Icom IC-756PRO III Service Manual - page 84
J2
C3 0.0047
44
45
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
82
81
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
15
13
12
11
10
9
8
7
6
5
4
3
2
1
P81/SEG26
P82/SEG27
P83/SEG28
P84/SEG29
P85/SEG30
P86/SEG31
P87/SEG32
P90/SEG33
P91/SEG34
P92/SEG35
P93/SEG36
P94/SEG37/M
P95/SEG38/D0
P96/SEG39/CL2
P97/SEG40/CL1
P15/IRQ1/TMIB
P14/PWM
P16/TRQ2/TMIC
P17/IRQ3/TMIF
P40/SCK3
P41/RXD
P42/TXD
P43/IRQ0
A
VCC
PB0/AN0
PB1/AN1
PB2/AN2
PB3/AN3
PB4/AN4
PB5/AN5
PB6/AN6
PB7/AN7
PC0/AN8
PC1/AN9
PC2/AN10
P37/CS
PC3/AN11
AVSS
TEST
X2
X1
VSS
OSC1
OSC2
RES
MDO
P20/IRQ4/ADTRG
P21/UD
P22
P23
P24
VSS
V3
V2
V1
VCC
P
A3/COM4
P
A2/COM3
P
A1/COM2
P
A0/COM1
P50/WKP0/SEG1
P51/WKP1/SEG2
P52/WKP2/SEG3
P53/WKP3/SEG4
P54/WKP4/SEG5
P55/WKP5/SEG6
P56/WKP6/SEG7
P57/WKP7/SEG8
P60/SEG9
P61/SEG10
46
80
P13/TMIG
P62/SEG11
P63/SEG12
P12/TMOFH
79
47
48
78
P11/TMOFL
P64/SEG13
P65/SEG14
P10/TMO
W
77
49
60
16
P80/SEG25
P25
P66/SEG15
VCC
76
50
59
17
P77/SEG24
P26
58
18
P76/SEG23
P27
57
19
P75/SEG22
P30/SCK1
56
20
P74/SEG21
P31/SI1
55
21
P73/SEG20
P32/SO1
54
22
P72/SEG19
P33/SCK2
53
23
P71/SEG18
P34/SI2
52
24
P70/SEG17
P35/SO2
51
25
P67/SEG16
P36/STRB
14
IC401
HD6473834H
5VF
C401
12p
C402
12p
R401
1M
X401
CR-567
11
10
9
12
13
14
15
16
7
6
8
5
4
3
2
1
IC411
BU4051BCFV
X4
VDD
X6
X
X7
X5
INH
VEE
VSS
X2
X1
X0
X3
A
B
C
C411
0.1
SPLK
5VF
R404 47k
R405 47k
R406 47k
R407 47k
C711 0.0047
R711 47k
R712
EVU-FLAE02B14
(MIC GAIN)
C712 0.0047
R713 47k
R714
EVU-FLAE02B14
(RF POWER)
C713 0.0047
R715 47k
R716
EVU-FLAE02B14
(COMP)
C714 0.0047
R717 47k
R718
EVU-FLAE02B14
(KEY SPEED)
C715 0.0047
R719 47k
R720
EVU-FLAE02B14
(BK-IN DELAY)
MIGL
PWRL
CMPL
KYSL
DELL
5VF
C2 0.0047
C1
0.0047
R1
330
R2 330
L2
HF50ACC322513-B
L1
HF50ACC322513-B
PHE
PHO
PHE
PHNI
PHONE BOARD
J1
J941
J2
DOT
DASH
J1
J921
C2
0.0047
C1
0.0047
KEY BOARD
NOTL
5VF
J1
J601
PBT BOARD
PITL
PB1A
PB1B
R3 47k
R4 47k
C1
0.0047
C2
0.0047
(PITCH)
(NOTCH)
R1
RV-314
R702
RV-308
(BAL)
(NR)
R701
RV-308
(AF)
(RF/SQL)
R704
47k
R703
47k
C702
0.1
C701
0.1
RFL
AFL
NRL
BALL
R706
47k
R705
47k
C704
0.0047
C703
0.0047
J451
J452
SSPE
SSP
to
MAIN unit
J352
R914
330
DS904
CL-200YG
UP
E
DN
RDN
5VF
RUP
5VF
RDN
RUP
J120
J1
RIT BOARD
S1
EVQ-VCJF0324B
5VF
J101
F4K
F3K
F5K
J201
J1
R201 1k
R202 1k
