Tait TB8100 - Page 145

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TB8100 Service Manual Power Amplifier Fault Finding 145

Task 5 —

Additional Checks

for 12V PA

The circled numbers in the following instructions refer to Figure 8.7 on

page 147.

1. Check the DC input filter capacitors

b on the boost regulator board

for damage (e.g. overvoltage).

2. Check the DC supply

c to the 6W board.

3. Check the DC supply

d to the 60W board, including the ground

connection

Main Page

Default Chapter2
- Issue2
- Table of Contents3
- Tait Electronics Limited September8
Preface12
- Scope of Manual12
- Document Conventions12
- Associated Documentation13
- Publication Record14
1 Safety and Servicing Information15
- Personal Safety15
- Equipment Safety17
- Regulatory Information18
- General Servicing Information19
- Recommended Tools22
- Identifying Screw Types23
- Replacing Components25
2 Reciter Circuit Description27
- Figure 2.1 Reciter High Level Block Diagram28
- Digital Circuitry29
- Reference Switch35
- Receiver RF Circuitry - VHF Reciter38
- Receiver RF Circuitry - UHF Reciter42
- Exciter RF Circuitry47
- System Interface Boards54
- Figure 2.12 Reciter System Interface Board Block Diagram56
- Power Supply59
- Figure 2.13 Reciter Power Supply Block Diagram60
- Figure 2.14 Identifying the Circuitry on the Digital and System Interface Boards61
- Figure 2.15 Identifying the Circuitry on the RF Board - B and C Bands63
- Figure 2.16 Identifying the Circuitry on the RF Board - H Band65
- Figure 2.17 Identifying the Circuitry on the RF Board - K and L Bands67
3 Reciter Fault Finding69
- Identifying the Reciter70
- Figure 3.1 Identifying the Reciter Boards71
- Test Equipment72
- Figure 3.2 Recommended Test Equipment Set-Up73
- Software and Firmware Compatibility74
- Board Replacement75
- Initial Checks76
- Figure 3.3 Typical 12.8Mhz Clock Wave Form80
- Figure 3.4 Location of the 12.8Mhz Clock Test Point on the RF Board81
- Visual Inspection82
- Figure 3.5 Visual Inspection Points for the Reciter83
- Digital if84
- Receiver85
- Exciter86
- Audio89
- Figure 3.6 Recommended Test Equipment Set-Up for Audio Checks90
- Figure 3.7 Location of Audio Test Points on the Digital Board91
- Figure 3.8 Location of Audio Test Points on the System Interface Board94
- Final Tasks95
4 Reciter Disassembly and Reassembly99
- Screw Torque Settings100
- Removing the Covers100
- Removing the Front and Rear Panels100
- Tait Electronics Limited September101
- Refitting the Front and Rear Panels102
- Refitting the Covers102
5 Reciter Board Replacement103
- Replacing the System Interface Board104
- Figure 5.1 Replacing the System Interface Board106
- Figure 5.2 Reconnecting the Flexible Connector107
6 Reciter Spare Parts109
- Figure 6.1 Reciter Mechanical Assembly111
7 Power Amplifier Circuit Description113
- Figure 7.1 PA High Level Block Diagrams114
- Microprocessor Control Circuitry115
- RF Circuitry120
- Boost Regulator Circuitry (12V PA Only)122
- Figure 7.3 Identifying the Circuitry on the 28V PA Boards123
- Figure 7.4 Identifying the Circuitry on the 12V PA Boards125
8 Power Amplifier Fault Finding127
- Safety Precautions128
  - Personal Safety128
  - Equipment Safety128
- Identifying the PA129
- Figure 8.1 Identifying the Circuit Boards in a 28V PA130
- Figure 8.2 Identifying the Circuit Boards in a 12V PA131
- Test Equipment132
- Figure 8.3 Recommended Test Equipment Set-Up for Initial Checks - 28V PA134
- Figure 8.4 Recommended Test Equipment Set-Up for Initial Checks - 12V PA135
- Software and Firmware Compatibility136
- Board Replacement137
- Initial Checks138
- Figure 8.5 Connections on the Fan Contact Board140
- Visual Inspection144
- Figure 8.6 Visual Inspection Points for a 28V PA146
- Figure 8.7 Additional Visual Inspection Points for a 12V PA147
- Control Board148
- Figure 8.8 Recommended Test Equipment Set-Up for Circuit Board Checks - 28V PA149
- Figure 8.9 Recommended Test Equipment Set-Up for Circuit Board Checks - 12V PA150
- Figure 8.10 Location of Test Points on the Control Board153
- Board155
- Figure 8.11 Location of Test Points on the 6W Board155
- Splitter and Combiner Boards (100W PA Only)160
- Figure 8.12 Location of Test Points on the Splitter and Combiner Boards160
- Board162
- Figure 8.13 Location of Test Points on the 60W Board162
- Low Pass Filter and Directional Coupler Board165
- Figure 8.14 Location of the Test Points and Input Coupling Components on the Lpf/Directional Coupler Board166
- Boost Regulator Board (12V PA Only)168
