I've gotta make a write up on this at some point. I keep getting stuck into one project after another and I'm slowly working through them - the most frustrating lately has been a Toshiba Portege 3010CT laptop that I dropped off a tall shelf. The laptop was fine but the CCFL in the LCD was smashed. CCFLs are expensive so I opted to put an LED backlight in instead but it turned out to be a big can of worms.
To start with, this is a super thin laptop so it barely fit and the LED backlight needs 12v where the laptop gives 5. So I reverse engineered a small 5v > 12v boost converter and put it onto the protoboard I was gonna use for mounting:
This actually lead to KiCAD to figure out how it fit together to re-make it. That mess of wire works.
Then I found that the dimming method Toshiba use for these old laptops uses some pins for a binary counter i.e. 00, 01 etc. The new LED backlight uses an analogue voltage for brightness, so 5v = dimmest and 2v = brightest. Apparently that's the more common / later standard.
This lead me on to using an Arduino / Attiny2313 I had laying around to do the reading and have it make a PWM signal - I haven't done anything with arduino in a few years so there was a lot to pick back up 😀
It's a really cheap backlight board which apparently isn't the best - it flickers at low brightness so when the hard drive was busy, it would flicker. Solved that with an RC filter on the PWM signal so now it doesn't really flicker. The brightness controls actually work, ranging from "this is a bit dim" to "agh my eyes"
There's still a couple of tweaks to make, which will involve pulling it apart again and reflashing the attiny in circuit again, but overall this has been a nice project. It's really rejuvenated the look of this laptop compared to its original CCFL.