XR-C6120 - Sony Car Audio Service Manual (repair manual). Page 25

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Pin No.

Pin Name

I/O

Function

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

37

AMP ON

O

Standby on/off control signal output to the power amplifier (IC751)
“L”: standby mode, “H”: amp on

38

PLL-CKO

O

PLL serial data transfer clock signal output to the FM/AM PLL (IC21)

39

PLL-CE

O

PLL chip enable signal output to the FM/AM PLL (IC21)    “H” active

40

PLL-SO

O

PLL serial data output to the FM/AM PLL (IC21)

41

PLL-SI

I

PLL serial data input from the FM/AM PLL (IC21)

42

LCD-SO

O

Serial data output to the liquid crystal display driver (IC901)

43

LCD-CE

O

Chip enable signal output to the liquid crystal display driver (IC901)    “H” active

44

LCD-CKO

O

Serial data transfer clock signal output to the liquid crystal display driver (IC901)

45

VOL-SIO

I/O

Two-way data bus with the electrical volume (IC331)

46

NCO

O

Not used (open)

47

VOL-CKO

O

Bus clock signal output to the electrical volume (IC331)

48

ACC-IN

I

Accessory detect signal input terminal    “L”: accessory on

49

MUT

O

Audio line muting on/off control signal output terminal    “H”: muting on

50

NCO

O

Not used (open)

51

AMSON

O

Tape auto music sensor control signal output to the CXA2510AQ (IC301)
“L” is output to lower the gain for audio level at FF/REW mode

52

N/R-OUT

O

Forward/reverse direction control signal output to the CXA2509AQ (IC301)
“L”: forward direction, “H”: reverse direction

53

MTLON

I/O

METAL control in/out terminal
At initial mode: valid/invalid selection input of METAL function (valid at “L” input)
At normal mode: METAL on/off control signal output to the CXA2510AQ (IC301) 
(METAL on at “H” output)

54

TAPE-MUT

O

Tape muting on/off control signal output to the CXA2510AQ (IC301)    “H”: muting on
Active at ATA, FF/REW mode

55

DOLON

I/O

Dolby control in/out terminal
At initial mode: valid/invalid selection input of dolby function (valid at “L” input)
At normal mode: dolby on/off control signal output to the CXA2510AQ (IC301) 
(dolby on at “H” output)

56

AMSIN

I

Whether a music is present or not from CXA2510AQ (IC301) is detected at auto music sensor
“L”: music is present, “H”: music is not present

57 to 75

NCO

O

Not used (open)

76

ST-MONO

I/O

FM stereo broadcasting detection signal input from the FM/AM tuner unit (TU1), or forced 
monaural control signal output to the FM/AM tuner unit (TU1)
“L” is input in the FM stereo mode, or “L” is output in the forced monaural mode

77

SD-IN

I

Station detector detect input from the FM/AM tuner unit (TU1)
Stop level for SEEK, BTM, etc. is determined    SD is present at input of “H”

78

RE-IN0

I

79

RE-IN1

I

80

AD-ON

O

A/D converter power control signal output terminal
When the KEYACK (pin @§) that controls reference voltage power for key A/D conversion input 
is active, “L” is output from this terminal to enable the input

81

POWSEL

I

Power select switch (S501) input terminal    “L”: off (halt mode), “H”: on (operation mode)

82

ILL-ON

O

83

REEL

I

Rotation detect signal input from supply reel sensor and take-up reel sensor on the deck 
mechanism

Power on/off control signal output of the illumination LED and liquid crystal display driver 
(IC901)    “H”: power on    Depends on initial setting of power select switch (S501)
Power select switch (S501) on: “H” output at the accessory on
Power select switch (S501) off: “H” output at the power on

Dial pulse input of the rotary encoder (RE900)
 (for VOLUME/BASS/TREBLE/BALANCE/FADER control)