Icom IC-T81A Service Manual Download Page 38

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BOTTOM VIEW

9 - 2

C76

R334

R210

C209

R209

C208

R203

C17

C207

C75

Q201

Q308

Q202

R205

R204

R342

C162

R208

R207

R211

R343

C205

IC3

C709

IC701

C913

C910

C912

C909

C706

C737

C703

C712

R727

R713

R714

C701

C319

R267

R250

C318

R318

R196

R362

R361

R253

R215

R335

C325

C310

R312

C308

R251

C250

R252

R320

C907

C906

C707

C700

C714

C715

C720

C243

C313

C217

C215

C220

C201

C214

IC202

C213

C210

IC201

C212

C206

C361

C248

C309

C914

R717

R726

R729

C249

R249

R315

R319

R363

R254

R197

R212

R206

R201

C251

C362

C324

C323

R316

R317

R314

R336

C312

R313

C314

C307

R706

R715

C708

D702

D701

Q702

IC751

C253

C252

C216

D304

Q361

Q303

Q302

C316

C317

C718

Q753

C306

C31

C904

C903

FI701

S401

S402

C147

IC4

C142

C149

R301

R306

R307

R309

R918

R39

R144

C148

C923

C141

C150

C917

R24

R38

R23

R32

R27

R28

R31

R17

R33

R34

R36

R12

R10

R14

R13

R148

C10

R142

R30

R333

C13

C145

R302

R51

R145

C21

R324

R341

R53

R54

R55

R56

R21

R22

R16

R42

R26

R25

R37

C93

C92

C91

C90

C151

R143

146

D143

D144

C143

C315

R31

R310

R304

R303

C304

R308

Q301

Q142

C152

Q307

C919

C11

C303

C301

C305

C146

C12

C302

IC301

Q145

IC142

IC141

IC1

C204

C203

R202

C202

EURDEV

FSET

PLST2

GND

MOD

GND

BDET

PDA1/UL

PLST1

LOCKV

VCC

PDA2/UL

+3C

GND

PSET

GND

IFIN

DC-DC

GND

6MVCO

CHGC

R+3

GND

WFM

12VCO

TXC

UVCO

VHVCO

TUNE

AGC

ATA

IOST

THERM

GND

2NDLO

J1 to RF unit J4

Summary of Contents for IC-T81A

Page 1: ...SERVICE MANUAL MULTIBAND FM TRANSCEIVER...

Page 2: ...ZK IC T81A E Chassis 10 pieces Addresses are provided on the inside back cover for your convenience 1 Make sure a problem is internal before disassembling the transceiver 2 DO NOT open the transceiver...

Page 3: ...4 5 4 5 PORT ALLOCATIONS 4 6 SECTION 5 ADJUSTMENT PROCEDURES 5 1 PREPARATION 5 1 5 2 PLL ADJUSTMENT 5 2 5 3 RECEIVER ADJUSTMENT 5 4 5 4 TRANSMITTER ADJUSTMENT 5 8 SECTION 6 PARTS LIST SECTION 7 MECHA...

Page 4: ...ht with BP 197 Ant 290 g 10 2 oz M TRANSMITTER Output power at 13 5 V DC High 5 0 W typical 1 0 W at 1200 MHz band Low 1 0 W typical 0 1 W at 1200 MHz band Modulation system Variable reactance modulat...

Page 5: ...d AM 50 MHz only Less than 0 56 V Threshold WFM Less than 5 6 V Threshold Selectivity except WFM More than 15 kHz 6 dB Less than 30 kHz 60 dB Spurious and image rejection ratio 50 144 MHz More than 60...

Page 6: ...1 TA7368F AF volume IC202 M5222FP AF mute switch Q361 2SJ364 CPU IC1 M38267M8LGP BOTTOM VIEW VCO circuit 1st mixer IC601 PC2757T WFM RF amplifier circuit APC sensor drive amplifier Q911 UN9215 Q913 XP...

Page 7: ...E LOGIC UNIT 1 Remove the sealing rubber 2 Unsolder 1 point D to separate a SENSOR control 3 Unscrew 3 screws E 4 Unplug J1 to separate LOGIC unit and RF unit 5 Remove the LOGIC unit in the direction...

Page 8: ...MHz Thus transmit signals are blocked from entering the receiv er circuits The antenna switching circuit employs a 1 4 type diode switching system The passed signals are then applied to each RF ampli...

