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Two-Way Radio
HT Series
Motorola HT Series Service Manual
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8-34
Maintenance:
VHF Troubleshooting Charts
8.12.8
T
roubleshooting Flow
Chart for Synthesizer
5V
at pin 6 of
D3701
Is information
from
µ
P U409
correct?
Is U3701
Pin 18 A
T
4.54 VDC?
Is U3701 P
in 47
AT
=
1
3
V
D
C
Is U3701 Pin 19
<0.7 VDC in RX &
>4.3 VDC in TX?
Sta
r
t
Visual
check of the
Board OK?
Correct
Problem
Check 5V
Regulator
+5V at
U3701
Pin’s
13 & 30?
Is 16.8MHz
Signal at
U3701 Pin
19?
Check Y3761,
C3761, C3762,
C3763, D376
1 &
R3761
Are signals
at Pin’s 14
&
15 of U3701?
Check
L3701,
R3701
Check Q260,
Q261 & R260
U3701 pin 2
at
>3V in Tx and
<0.7V in Rx
Remove
Shorts
Is there a short
between Pin
47 and
Pins 14 & 15 of
U3701?
Replace or
resolder
necessary
component
s
Is RF level at
U3701 Pin 3
2
>-30 dBm?
Are C3721,
C3722,C372
3,
R3721, R372
2,
R3723 OK?
Replace
U3701
If R3727, C372
6 & C3727
are OK, then se
e VCO
troubleshooti
ng chart
Are Waveforms
at Pins 14 &
15
triangular?
Do Pins 7,
8 & 9
of U3701 togg
le
when channel is
changed?
Check programming
lines between U409
and U3701 Pins 7,8 & 9
Replace
U3701
Check uP U409
Tro
ubleshooting
Chart
NO
YES
NO
YES
NO
YES
NO
YES
NO
NO
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
Check D3701,
D3702, U37
01,
C3701 - C3
707
3.3V at
U3701
pins 5, 20, 34
& 36
Check U320
1,
L3731
Is
16.8MHz
signal at
U3701 pin
23?
Replace
U3701
YES
NO
NO
YES
NO
YES
Replace U3
701
123
125
Table of Contents
Table of Contents
7
Foreword
6
Manual Revisions
6
Computer Software Copyrights
6
Document Copyrights
6
Disclaimer
6
Trademarks
6
Table of Contents
7
List of Figures
15
Chapter 9 Schematic Diagrams, Overlays, and Parts Lists
15
Keypad-Controller Interconnect Flex Schematic
15
List of Figures
15
UHF Band
18
Intrinsically Safe Radio Information
23
FMRC Approved Equipment
23
Relabeling
24
Repair
24
Repair of FMRC Approved Products
24
Do Not Substitute Options or Accessories
25
Chapter 1 Introduction
27
Scope of Manual
27
Warranty and Service Support
27
After Warranty Period
27
Return Instructions
27
Warranty Period
27
Related Documents
28
Technical Support
28
Piece Parts Availability
28
Radio Model Chart and Specifications
29
Radio Model Information
29
Chapter 2 Radio Power Distribution
31
Figure 2-1. DC Power Distribution Block Diagram
31
Chapter 3 Keypad
33
Controller Board
33
Figure 3-1. Keypad Block Diagram
33
Figure 3-2. Controller Block Diagram
34
MCU Digital
34
Real Time Clock
34
Circuit Description
35
Figure 3-3. RTC Circuit
35
MODB/VSTBY Supply
35
Audio/Signaling
36
Chapter 4 UHF Band 1 Theory of Operation
37
Transmitter
37
Figure 4-1. Transmitter Block Diagram
37
General
37
Power Amplifier
37
Antenna Matching Network
38
Antenna Switch
38
Harmonic Filter
38
Power Control Integrated Circuit (PCIC)
38
Receiver
39
Figure 4-2. UHF Receiver Block Diagram
39
Receiver Front-End
39
Receiver Back-End
40
Frequency Generation Circuitry
40
Figure 4-3. Frequency Generation Unit Block Diagram
40
Synthesizer
41
Figure 4-4. Synthesizer Block Diagram
41
Voltage-Controlled Oscillator (VCO)
42
Figure 4-5. VCO Block Diagram
42
Chapter 5 UHF Band 2 Theory of Operation
45
Transmitter
45
Figure 5-1. Transmitter Block Diagram
45
General
45
Power Amplifier
45
Antenna Matching Network
46
Antenna Switch
46
Harmonic Filter
46
Power Control Integrated Circuit (PCIC)
46
Receiver
47
Figure 5-2. UHF Receiver Block Diagram
47
Receiver Front-End
47
Receiver Back-End
48
Frequency Generation Circuitry
48
Figure 5-3. Frequency Generation Unit Block Diagram
