The contrast on the M200 isn't great but if it is actually *unreadable* then I think something else may have gone wrong that might be easier to fix than modding. I use mine often and, while I would prefer better contrast, a bigger problem for me is the glare from point lights. Here are some photos <https://github.com/hackerb9/Tandy-Terminfo/blob/master/README.md.d/td200-charset.gif> I took of my screen. As you can see, the contrast could be better, but the text is legible.
Just to double check some assumptions: You're in a room with adequate ambient light? The contrast knob has a complete range (light text on light background to dark text on dark background)? You're looking at the screen straight on? If using NiCd batteries, do you get a better picture when you plug into a wall wart? If all that checks out and your picture is not as good as my photos, then I suspect something in your M200 — perhaps the contrast knob? — has degraded and needs to be replaced. * * * * * I had never heard of the "bivert mod" for the Gameboy, but it looks like it is simply rotating the polarizing film 90° (which inverts the image) and adding a hex inverter <https://blog.gg8.se/wordpress/2009/11/23/how-to-patch-your-dmg-to-use-a-biverted-palette/> (74HC04) to un-invert it. I don't get why it works, but rotating the film clearly helps with the gameboy contrast <https://www.inspektorgadjet.com/inverted-screen/>: [image: image.png] <https://www.inspektorgadjet.com/inverted-screen/> Does anyone here understand the mechanism and if there is any reason to believe this technique might be applicable to the M200? Surely engineers in the 80s would have known about this, so what are the downsides of rotating the film? Lower battery life? —B9 On Fri, Dec 24, 2021 at 6:45 PM Stephen Adolph <[email protected]> wrote: > Well, > Boy do I wish there was a good fix! I agree..contrast is weak enough to > make it hard to use. > > > > On Friday, December 24, 2021, Scott Lawrence <[email protected]> wrote: > >> The lcd on my 200 has horrible contrast. I’d use the thing more but I >> just can’t read the screen. Have any of you done any mods/repairs for this? >> >> Would the “bivert mod” common for gameboy DMGs work? (Electronically >> invert the screen, and replace the polarizer with a modern one rotated 90) >> >> Are there maybe power supply repairs that would help? >> >> Thoughts? >> >> Sent from your iPhone. > >