Page 9: ...components The filtered 1st IF signal is applied to the IF amplifier IC701 The amplified signal is applied to the 2nd mixer circuit LOGIC unit IC701 pin 16 WFM band The RF signals are mixed with 1st L...

Page 10: ...e filter section amplifies and filters noise components The filtered signals are applied to the noise detector section and output from IC701 pin 13 as NOISE signal The NOISE signal from IC701 pin 13 i...

Page 11: ...and is then amplified at the power amplifier Q922 to obtain 5 0 W of RF power The amplified signal is passed through the antenna switch ing circuit D101 and D102 low pass filters and high pass filters...

Page 12: ...signal at the 440 VCO circuit VCO unit Q321 Q322 D321 and Q322 is amplified at the buffer amplifiers VCO unit Q323 The amplified signal is applied to the PLL IC IC801 pin 19 via a buffer amplifier Q8...

Page 13: ...tter circuit Buff Q816 Pin Port Description number name 4 5 6 7 11 12 13 14 Q1 Q2 Q3 Q4 Q8 Q7 Q6 Q5 Outputs VHVCO3 regulator control signal Outputs VLVCO3 regulator control signal Outputs 6MVCO3 regul...

Page 14: ...strobe signals to the PLL IC2 RF unit IC802 pin5 Outputs strobe signals to the PLL IC1 RF unit IC801 pin 3 Output port for the cloning signal 20 21 22 23 24 25 26 27 28 29 30 31 32 33 39 41 42 43 46...

Page 15: ...QUIPMENT DC power supply RF power meter terminated type Frequency counter FM deviation meter GRADE AND RANGE Output voltage 13 5 V DC Current capacity 3 A or more Measuring range 1 10 W Frequency rang...

Page 16: ...MHz USA 1 only 435 000 MHz ohter Connect an SSG to the antenna connector and set as Level 1 mV 47dBm Modulation OFF Receiving RF Top Pannel LOGIC Connect the DC voltmeter or an oscilloscope to VLV Con...

Page 17: ...ULV PLL lock voltage check point for 440 MHz PLL lock voltage check point for 1200 MHz RF UNIT BOTTOM VIEW 6MLV PLL lock voltage check point for 50 MHz TX RF UNIT TOP VIEW L702 Detector Output voltag...

Page 18: ...z Modulation 1 kHz Receiving Displayed frequency 107 000 MHz Receiving Displayed frequency 108 000 MHz Set an SSG as Frequency 108 000 MHz Level 1 0 V AM 107 dBm Modulation 1 kHz Mod depth 30 Receivin...

Page 19: ...5 5 LOGIC UNIT TOP VIEW 50 MHz WFM BAND AIR BAND and 145 MHz Sensitivity check point SD...

Page 20: ...layed frequency 92 000 MHz SEA USA 1 98 000 MHz EUR UK ITA AUS Connect the SSG to the antenna connector and set as Level 2 V 101 dBm Modulation 1 kHz Deviation 52 5 kHz Connect a terminator to the SP...

Page 21: ...level for the S meter to S3 Receiving Increase an SSG output level Receiving Displayed frequency 445 000 MHz USA 1 435 000 MHz other Connect the SSG to the antenna connector and set as Level 0 1 V 12...

Page 22: ...cy 1270 000 MHz Output power High Transmitting Output power Low Transmitting Top panel Top panel Top panel Top panel Connect an RF power meter to the antenna connector Connect an RF power meter to the...

Page 23: ...ransmitting Displayed frequency 445 000 MHz USA 1 only 435 000 MHz AUS SEA only Push D key while transmitting Transmitting Displayed frequency 435 000 MHz Push center of the multi func tion key while...

Page 24: ...GEJ 103 X 10 k R9 7030005110 S RESISTOR ERJ2GEJ 224 X 220 k R10 7030005220 S RESISTOR ERJ2GEJ 223 X 22 k R12 7030005840 S RESISTOR RR0510R 473 D 47 k R13 7030005840 S RESISTOR RR0510R 473 D 47 k R14 7...

Page 25: ...J 103 X 10 k R752 7030005230 S RESISTOR ERJ2GEJ 334 X 330 k R753 7030005000 S RESISTOR ERJ2GEJ 471 X 470 R754 7030005240 S RESISTOR ERJ2GEJ 473 X 47 k R755 7030005120 S RESISTOR ERJ2GEJ 102 X 1 k R756...

