Icom IC-T90A Marine Radio Official Manual - Inside Views

SECTION 2 INSIDE VIEWS

• LOGIC UNIT

Top view

RESET IC

(IC142: S-80928CNMC)

EEPROM

(IC2: HN58X24128FPI, Q2: UN9115)

• LOGIC UNIT

Bottom view

Crystal oscillator for CPU clock

(X1: CR-687, 6.7584 MHz, Q40: UN9215)

CPU

(IC1: M30220MA-114RP)

Microphone mute (Q310: XP6501)

Microphone amplifier (Q311: XP5601, Q312: XP6501)

AF regulator (Q201: 2SB1201, Q202: XP1501)

+3 regulator (Q8: 2SB1132, Q9: XP1501)

+3C regulator (Q142: XP1501, Q145: 2SB1132, D143: MA2S111)

CPU3 regulator (IC141: NJM2370U32)

440 MHz band modulation switch (Q304: 2SJ364)

145 MHz band modulation switch (Q305: 2SJ364)

50 MHz band modulation switch (Q342: 2SJ364)

2 - 1

Image 6

Icom IC-T90A manual Inside Views, Logic Unit, Top view, Bottom view

Contents

IC-t90a Repair Notes IntroductionOrdering Parts Sample Order Table of Contents Specifications GeneralTransmitter WFM ReceiverFrequency MHz WFM Top view Inside ViewsLogic Unit Bottom view AF Unit RF UnitTop view Bottom view Disassembly Instructions Removing the rear panel Removing the AF unit Circuit Description Receiver Circuits 4 1ST Mixer and 1ST if Circuits RF, AF and VCO Units 5 2ND if and Demodulator Circuits AF UnitRF Circuit AF Amplifier Circuit AF Unit Squelch Circuitaf and Logic Units2ND if and Demodulator Circuit Transmitter Circuits General PLL CircuitsAPC Circuit RF Unit APC Circuit VCO Divider Circuit VCO and RF Units PLL Circuit Port Allocations Power Supply Circuits2 R3V Switch IC AF Unit IC51 Voltage Line CPU Logic Unit IC1 LCD CtselDtcs SEG35 Operation on the Output Power Adjustment Adjustment ProceduresOperation on the Adjustment Mode Preparation Connection JIGAD-92SMA VCO Trimmer AdjustmentPLL Lock Voltage L16 L456 VCO UnitRF Unit L19 Dial Adjustment Mode AdjustmentsReference Frequency Adjustment Mode Adjustments PH ch 53.900 MHz Transmitting 8V 145 MHz Displayed frequency Connect an amme 45 a R365 Logic UnitR325 R326 Ctcss Detector CoilTracking IC151, pin 12 SD line AF UnitCP0 L151 Displayed frequency Connect a DC volt Maximum voltage Adjustment Adjustment Condition Operation Meter Section Parts List Order Description Coil Eljre 3N9Z-F Ceramic ECJ0EB1H681K Connector AXK6S30445P Ceramic ECJ0EC1H060C Encoder Trimmer Tantalum ECST1EY474R Ceramic ECJ0EC1H2R5B Mechanical Parts and Disassembly AccessoriesChassis Parts Chassis Parts Logic UnitRF Unit AF Unit VCO Unit Diodes SEMI-CONDUCTOR InformationTransistors and Fets Name MC1 Microphone Board LayoutsTOP View DUP SP1 Logic unitBottom View SQL PTT RF Unit RF unit AF Unit VCO UnitEXT.SP EXT.MICREMOTO S253S252 Block Diagram Logic Unit Chassis Loop LPF HPF Drive BPF ANT FIL AMP Voltage Diagram 11 1 Logic Unit IC5 11 2 RF Unit 2SK3476 11 3 AF Unit BU4094BCFV URL 32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan