Puxing PX-777 User manual

UHF/VHF FM TRANSCEIVER
PX-777/328/338
SERVICE MANUAL
------------------CONTENTS--------------------------
INTRODUCTION……………………………………………………2
GENERAL ................................................................................. 2
REALIGNMENT……………………………………………………..3
TROUBLE SHOOTING GUIDE……………………………………6
TECHNICAL SPECIFICATION ............................................. …7
FUNCTION SPECIFICATION…………………………………….8
CIRCUIT DESCRIPTION ......................................................... 9
SEMICONDUCTOR DATA.............................................……. 16
PARTS LIST............................................................................ 17
BLOCK DIAGRAM …………………........................................ 22
PCB BOARD………………………………………………………23
SCHEMATIC DIAGRAM....................................................... 25

INTRODUCTION
SCOPE OF THIS MANUAL
This manual is intended for use by experienced technicians
familiar with similar types of commercial grade communications
equipment. It contains all required service information for the
equipment and is current as of the publication data. Changes
which may occur after publication are covered by either Service
Bulletins or Manual Revisions. These are issued as required.
ORDERING REPLACEMENT PARTS
When ordering replacement parts or equipment information,
the full part identification number should be included. This
applies to all parts : components, kits, or chassis. If the part
number is not known, include the chassis or kit number of which
it is a part, and a sufficient description of the required
component for proper identification.
PERSONNEL SAFETY
The following precautions are recommended for personnel
safety:
DO NOT transmit until all RF connectors are verified secure
and any open connectors are properly terminated.
SHUT OFF and DO NOT operate this equipment near
electrical blasting caps or in an explosive atmosphere.
This equipment should be serviced by a qualified technician only.
SERVICE
This radio is designed for easy servicing. Refer to the
schematic diagrams, printed circuit board views, and alignment
procedures contained within.
GENERAL
Your Transceiver is an electronic product of exact design and should be treated with care .The
suggestions below will help you to fulfill any warranty obligations and to enjoy this product for many
years.
 Do not attempt to open the unit. Non-expert handling of the unit may damage it.
 When using regulated power supply, take notice of power voltage must be between 6V and 8V to
avoid damaging the unit.
 Do not store the Radio under the sunshine or in hot areas.
High temperatures can shorten the life of electronic devices, and warp or melt certain plastics.
 Do not store the Radio in dusty, dirty areas
 Keep the Radio dry. Rainwater or damp will corrode electronic circuits.
 If it appears that the Radio diffuses peculiar smell or smoke, please shut off its power
immediately and take off charger or battery in the Radio, then contact with PUXING agency.
 Do not transmit without antenna.

2. LCD DISPLAY

3. SELF-PROGRAMMING MODE
For frequency,signal,feature write to the radio

TECHNICAL SPECIFICATION
General
Frequency Range 136 ―174MHz，350—390MHz，400—
470MHz,245Mhz
Working Temperate －20℃―＋50℃
Operating Voltage DC 7.2V
Operate Mode Simplex or Semi-duplex
Channel spacing 25Khz/12.5Khz
Dimension 100mm×55mm×32mm (Not included Antenna)
Weight 220g (Including battery)
Antenna impedance 50Ω
Transmitter
Frequency Stability ±2.5PPM
Output Power 5W/4W ±0.5W
Max Frequency Deviation ≦5KHz
Audio Distortion ≦3%
Modulation Character +3dB—-3dB
Adjacent Channel Power ≥65dB
Spurious Radiation ≤7.5UW
Occupied Bandwidth ≤16KHz
Receiver
RF Sensitivity ＜0.2UV
Audio Distortion ≦3%
Audio Response +2dB—-10dB
Adjacent Channel Selectivity ≥60dB
Intermodulation Rejection ≥60dB
Spurious Response ≥60dB
Blocking ≥80dB

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PDFcreated withpdfFactoryProtrialversion www.pdffactory.com

