Service manual
VDM SCHEMATIC (2 OF 2)
FIGURE 7-8
7-12
March 2000
Part No. 001-3139-502
U1A
3447
+5V
7
4
3
5
6
5
6
1
2
3
4
14
15
11
12
13
10
7
9
U25A/B
55121
TX PCM PRIMARY 18
TX PCM PRIMARY 20
TX PCM SECONDARY 5
+5V
U7-48 (1) Tx PSC
U21A
74HC00
U21D
U21C
1
2
3
11
13
12
U7-51 (1)
TxPPC
8
9
10
16
DX
17
TS/D CLK
R31
10k
+5V
5
6
9
-5V
DX
CLK SEL
D CLK
PCM LOOP U7-6 (1)
PCM E-LEAD U7-62 (1)
PCM M-LEAD U7-52 (1)
7
8
18
LOOP
SIG
SIGX/ASEL
U19
29C14
10
DR
14
CLK X
VTM PCM 23
VTM PCM 55
2
13
1
U27C
RX PCM SEC
U59B
3447
+5V
13
15
14
1
2
RX PCM SECONDARY 6
6
8
U27D
RX PCM PRI
9
U59A/B/C
3447
+5V
13
15
14
1
2
RX PCM PRIMARY 19
RX PCM PRIMARY 51
6
8
U27D
RX PCM PRI
9
+5V
7
4
3
5
6
MAS SYNC 16
MAS SYNC 48
+5V
9
11
10
12
MAS CLK 17
MAS CLK 49
R850
620
221
VFXI+PWR0+
11
FSR
U54
74HC574
D0
D1
D2
D3
D4
D5
D6
D7
7
7
16
12
13
14
15
1917
18
2
3
4
5
6
7
8
9
Q3
Q7
Q6
Q5
Q4
Q1
Q2 Q0
CLK
OC
D0
D1
D2
D3
D4
D5
D6
D7
U52B
U52D
U52A
74HC08
U52C
+5V
U3B
74HC04
U3A
RX PCM SLOT
ADDRESSING
U17C
8
9
10
U7-2 (1) MREQ
U12-6 (1) CS5
6
4
511
13
12
3
8
9
10
1
2
34
21
6
5
4
3
RES
EN T
EN P
15
P3
P2
P1
P0
2
9
1
10
7
RC0
EN T
EN P
P0
RES
2
9
1
3
7
10
15
611
CLK
LOAD
RC0
P3
Q3
LOADCLK
+5V
5
P2
13
12
Q1
Q2
P1
4
CLK R
13
GSR
PRO -
4
3
23
22
15
GSX
VFXI -
FSX
TP5
EXT E-LEAD (EA) 29
EXT E-LEAD (EB) 30
C201
.022
R51
2.2k
1
2
5
4
R6
10k
+5V
U7-61 (1) TI
U29
4N35
1
2
3
-48V
-15V
J36
K1
EXT M-LEAD (MB) 62
EXT M-LEAD (MA) 61
CR3
+12V
Q12
3658
R65
4.7k
R53
4.7k
+5V
K2
ALARM 58
ALARM 57
CR4
+12V
Q11
3658
R64
4.7k
R54
4.7k
+5V
P1
Q17
3657
R123
10k
R56
10k
+5V
R124
430
CR402 (RED)
ALRM LED
Q6
3658
R71
1.5k
+12V
R155
10k
CR401 (GRN)
Q7
3658
R70
1.5k
+12V
R66
10k
CR403 (YEL)
U41
74HC574
17
15
14
12
13
2
3
4
5
6
7
8
9
Q4
Q6
Q8
Q7
Q3
D0
D1
D2
D3
D4
D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
Q5
16
18
19
Q2
Q1
5
6
9
10
D
C
B
A
7
LE
U18
14495
7-SEGMENT
DRIVER
DS1
(GREEN)
a
b
c
d
e
f
g
h
7
3
2
4
5
8
9
1012
13
14
15
1
2
3
4
A (DP)
A (g)
A (f)
A (e)
A (d)
A (c)
A (b)
A (a)
C(5)
C(5)
16
OC LE
U49C
8
9
10
U7-2 (1) MREQ
U12-11 (1) CS10
11
1
Q18
3658
R27
10k
U6-15 (1)
FSK LOOP
R167
10k
+9V
1
3
4
5
6
7
8
2
11
9
J32
+5V
+9V
+12V
-12V
-48V
10
S1-8 (1)
PCM FSK
+
C112
2.2
R165
100k
+4.5V
89
6
U57C
R164
100k
+4.5V
+
C113
2.2
+
C102
2.2
R120
100k
+4.5V
U31B
4
5
3
TX PCM
U46-1 (1)
R61
100k
+4.5V
+
C77
2.2
R133
10k
U31C
9
6
8
