - but I suppose swapping in LEDs would completely remove brightness adjustment... wouldn't it?

Most laptop LCDs are not that hard to take apart and can be put back together well enough with some aluminum tape and capstan tape.

It depends when the laptop was made and what kind of system it already uses to control brightness. 90s Toshibas don't really have much to control backlight brightness, just one kind of high/low setting. When I upgraded a laptop from DSTN to TFT, I also upgraded it to an LED backlight. One neat thing is that it uses the contrast adjust wheel to adjust the brightness now instead. That one had to be upgraded to LED to even fit since the LCD is out of a TV and just barely fits in the screen housing after dremeling 😀
The LED backlighting is far brighter than the CCFL so it's kind of like you can adjust it once while building it using an adjustable resistor to 5v. On laptops that have it though, you could probably re-use the brightness slider.
Something to be aware of is that even though the LEDs are usually a warm-ish white, they're not as 'warm' as CCFLs so the screen can sometimes be more 'blue' tone than the original backlight.

The older Toshibas you will need to add in a step-up voltage converter since they run the backlight from 5v. I'm not sure how it is on other brands like IBM in the 90s era though.

Upgrading my Thinkpad 240 to an LED backlight was mostly a drop-in replacement once I worked out what the Enable and Adjust signals were - that's from ~1999 and is kind of an Acer / IBM hybrid thinkpad. The enable & adjust signals match up with the LED backlight driver board I used and the inverter power supply was the right voltage, so the LED driver drops in where the inverter once was and the brightness adjustment works properly.
Something to consider with current cheapy LED retrofit kits is that they use a row of individual LEDs rather than many smaller lights like you can get with CoB rope lights now. On the 240 it's a quite slim LCD panel that uses a thin CCFL, when I put the LED backlight strip in it had lots of points of light which just seems to happen with some LCD panels. Fixed that by putting in some extra fresnel sheets from a broken LCD panel.

It's random chance though, I upgraded my Portege 3010CT to LED backlight and that's maybe thinner than the Thinkpad 240's LCD but it doesn't have the bright spots problem at all.

Enable signal - allows the inverter to be powered but disables the output. Used to avoid displaying a blank white screen if the backlight powers up before the LCD panel begins displaying. Off when at 0v.
Adjust signal - an analogue voltage signal that ranges between ~2 to 5v with 5v being dimmest and 0v being brightest. The LED drivers I use are pretty dumb and will happily run the LEDs beyond a safe current if the adjust signal is wrong. This seems to be fairly standardised after a certain point, kind of. later Thinkpads use PWM instead apparently.

I think that the LEDs showing up as points can be a fairly common complaint with these retrofits. Mostly with the older laptops like 10.4" to 12.1" from 1995 - 1999 the screens seem to work quite well with the individual LEDs instead of the CCFL without that spotlight effect. In the older laptops it should be easier overall, the CCFLs are often bigger and designed for replacement. More room to work with as well.

If anyone wants to try out an LED retrofit then I could give some pointers, I've upgraded all the ones I intend to for now.