diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 482a74db..b381411a 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -2742,6 +2742,7 @@ Milan Cvijanovic <elcom_cvijo@hotmail.com>
 
 Frank Neumann <frank.neumann@hp.com>
  for suggesting to reduce the thread and I/O priority cCuttingThread::Action()
+ for reporting a problem with tuning timeouts when using SCR with multiple tuners
 
 Gerald Dachs <vdr@dachsweb.de>
  for reporting a problem with checking for minimum line length of 21 characters in
diff --git a/HISTORY b/HISTORY
index 70e14e00..2108f02d 100644
--- a/HISTORY
+++ b/HISTORY
@@ -6801,3 +6801,5 @@ Video Disk Recorder Revision History
   DTV_ENUM_DELSYS call. With older drivers it will fall back to one delivery
   system per frontend.
 - Updated the Hungarian language texts (thanks to István Füley).
+- cDvbTuner::ExecuteDiseqc() now makes sure only one tuner sends SCR commands
+  at any given time (reported by Frank Neumann).
diff --git a/dvbdevice.c b/dvbdevice.c
index c93328f5..acd71264 100644
--- a/dvbdevice.c
+++ b/dvbdevice.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: dvbdevice.c 2.51 2012/01/07 10:42:47 kls Exp $
+ * $Id: dvbdevice.c 2.52 2012/01/08 14:30:04 kls Exp $
  */
 
 #include "dvbdevice.h"
@@ -642,6 +642,9 @@ void cDvbTuner::ExecuteDiseqc(const cDiseqc *Diseqc, unsigned int *Frequency)
      CHECK(ioctl(fd_frontend, FE_SET_VOLTAGE, SEC_VOLTAGE_13)); // must explicitly turn on LNB power
      lnbPowerTurnedOn = true;
      }
+  static cMutex Mutex;
+  if (Diseqc->IsScr())
+     Mutex.Lock(); 
   struct dvb_diseqc_master_cmd cmd;
   const char *CurrentAction = NULL;
   for (;;) {
@@ -662,6 +665,8 @@ void cDvbTuner::ExecuteDiseqc(const cDiseqc *Diseqc, unsigned int *Frequency)
       }
   if (scr)
      ResetToneAndVoltage(); // makes sure we don't block the bus!
+  if (Diseqc->IsScr())
+     Mutex.Unlock(); 
 }
 
 void cDvbTuner::ResetToneAndVoltage(void)