R203 1k
R204 1k
R205 1k
R206 1k
R207 1k
R208 1k
R209 1k
R210 1k
R211 1k
F5K
F4K
F3K
F2K
F1K
SPEK
EXTK
FILK
AMK
CWK
SSBK
KI2
KI1
5VF
R215
47k
R214 47k
R213 47k
R212 47k
F2K
F1K
SPEK
EXTK
FILK
AMK
CWK
SSBK
KI2
KI1
5VF
R224 1k
R227 1k
R226 1k
R225 1k
R230 1k
R229 1k
R228 1k
R223 1k
J221
R222 1k
R221 1k
R231 1k
14K
10K
7K
3K
SPLK
1K
18K
21K
24K
28K
50K
R232 1k
GENK
R233 1k
FINK
R234 1k
MPWK
R235 1k
MPRK
R244 1k
R247 1k
R246 1k
R245 1k
R251 1k
R250 1k
R249 1k
R248 1k
R243 1k
J241
R242 1k
R241 1k
XFCK
TSK
MCLK
MWK
MUPK
MDNK
LOCK
PBTK
NOTK
KI4
5VF
KI3
LDV
R252 1k
LOCD
R253 1k
TXD
R254 1k
RXD
R255 1k
NOTD
PBTD
M8V
MICI
J2
J322
MUD
SQLS
MSND
GND
MMICE
AFO
J531
to
LCD
unit
1
2
3
4
5
6
7
8
L1 100uH
L3 100uH
L4 100uH
J1
C1
0.0047
C6
0.0047
C7 100p
C5
0.0047
C4
0.0047
C3
0.0047
C2
0.0047
MIC BOARD
S5
(F-5)
S4
(F-4)
S3
(F-3)
S2
(F-2)
S1
(F-1)
S10
(EXIT)
S9
(FILTER)
S8
(AM/FM)
S7
(CW/RTTY)
S6
(SSB)
S11
(SPEECH)
S17
(F)
S15
(D)
S14
(C)
S13
(B)
S12
(A)
S18
(G)
S16
(E)
R1
6.8k
R5
6.8k
R2
2.2k
R3
4.7k
R4
15k
R6
2.2k
R7
4.7k
C2 0.1
C1
0.1
MODE BOARD
J1
J2
S24
(PBT-CL)
PBTK
S25
(NOTCH)
NOTK
S26
(RIT)
S27
(
∆
TX)
S28
(CLEAR)
KI4
C2
0.1
R5
6.8k
R6
2.2k
R7
4.7k
S18
(UP)
MUPK
S19
(DOWN)
MDNK
S20
(MW)
MWK
S21
(M-CL)
MCLK
S22
(TS)
TSK
S23
(XFC)
XFCK
S14
(7)
7K
S15
(18)
18K
S16
(28)
28K
S17
(F-INP)
FINK
S30
(MP-R)
MPRK
S31
(LOCK)
LOCK
S10
(3.5)
3K
S11
(14)
14K
S12
(24)
24K
S13
(50)
50K
S6
(1.8)
1K
S7
(10)
10K
S8
(21)
21K
S9
(GENE)
GENK
S29
(MP-W)
MPWK
S1
(SPLIT)
SPLK
S2
(DW)
S3
(CHANGE)
S4
(V/M)
S5
(M/S)
C1
0.1
R2
2.2k
R3
4.7k
R4
15k
R1
6.8k
TEN-KEY BOARD
Q1
DTC114EE
R8
5.6k
DS1
CL-200HR
(LOCK) LED
Q2
DTC114EE
R9
5.6k
DS2
CL-200HR
(TX) LED
Q3
DTC114EE
R10
680
DS3
CL-220YG
(RX) LED
Q4
DTC114EE
R11
1k
DS4
CL-220YG
(NOTCH) LED
Q5
DTC114EE
R12
1k
DS5
CL-220YG
(TWIN PEAK FILTER) LED
J801
1
14
7
3
2
10
9
8
R102
15k
C102
0.001
5
C104
0.001
R104
47k
6
4
C103
0.001
R103
15k
11
13
12
4
6
5
3
14
7
2
1
IC101c
uPD4030BG
IC101b
uPD4030BG
IC101d
uPD4030BG
IC102b
MC14071BFEL
IC102a
MC14071BFEL
IC101a
uPD4030BG
IC102d
MC14071BFEL
12
11
13
R126
220k
R127
100k
R128 1M
C122
0.001
R125
100k
C121
0.001
R121
100k
R124 1M
R123
100k
R122
220k
9
10
8
IC102c
MC14071BFEL
RSB
RSA
DS903
CL-200YG
R912
330
DS902
CL-200YG
DS901
CL-200YG
METER BACK LIGHT
TNRD
Q622
DTC114EE
DS622
