I bought two of S3 Trio 3D/2Xs recently and they both exhibit the same issue. In text mode only, blacks are washed out and there are vertical bars when viewed on an LCD. The vertical bars do not appear on my CRT but the blacks are still washed out.
I saw a video by Phil where he talked about this issue on the S3 Trop64V+ but I didn't realize that the problem extended to other models as well. I've included a photo of some markings on the back from the manufacturer which suggests that both of these cards were manufactured around the same time or are simply an identical revision.
Here is a link to Phil's video:
I can confirm that the following workaround successfully corrects the issue temporarily until the next reboot:
S3 AGP Cards (and possibly others) Too Bright
If I want this to be a permanent fix then I would need to replace the BIOS chip. What would be the cheapest chip programmer that would be able to do this? I don't have one.
The BIOS chip on these beneath the sticker are a A276308-70 which I think are only one-time programmable (as indicated by OTP on the datasheet). What kind of chip would be a suitable replacement?