A guy on the digitpress forum made me a Euro SCART to VGA cable and while my systems (SNES, Genesis, etc) worked fine with SCART cables connected to a Mitsubishi Megaview 33" monitor I used to have, they don't work with my Mitsubishi XC 3730-C or my NEC XM29 plus. All 3 of these monitor support 15khz and 31khz signals.
Any ideas?
They probably only support 15Khz on the RGB port, the VGA input may only support 31Khz.
The XM29 (can't speak to the plus version) accepts 15kHz RGB on both DB15 and BNC connectors. However, make sure you're feeding the monitors CSYNC and NOT composite video for sync. The XM29 does not strip the sync when composite video (or luma/Y) is fed into the CSYNC/HSYNC pin/connector. So, check your SNES, Genesis, ect to see what kind of sync signal you're feeding your monitor. Otherwise, you'd have to run the composite sync through a sync stripper device, or build a circuit.... if the problem is related to sync (likely from the "don't work" symptom you stated). :-\