1 2 3 4 5 6
D
C
B
A
RV378
100K
C378
104P
3
2
5
4
1
JK511
ST-301
2
5
4
1
JK611
ST-106
R368
560R
C313
101P
R367
560R
C314
101P
R365
2K2
C315
101P
R366
6K8 R364 4K7
E367
0.1uF E363
1uF E364 0.1uF
L361
101T
PR311
1K
R363
0R
R362
150R
5CC
P-TX/RX
PLL_CS
PC3
N/W/LD
DQTo
PC1 PC2 PC3 PC4
28.8MHZ
R361
0R
C834
101P
C835
101P C836 101P C837 101P C838 101P
C831
101P C832 101P C833 101P
PR811
47K
PR812
1K
C853
101P
C856
392P
C850
104P
C857
105P
C852
221P
C858
221P
C855
333F
E854
4.7uF
R853
58K
R855
68K
R854
82K
R852
R-1
R858
2K2
R857
22K
L851
101T
D813
RED
D814
GREEN
T813
DTC114EE T814
DTC114EE
R814
560R
R815
4K7
R813
560R
C817
104P
T815
DTA114EE
R817
4K7
R816
10K
C818
104P
R818
4K7
A0
1A1
2
GND
4DA 5
CK 6 A2
3WP 7
Vcc 8
U821
24C08 C827
103P
R827
10K
PC0
R834
8K2
C372
103P
C371
223P
R371
4K7
R375
4K7
R374
1K2
R373
2K7
R372
4K7
PC7 PB3 PB4 PB5
CR881
32.768KHz C883
104P
C886
104P R885
15K
R884
82K
R883
100K
L886
301T
C811
27P C882
27P
T881
2SB624
R886
0R
C885
103P
R701
0R
102P
R333
15K L347
100nH
C351
100P
L351
270nH
D352
1SV325
L329
101T C347
102P
R351
180R
L352
270nH
L353
18nH
L355
3.3uH
D351
1SV325
C352
2P
C353
33P
C355
15P
C359
5P
C360
7P
C361
10P
C362
1P
T351
2SK508NV(K52)
MOD
C272
33P
C284
104P
C285
221P
C286
221P
C287
10P
C288
471P
C276
27P
C278
104P
C275
104P C274
104P
C280
103P E283
10uF
R285
180K
R287
3K9
R286
180K
R288
3K3
R276
27K R274
1K2
R277
100K
R283
100R
OSC in 1
Dec 6
FIL out 7
IF out
11
IF in 5
MIX in
16
AF out
9
RSSI
12
QUAD
10
MIX out 3
OSC out 2
FIL in 8
N-det
13
N-rec
14 Vcc 4
GND
15
U261
TA31136F
CR271
C28
T275
DTA114EE
C283
104P C282
104P
R278
0R
C830
102P
R833
150K
R831
150K R832
150K
5V
PB1
RXi
