I got it. Putting everything else on the Tripp Lite, and connecting the Trinitron directly to the wall removes the lines completely.
Too bad the second Trinitron's tube is completely worn out, it is nice.
The '89 KV-20TS20 Trinitron has an interesting picture. The white sections are very bright, even with picture low, and the picture is very sharp, but it seems like dark details (such as shadows) have very little detail, even with brightness calibrated. The problem is very similar to the one described
here.
I don't know if it is simply the decoder or something with the tube or circuitry. It does make some scenes appear very dim.