FSR
U46-3 (1)
R60
100k
+
C75
2.2
7
6
5
+4.5V
R87
1k
R86
100k
+4.5V
+
C66
2.2
U16-8 (1)
TX FSK
TP4
U31A
4066
2
13
1
TX DTMF
U46-13 (1)
R58
100k
+
C73
2.2
+4.5V
S1-7 (1)
U49D
U49A
11
3
13
12
2
1
U12-10 (1) CS9
U7-2 (1) MREQ
U12-4 (1) CS3
+
C111
2.2
R170
1.5k
R163
620
8
14
+5V
7
X EN
D IN
L IN
Y4
3.58 MHz
R162
10M
5
17
18
19
9
10
DE
LATCH
D4
D5
X OUT
X IN
D0
D1
D2
D3
DV
DET
D6
D7
21
20
15
22
1
2
3
4
R168
10k
R159
10k
R160
10k
+5V
11
LE
9
8
7
6
5
4
3
2
D7
D6
D5
D4
D3
D2
D1
D0
Q7
Q6
Q5
Q4
Q3
Q2
Q1
Q0
1
OC
U12-5 (1) CS4
U50
74HC573
+
C65
10
+
R122
10k
U28D
+
R42
10k
J11
R41
100k
+4.5V
R40
10k
C64
.1
13
12
14
U28C
+
R37
100k
R39
220k
8
9
10
R38
220k
PRIMARY AUDIO RX
+4.5V
C63
.1
R36
100k
C62
.1
R135
300
R136
300
R130
100k
1
2
J21
1
3
4
2
2
4
3
5
1
7
8
9
10
6
J1
RX
31
32
P1
U28A
+
R47
10k
R44
100k
+4.5V
2
3
1
J12
C67
.1
R151
10k
U28B
+
+4.5V
6
5
7
R45
10k
+
C69
10
R49
300
R128
100k
R129
100k
R131
0
1
2
J22
5
6
2
4
3
5
1
7
8
9
10
6
J2
63
64
P1
P33
+
C69
10
R49
300
TX
R43
10k
+
C103
2.2
R121
100k
R59
100k
11
10
12
U46-9 (1)
AUDIO
U31D
+
C74
2.2
+
C72
2.2
2
3
1
J27
R63
100k
+4.5V
4
3
5
U46-5 (1)
RCM
R4
10k
U22
74HC163
6
5
4
3
P3
P2
P1
P0
U7-58 (1)
U7-57 (1)
U7-56 (1)
U7-55 (1)
TX PCM
SLOT
ADDRESS
2
9
CLK LOAD
U23
74HC163
9
2
LOAD
CLK
R125
2.2k
+5V
15
7
3
10
1
7
10
1
RES
EN T
P0
EN P
RC0EN P
EN T
RES
RC0
15
U20A
74HC08
3
2
1
U20D
11
13
12
U20B
6
4
5
+5V
+5V
11
Q3
U20C
8
10
9
U36B
43
U36A
74HC04
21
13
12
Q1
Q2
4
5
P1
P3
6
U7-54 (1)
C60
.01
R69
10k
C200
3900pF
U32A
3403
+
R84
10k
R83
100k
+4.5V
2
3
1
TP3
R57
100k
+4.5V
+
C71
2.2
21
13
U46-11 (1)
PCM LOOP
U30A
4066
R14
10k
U32C
+
+4.5V
9
10
8
R8
10k
R96
22k
+
C61
10
TP6
U38C
+
9
10
8
R145
75k
+4.5V
R144
10k
+
C108
10
C107
.0047
C106
.001
R79
1k
+
C105
10
U38C
+
R76
3.3k
7
8
7
2
5
R77
100k
6
+4.5V
+
C109
10
1
R75
1M
+
C104
47
U37
6270
R80
100k
U38A
+
+4.5V
R78
1k
3
2
1
R74
10k
U38D
+
13
12
+4.5V
14
R158
10k
+
C80
10
+
C79
10
4
5
HF
OUT
BS IN
BS IN
ACC PLG
ROLLOFF
AGC
J3
PRIMARY TRANSMIT AUDIO
DTMF RECEIVER
NOTES:
1. ALL RESISTORS ARE IN OHMS AND CAPACITORS IN MICROFARADS
UNLESS OTHERWISE SPECIFIED.
2. IC PINS NOT SHOWN:
U3, U17, U20, U21, U27, U30,
U33, U36, U49, U52, U57
U18, U22, U23, U25, U26
U55, U56, U59
U28, U32, U38
U31
U37
U41, U50, U54
U19
U51
IC
PIN NUMBER
+5V -5V +9V GND
14
16
3
20
24
6
1
14
4
7
11
6
10
12/20
12
8
7