Voltage Diagrams; Front Unit - Icom IC-756PROIII Service Manual

SECTION 10

VOLTAGE DIAGRAMS

10-1 FRONT UNIT

M UP
M DN
RIT DIAL UP RIT DIAL DOWN
RSA 4.8V
RSB 4.8V
MODE BOARD
S1 S2 S3 S4
(F-1) (F-2) (F-3) (F-4)
S6 S7 S8 S9
(SSB) (CW/RTTY) (AM/FM) (FILTER) (EXIT)
R1 R2 R3 R4 R5
6.8k 2.2k 4.7k 15k 6.8k
S12 S13 S14 S15
(A) (B) (C) (D)
C2 0.1
S1 S6 S10 S14 S18
SPLK 1K 3K 7K MUPK
(SPLIT) (1.8) (3.5) (7) (UP)
S2 S7 S11 S15 S19
10K 14K 18K MDNK
(DW) (10) (14) (18) (DOWN)
S3 S8 S12 S16 S20
21K 24K 28K MWK
(CHANGE) (21) (24) (28) (MW)
S4 S9 S13 S17 S21
GENK 50K FINK MCLK
(V/M) (GENE) (50) (F-INP) (M-CL)
S5 S22
TSK
(M/S) (TS)
S29 S30 S23
MPWK MPRK XFCK
(MP-W) (MP-R) (XFC)
S31
LOCK
(LOCK)
Q1 DS1 Q4
DTC114EE R8 CL-200HR DTC114EE
5.6k
(LOCK) LED
Q2 DS2 Q5
DTC114EE R9 CL-200HR DTC114EE
ON 4.5V
5.6k
OFF 0V
(TX) LED
Q3 DS3
DTC114EE R10 CL-220YG
ON 4.5V
680
OFF 0V
(RX) LED
TEN-KEY BOARD
CP101
J101
5VF
CP102 CP103
MUP
MAIN DIAL UP MAIN DIAL DOWN
MDN
4.6V GND
R124 1M
R122 R123
220k 100k
4.6V 8
CP104 10
9
IC102c
S1
FRONT MC14071BFEL
EVQ-VCJF0324B
J120
J1
W4
R128 1M
RUP RUP
UP
R126 R127
5VF 5VF
E
220k 100k
RDN RDN 12
11
DN
GND 13
GND
IC102d
GND
MC14071BFEL
GND
GND
GND
RIT BOARD GND
5VF
FRONT
J201
J1 W6
F5K F5K
R201 1k
F4K R202 1k F4K
F3K F3K
R203 1k
F2K F2K
R204 1k
F1K R205 1k F1K
S5 SPEK SPEK
R206 1k
EXTK EXTK
R207 1k
FILK FILK
R208 1k
(F-5)
AMK R209 1k AMK
CWK CWK
R210 1k
SSBK SSBK
R211 1k
KI2 KI2
KI1 KI1
S10 S11 5VF 5VF
GND
GND
(SPEECH) OFF 4.8V
KI4
A 0V
B 1.2V
OFF 4.8V
C 2.4V KI3
E 0V
D 3.7V
R6 R7
F 1.2V
2.2k 4.7k
G 2.4V
S16 S17 S18
(E) (F) (G)
FRONT
J1 J221
W7
SPLK R221 1k SPLK
1K 1K
R222 1k
3K 3K
R223 1k
7K R224 1k 7K
10K R225 1k 10K
S24 14K 14K
R226 1k
PBTK 18K 18K
R227 1k
21K R228 1k 21K
(PBT-CL)
24K 24K
R229 1k
S25 28K 28K
R230 1k
NOTK 50K R231 1k 50K
GENK R232 1k GENK
(NOTCH)
FINK FINK
R233 1k
S26 MPWK MPWK
R234 1k
MPRK R235 1k MPRK
GND
(RIT)
OFF 4.8V
S27 RIT 0V
∆TX 1.2V
CLEAR 2.4V
FRONT
J2 J241
( TX) W8
MUPK R241 1k MUPK
S28
MDNK R242 1k MDNK
MWK R243 1k MWK
MCLK R244 1k MCLK
(CLEAR)
TSK R245 1k TSK
XFCK R246 1k XFCK
LOCK R247 1k LOCK
PBTK R248 1k PBTK
NOTK R249 1k NOTK
KI4 R250 1k KI4
5VF 5VF
KI3 R251 1k KI3
LDV LDV
LOCD R252 1k LOCD
TXD R253 1k TXD
RXD R254 1k RXD
NOTD R255 1k NOTD
PBTD R256 1k PBTD
GND
DS4 GND
R11 CL-220YG GND
1k
GND
GND
OFF 4.8V
GND
(NOTCH) LED
DUAL WATCH 0V
DS5 CHANGE 1.2V
R12 CL-220YG VFO/MEMO 2.4V
1k MAIN/SUB 3.7V
L803