CL-200YG
R626
680
MONO
Q623
DTC114EE
DS623
CL-200YG
R627
680
NBD
Q624
DTC114EE
DS624
CL-200YG
R628
680
NRD
Q625
DTC114EE
DS625
CL-200YG
R629
680
8
7
6
5
4
3
2
1
CD
CS
ES
CT
GND
SI
V+
INVIN
C848
0.1
C847
220
L843
D10F-A814AY-101K
D841
RB050L-40
C843
330p
L842
SLF12565T-680M2R0
C844
220
C845
0.1
R845
1.2k
R846
27k
C842
0.1
C841 220
IC841
NJM2360M
C805
15p
C804
0.047
R805
3.3k
R804
3.3k
L802
D10F-A814AY-101K
D801
RD3.0M
R801
33k
C801
10
C803
47
R803
220
L803
D818HN-1107
C802
10
L801
100uH
R802
33k
Q802
2SB1201
Q801
2SC4081
5VF
Q804
2SC3647
Q803
2SC3647
C101
0.1
14K
10K
7K
3K
SPLK
1K
18K
21K
24K
28K
50K
GENK
FINK
MPWK
MPRK
XFCK
TSK
MCLK
MWK
MUPK
MDNK
LOCK
PBTK
NOTK
KI4
5VF
KI3
LDV
LOCD
TXD
RXD
NOTD
PBTD
FRONT
W4
FRONT
W6
FRONT
W7
FRONT
W8
to
LCD
MUP
MDN
GND
+
-
SP
CHASSIS
FRONT
W1
FRONT
W2
SSP
SPE
P1
J802
to
LCD
Q805
DTC114EE
W801
R256 1k
C242
0.1
C241
0.1
R101
100
R105
100
C105
0.1
KI4
KI3
R447
100
KI0
D421
DAN222
D423
DAN222
D422
DAN222
R431
2.2k
R421
1k
R424
1k
D425
DAN222
D424
DAN222
D431
DAN222
D432
DAN222
R432 47k
C431 0.1
R403
100k
R402
1k
SRES
DASH
DOT
DOTK
DSHK
MUD
+14V
BKL
V
C846 220
L841
D10F-A814AY-101K
R841
0.33
R842
0.33
-15V
+18V
+14V
5VF
C823
0.0047
C828
10
C826
4.7
C830
10
D822
RD20M
C829
4.7
C825
0.0047
C827
4.7
C824
0.0047
C822
47
C821
0.1
Q821
2SC4081
R824
10k
L823
1000uH
R821
1.2k
IC821
BA6161F
D821 1SS322
L822
NLFC565050T-472K
L821
HF50A
CC322413-B
8
7
6
5
1
2
3
4
F1K
ASL1
MSB
ASL0
F2K
F3K
F4K
F5K
SSBK
CWK
AMK
FILK
EXTK
SPEK
ASL2
PITL
NO
TL
DELL
KYSL
CMPL
PWRL
MIGL
NRL
BALL
RFL
AFL
PB2B
LFMD
LMFD
PB2A
RSB
MSA
RSA
PB1B
BKL
V
CNTV
PB1A
METV
MSA
R446 10k
R445 10k
R444 10k
R443 47k
R442 47k
R441 10k
L401
HF50A
CC322513-B
C404
0.1
C405
0.1
C406
10
1K
3K
7K
10K
14K
18K
21K
24K
28K
50K
GENK
FINK
MPWK
MPRK
MUPK
MDNK
MWK
MCLK
TSK
NOTD
PBTD
RXD
TXD
LOCD
NRO
NBO
MONO
TNRD
MDM2
MDM1
MDN0
BKLS
HDD2
HDD1
HDD0
MAT1
PHNI
DSHK
DOTK
TRAK
NOTK
PBTK
LOCK
XFCK
R416 47k
R415 47k
R414 47k
R413 47k
R412 47k
R411 47k
R410 47k
R409 47k
R408 47k
C403
0.1
R861
12
R862
12
R863
12
C861 10
C862 0.1
C863 0.1
C864 22
I
O
G
IC861
TA7805F
CP400
O
I
R882
56
R881
56
C881 10
C882 0.1
C883 0.1
C884 22
G
IC881
TA79LO8F
O
I
C501 10
C502 0.1
C503 0.1
C504 22
G
IC501
TA79LO8F
D501
1SS322
COGC
(COMMON GAIN)
(CLAMP CONTROL)
CPCN
D509 1SS322
+4R5V
