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– 77 –

Pin No.

Pin Name

I/O

Function

74

X0A

I

Sub system clock input terminal (32.768 kHz)

75

NC

O

Not used (open)

76

BU-IN

I

Battery detect signal input from the SONY bus interface (IC600) and battery detect circuit
“L” is input at low voltage

77, 78

NC

O

Not used (open)

79

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”

80

TEL-ATT

I

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

81

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

82

SEEKOUT

O

Seek control signal output to the FM/AM tuner unit (TU1)
AM mode: Used for IF count output/SD output request/AGC cut at SEEK or BTM
FM mode: Used for SD speed up at SEEK, BTM, or AF
“L” is output at tuner off

83

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”

84

MONO

O

Not used (open)

85

PLL CE

O

PLL serial chip enable signal output terminal    Not used (open)

86

HSTX

I

Hardware standby input terminal    “L”: hardware standby mode    Reset signal input in this set

87

MD2

I

Setting terminal for the CPU operational mode (fixed at “L” in this set)

88

MD1

I

Setting terminal for the CPU operational mode (fixed at “H” in this set)

89

MD0

I

Setting terminal for the CPU operational mode (fixed at “H” in this set)

90

RESET

I

System reset signal input from the reset signal generator (IC501) and reset switch (S900)
“L”: reset    “L” is input for several 100 msec after power on, then it changes to “H”

91

VSS

—

Ground terminal

92

X0

I

Main system clock input terminal (3.68 MHz)

93

X1

O

Main system clock output terminal (3.68 MHz)

94

VCC

—

Power supply terminal (+5V)

95

POW-SEL

I

Power select switch input terminal    “L”: off (halt mode), “H”: on (operation mode)
Not used (open)

96

POL MONO

I

Polar monaural detection signal input terminal    Not used (open)

97 to 99

NC

O

Not used (open)

100

BAND         

(9K-10K)

I

Frequency select switch (S701) input terminal
“L”: MW10k step/FM 200k step, “H”: MW 9k step/FM 50k step
Used for the E model only (Except E models: fixed at “H”)

101

NC

O

Not used (open)

102

RAMBU

I

Internal RAM reset detection signal input from the RN5VD23AA (IC802)
Input terminal to check that RAM data are not destroyed due to low voltage
This checking is made within 100 msec after reset

103

NC

O

Not used (open)

104

LCD CE

O

Chip enable signal output to the liquid crystal display driver (IC501)    “H” active

105

FLASH-W

I

Internal flash memory data write mode detection signal input terminal    “L”: data write mode
Not used (fixed at “H” in this set)

106

RE-IN0

I

107

RE-IN1

I

108

LAMP ON

(ILL ON)

O

Power on/off control signal output of the illumination LED and liquid crystal display driver 
(IC501)    “H”: power on

109

PW-ON

O

Main system power supply on/off control signal output to the BA3918 (IC800)    “H”: power on

Dial pulse input of the rotary encoder (RE501)
 (for VOLUME/BASS/TREBLE/BALANCE/FADER control)

– 78 –

Pin No.

Pin Name

I/O

Function

110

FM-ON

O

FM system power supply on/off control signal output to the BA3918 (IC800)
“L”: AM power on, “H”: FM power on

111

TU-ON

O

Tuner system power supply on/off control signal output to the BA3918 (IC800)
“H”: tuner power on

112 to 118

NC

O

Not used (open)

119

VSS

—

Ground terminal

120

NC

O

Not used (open)

– 79 –

Les composants identifiés par une
marque 

! sont critiquens pour la

sécurité.
Ne les remplacer que par une pièce
portant le numéro spécifié.

The components identified by
mark 

! or dotted line with mark

! are critical for safety.

Replace only with part number
specified.

• Items marked “*” are not stocked since they

are seldom required for routine service. Some
delay should be anticipated when ordering
these items.

• The mechanical parts with no reference num-

ber in the exploded views are not supplied.

• Hardware (# mark) list and accessories and

packing materials are given in the last of the
electrical parts list.

NOTE:

• -XX and -X mean standardized parts, so they

may have some difference from the original
one.

• Color Indication of Appearance Parts

Example:
KNOB, BALANCE (WHITE) . . . (RED)

↑

↑

Parts Color Cabinet's Color

Ref. No.

Part No.

Description

Remark

Ref. No.

Part No.

Description

Remark

1

X-3376-960-1 PANEL ASSY, SUB

2

3-025-483-01 DOOR (MD)

3

3-025-484-01 SPRING (DOOR)

4

3-022-338-01 BUTTON (EJECT)

5

X-3376-686-1 GEAR ASSY

* 6

1-672-684-11 SUB BOARD

7

X-3376-687-1 LOCK ASSY

* 8

X-3376-959-1 CHASSIS ASSY

* 9

3-033-748-01 SHEET (INSULATING)

10

3-376-464-11 SCREW (+PTT 2.6X6), GROUND POINT

* 11

A-3294-651-A MAIN BOARD, COMPLETE

(C7970: US, Canadian)

* 11

A-3294-657-A MAIN BOARD, COMPLETE (C7970: E)

* 11

A-3294-669-A MAIN BOARD, COMPLETE (C7970R: AEP, UK)

* 11

A-3294-678-A MAIN BOARD, COMPLETE (C7970R: German)

* 12

3-011-078-01 BRACKET (POWER IC)

* 13

3-022-317-01 BRACKET (AMP)

* 14

3-033-716-01 HEAT SINK

15

3-011-999-01 CUSHION (MD)

* 16

3-033-744-01 COVER

17

3-932-860-01 SCREW (2.6X4) (C TIGHT), +PTT

18

1-776-207-72 CORD (WITH CONNECTOR) (POWER) (C7970)

18

1-776-527-71 CORD (WITH CONNECTOR) (ISO) (POWER)

(C7970R)

19

3-360-123-01 PLATE (C), GROUND

F1

1-532-877-11 FUSE (BLADE TYPE) (AUTO FUSE) (10A)

F1

#3

#3

MG-164N-138

#2

#1

#4

#1

#2

Front panel section

– 80 –

Ref. No.

Part No.

Description

Remark

Ref. No.

Part No.

Description

Remark

51

3-030-949-01 BUTTON (1-10)

(SHIFT. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10)

52

3-030-950-11 BUTTON (OPEN)

53

3-032-321-01 SPRING (OPEN)

54

3-030-966-01 KNOB (D-BASS)

55

3-030-944-01 LEVER (SEEK/AMS) (+. -)

56

X-3377-540-1 PANEL ASSY, FRONT (C7970R)

56

X-3377-541-1 PANEL ASSY, FRONT (C7970)

57

3-030-904-01 BUTTON (MODE) (MODE. SOUND. DSPL. OFF)

(C7970R)

57

3-030-948-01 BUTTON (MODE) (MODE. SOUND. OFF)

(C7970)

58

3-030-898-01 BUTTON (PTY) (PTY. AF/TA) (C7970R)

58

3-030-942-01 BUTTON (DSPL) (LIST. DSPL) (C7970)

* 59

3-030-932-01 PLATE (LCD), GROUND

* 60

3-032-271-01 SHEET (S), LCD

* 61

3-030-933-01 SHEET (DIFFUSION)

* 62

X-3376-697-1 HOLDER ASSY, LCD

63

3-030-947-01 BUTTON (SOURCE)

64

3-030-943-01 KNOB (VOL)

65

3-030-945-01 RING

66

X-3376-696-1 PANEL ASSY, FRONT BACK

LCD501 1-803-444-11 DISPLAY PANEL, LIQUID CRYSTAL

LCD501

#10

not supplied
(DISPLAY board)