(TWIN PEAK FILTER) LED D818HN-1107
J801
to
CFL+
LCD
C805
J802 15p
to
CFL-
LCD
Q804
2SC3647
10 - 1
5VF
IC101a IC101c
BU4030BF BU4030BF
14 8
1 10
3 9
2
14
R102
1
7 15k MSA
2
C406
IC102a
3 10
R104 7 MC14071BFEL
47k
5
5 4
C405
4 6
6 0.1
IC101b
IC102b BU4030BF 0.1µS
MC14071BFEL
12
11 1.5V
13
R103 IC101d
15k BU4030BF
AS0
C401 X401
12p CR-567
C402
12p
ASL0
MSB
IC411 ASL1
BU4051BCFV
ASL2
1 16 F1K
X4 VDD
2 15 F2K
X6 X2 R402
3 14 F3K
1k
X X1
4 13 F4K
X7 X0
5 12 F5K
X5 X3
6 11 SSBK
INH A
7 10 CWK
VEE B
8 9 AMK
VSS C
FILK
EXTK
SRES SPEK
MUDK
DASH
DOT
D421 D423
DAN222 DAN222
SPLK
D422
DAN222
DOTK
DSHK
D425 D424
DAN222 DAN222
IC881
R881 TA79LO8F
56
MUD
I
D431
DAN222 G
R882
56
D432
DAN222
18.6V
IC861 Q821
TA7805F 2SC4081
R861
12
5VF
I O
G
R862
12
R863
12
+14V
5VF
Q841
2SB1124S
L801
Q802
100µH
2SB1201 LCD BACKLIGHT
MAX 4.8V
Q801
MIN 0V
2SC4081 L843
D10F-A814AY-101K
R801
33k
L802 D801
D10F-A814AY-101K RD3.0M
-15.4V
Q805
DTC114EE
-15V
+18V
W801
Q803 +14V
2SC3647 5VF
R441 10k
R442 47k
R443 47k
R444 10k
R445 10k
4.8V
R446 10k
1 75
PC3/AN11 P97/SEG40/CL1
2 74
AVSS P96/SEG39/CL2
3 73
TEST P95/SEG38/D0
4 72
X2 P94/SEG37/M
5 71
X1 P93/SEG36
6 70
VSS P92/SEG35
7 69
OSC1 P91/SEG34
8 68
OSC2 P90/SEG33
9 67
RES P87/SEG32
10 66
MDO P86/SEG31
11 65
P20/IRQ4/ADTRG P85/SEG30
12 64
P21/UD P84/SEG29
13 IC401 63
P22 P83/SEG28
HD6433832SD66H
14 62
P23 P82/SEG27
15 61
P24 P81/SEG26
16 60
P25 P80/SEG25
17 59
P26 P77/SEG24
18 58
P27 P76/SEG23
19 57
P30/SCK1 P75/SEG22
20 56
P31/SI1 P74/SEG21
21 55
P32/SO1 P73/SEG20
22 54
P33/SCK2 P72/SEG19
23 53
P34/SI2 P71/SEG18
24 52
P35/SO2 P70/SEG17
25 51
P36/STRB P67/SEG16
5VF
R404 47k
R405 47k
R406 47k
R407 47k
IC501
TA79LO8F D501
1SS322
-8V -7R5V
O I O
+4R5V
G
D821 1SS322
R821
L823
IC821
1.2k
1000µH
L822
BA6161F
NLFC565050T-472K
8 1
R824
7 2
10k
L821
6 3
HF50ACC322413-B
5 4
R850 330
IC841
R848 470 NJM2360AM
1 8
CS CD
R849 470 2 7
ES SI
3 6
CT V+
4 5
C843 GND INVIN
L841 CNTV
330p
D10F-A814AY-101K
R845
1.2k
D841
RB050L-40
L842
SLF12565T-680M2R0
+14V
L401
HF50ACC322513-B
KIO
CP400
NOTD
PBTD
RXD
TXD
LOCD
NRD
NBD
MOND
TNRD
MDM2
MDM1
MDN0
BKLS
HDD2
HDD1
RFL
HDD0
MAT1
PHNI
DSHK
DOTK AFL
TRAK
NOTK
PBTK
LOCK NRL
XFCK
BALL
5VF
DELL
KYSL
CMPL
PWRL
MIGL
–8V
CNTV
+14V
Explanatory notes
VOLTAGE LINE
(INPUT SELECT)
CPCN
1.3V
(CLAMP CONTROL)
COGC
1.6V
(COMMON GAIN)
DISPLAY BOARD
-15V
-18V
+14V
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
AA
AB
AC
AD
AE
AF
AG
AH
AI