-7R5V
R1104
22k
GAM1
(GAMMA 1)
BRGT
R1107
12k
R1101
47k
B
G
R
C1404 0.1
C1405 0.1
C1406 0.1
SW
CPCN
COGC
COMO
BASC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
IC1401
M52338FP
MAIN IN R
CLAMP R
MAIN IN G
CLAMP G
MAIN IN B
CLAMP B
SW
HD IN
CP CONT
VCC2
VEE
FRP2 IN
COM GAIN
COM OUT
BIAS CONT
GND
VCC1
EXT IN B
SUB CONT B
EXT IN G
SUB CONT R
EXT IN R
GAM2
GAM1
CONTRAST
BRIGHT
FRP1 IN
R OUT
SUB BIAS R
G OUT
SUB BIAS B
B OUT
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
C1401
0.1
C1402
0.1
C1409
0.1
C1408
0.1
C1407
0.1
C1403
0.1
GAM2
GAM1
CONT1
BRGT
C1201
0.1
R1203
2.7k
R1202
1.2k
R1201
150
D1201
MA8030
Q1201
2SA1576
Q1211
2SA1576
R1213
2.7k
R1212
1.2k
D1211
MA8030
C1211
0.1
R1211
150
D1221
MA8030
R1222
1.2k
R1223
2.7k
Q1221
2SA1576
R1221
150
C1221
0.1
+
-
R1541
10k
C1541
10
R1545
2.2k
R1543 22k
R1544
2.2k
IC1521b
M5218AFP
R1542
22k
CONT1
+
-
C1521 0.1
R1526
100
R1527
100
C1522
0.1
8
3
2
4
1
IC1521a
M5218AFP
5
6
7
HD
POLC
+14V
BL
GL
RL
-15V
+18V
+14V
5VF
KIO
TRAK
PWRK
TMD
C621
0.1
R622
6.8k
R623 2.2k
R624 4.7k
R625 15k
R621
2.2k
DS621
CL-200HR
S622
(TRANSMIT)
S621
(POWER)
S623
(TUNER)
S624
(MONITOR)
S625
(NB)
S626
(NR)
(TIMER)
Q901
DTC114EE
Q902
DTC114EE
Q903
DTC114EE
R904
4.7k
R905
6.8k
R906
15k
R910
560
R908
4.7k
R909
470
R907
15k
D901
RD5.1M
Q904
2SC4081
Q905
2SB1201
5VF
MDM2
MDM1
MDM0
LDV
+
-
METV
R917
4.7k
R916
2.2k
C901
10
S1
(PBT2)
(PBT1)
2
3
1
5
6
4
A
B
COM
A
B
COM
PB2A
PB2B
FRONT
W3
FRONT
W5
L5V
HD
VD
POLC
GND
L5V
RL
GL
BL
VCOM
GND
L/R
U/D
N/P
L18V
-15V
W506
R520
220k
R519
220k
R518
220k
R532
39k
R531 1.8k
C531 0.0047
D531 MA8030
R533
10k
Q515
DTC114EE
IC511c
NJM2902V
10
9
8
+
-
IC511b
NJM2092V
Q514
2SB1132
Q512
2SB1132
IC511a
NJM2092V
IC511d
NJM2902V
-
+
+
-
14
12
13
7
5
6
1
4
2
3
11
Q511
DTC114EE
Q513
DTC114EE
C513
0.1
R511
10k
D511
MA8030
R514 820
R515
10k
8
7
6
5
1
2
3
4
IC542
TK16105M
HDD2
HDD1
HDD0
HSYNC
BKLS
5VF
NOTL
PITL
PB1A
PB1B
PB2A
PB2B
GND
GND
GND
C601 0.0047
C602 0.0047
C603 0.001
C604 0.001
C605 0.001
C606 0.001
R601 47k
R602 47k
PHE
AFO
PHNI
GND
GND
GND
GND
GND
GND
C922 0.0047
C921 0.0047
DASH
DOT
GND
GND
GND
GND
GND
GND
GND
GND
SSPE
SSP
MICI
M8V
MUD
SQLS
MSND
GND
MMICE
AFO
J301
LFMD
LMFD
SRES
YOBI
R
G
B
HSYNC
VSYNC
GND
GND
GND
GND
-8V
-8V
+18V
14V
14V
14V
from MAIN
unit J891
J321
from MAIN
