Icom IC-T90A manual Introduction, Ordering Parts, Repair Notes, Sample Order

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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

T90A

General

GEN

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

<SAMPLE ORDER>

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.

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Contents IC-t90a Repair Notes IntroductionOrdering Parts Sample OrderTable of Contents Transmitter SpecificationsGeneral WFM ReceiverFrequency MHz WFMTop view Inside ViewsLogic Unit Bottom viewTop view Bottom view AF UnitRF Unit Disassembly Instructions Removing the rear panel Removing the AF unitCircuit Description Receiver CircuitsRF Circuit 4 1ST Mixer and 1ST if Circuits RF, AF and VCO Units5 2ND if and Demodulator Circuits AF Unit 2ND if and Demodulator Circuit AF Amplifier Circuit AF UnitSquelch Circuitaf and Logic Units Transmitter Circuits General PLL CircuitsAPC Circuit RF Unit APC CircuitVCO Divider Circuit VCO and RF Units PLL CircuitPort Allocations Power Supply Circuits2 R3V Switch IC AF Unit IC51 Voltage LineCPU Logic Unit IC1 LCD CtselDtcs SEG35Operation on the Output Power Adjustment Adjustment ProceduresOperation on the Adjustment Mode PreparationAD-92SMA ConnectionJIG VCO Trimmer AdjustmentPLL Lock VoltageL16 L456 VCO UnitRF Unit L19Dial Adjustment Mode AdjustmentsReference FrequencyAdjustment Mode Adjustments PH ch 53.900 MHz Transmitting 8V 145 MHz Displayed frequency Connect an amme 45 a R365 Logic UnitR325 R326Ctcss Tracking DetectorCoil IC151, pin 12 SD line AF UnitCP0 L151Displayed frequency Connect a DC volt Maximum voltage Adjustment Adjustment Condition Operation MeterSection Parts List Order DescriptionCoil Eljre 3N9Z-F Ceramic ECJ0EB1H681K Connector AXK6S30445P Ceramic ECJ0EC1H060C Encoder Trimmer Tantalum ECST1EY474R Ceramic ECJ0EC1H2R5B Chassis Parts Mechanical Parts and DisassemblyAccessories Chassis Parts Logic UnitRF Unit AF Unit VCO UnitDiodes SEMI-CONDUCTOR InformationTransistors and Fets NameMC1 Microphone Board LayoutsTOP View DUPSP1 Logic unitBottom View SQL PTTRF Unit RF unit EXT.SP EXT.MICREMOTO AF UnitVCO Unit S253S252 Block Diagram Logic UnitChassis Loop LPF HPF Drive BPF ANT FIL AMPVoltage Diagram 11 1 Logic UnitIC5 11 2 RF Unit 2SK347611 3 AF Unit BU4094BCFVURL 32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan