Marantz SC7S1/F1N, Руководство по обслуживанию

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Circuit Description
The P271 board is the bus connection interface board. The 8-pin Mini DIN cable is used for the reomote bus connection between
the units.
IN (J272)
Number Terminal Terminal description
1 IN-H Remote IN Hot
2 IN-C Remote IN Cold
3 Return-H Return Hot from End Slave
4 Return-C Return Cold from End Slave
5 M-G ND Master GND
6 M-G ND Master GND
7 +12V Relay drive +12V supplied from Master
8 -12V Relay drive -12V supplied from Master
OUT (J273)
Signal 3 and 4 are Return signals from the End Slave to the Master, so the remote cable connectiong from the End Slave to the
Master is not necessary.
The +12V (7) and -12V (8) are supplied from the Master, and drive the End relay (L275) when the End Slave is detected. M-GND
is also connected to Master GND as with the 12V power supply.
Relay L275 is switched ON when the unit is the End Slave. As this relay is driven from the Master, it is switched ON even if the
End Slave power is OFF.
Relays L273 and L274 are ON when the unit is set as the Master.
Relays L271 and L272 are ON when power is turned ON. This establishes the communications route even if Slave power is OFF.
The photocoupler Q273 is the interface which sends the signal input to J272 to the microcomputer. It is being floated for sound
quality.
End Slave Detection
The End Slave is detected from the voltage difference between OUT (J273) 5 and 6.
When a further slave is connected, OUT (J273) is connected to the IN (J272) of this unit.
As IN (J272) 5 and 6 are short-circuited, the transistor (Q277) and the End relay (L275) are switched OFF.
When a further slave is not connected, 5 and 6 are not short-circuited so the unit is detected as the End Slave. The transistor
(Q277) and the End relay (L275) are switched ON.
When the End relay (L275) is switched ON the circuit is switched to send Return signal to the Master, so that the bus connection
is established.
Number Terminal Terminal description
1 OUT-H Remote OUT Hot
2 OUT-C Remote OUT Cold
3 Return-H Return Hot from End Slave
4 Return-C Return Cold from End Slave
5 Det ect End Slave detect
6 M-G ND Master GND
7 +12V Relay drive +12V supplied from Master
8 -12V Relay drive -12V supplied from Master
ID
number
Set voltage
1 4.5 to 5.0V
2 3.7 to 4.5V
3 2.9 to 3.7V
4 2.2 to 2.9V
5 1.4 to 2.2V
6 0 to 1.4V