diff --git a/src/devices/machine/z80ctc.cpp b/src/devices/machine/z80ctc.cpp
index 7f0049b28e8..b5d87818985 100644
--- a/src/devices/machine/z80ctc.cpp
+++ b/src/devices/machine/z80ctc.cpp
@@ -368,7 +368,11 @@ u8 z80ctc_channel_device::read()
 		if(!m_timer->remaining().is_never())
 			return u8((m_timer->remaining().as_double() / period.as_double()) + 1.0);
 		else
-			return 0;
+        {
+            // value read-back is required by x1turbo for YM internal board detection.
+            // cfr. x1turbo40 argus wpiset 0x704,1,rw
+			return m_down;
+        }
 	}
 }