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Motorola IC-T81A, IC-T81E SECTION 3 DISASSEMBLY INSTRUCTIONS

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SECTION 3 DISASSEMBLY INSTRUCTIONS

BChassis panel C

Sealing rubber

LOGIC unit

Chassis panel

LOGIC unit

Shield plate

•REMOVING THE CHASSIS PANEL

1Remove 1 knob A, and unscrew 1 nut B.

2Unscrew 2 screws C.

3Remove the chassis panel in the direction of the arrow.

•REMOVING THE LOGIC UNIT

1Remove the sealing rubber.

2Unsolder 1 point, D, to separate a SENSOR control.

3Unscrew 3 screws, E.

4Unplug J1 to separate LOGIC unit and RF unit.

5Remove the LOGIC unit in the direction of the arrow.

•REMOVING THE RF UNIT

1Unsolder 1 point, G, to separate [ANT] plug.

2Unscrew 8 screws, H, to separate the RF unit.

3Remove the RF unit in the direction of the thick arrow.

•REMOVING THE SHIELD PLATE

1Unsolder 10 points, F, to separate the shield plate and

LOGIC unit.

[ANT] plug

RF unit

Contents

Main INTRODUCTION DANGER ORDERING PARTS REPAIR NOTES TABLE OF CONTENTS MGENERAL MTRANSMITTER SECTION 1 SPECIFICATIONS MRECEIVER SECTION 2 INSIDE VIEWS ( ) SECTION 3 DISASSEMBLY INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS 4-1-1 DUPLEXER CIRCUIT (RF UNIT) 4-1-2 ANTENNASWITCHING CIRCUITS (RF UNIT) 4-1-3 50 MHz BAND RF CIRCUIT (RF UNIT) 4-1-5 440 MHz BAND RF CIRCUIT (RF UNIT) 4-1-6 1200 MHz BAND RF CIRCUIT (RF UNIT) 4-1-7 1ST MIXER CIRCUIT (RF UNIT) 4-1-8 2ND IF AND DEMODULATOR CIRCUITS (RF AND LOGIC UNITS) 4-1-9 AF AMPLIFIER CIRCUIT (LOGIC UNIT) 4-2 TRANSMITTER CIRCUITS 4-2-1 MICROPHON AMPLIFIER CIRCUIIT (LOGIC UNIT) 4-2-2 MODULATION CIRCUIT (VCO AND RF UNIT) 4-2-3 DRIVE/POWER AMPLIFIER CIRCUITS (RF UNIT) 4-2-4 APC CIRCUITS (RF UNIT) 4-3 PLL CIRCUITS 4-3-1 50 MHz BAND PLL CIRCUIT (RF UNIT) VOLTAGE LINE 4-3-2 144 MHz BAND PLL CIRCUIT 4-3-3 440 MHz BAND PLL CIRCUIT 4-5 PORT ALLOCATIONS 4-5-3 CPU (LOGIC UNIT; IC1) - SECTION 5 ADJUSTMENT PROCEDURES + CAUTION: 5-1 PREPARATION 5-2 PLL ADJUSTMENT Page 5-3 RECEIVER ADJUSTMENT Page Page RECEIVER ADJUSTMENT (Continued) LOGIC UNIT TOP VIEW R733 5-4 TRANSMITTER ADJUSTMENT LOGIC UNIT TOP VIEW R322 R338 R325 TRANSMITTER ADJUSTMENT (Continued) SECTION 6 PARTS LIST 6 - 1 6 - 2 6 - 3 6 - 4 6 - 5 6 - 6 6 - 7 6 - 8 [VCO BOARD] 6 - 9 6 - 10 [VCO BOARD] [VCO BOARD] 7 - 1 SECTION 7 MECHANICAL PARTS AND DISASSEMBLY EP3 [ACCESSORIES] [VCO UNIT] [CHASSIS PARTS] LOGIC unit VCO unit RF unit SECTION 8 SEMI-CONDUCTOR INFORMATION 8 - 1 9 - 1 SECTION 9 BOARD LAYOUTS L702 R733 9-1 LOGIC UNIT DS1 S1 J4 9-2 RF UNIT 9 - 3 C961 40 21 DC-DC MP1 C842 C815 IC802 C86 9-3 VCO BOARD 9 - 6 VCO BOARD BUS TX COMMON RX SECTION 10 BLOCK DIAGRAM 10 - 1 Page VCO BOARD BUS 10 - 1 TX SECTION 10 BLOCK DIAGRAM Q307 Q304 IC201 TA7368F XP4315 SECTION 11 VOLTAGE DIAGRAM 11-1 LOGIC UNIT 4 3 11 - 1 COMPLETE VIEW A 64 Q XC6371A500PR B SECTION 11 VOLTAGE DIAGRAM 11-1 LOGIC UNIT 11 - 1 Q322 Q311 VCO BOARD RF UNIT 11-2 RF UNIT CHG + - 50MHz 3SK292 1200MHz 3SK291 SC5195 VCO BOARD RF UNIT 11-2 RF UNIT INTRODUCTION DANGER ORDERING PARTS REPAIR NOTES