unit J861
14V
14V
14V
PHE
AFO
PHE
TMD
PWRK
GND
GND
GND
GND
MICI
8V
MSND
MICE
SQSS
C331 470p
C332 0.0047
L323 HF50A
CC32513-B
L322 HF50A
CC32513-B
L321 HF50A
CC32513-B
Q321
DTC114EE
R301 1k
R312 1k
R313 1k
R314 1k
R315 47
R316 47
R317 47
R318 1k
R319 1k
GND
GND
GND
GND
GND
GND
GND
R107
220k
R106
220k
GND
GND
GND
GND
GND
GND
GND
GND
GND
+14V
R915
10k
PHE
AFO
D
ASH
DO
T
R502
15k
R501
1k
R503
1k
VSYNC
VD
-
+
R707
3.9k
NOTL
PITL
PB1A
PB1B
PB2A
PB2B
CP101
CP102
CP103
CP104
MUDK
R1103
10k
R1106
18k
R1109
33k
R1110
68k
(INPUT SELECT)
R1112
33k
R1113
27k
R1121
27k
R1122
4.7k
R1127
2.7k
R1128
82k
C1104
0.1
C1101
0.1
C1107
0.1
C1307 0.1
C1308 0.1
C1309 0.1
CNTV
C1106 0.1
C1109 0.1
C1102 0.1
C1110
0.1
R1553
220k
R1555
22k
Q1551
2SC4081
Q1552
2SA1576
C1554
10
R1560
5.6k
R1561
27k
R1554
220k
C1555
0.1
C1552
10
C1556
0.1
R1552
100
R1551
100
Q1553
2SA1576
Q1554
2SC4081
R1556
22k
C1551
10
VCOM
COMO
C1553
10
R521
1.8k
D512
RD5.1M
R513
1.2k
R512
2.2k
W502
W504
CP5
+
-
CP401
CP402
CP411
CP412
PHONE
ELEC-KEY
LMFD
LFMD
SRES
R
G
B
HSYNC
VSYNC
GAM2
CFL+
CFL-
R807
27
R808
27
C849 220
C850 220
R850 330
Q841
2SB1124S
PHE
R709
10k
R708
2.2k
Q701
DTC114EE
D701
DAN222
DISPLAY BOARD
(BIAS CONTROL)
(BRIGHT CONTROL)
(GAMMA2)
C1105 0.1
C1108 0.1
+4R5V
L6
HF50ACC322513-B
R321 10k
-7R5V
W512
C545 10
C542 0.1
R544 10
R541
10k
1
2
3
5
4
5
1
2
3
4
IC492
TC4S81F
IC490
S-80942ANMP-DD6
OUT
VDD
VSS
CO
NC
R491 47k
R490 39k
C492 0.0047
R494 100k
R493 1k
R492 10k
C490 0.1
R848 470
R849 470
C491
12p
4.8V
4.8V
RSB
RSA
RIT DIAL UP
RIT DIAL DOWN
4.6V
MAIN DIAL DOWN
MAIN DIAL UP
4.6V
M UP
M DN
OFF 4.8V
A 0V
B 1.2V
C 2.4V
D 3.7V
OFF 4.8V
E 0V
F 1.2V
G 2.4V
OFF 4.8V
RIT 0V
TX 1.2V
CLEAR 2.4V
OFF 4.8V
DUAL WATCH 0V
CHANGE 1.2V
VFO/MEMO 2.4V
MAIN/SUB 3.7V
ON 4.5V
OFF 0V
ON 4.5V
OFF 0V
LCD BACKLIGHT
MAX 4.8V
MIN 0V
-15.4V
18.6V
1.5V
0.1uS
4.8V
OFF 4.8V
TUNER ON 0V
MONITOR ON 1.2V
NB ON 2.4V
NR ON 3.7V
OFF 0V
ON 4.7V
1.3V
1.6V
4.3V
3.1V
1.7V
3.0V
LCD CONTRAST
MAX 8.7V
MIN 0.9V
-7.5V
4.5V
METER BACKLIGHT
MAX 11.9V
MIN 5.1V
A
B
4.8V
right
turn
A
B
left
turn
PB(1/2)A,PB(1/2)B
OFF 4.8V
UP 0.6V
DOWN 1.2V
12.1V
12.1V
MEASUREMENT CONDITIONS
VOLTMETER
:50k
Ω
/VDC
OSCILLOSCOPE :20MHz 1M
Ω
25pF
SUPPLY VOLTAGE:13.8V
DISPLAY
: 14.1MHz USB
SECTION 10
VOLTAGE DIAGRAM
10 - 1
10-1 FRONT UNIT