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152 Power Amplifier Fault Finding TB8100 Service Manual

7. Measure the FINALX

-BIAS-MICRO voltage of the final

transistor(s) at the following test points:

■ 50W PA pin 2 of SK106

■ 100W PA final 1 pin 2 of SK105

■ 100W PA final 2 pin 2 of SK107.

The voltage should be 4V (typical). If it is, go to “6W Board” on

page 155. If it is 0V, replace the control board. If it is greater than

0V, but less than 4V (typical), go to “60W Board” on page 162.

1. X = final 1 or final 2.

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 152

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