Read Sony TC-TX77 / TC-TX770 Service Manual online
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1
METER-R
I
Digital peak level meter signal input (R-ch)
2
METER-L
I
Digital peak level meter signal input (L-ch)
3
KEY-Y
I
Key input (A/D convert input) *1
4
KEY-X
I
5
FWD-TAB
I
Record proof detection input from S902 (FWD side)
“H”: Not nail
6
CHROM SW
I
Tape type detection input from S903
“L”: Type I
7
RVS-TAB
I
Record proof detection input from S904 (REV side)
“H”: Not nail
8
METAL SW
I
Metal cassette detection input from S906
9
PLAY SW
I
Playback and stop detection input from S907
“L”: Playback
10
TEST MODE
I
Test mode terminal
Normal: “H”
Test mode: “L”
11
POWER OUT
O
Audio and mechanism power on/off output
“L”: Off
12
POWER DET
I
Primary power on/off input
“H”: On
13
CLOSE
O
Loading motor (M901) drive output *2
14
OPEN
O
15
—
—
16
—
—
17
—
—
Not used (Fixed at “L”)
18
—
—
19
—
—
20
—
—
21
CLOCK
O
Clock signal output to back-up memory (IC803)
22
DATA
I/O
Data signal input/output to back-up memory (IC803)
23
RELAY
O
Relay drive output
“L”: On
24
BIAS
O
Control output to recording bias switch (Q352)
“L”: On
25
AU BUS-OUT
O
Audio bus output
26
AU BUS-IN
I
Audio bus input
27
RESET
I
Reset input
28
X CIN
I
Not used (Fixed at “L”)
29
X COUT
O
Not used (Open)
30
X IN
I
Main system clock input (4 MHz)
31
XOUT
O
Main system clock output (4 MHz)
32
Vss
—
Ground
33
REC MUTE
O
Recording mute on/off control output
“L”: Mute on
34
LINE MUTE
O
Line mute on/off control output
“L”: Mute on
35
—
—
Not used (Fixed at “L”)
36
PB MUTE
O
Playback mute on/off control output
“L”: Mute on
37
REC/PB
O
Mode control output to DOLBY NR amplifier (IC301)
When recording: “L”
38
DOLBY B/C
O
DOLBY B/C select signal output
“L”: DOLBY C, “H”: DOLBY B
39
DOLBY ON/OFF
O
DOLBY on/off select signal output
“L”: DOLBY On, “H”: DOLBY Off
40
—
—
Not used (Open)
41
—
—
Not used (Open)
42
—
—
Not used (Open)
43
CD SYNC
O
Control output to CD SYNC LED (D851)
44
P17
O
45
P16
O
Segment signal output to fluorescent indicator tube (FLT851)
46
P15
O
5-1.
IC PIN FUNCTION DESCRIPTION
SYSTEM CONTROL BOARD IC801 M38172M4-150FP (SYSTEM CONTROL)
Pin No.
Pin Name
I/O
Function
SECTION 5
DIAGRAMS
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