Page 26: ...102KBQ C927 4030013850 S CERAMIC ECUE1E102KBQ J1 6510019860 S CONNECTOR AXK6S40645P J3 6450002010 S CONNECTOR HSJ1501 011010 J4 6450001680 CONNECTOR HSJ1122 010010 DS1 5040002230 S LED CL 200YG C TS D...

Page 27: ...50000360 S DIODE 1SS364 TE85L D721 1750000360 S DIODE 1SS364 TE85L D801 1790000850 S DIODE MA132WK TX D802 1790001260 S DIODE MA2S077 TX D803 1790001260 S DIODE MA2S077 TX D804 1790001260 S DIODE MA2S...

Page 28: ...X 6 8 k R52 7030005040 S RESISTOR ERJ2GEJ 472 X 4 7 k R53 7030005570 S RESISTOR ERJ2GEJ 820 X 82 R57 7030005120 S RESISTOR ERJ2GEJ 102 X 1 k R58 7030007270 S RESISTOR ERJ2GEJ 151 X 150 R100 7030005090...

Page 29: ...RESISTOR ERJ2GEJ 103 X 10 k R855 7030005290 S RESISTOR ERJ2GEJ 682 X 6 8 k R857 7030008370 S RESISTOR ERJ2GEJ 561 X 560 R862 7030005290 S RESISTOR ERJ2GEJ 682 X 6 8 k R864 7030004980 S RESISTOR ERJ2G...

Page 30: ...50 S CERAMIC ECUE1E102KBQ C120 4030016820 S CERAMIC ECUE1HR75BCQ C121 4030013850 S CERAMIC ECUE1E102KBQ C123 4030014120 S CERAMIC ECUE1H100CCQ C124 4030013850 S CERAMIC ECUE1E102KBQ C131 4030013850 S...

Page 31: ...7 4030014280 S CERAMIC ECUE1H0R3BCQ C728 4030014100 S CERAMIC ECUE1H070CCQ C729 4030014020 S CERAMIC ECUE1H020BCQ C730 4030009820 S CERAMIC C1005 JB 1C 103K T A C731 4030009820 S CERAMIC C1005 JB 1C 1...

Page 32: ...CUE1E102KBQ C976 4030013850 S CERAMIC ECUE1E102KBQ C977 4030013850 S CERAMIC ECUE1E102KBQ C978 4030013850 S CERAMIC ECUE1E102KBQ C979 4030013850 S CERAMIC ECUE1E102KBQ C980 4030013850 S CERAMIC ECUE1E...

Page 33: ...KBQ C316 4030014280 S CERAMIC ECUE1H0R3BCQ C317 4030013850 S CERAMIC ECUE1E102KBQ C318 4030013850 S CERAMIC ECUE1E102KBQ C319 4030013850 S CERAMIC ECUE1E102KBQ C320 4030013850 S CERAMIC ECUE1E102KBQ C...

Page 34: ...EUR UK ITA 1 MP25 8930044470 1903 DC cap 1 MP26 8930044480 1903 Lens 1 MP28 8810008990 Screw PH BT M2x10 ZX 2 MP29 8810009510 Screw FH BT M2x4 NI ZU 11 MP30 8810009630 Screw FH No 0 M2x4 5 NI B 2 MP3...

Page 35: ...P1 C LOGIC unit VCO unit RF unit MP3 C MP18 C MP29 C MP9 C SP1 C MP22 C EP2 L MP25 C MP26 C MP6 C MP2 L MP29 C DS4 L MP1 L S1 C MP30 C J1 C MP21 C MP28 C MP2 C MP20 C MP17 C MP2 RF MP1 V MP31 C MP13 C...

Page 36: ...8A B E C UN9210 Symbol 8L B E C UN9211 Symbol 8A B E C B E C B E C UN9215 Symbol 8E UN921E Symbol 8N B E C XP1115 Symbol 9L XP1116 Symbol 7N XP1501 AB Symbol 5R B1 E B2 C1 C2 B1 E B2 C1 C2 B1 E B2 C1...

Page 37: ...3 R154 R305 R322 R18 R19 C321 R329 C322 R330 C328 R339 C320 R328 C326 R15 C77 C901 IC5 IC2 S7 DS3 R901 C927 C926 C751 C758 C754 Q754 C757 C241 C240 Q752 Q603 Q602 R752 R718 R730 R736 R735 C713 R734 R7...

