Icom IC-T90A manual Disassembly Instructions, Removing the rear panel Removing the AF unit

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SECTION 3 DISASSEMBLY INSTRUCTIONS

	1. Removing the rear panel		3. Removing the AF unit
	B		Vol lead F H
	Rear panel		Vol lead F H
	Rear panel	C	G Vol plate F
		C	G Vol plate F
	A
			Antenna
			plate
			F

AF unit

J251

Rear panel

Lock plate

qUnscrew 1 screw A (M2 ⋅ 4 mm, black).

wUnscrew 2 screws B (M2 ⋅ 20 mm, black), and 4 screws

C(M2 ⋅ 6 mm, black) from the rear panel.

eTake off the rear panel in the direction of the arrow.

2. Removing the LOGIC unit

	W1 (L)
E	Main seal
4	Main seal
4
J1		E
	3	E
5	3
5

qTake off the lock plate.

wUnsolder 5 points F at the antenna plate, vol plate and lead.

eUnscrew 1 screw G (2 ⋅ 4 mm, silver), and 2 screws H (M2 ⋅ 12 mm, black) from the AF unit.

rTake off the AF unit in the direction of the arrow to sepa- rate the rear panel.

4. Removing the RF unit

J

RF unit

Antenna rug

Antenna connector

6

2

1

D

LOGIC unit

qUnplug the flexible cable W1 from J1 on the LOGIC unit to separate the rear panel.

wTake off the main seal.

eUnsolder 2 points D at the speaker lead.

rUnscrew 6 screws E (2 ⋅ 4 mm, silver) to separate the LOGIC unit.

NOTE:

When you tighten 6 screws E, tighten those in turn of 1–6.

I

Rear panel

qUnsolder 2 points I at the antenna rug plate and anten- na connector.

wUnscrew 2 screws J (M2 ⋅ 4 mm, silver) from the FRONT panel.

eTake off the RF unit in the direction of the arrow to sepa- rate the rear panel.

3 - 1

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Contents IC-t90a Introduction Ordering PartsRepair Notes Sample OrderTable of Contents Transmitter SpecificationsGeneral Receiver Frequency MHzWFM WFMInside Views Logic UnitTop view 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 PLL Circuits APC Circuit RF UnitGeneral APC CircuitVCO Divider Circuit VCO and RF Units PLL CircuitPower Supply Circuits 2 R3V Switch IC AF Unit IC51Port Allocations Voltage LineCPU Logic Unit IC1 Ctsel DtcsLCD SEG35Adjustment Procedures Operation on the Adjustment ModeOperation on the Output Power Adjustment PreparationAD-92SMA ConnectionJIG Trimmer Adjustment PLL LockVCO VoltageVCO Unit RF UnitL16 L456 L19Adjustment Mode Adjustments ReferenceDial FrequencyAdjustment Mode Adjustments PH ch 53.900 MHz Transmitting 8V 145 MHz Displayed frequency Connect an amme 45 a Logic Unit R325R365 R326Ctcss Tracking DetectorCoil AF Unit CP0IC151, pin 12 SD line 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 Logic Unit RF UnitChassis Parts AF Unit VCO UnitSEMI-CONDUCTOR Information Transistors and FetsDiodes NameBoard Layouts TOP ViewMC1 Microphone DUPLogic unit Bottom ViewSP1 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