CYRUS DVD6 THE MC-BUS SYSTEM
© Cyrus Electronics Ltd Dec 2003
Cyrus DVD6 Service Manual Issue 1
16
The MC-Bus system
MC-Bus is a system which provides communication between the control systems of a number of
Cyrus products. The communication takes the form of a serial data stream which is sent from a
'master' product and received and repeated by 'slave' products. The data is thus passed from one
product to another around a loop. The master product should then receive the message back which
confirms that loop connections have been correctly made. The DVD6 is a 'slave' product and listens
for 'DVD' commands from the master product in the loop (usually an amplifier or surround
decoder).
MC-Bus internal signal routing
MC-Bus control is provided by the system microcontroller IC403. The signals are buffered into and
out of this IC as shown in the diagram, The resistor bias at the MC-Bus input ensures that the line
idles high (+5V) if no MC-Bus connection is made to another product.
MC-Bus system tests
The MC-Bus system can be tested by connecting the DVD6 into a known working Cyrus system.
Note that MC-Bus must be connected as a closed loop as shown in the diagram below. It is also
important to connect the audio signal cables between components to provide an adequate ground
return path for the MC-Bus signals. Switch on the power to the system and set all components to
Standby. Selecting the AV input on the amplifier or switching on a surround decoder will now
activate the DVD6. When the amplifier is set to Standby, all other components connected to the
MC-Bus loop will also set to Standby.
IC402-E
+5V
IC402-F
IC402-C
IC402-A
IC403
MC-Bus out
MC-Bus in
48
49
DVD7
Surround Decoder
or Amplifier
MC-Bus output
MC-Bus output
MC-Bus input
MC-Bus input
