diff --git a/src/emu/video/ef9340_1.c b/src/emu/video/ef9340_1.c
index 03a23571940..7365eb38c6a 100644
--- a/src/emu/video/ef9340_1.c
+++ b/src/emu/video/ef9340_1.c
@@ -100,9 +100,13 @@ UINT16 ef9340_1_device::ef9340_get_c_addr(UINT8 x, UINT8 y)
 void ef9340_1_device::ef9340_inc_c()
 {
 	m_ef9340.X++;
-	if ( m_ef9340.X >= 40 )
+	if ( m_ef9340.X == 40 || m_ef9340.X == 48 || m_ef9340.X == 56 || m_ef9340.X == 64 )
 	{
-		m_ef9340.Y = ( m_ef9340.Y + 1 ) % 24;
+		m_ef9340.Y = ( m_ef9340.Y + 1 ) & 0x1f;
+		if ( m_ef9340.Y == 24 )
+		{
+			m_ef9340.Y = 0;
+		}
 		m_ef9340.X = 0;
 	}
 }
diff --git a/src/emu/video/i8244.h b/src/emu/video/i8244.h
index 59c8514b09e..ed73f86e4b7 100644
--- a/src/emu/video/i8244.h
+++ b/src/emu/video/i8244.h
@@ -105,6 +105,7 @@ public:
 
 	// Global constants 
 	static const int START_ACTIVE_SCAN = 42;
+	static const int BORDER_SIZE       = 10;
 	static const int END_ACTIVE_SCAN   = 42 + 10 + 320 + 10;
 	static const int START_Y           = 1;
 	static const int SCREEN_HEIGHT     = 243;
diff --git a/src/mess/drivers/odyssey2.c b/src/mess/drivers/odyssey2.c
index 1782933e054..9db2cf20cfd 100644
--- a/src/mess/drivers/odyssey2.c
+++ b/src/mess/drivers/odyssey2.c
@@ -441,14 +441,16 @@ WRITE16_MEMBER(odyssey2_state::scanline_postprocess_g7400)
 	bitmap_ind16 *ef934x_bitmap = m_ef9340_1->get_bitmap();
 
 	// apply external LUM setting
+	int x_real_start = i8244_device::START_ACTIVE_SCAN + i8244_device::BORDER_SIZE;
+	int x_real_end = i8244_device::END_ACTIVE_SCAN - i8244_device::BORDER_SIZE;
 	for ( int x = i8244_device::START_ACTIVE_SCAN; x < i8244_device::END_ACTIVE_SCAN; x++ )
 	{
 		UINT16 d = bitmap->pix16( vpos, x );
 
-		if ( ! m_g7400_ic678_decode[ d & 0x07 ] )
+		if ( ( ! m_g7400_ic678_decode[ d & 0x07 ] ) && x >= x_real_start && x < x_real_end )
 		{
 			// Use EF934x input
-			d = ef934x_bitmap->pix16( y, x - i8244_device::START_ACTIVE_SCAN ) & 0x07;
+			d = ef934x_bitmap->pix16( y, x - x_real_start ) & 0x07;
 
 			if ( ! m_g7400_ic674_decode[ d & 0x07 ] )
 			{