ATX
QT
D0
D1
D2
D3
PC7
PB3
PB4
HT1621-CS
GND_D
PC6
5V
PB1
PB5
SB
PC4
C854
103P
TX in
6N.C. 7
RX in
11
V bias 9
N.C. 10
Vss
8
C539
120P
R539
100K
R540
100K
C540
104P
R527
22K
C527
150P
C526
223P
C525
223P
C524
104P
R528
100K
R529
22K
C542
104P R541
47K
C528
120P
R866
10K
R867
10K
R864
3K3
R862
1K8
R865
20K
R863
100R
C867
104P C862
332P
C863
470P
T461
2SK1824
C872
473P
C871
472P
R873
4K7
R872
4K7
R871
4K7 E871 10uF
in
Gnd
out
U906
5A
C907
103P
E907
10uF E905
10uF
C905
103P
C906
471P
5V
D/A
20 ATX
21 ARX
22
AD1
23 AD2 24 AD3 25 OSCI 26 OSCO 27 Vss 28
Reset
32 Vdd 33
PA0 34
PA1 35
PA2 36
PA3 37
PA4 38
PA5 39
PA6 40
PA7 41
PB0 42
PB1 43
PB2 44
PC0 1 PC1 2 PC2 3 PC3 4 PC4 5 PC5 6 PC6 7 PC7 8 PB3 9 PB4 10 PB5 11
PD3
31 PD1 29 PD2 30
AVdd
12 RXO
13 RXI
14 TXI
15 TXO
16 Tone
17
AVss
19 LC
18 U811
U-EM44
R868
4K7
R861
RES
R717
10K
C864
104P
C529
104P
5V
5CC
P-TX/RX
MOD
28.8MHZ C281
102P
GREEN
TXD/RED
R379
NC
R378
NC
N/W/LD
C271
20P
CR272
21.250MHz
DEV
MIXIN
SQL
CV
1
2
3
4
5
6
7
8
9
10
11
12
13
18
17
16
15
14
JP811
JP18
GND_D
R304
100R
R713
100R
R714
100R
R712
1K
L711
101T
C304
NC
C731
102P
5V
5C 5C
R718
10K
C712
221P
R846
4K7
R845
0R
R844
100R
R841
47K
R842
47K
R843
100R
3 2 1
SW811A
SW/VOL
C842
103P
C841
103P
SB
D3
PB5
MIC+
SP+
PTT/RXD
L902
101T
TXi TXi
P-AMP
MIC
SB
AFin
APC/TUNE
D3
MONI
PB5
PTT
SP
N/W
VOX
MIC
SB
APC/TUNE
D3
MONI
PB5
PTT
SP
SQL
VOX
O I
FL261
450K
PC6
PB1
D0
D1
D2
D3
K1
K2
K3
K4
LCD CS
LAMP2
LAMP1
SB
SB
(T.Y.)
BEEPBEEP
BEEP
TXD/RED
BEEP
VOUT
4VDD 5
GND
3SDA
1RST 7
GND 6
OSC
2SCL 8
U511
AUDIO
R548
680R
C548
104P
C549
104P
R549
4K7
C547
103P
C546
104P
R546
330K
R545
10K
R702
0R
5M5M DQTo
C851
104P

