SNES core doesn't display on old VGA screen
I have a friend who has an old 4:3 LCD TV that only has SCART and VGA inputs, and he wants to use his mister on it. So far all cores work OK both using forced_scandoubler=1 or vga_scaler=1, but the SNES one. He says he gets a black screen and "resets every 2-3 seconds". He has tried it in another, more modern 16:9 TV that also has VGA input, and it works. I can also make the snes core work in an old CRT, VGA-only PC monitor from circa 2000.
Is there any option in the ini we could try, or any possible solution? Thanks!