XR-3750, XR-3758, XR-3759, XR-7750, XRS-888 - Sony Car Audio Service Manual (repair manual). Page 18

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Pin No.

Pin Name

I/O

Function

42

BU IN

I

Battery detect signal input terminal    “H”: battery on

43

MTLSEL

I/O

44

DOLON

I/O

45

AMSIN

I

Whether a music is present or not from CXA2509AQ (IC301) is detected at auto music sensor
“L”: music is present, “H”: music is not present

46

ST

I/O

47

AMS ON

O

Tape auto music sensor control signal output to the CXA2509AQ (IC301)
“L” is output to lower the gain for audio level at FF/REW

48

N/R OUT

O

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

49

TAPMUT

O

Tape muting on/off control signal output to the CXA2509AQ (IC301)    “H”: tape muting on

50

ILLON

O

51

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”

52

NOSESW

I

Detects the removal of the attaching and removing type front panel block    “L”: attaching

53

TELMUT

I

Telephone muting signal input terminal    At input of “L”, the signal is attenuated by –20 dB

54

REL T

I

Reel table rotation detect signal input from the take-up and supply reel sensor

55

ACCIN

I

Accessory detect signal input terminal    “L”: accessory on

56

TESTIN

I

Setting terminal for the test mode    “L”: test mode (normally fixed at “H”)

57

RC IN1

I

Rotary remote commander shift key A/D input terminal

58

PW SEL

I

Power select switch (S501) input terminal
“L”: position A (halt mode), “H”: position B (operation mode)

59

MTLIN

I

Input terminal to set whether the auto metal function is present or not
“L”: auto metal function is present (fixed at “H”)

60

ADON

O

Power supply on/off control signal output for the A/D conversion

61

KEYSEL

I

Setting terminal for the key (fixed at “H”)

62

SEKOUTSEL

I

Active selection terminal for the SEKOUT (pin #•) (fixed at “L”)

63

COLORSEL

I

Setting terminal for the illumination color    “L”: amber, “H”: green (fixed at “H”)

64

LCDCE

O

Chip enable output to the liquid crystal display driver (IC901)

65

LCDCKO

O

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

66

LCDSO

O

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

67

LCDINH

O

Blank indicate control signal output to the liquid crystal display driver (IC901)
“L”: no display

68

UNICKI

I

Serial data reading clock signal input terminal    Not used

69

UNISO

O

Serial data output terminal    Not used (open)

70

UNISI

I

Serial data input terminal    Not used (fixed at “L”)

71

UNICKO

O

Serial data transfer clock signal output terminal    Not used (open)

Input of FM stereo detection signal from FM/AM tuner unit (TU1), and output of forced
monaural control signal to FM/AM tuner unit (TU1)  (Commonly used for stereo display input
and forced monaural output)
FM stereo detection at input of “L”, forced monaural at output of “L”

Dolby control in/out terminal
At initial mode: valid/invalid selection input of dolby function (“L” input: valid)
At normal mode: dolby on/off control signal output (“H” output : dolby on)
Not used this function in this set (fixed at “H”)

METAL control in/out terminal
At initial mode: auto/manual mode selection input of METAL function    “L”: manual mode
At manual mode: METAL on/off control signal output terminal (“H” output: METAL on)
At auto mode: input at MTLIN (pin %ª)
Not used this function in this set (fixed at “H”)

Power supply on/off control signal output terminal at the illumination and liquid crystal display
driver (IC901)    “H”: power on
At power select switch (S501) on mode: “H” output at the accessory on
At power select switch (S501) off mode: “H” output at the power on