You can try this sony trinitron setting inside mame.ini (15 Khz)
monitor custom
crt_range0 "15625-16200, 55.10-65.00, 2.000, 5.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 192, 240, 0, 0"
crt_range1 "15625-16200, 49.50-54.253, 2.000, 5.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 192, 256, 0, 0"
crt_range2 "15625-16200, 49.50-65.00, 2.000, 5.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 0, 0, 448, 576"