Sony XR-C4120, Service Manual

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6-7. IC PIN FUNCTION DESCRIPTION
•
MAIN BOARD IC501 MN101C12GTC1 (SYSTEM CONTROLLER)
Pin No. Pin Name I/O Function
1 AVREF–
I
Reference voltage (0V) input terminal (for A/D converter)
2 VSM I
FM and AM signal meter voltage detection input from the FM/AM tuner unit (TU1)
(A/D input)
3 KEYIN1 I
Key input terminal (A/D input) (LSW921 to LSW923, LSW927 to LSW933)
6
, PRESET DISC –/+, DSPL, 6, 5, 4
n
, 3 PLAY MODE, 2 SET UP, 1
N
keys input
4 KEYIN0
I
Key input terminal (A/D input) (LSW901 to LSW903, S901, LSW905, LSW906)
OFF, SOURCE, MODE
*
, SEEK/AMS
= 0
–
+ )
+, SOUND, SHIFT keys
input
5 D-BASS IN I D-BASS switch (S981) input terminal (A/D input)
6 DSTSEL I Destination setting terminal (fixed at “L” in this set)
7 FUNC-SEL I Setting terminal for the function select (fixed at center voltage in this set)
8 NCO O Not used (open)
9 RC-IN0 I Rotary remote commander key input terminal (A/D input)
10 AVREF+ I Reference voltage (+5V) input terminal (for A/D converter)
11 VDD — Power supply terminal (+5V)
12 OSC OUT O Main system clock output terminal (18.432 MHz)
13 OSC IN I Main system clock input terminal (18.432 MHz)
14 GND — Ground terminal
15 XT IN I Sub system clock input terminal (32.768 kHz)
16 XT OUT O Sub system clock output terminal (32.768 kHz)
17 GND — Ground terminal
18 RC-IN1 I Rotary remote commander shift key input terminal “L”: shift
19 SYSRST O Reset signal output to the SONY bus interface (IC581) “L”: reset
20 BUS-ON O Bus on/off control signal output to the SONY bus interface (IC581) “L”: bus on
21 UNISO O Serial data output to the SONY bus interface (IC581)
22 UNISI I Serial data input from the SONY bus interface (IC581)
23 UNICKO O Serial data transfer clock signal output to the SONY bus interface (IC581)
24 UNICKI I Serial data reading clock signal input for the SONY bus interface Not used (open)
25 NCO O Not used (open)
26 KEYACK
I
Input of acknowledge signal for the key entry Acknowledge signal is input to accept function
and eject keys in the power off status On at input of “H”
27 NOSESW I
Front panel block remove/attach detection signal input terminal
“L”: front panel is attached
28 BU-IN
I
Battery detect signal input from the SONY bus interface (IC581) and battery detect circuit
“L” is input at low voltage
29
SIRCS
I
Sircs remote control signal input terminal Not used (fixed at “L”)
30
TEL-ATT I Telephone muting signal input terminal At input of “H”, the signal is attenuated by –20 dB
31 TEST-IN
I Setting terminal for the test mode “L”: test mode, Normally: fixed at “H”
32 RAMBU I
Internal RAM reset detection signal input terminal
Input terminal to check that RAM data are not destroyed due to low voltage
This checking is made within 100 msec after reset Fixed at “L” in this set
33 RESET I
System reset signal input from the reset signal generator (IC551) and reset switch (S551)
“L”: reset “L” is input for several 100 msec after power on, then it changes to “H”
34 VOL-MUT O
Muting control signal output to the electrical volume (IC331)
Volume minimum: “
∞
” output (“H” active)
35
BEEP O Beep sound drive signal output terminal
36 AMP-MUT
O Muting on/off control signal output to the power amplifier (IC751) “L”: muting on