EFJohnson 001-9800-001 User Manual

TABLE OF CONTENTS (CONT’D)

iii

February 2001

Part No. 001-9800-001

TABLE OF CONTENTS

3.10

SYNTHESIZER CIRCUIT DESCRIPTION

(800/900 MHz MODELS)

. . . . . . . . . . . . . . . 3-22

Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3-22
Voltage-Controlled Oscillator  . . . . . . . . . . . . .   3-22
VCO and TCXO Modulation . . . . . . . . . . . . . .   3-24
Active Filter (Q800) . . . . . . . . . . . . . . . . . . . . .   3-25
Buffer Amplifier (Q801), Tx/Tx Switch

(CR801/CR802) . . . . . . . . . . . . . . . . . . . . . . 3-25

Synthesizer Integrated Circuit (U804) . . . . . . .   3-26
Lock Detect  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3-27
Charge Pump  . . . . . . . . . . . . . . . . . . . . . . . . . .   3-27
Shift Register (U800, U801) and Digital

Potentiometer (U802) Programming . . . . . . 3-27

3.11

RECEIVER CIRCUIT DESCRIPTION

(800/900 MHz MODELS)

. . . . . . . . . . . . . . . 3-27

Front End Filter  . . . . . . . . . . . . . . . . . . . . . . . .   3-27
RF Amplifier (Q201)  . . . . . . . . . . . . . . . . . . . .   3-27
First Mixer (Q202), Crystal Filter (Z204)  . . . .   3-28
Second Mixer/Detector (U201)  . . . . . . . . . . . .   3-28

3.12

TRANSMITTER CIRCUIT DESCRIPTION

(800/900 MHz MODELS)

. . . . . . . . . . . . . . . 3-29

Predriver (Q506), Driver (Q507) . . . . . . . . . . .   3-29
Power Amplifier Module (U600), Final (Q651) 3-30
Antenna Switch  . . . . . . . . . . . . . . . . . . . . . . . .   3-30
Directional Coupler, Low-Pass Filter. . . . . . . .   3-30
Power Control (U500A/B, Q500-Q503)  . . . . .   3-31

SERVICING

4.1

GENERAL

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Periodic Checks  . . . . . . . . . . . . . . . . . . . . . . . . .   4-1
Schematic Diagrams and Component Layouts. .   4-1
Replacement Parts  . . . . . . . . . . . . . . . . . . . . . . .   4-1
Configuring Transceiver for Testing  . . . . . . . . .   4-1

4.2

SURFACE MOUNTED DEVICES (SMDs)

. . 4-1

Servicing Techniques . . . . . . . . . . . . . . . . . . . . .   4-1
Identifying SMD Resistors . . . . . . . . . . . . . . . . .   4-1
SMD Capacitor Identification  . . . . . . . . . . . . . .   4-2
SMD Inductor Identification  . . . . . . . . . . . . . . .   4-3
Transistor/Diode Identification  . . . . . . . . . . . . .   4-3

4.3

SYNTHESIZER TROUBLESHOOTING

. . . . 4-3

Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4-3
Reference Oscillator (U806). . . . . . . . . . . . . . . .   4-4
VCO Module  . . . . . . . . . . . . . . . . . . . . . . . . . . .   4-4
Synthesizer IC (U804)  . . . . . . . . . . . . . . . . . . . .   4-4
Determining Synthesizer Counter Divide

Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.4

RECEIVER SERVICING

. . . . . . . . . . . . . . . . . . 4-5

4.5

TRANSMITTER SERVICING

. . . . . . . . . . . . . 4-5

4.6

AUDIO/LOGIC BOARD SERVICING

. . . . . . . 4-5

Digital Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Analog Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

PARTS LIST

Exploded Views

Front Panel  . . . . . . . . . . . . . . . . . . . . . . . . . .  5-31
Front and Top . . . . . . . . . . . . . . . . . . . . . . . .  5-32
Bottom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5-32
Remote Control Unit . . . . . . . . . . . . . . . . . . .  5-33
Remote Transceiver  . . . . . . . . . . . . . . . . . . .  5-33

SCHEMATIC DIAGRAMS AND

COMPONENT LAYOUTS

Amplified Dynamic Microphone  . . . . . . . . . . . .  6-2
Transceiver Top Photo  . . . . . . . . . . . . . . . . . . . .  6-3
Transceiver Bottom Photo. . . . . . . . . . . . . . . . . .  6-3
Interconnect Schematic. . . . . . . . . . . . . . . . . . .  6-4
Interface Board Layout. . . . . . . . . . . . . . . . . . .  6-4
Display Board

Top View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Bottom View . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

RPI (P.N. 023-9800-000)

Board Layout. . . . . . . . . . . . . . . . . . . . . . . . . .  6-6
Schematic  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6-6
Programming Cable (P.N. 597-2002-200) . . .  6-6

Component Locator Guides

UHF RF Board  . . . . . . . . . . . . . . . . . . . . . . . .  6-7
800/900 MHz RF Board . . . . . . . . . . . . . . . .  6-10
Audio/Logic Board . . . . . . . . . . . . . . . . . . . .  6-12

430-470 MHz RF

RF Board Schematic (Revised Board . . . . . .  6-15
PA Board Schematic (25W) . . . . . . . . . . . . .  6-15
RF Board Layout (Revised Board) . . . . . . . .  6-16
VCO Board Layout . . . . . . . . . . . . . . . . . . . .  6-17
PA Board Layout (25W) . . . . . . . . . . . . . . . .  6-17
PA Board Schematic (40W) . . . . . . . . . . . . .  6-18
PA Board Layout (40W) . . . . . . . . . . . . . . . .  6-19
RF Board Schematic (Unrevised Board)  . . .  6-20
RF Board Layout (Unrevised Board) . . . . . .  6-21