48
Synthesizer
49
Figure 5-4. Synthesizer Block Diagram
49
Voltage-Controlled Oscillator (VCO)
50
Figure 5-5. VCO Block Diagram
50
Chapter 6 VHF Theory of Operation
53
Transmitter
53
Figure 6-1. Transmitter Block Diagram
53
General
53
Power Amplifier
53
Antenna Matching Network
54
Antenna Switch
54
Harmonic Filter
54
Power Control Integrated Circuit (PCIC)
54
Receiver (for All Models Except those with PCB 8486473Z04)
55
Figure 6-2. VHF Receiver Block Diagram
55
Receiver Front-End
55
Automatic Gain Control Circuit
56
Receiver Back-End
56
Receiver (for Models with PCB 8486473Z04)
57
Figure 6-3. VHF Receiver Block Diagram
57
Receiver Back-End
58
Receiver Front-End
58
Automatic Gain Control Circuit
59
Frequency Generation Circuitry
60
Figure 6-4. Frequency Generation Unit Block Diagram
60
Synthesizer
61
Figure 6-5. Synthesizer Block Diagram
61
Voltage-Controlled Oscillator (VCO)
62
Figure 6-6. VCO Block Diagram
62
Chapter 7 Low Band, 800 Mhz, Passport & 900 Mhz Theory of Operation
65
Introduction
65
Low Band Transmitter
65
Figure 7-1. Low Band Transmitter Block Diagram
65
Power Amplifier (PA)
65
Antenna Matching Transformer
66
Antenna Switch
66
Electrostatic Discharge (ESD) Protection Circuit
66
Harmonic Filter
66
Power Control Integrated Circuit (PCIC)
66
Temperature Cut Back Circuit
66
Low Band Receiver
67
Figure 7-2. Low Band Receiver Block Diagram
67
Receiver Front-End
67
Automatic Gain Control (AGC)
68
Frequency Generation Circuit
68
Receiver Back-End
68
Synthesizer
69
Figure 7-3. Low Band Frequency Generation Unit Block Diagram
69
Voltage Control Oscillators (VCO)
70
Buffer
70
Figure 7-4. Low Band Synthesizer Block Diagram
70
Receive VCO
70
Transmit VCO
70
Diplexer/Output Filters
71
Prescalar Feedback
71
800 Mhz Transmitter
71
Figure 7-5. 800 Mhz Transmitter Block Diagram
71
Power Amplifier
71
Antenna Switch
72
Harmonic Filter
72
Power Control Integrated Circuit (PCIC)
72
800 Mhz Receiver
73
Figure 7-6. 800 Mhz Receiver Block Diagram
73
Receiver Front-End
73
Automatic Gain Control Circuit
74
Receiver Back-End
74
Figure 7-7. 800 Mhz Frequency Generation Unit Block Diagram
75
Frequency Generation Circuit
75
Synthesizer
76
Figure 7-8. 800 Mhz Synthesizer Block Diagram
76
Figure 7-9. 800 Mhz VCO Block Diagram
77
Voltage Control Oscillator (VCO)
77
Trunked Radio Systems
78
LTR™ Trunked Systems
78
MPT Trunked Systems
78
Privacy Plus Trunked Systems
78
Keyboard Circuit
79
Low Speed Data Filter
79
Microcontroller (MCU)
79
Passport™ Trunked Systems
79
Power Supplies
79
Backlight Driver and Led's
80
Voice Storage
80
900 Mhz Transmitter
80
Figure 7-10. Transmitter Block Diagram
80
Antenna Switch
81
Harmonic Filter
81
Power Amplifier
81
Power Control Integrated Circuit (PCIC)
81
900 Mhz Receiver
82
Figure 7-11. 900 Mhz Receiver Block Diagram
82
Receiver Front-End
82
Hear Clear IC
83
Receiver Back-End
83
Automatic Gain Control Circuit
84
Hear Clear Routing of Data/Signaling
84
Receive Path for Radios with Hear Clear
84
Frequency Generation Circuitry
85
Figure 7-12. Frequency Generation Unit Block Diagram
85
900 Mhz Synthesizer
86
Figure 7-13. Synthesizer Block Diagram
87
900 Mhz Voltage Control Oscillator (VCO)
88
Figure 7-14. VCO Block Diagram
88
Chapter 8 Maintenance
91
Introduction
91
Preventive Maintenance
91
Inspection
91
Cleaning
91
Safe Handling of CMOS and LDMOS
92
General Repair Procedures and Techniques
92
Recommended Test Tools
94
Replacing the Circuit Board Fuse
95
Figure 8-1. Uhf/Vhf/Low Band/800 Mhz/900 Mhz Circuit Board Fuse Locations
96
Removing and Reinstalling the Circuit Board
97
