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MULTIBAND FM TRANSCEIVER

iC-t90a
INTRODUCTION
This service manual describes the latest service information for
the IC-T90A MULTIBAND FM TRANSCEIVER at the time of
publication.

MODEL VERSION SYMBOL
U.S.A. USA
General GEN
T90A
Canada CAN
S.E. Asia SEA

To upgrade quality, all electrical or mechanical parts and inter-
nal circuits are subject to change without notice or obligation.




DANGER
NEVER connect the transceiver to an AC outlet or to a DC
power supply that uses more than 12 V. Such a connection
could cause a fire hazard and/or electric.

DO NOT expose the transceiver to rain, snow or any liquids.

DO NOT reverse the polarities of the power supply when
connecting the tranceiver.

DO NOT apply an RF signal of more than 20 dBm (100 mW)
to the antenna connector. This could damage the transceiver s
front end.




ORDERING PARTS
Be sure to include the following four points when ordering
replacement parts:

1. 10-digit order numbers
2. Component part number and name
3. Equipment model name and unit name
4. Quantity required


1130006220 S.IC TC4W53FU IC-T90A LOGIC UNIT 1 piece
8930054290 2372 Main seal IC-T90A Chassis 5 pieces
Addresses are provided on the inside back cover for your
convenience.




REPAIR NOTES
1. Make sure a problem is internal before disassembling the transceiver.
2. DO NOT open the transceiver until the transceiver is disconnected from its power source.
3. DO NOT force any of the variable components. Turn them slowly and smoothly.
4. DO NOT short any circuits or electronic parts. An insulated tuning tool MUST be used for all adjustments.
5. DO NOT keep power ON for a long time when the transceiver is defective.
6. DO NOT transmit power into a signal generator or a sweep generator.
7. ALWAYS connect a 40 dB or 50 dB attenuator between the transceiver and a deviation meter or spectrum analyser when
using such test equipment.
8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver.
TABLE OF CONTENTS

SECTION 1 SPECIFICATIONS



SECTION 2 INSIDE VIEWS



SECTION 3 DISASSEMBLY INSTRUCTIONS



SECTION 4 CIRCUIT DESCRIPTION

4-1 RECEIVER CIRCUITS ................................................................................................... 4 - 1

4-2 TRANSMITTER CIRCUITS ............................................................................................ 4 - 4

4-3 PLL CIRCUITS................................................................................................................. 4 - 5

4-4 POWER SUPPLY CIRCUITS .......................................................................................... 4 - 7

4-5 PORT ALLOCATIONS ..................................................................................................... 4 - 7



SECTION 5 ADJUSTMENT PROCEDURES

5-1 PREPARATION................................................................................................................ 5 - 1

5-2 TRIMMER ADJUSTMENT ............................................................................................... 5 - 3

5-3 ADJUSTMENT MODE ADJUSTMENTS ......................................................................... 5 - 5



SECTION 6 PARTS LIST



SECTION 7 MECHANICAL PARTS AND DISASSEMBLY



SECTION 8 SEMI-CONDUCTOR INFORMATION



SECTION 9 BOARD LAYOUTS

9-1 LOGIC UNIT .................................................................................................................... 9 - 1

9-2 RF UNIT........................................................................................................................... 9 - 3

9-3 AF UNIT / VCO UNIT ...................................................................................................... 9 - 5



SECTION 10 BLOCK DIAGRAM



SECTION 11 VOLTAGE DIAGRAM
SECTION 1 SPECIFICATIONS

M GENERAL