diff --git a/src/mame/drivers/sigmab52.cpp b/src/mame/drivers/sigmab52.cpp
index b301c3328b6..f8589119a54 100644
--- a/src/mame/drivers/sigmab52.cpp
+++ b/src/mame/drivers/sigmab52.cpp
@@ -600,7 +600,7 @@ MACHINE_CONFIG_START(sigmab52_state::jwildb52)
 	MCFG_DEVICE_ADD("audiocpu", MC6809, XTAL(8'000'000))
 	MCFG_DEVICE_PROGRAM_MAP(sound_prog_map)
 
-	MCFG_DEVICE_ADD("6840ptm_1", PTM6840, XTAL(8'000'000)/4) // FIXME
+	MCFG_DEVICE_ADD("6840ptm_1", PTM6840, XTAL(8'000'000)/8) // FIXME
 	MCFG_PTM6840_IRQ_CB(INPUTLINE("maincpu", M6809_IRQ_LINE))
 
 	MCFG_DEVICE_ADD("6840ptm_2", PTM6840, XTAL(8'000'000)/8) // FIXME
@@ -609,7 +609,7 @@ MACHINE_CONFIG_START(sigmab52_state::jwildb52)
 	MCFG_NVRAM_ADD_NO_FILL("nvram")
 
 	MCFG_SCREEN_ADD("screen", RASTER)
-	MCFG_SCREEN_REFRESH_RATE(30)
+	MCFG_SCREEN_REFRESH_RATE(60)
 	MCFG_SCREEN_VBLANK_TIME(ATTOSECONDS_IN_USEC(0))
 	MCFG_SCREEN_SIZE(1024, 1024)
 	MCFG_SCREEN_VISIBLE_AREA(0, 544-1, 0, 436-1)