Power up Self-Test Error Codes
97
Figure 8-2. Circuit Board Removal and Reinstallation
97
UHF Band 1 Troubleshooting Charts
99
Troubleshooting Flow Chart for Controller for All Models Except
99
Troubleshooting Flow Chart for Controller for Models with PCB 8486458Z03
100
PCB 8486458Z03 (Sheet 1 of 2)
101
Troubleshooting Flow Chart for Receiver for All Models Except
101
PCB 8486458Z03 (Sheet 2 of 2)
102
Troubleshooting Flow Chart for Receiver for All Models Except
102
Troubleshooting Flow Chart for Receiver, for Models with PCB 8486458Z03 (Sheet 1 of 2)
103
Troubleshooting Flow Chart for Receiver, for Models with PCB 8486458Z03 (Sheet 2 of 2)
104
Troubleshooting Flow Chart for Transmitter
105
Troubleshooting Flow Chart for Synthesizer
106
Troubleshooting Flow Chart for VCO
107
UHF Band 2 Troubleshooting Charts
108
Pcb 8486686Z02
108
Troubleshooting Flow Chart for Controller for All Models
108
Troubleshooting Flow Chart for Controller for Models with PCB 8486686Z02
109
Troubleshooting Flow Chart for Receiver, for All Models Except those with PCB 8486686Z02 (Sheet 1 of 2)
110
Troubleshooting Flow Chart for Receiver, for All Models Except those with PCB 8486686Z02 (Sheet 2 of 2)
111
Troubleshooting Flow Chart for Receiver, for Models with PCB 8486686Z02 (Sheet 1 of 2)
112
Troubleshooting Flow Chart for Receiver, for Models with PCB 8486686Z02 (Sheet 2 of 2)
113
Troubleshooting Flow Chart for Transmitter
114
Troubleshooting Flow Chart for Synthesizer
115
Troubleshooting Flow Chart for VCO
116
VHF Troubleshooting Charts
117
Troubleshooting Flow Chart for Controller for All Models
117
Troubleshooting Flow Chart for Controller for Models with PCB 8486473Z04
118
Except those with PCB 8486473Z04
119
Troubleshooting Flow Chart for Receiver, for All Models
119
Troubleshooting Flow Chart for Receiver, for All Models Except those with PCB 8486473Z04 (Sheet 1 of 2)
119
Troubleshooting Flow Chart for Receiver, for All Models Except those with PCB 8486473Z04 (Sheet 2 of 2)
120
Troubleshooting Flow Chart for Receiver for Models with PCB 8486473Z04 (Sheet 1 of 2)
121
Troubleshooting Flow Chart for Receiver for Models with PCB 8486473Z04 (Sheet 2 of 2)
122
Troubleshooting Flow Chart for Transmitter
123
Troubleshooting Flow Chart for Synthesizer
124
Troubleshooting Flow Chart for VCO
125
Low Band Troubleshooting Charts
126
Troubleshooting Flow Chart for Controller
126
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
127
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
128
Troubleshooting Flow Chart for Transmitter
129
Troubleshooting Flow Chart for Synthesizer
130
Troubleshooting Flow Chart for VCO
131
800 Mhz Troubleshooting Charts
132
Troubleshooting Flow Chart for Controller
132
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
133
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
134
Troubleshooting Flow Chart for Transmitter
135
Troubleshooting Flow Chart for Synthesizer
136
Troubleshooting Flow Chart for VCO
137
Passport Trunking Troubleshooting Chart
138
Keypad Troubleshooting Chart
139
Mhz Troubleshooting Charts
140
Troubleshooting Flow Chart for Controller (Sheet 2 of 2)
141
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
142
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
143
Troubleshooting Flow Chart for VCO
146
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Detailed Service Manual
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Motorola HT Series Specifications
General
Brand
Motorola
Model
HT Series
Category
Two-Way Radio
Language
English
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