Posted by u/starboyk 9 months ago

Fully backlit Alphasmart Neo 2 mod

After a month of testing, I'm pleased to roll this one out!

Fully backlit Alphasmart Neo2.

I've done a few years of vintage console mods and repairs, nothing too exciting or advanced. My most impressive was isolating an issue on a Sega CD to an obscure little controller chip, procuring a new, 28-year-old chip (from Alibaba of all places), and having that successfully resolve the issue. Most fun mods are the GameBoy DMG backlit mods. One night, had a bit of a shower thought: what if the LCD on the Neo2 is similar to a GameBoy? Bought one off eBay (as I didn't want to potentially ruin my beautifully painted working one), tore it down, removed the reflective polarizer behind the screen, cleaned it up, and slid a translucent polarizer and a spare GameBoy LED backlight in there.

And I'll be dipped: it worked.

Now, the display itself is 157mm x 44mm. The DMG LED panels are 52mmx52mm. Three of these fit in there side-by-side rather well (not perfectly, not poorly). I trimmed the metal screen mount and some of the battery casing supports to allow for the overhang of 8mm vertically, as I was worried that trimming the LED displays themselves might lead to some light bleed along the top. This does not impact performance at all, or even the ease of replacing batteries, as everything trimmed is inside the closed case anyway.

The only major concern is the thickness. The panels are already a tight fit at 1.23mm thick. The screen is rather tightly soldered through a ribbon cable to its controller board, only allowing about 0.8mm of comfortable clearance. It can be gently forced to fold flat with minimal strain on the ribbons with just the LED panels in there, but with the addition of the polarizers (at 0.3mm thickness), and two stacks of lens tape (0.2mm, with one strip to hold the polarizers in place, and another on top of that to hold the panels in place), there isn't a way to comfortably closed the whole thing flush. The solution? - let it flop loosely at a roughly 30 degree angle, line the back of the logic board with kapton tape (to prevent shorts from where the two boards touch), and screw the logic board into place. This eases nicely into an angle behind the screen and its logic board, gently holding everything in place, while applying juuuuuust enough pressure to both hold the LCD panels in place without putting pressure on the soldered LCD ribbons.

The rest was pretty straightforward. The GameBoy DMG LED panels HandHeldLegend sells include the necessary resistors. So, found the 4.5v rail, wired that to an on/off switch, wired that to a 1k dial wheel potentiometer, and ran the output to all three LED panels.

Loosened a bit of metal and flush cut some plastic, and in it all went!

Can be dimmed and brightened, uses an independent power switch, and my first round of testing at medium brightness yielded a hair over 500 hours of battery life. Which is pretty impressive, considering the normal battery life for the Neo2 is 700+.

For reference to how the screen normally looks, including a pic of my unmodified Neo2 (well, apart from the paint job).

Only major drawback is that these are three different panels, after all. I was able to bring the gap between each as tightly as possible. In use, there's a bit of a slightly dim line between each panel (see the angled picture; note: contrast is slightly inverted from that angle, so the brightspots are actually dim to the human eye from a normal viewing angle). Not a completely dark break between panels, just a few nits dimmer - which my brain tunes out after a minute or two. I was worried if I used something like epoxy to join the panels that might result in some hotspots, as there wouldn't be a diffuser over those connected gaps, resulting in bright vertical lines. I'd personally rather have two coldspots than two hotspots, definitely user preference.

The display frame. Ended up cutting the bent tabs out completely and sanding the sharp bits down.

The trimming around the battery compartment.

The screen resting naturally on the LED panels. Note: those tabs were curled up and inside the case on closing it, so they are not visible from the assembled battery compartment.

Angle test to show where the dim spots are. As you can see from the header, they're REALLY not noticeable. Just feel like I'd be doing a disservice but not pointing out that they are present. They're about a third of the darkness as the letters themselves when in use, so it's very easy to tune out.

Now I just need to first cap all of these, then cutout a home for them in the case.

My Double-Y daily runner.

Now to integrate the power and dimmer into the case at some point rather than having them dangle out the rear...

OP·9m

absolutely worth the shot! If you go through Handheld Legends, let them know what you're purchasing for. I briefly spoke to their team about making custom LED panels that matched these dimensions, but they can only sell customs in large enough lots (which is absolutely fair, as manufacturing is a lengthy, pricey process). If they were to start making these, I would absolutely retrofit my daily rider with a pink or aquamarine LED light...

For reference to all: The LED panels can be ordered in an array of colors. I liked the way the green backlight worked for this setup. Most would likely prefer the plain white, which will make it look like a washed out blue-white, after going through the polarizers.

level 2

·9m·edited 9m

Do you know by any chance how many orders would be required to do a large enough lot that fits all the specs of the Neo 2?

level 3

OP·9m

for the dims that match the display, 500 pcs. was the quote the owner provided me, and that's from their supplier's minimum order quantity (MOQ). That doesn't account for thickness, as my original inquiry was an attempt to utilize any existing inventory (at 1.23mm thick). Suppose if start from scratch, something thinner could be on the table, but might make the price pop up.

level 4

·9m

I see. I will have to stick to the USB lamp mod, hah. But as an owner of an IPS v2 GBA backlight, that'd be really awesome to have in the Neo 2.

That being said, your backlight looks really sharp. Great job on that.

level 5

·9m

I dunno if we get enough people , you’d be surprised how many would be interested, however, it may dry up the aplha smarts available in local marketplace, as we are starting to see happen with DMGs. Moders will literally buy the alpha smart just to mod it :D

I’ve done that ips mod, it was a great way to make use of all the dmg motherboards I had left over from the original backlight and front light modes I botched when I was first learning to do mods.