7 8 9 10 11 12
O I
FL253
29.250MHZ
R433
1K8
L253
270nH
5V
C181
102P
E181
4.7uF
T103
2SB624 R102
4K7
R101
4K7 C102
104P
T201
DTA114EE
C101
104P
C201
103P
R441
33K
C441
473P
R443
1M8
R442
33K
C444
104P
R444
10K
C446
470P
C445
473P
DTA114EE
C303
470P
C302
103P
C442
332P
C443
680P
5C
5R
5R
5R
5T
5T 5T
5T
MIC
5V
5V
5V
5CC
P-TX/RX P-TX/RX
R256
18K
R171
0.39R
R172
0.39R
R173
0.39R
R198
150K
R195
150K
R196
150K
R197
150K
R194
150K
R192
150K
R185
10K
R193
NC
R184
220K
R183
47K
R186
NC
R182
1M
R181
10K
R187
39K
R188
47K
R189
18K
C195
471P
C198
NC
C173
103P
C192
101P
C191
102P
C185
470P
C186
103P
C188
104P
2
3
1
84
U161A
LM2904V
76
5
U161B
LM2904V
T191
DTC114EE
T181
DTC114EE
APC/TUNE APC/TUNE
BATT
5T
5T
C447
820P
C172
105P C171
103P
C451
103P
C448
332P
R449
10K
R447
1M8
R448
33K
R451
3K3
T451
2SC4617
R452
47K
T441
2SC4617
R446
33K
E451
2.2uF
R453
22K
C256
103P
L402
101T
R401
470R
C402
104P
R402
1K8
C403
470P
R403
100K
C404
273P
R404
18K
C407
102P
R406
750K
C406
223P
R421
820R
C422
104P
E421
2.2uF
R405
22K
R431
30K C405
102P
E431
4.7uF
R432
1K5
R434
51K
C431
223P
R435
4K7
2
3
1
84
U411A
LM4558
76
5
U411B
LM4558
33
1
1
2
2
D422
1SS372 T421
MRF497
C438
470P
R438
100R
R437
3K3
R436
1K8
5T
C408
102P
C401
103P
T431
2SK1824
C434
10P
C214
3P
C215
N.U.
C216
470P
C217
0.3P
VC220
6P
C221
3P5
C222
470P
C223
0.3P
VC226
6P
C227
4P5
C228
470P
C231
102P
C232
102P
C233
470P
C234
8P
C237
10P
C238
0.5P
VC241
6P
C242
4P
C252
6P
C230
470P
R214
N.U.
R217
100K
R220
100K
R223
0R
R226
220K
R227
100K
R228
220R
R229
0R
R230
3K3
R231
100R
L212
3T
L213
3T
L214
3T
L216
3T
L219
39nH
L220
18nH
L223
3T
L224
3T
L231
22nH
D215
N.U.
D214
HVC350B
D217
HVC350B
D220
HVC350B
T231
3SK229
R213
100K
C205
102P
R212
0R
C212
15P
C272
33P C254
103P
C264
104P
C284
104P
R262
470R
T261
2SC4215
R261
680K
R264
2.7K
R274
1K2
OSC in 1
Dec
IF out
IF in 5
MIX in
16
RSSI
12
MIX out 3
OSC out 2
N-det
13
N-rec
14 Vcc 4
GND
15
C273
224P
C261
103P
C262
2P
C283
104P
C282
104P
R278
C243
470P
C246
0.5P
C247
4P
C250
103P
R234
100K
R237
0R
R238
1K
R239
220R L227
3T
T251
3SK229
L252
0.56uH C251
15P
R251
2.2K
R242
1K
C206
103P R252
1K
R254
470R
C253
15P
C263
13P
R417
1M
T411
2SC4738
3
311
22
D411
MA742
R416
0R
C417
104P C415 104P
R415
100R
C416
470P
R414
270R C414
103P
R413
5K6
5T
OSC out
1
TX in
6N.C. 7
RX in 11
TX Aout
5
Vdd 16
V bias 9
RX Aout 12
N.C. 10
N.C.
3
OSC in
2
Vss
8
RX out 13
CLR 14
TX out
4
CLK sel 15
U512
FX/MX128
1
122
CR537
3.58MHz
R537
1M C537
33P
C538
47P
C541
150P
C535
104P
R535
100K
C539
120P
R539
100K
R540
100K
C540
104P
C533
470P
C534
470P
R527
22K
C527
150P
C532
470P
C542
104P
R541
47K
T525
UMC4
R530
10K
R531
10K
D530
1N4148
D531
1N4148
5V 5T
C501
103P
C531
103P
C257
5P FL251
21.7MHz
FL252
21.7MHz
C281
102P
C255
5P T102
DTA114EE
C103
470P
MIC MIC
C271
20P
C270
15P
CR272
21.250MHz
R301
1K
R202
1K
MIXIN
P-AMP
MIC
SB
AFin
APC/TUNE
D3
MONI
PB5
PTT
SP
N/W
VOX
P-AMP
MIC
SB
AFin
APC/TUNE
D3
MONI
PB5
PTT
SP
N/W
P-AMP
MIC
SB
AFin
APC/TUNE
D3
MONI
PB5
PTT
SP
SB APC/TUNE
C279
104P
O I
FL261
450K
(T.Y.)
T401
DTA114EE
C409
470P
C410
103P
5VOX5V
R408
1K
5CC
5CC
(T.Y.)
(T.Y.)
(T.Y.)
BEEP BEEP BEEP
BEEP
E401
4.7uF
C413
103P
(T.Y.)
C412
103P
T402
DTA114EE
C411
470P
R409
1K
R669
1K
in
Gnd
out
U911
5A
C911
103P E911
10uF
E913
10uF
C913
103P
C912
471P
5M
BATTBATT
BATT
5M
C202
470P
C301
103P