- Figure 8.15 Test Equipment Set-Up for the Boost Regulator Board169
- Figure 8.16 Location of Test Points on the Boost Regulator Board169
- Final Tasks170
9 Power Amplifier Disassembly and Reassembly173
- Screw Torque Settings174
- Removing the Airflow Duct and Cover174
- Figure 9.1 Removing the Airflow Duct and Cover175
- Removing the Front Panel176
- Figure 9.2 Removing the Front Panel176
- Refitting the Front Panel177
- Refitting the Cover and Airflow Duct177
10 Power Amplifier Board Replacement179
- Circuit Board Connecting Links180
- Replacing the 6W Board180
- Figure 10.1 Circuit Board Connecting Links180
- Figure 10.2 Replacing the 6W Board181
- Replacing the 60W Board182
- Figure 10.3 Replacing the 60W Board183
- Replacing the 60W RF Power Transistor184
- Figure 10.4 Replacing the 60W RF Power Transistor185
- Replacing the Control Board186
- Figure 10.5 Replacing the Control Board187
- Replacing the Low Pass Filter/Directional Coupler Board188
- Figure 10.6 Replacing the Lpf/Directional Coupler Board189
- Replacing the Splitter/Combiner Boards190
- Figure 10.7 Replacing the Splitter/Combiner Boards191
- Replacing the Interconnect Boards192
- Replacing the Boost Regulator Board in a 12V PA193
- Figure 10.8 Replacing the Boost Regulator Board in a 12V PA194
11 Power Amplifier Spare Parts195
- Figure 11.1 PA Mechanical Assembly - 28V Pas197
- Figure 11.2 PA Mechanical Assembly - 12V Pas198
- Figure 11.3 PA Mechanical Assembly - Covers and Airflow Duct199
12 Power Management Unit Circuit Description201
- Figure 12.1 PMU High Level Block Diagram202
- Microprocessor Control Circuitry203
- Figure 12.2 PMU Microprocessor Functional Block Diagram204
- AC Module206
- Figure 12.3 PMU AC Module Block Diagram206
- DC Module208
- Figure 12.4 PMU DC Module Block Diagram208
- Figure 12.5 Identifying the Circuitry in the AC Module211
- Figure 12.6 Identifying the Circuitry in the DC Module213
13 Power Management Unit Fault Finding215
- Safety Precautions216
  - Personal Safety216
  - Equipment Safety216
- Identifying the PMU217
  - Colour Coding of Circuit Boards and Cards217
  - Figure 13.1 Identifying the Boards and Cards in the PMU218
- Test Equipment219
- Software and Firmware Compatibility220
- Board Replacement221
- Initial Checks222
- Figure 13.2 Recommended Test Equipment Set-Up for Initial and DC Checks222
- Figure 13.3 Location of Indicator Leds and DC Output Connectors223
- Figure 13.4 Connections on the Fan Contact Board227
- Auxiliary Power Supply Board229
- DC Module230
- AC Module240
- Figure 13.10 Location of Test Points on the AC Converter Board241
- Figure 13.11 AC Converter Test Equipment Set-Up243
- Figure 13.12 Typical Gate-Source and Drain-Source Waveforms for Fets244
- 13.10 Modifying the PFC Control Card246
- Figure 13.13 Modifying the PFC Control Card for Testing the AC Converter246
- 13.11 Final Tasks247
14 Power Management Unit Disassembly and Reassembly249
- Safety Precautions249
  - Personal Safety249
  - Equipment Safety250
- Mechanical Overview251
- Screw Torque Settings252
- Removing the Top and Bottom Covers252
- Removing the Front and Rear Panels253
- Figure 14.1 Removing the Front and Rear Panels253
- Disconnecting the AC and DC Modules254
- Reconnecting the AC and DC Modules254
- Figure 14.2 Disconnecting the AC and DC Modules255
- Figure 14.3 Reconnecting the AC and DC Modules256
- Refitting the Front and Rear Panels257
- Refitting the Top and Bottom Covers258
15 Power Management Unit Card and Board Replacement259
- Safety Precautions259
  - Personal Safety259
  - Equipment Safety260
- Colour Coding of Circuit Boards and Cards260
- Replacing the Plug-In Cards261
- Figure 15.1 Replacing the Plug-In Cards263
- Replacing the Auxiliary Power Supply Board265
- Figure 15.2 Replacing the Auxiliary Power Supply Board265
16 Power Management Unit Spare Parts267
- Figure 16.2 PMU Mechanical Assembly - Sheet 2270
17 Control Panel Circuit Description271
- Control Circuitry272
- Audio Circuitry272
- Power Save273
- Power Supply273
- Figure 17.1 Standard, Dual Base Station, and Power Save Control Panel High Level274
- Figure 17.2 Multi-Reciter Control Panel High Level Block Diagram275
18 Control Panel Servicing277
- Identifying the Control Panel278
- Screw Torque Settings278
- Replacing the Circuit Board279
- Figure 18.1 Replacing the Control Panel Board280
- Figure 18.2 Reconnecting the Flexible Connector281
- Replacing the Speaker282
- Figure 18.3 Replacing the Speaker283
- Spare Parts284

Tait TB8100 - Page 145

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