Radeon 4350 with UMSA, Windows 7, crt emudriver 2.0, groovymame 0.170.
I read that setting positive sync should solve the problem, but how to set it in VMM Maker?
It's done by editing the polarity fields in monitor.ini/mame.ini:
crt_range0 15625-16200, 49.50-65.00, 2.000, 4.700, 8.000, 0.064, 0.192, 1.024,
0, 0, 192, 288, 448, 576
0 means negative, 1 means positive.