I have got no idea then. Maybe try the non-interlaced modes.
I'm using GSM 0.38 stand-alone. This version only have PAL, NTSC, PS1 480p/576p and VGA modes.
That said I know the non-interlaced modes from OPL-GSM, I think they aren't made for CRT (or maybe are just for some precise games).
I don't know how it actually work. For example NTSC not interlaced, it seems like the TV get it as 240p but since it's 480 lines it doubles the image size (both horizontal and vertical size, so the picture overflows from the screen being about 3/4x bigger than normal).
Maybe on older versions it worked differently, like older Ulaunchelf.
Ulaunchelf 4.42 for example, in NTSC mode, interlaced on is 480i. Interlaced off, 240p. But on newer versions it introduced that behavior of 4x bigger picture. That option have been completely removed since some revisions.
Anyway, I checked a game ISO after renaming the EXE with disc patcher. It renames the ID and edits the SYSTEM.CNF accordingly.
Thus I done this way. Silent Hill PAL:
- renamed the EXE with Disc Patcher 3.0 (original is SLES_015.14, I named it SLUS_015.14)
- patched with Zapper 2000 setting the Vertical Position (Y-fix) to 0 - 0
This way, when booting the game from Ps2Browser/OSDSYS it boots in native PAL format.
If booting through PS1VModeNeg it boots in NTSC (240p).
As we said, conventional PAL/NTSC (like PAL4U and Z2K) don't work for setting the desired format. However the Z2K function for patching the vertical position do work. Without patching the Y-FIX the game is positioned so low that the CRT geometry settings range is not enough for center the picture.
This isn't a problem on digital TVs, but it seems also part of the picture's bottom is cutted (it'd be so in any type of monitor).
Patching Y position to 0 - 0 fixes it perfectly.