910 11 12 13 14
A
B
C
D
R433
1K8
C640
1uF
R646
0R
C181
102P
E181
4.7uF
nc 1
Vcc 2
nc 3
Vin 4
Ripple 5 NF
6Phase
7PreG
8PwG
9Pout
10
U641
TA7368
T602
2SB624
T611
DTC114EE
C612
470P
R612
2K2
C601
470P R613
2K2
C604
104P R601
10K C642
104P E641
1uF
C602
124P
R642
150R C641
220P
R644
10R
E642
10uF
C643
100P
C644
104P
E651
100uF
P-AMP
T103
2SB624 R102
4K7
R101
4K7 C102
104P
T201
DTA114EE
C101
104P
C201
103P
R441
33K
C441
473P
R443
1M8
R442
33K
C444
104P
R444
10K
C446
470P
C445
473P C442
332P
C443
680P
5T 5T
5T
MIC
5V
5V
P-TX/RX
R171
0.39R
R172
0.39R
R173
0.39R
R198
150K
R195
150K
R196
150K
R197
150K
R194
150K
R192
150K
R185
10K
R193
NC
R184
220K
R183
47K
R186
NC
R182
1M
R181
10K
R187
39K
R188
47K
R189
18K
C195
471P
C198
NC
C173
103P
C192
101P
C191
102P
C185
470P
C186
103P
C188
104P
2
3
1
84
U161A
LM2904V
76
5
U161B
LM2904V
T191
DTC114EE
T181
DTC114EE
APC/TUNE APC/TUNE
BATT
5T
5T
C172
105P C171
103P
R448
T441
2SC4617
R446
33K
L402
101T
R401
470R
C402
104P
R402
1K8
C403
470P
R403
100K
C404
273P
R404
18K
C407
102P
R406
750K
C406
223P
R421
820R
C422
104P
E421
2.2uF
R405
22K
R431
30K C405
102P
E431
4.7uF
R432
1K5
R434
51K
C431
223P
R435
4K7
2
3
1
84
U411A
LM4558
76
5
U411B
LM4558
33
1
1
2
2
D422
1SS372 T421
MRF497
C438
470P
R438
100R
R437
3K3
R436
1K8
5T
C408
102P
C401
103P
T431
2SK1824
C434
10P
C214
3P
C215
N.U.
C216
470P
C217
0.3P
VC220
6P
C221
3P5
C222
470P
C223
0.3P
VC226
6P
C227
4P5
C228
470P
C231
102P
C232
102P
C233
470P
C234
8P
C237
10P
C238
0.5P
VC241
6P
C242
4P
C230
470P
R214
N.U.
R217
100K
R220
100K
R223
0R
R226
220K
R227
100K
R228
220R
R229
0R
R230
3K3
R231
100R
L212
3T
L213
3T
L214
3T
L216
3T
L219
39nH
L220
18nH
L223
3T
L224
3T
D215
N.U.
D214
HVC350B
D217
HVC350B
T231
3SK229
R213
100K
C205
102P
R212
0R
C212
15P
T411
2SC4738
3
311
22
D411
MA742
C417
104P
C415
104P
R415
100R
C416
470P
R414
270R C414
103P
R413
5K6
5T
SW411A
RD91
R450
10R
PX4401
SCHEMATICDIAGRAM
PX4401 Revision E01D
Drawing ByLvWei Jun Netec 0540
T102
DTA114EE
C103
470P
MIC MIC
R202
1K
C901
105P
L901
101T
C902
102P
C903
103P
BATT
C904
103P BAT111
BATTERY
SW711
ANKEY
SW712
PTT
SW713
ANKEY
R715
0R
R716
4K7
C711
103P
C713
102P
P-AMP
MIC
SB
AFin
APC/TUNE
D3
MONI
PB5
PTT
SP
N/W
P-AMP
MIC
SB
AFin
APC/TUNE
D3
MONI
PB5
PTT
SP
P-AMP SB APC/TUNE SP AFin
B
(T. Y.)
SB
BATT
(T.Y.)
5VOX
(T.Y.)
(T.Y.)
BEEP BEEP
BEEP
BEEP
BEEP
E401
4.7uF
C413
103P
(T.Y.)
C412
103P
DTA114EE
C411
470P
R669
1K
in
Gnd
out
U911
5A
C911
103P E911
10uF
C912
471P
BATTBATT
BATT