Page 38: ...C252 C216 D304 Q361 Q303 Q302 C316 C317 C718 Q753 C306 C311 C904 C903 L2 FI701 S401 S402 C147 IC4 X1 J3 C142 C149 R301 R306 R307 R309 R918 R39 R2 R144 C148 C923 C141 C150 C917 R24 R38 R23 R32 R27 R28...

Page 39: ...5 C941 C923 R925 R158 C178 C873 C871 R839 C875 R10 C190 C345 R344 R343 R4 C93 R2 C88 C89 C937 C935 C939 C839 C180 C907 C908 R913 C802 C801 C831 C832 C827 R923 C924 R912 C915 C965 L917 L916 Q922 L912 L...

Page 40: ...51 R125 R124 R126 C135 R909 R908 C120 C121 C119 R110 C117 C114 R133 R414 C139 R895 C895 R894 C524 C521 C417 C900 R512 R615 R612 C991 C992 C 5 1 9 R870 R854 C816 R807 R869 R726 C731 R721 C726 R725 C192...

Page 41: ...322 C370 Q350 L330 L360 D351 L322 D322 L312 L302 Q301 Q302 L311 Q312 D312 L331 C389 C361 R369 R364 C365 C364 C363 R360 C322 D321 C321 C333 R301 R302 C302 C334 D302 D301 C304 R306 C323 C371 R324 C324 R...

Page 42: ...9 6 BOTTOM VIEW C388 R374 Q354 Q353 L333 L337 L336 R371 C380 C378 C381 C384 R373 L338 L335 L334 C375 C376 R372 C387 R321 C386 C385 C383 C303 C382 C379 C377...

Page 43: ...SW 430MHz BAND SW 144MHz Q306 2SJ364 Q305 2SJ364 Q304 2SJ364 DEV SW Q307 UN9214 BAMD SW 1200MHz REG 3C DC DC DATA CK DAST AF FILTER IC241 NJM2902V VOL Q751 XP1501 Q752 2SD2216 Q754 2SD2216 IC5 M62368...

Page 44: ...901 NJM3404AV PSET RX Lo FREQUENCY 50MHz BAND WFM BAND 144MHz BAND 430MHz BAND 1200MHz BAND Q301 3SK291 D309 MA2SV05 D310 MA2SV05 Q201 3SK292 D203 MA2S304 D306 MA2SV05 D202 MA2S304 RX FREQUENCY WFM BA...

Page 45: ...2SC4228 IC802 TB31242FN COMMON RX BUS 3C IC5 S 81332HG KC Q1 2SD2216 Q2 XP1501 Q3 2SB1132 T4 REG 3 TXC Q901 UN9211 Q902 2SD2216 Q903 2SB1132 D901 MA133 I O DC SW CHG VCC TO BATT DATA IC3 BU4094BCFV Q...

Page 46: ...1 K R248 470K C245 0 1 R246 120K C246 0 1 C247 100 P R247 100 K C243 0 1 R142 22 K C756 0 01 VCC VIN C718 0 1 R757 22 K R758 47 K C755 0 047 R760 1 M D I G C145 0 001 D143 MA2S111 R145 10 K C151 0 00...

Page 47: ...13 0 001 C720 0 047 R734 22 K C735 0 1 R733 20 K C736 0 001 SD NOISE L702 LS 528 Q702 UN9115 R729 1 8 K PSET 8 IC4 TC4W53FU C907 0 001 R1 NTCCF20124AH 473KCT TXC 5 6 7 4 3 2 1 C906 0 001 J1 AXK6S40645...

Page 48: ...20 0 1 C241 0 1 R241 1 M R244 82 K R243 82 K R242 470 K C242 0 039 R249 220 K C244 0 1 R245 82 K C240 0 0015 1 2 3 4 5 6 7 14 13 12 11 10 9 8 IC241 NJM2902V C252 0 0022 C251 0 001 R253 56K R254 56 K R...

Page 49: ...H Q341 2SC4215 O C347 0 01 C344 0 001 C348 3 P R351 15 R839 15 R867 220 Q813 2SC5107 O C854 0 001 C852 0 001 C833 0 001 R828 220 D810 MA6S121 C832 0 001 C831 0 001 L802 4 7 H C748 0 001 R726 4 7 K R72...

Page 50: ...4 0 001 C71 0 001 C213 0 001 C82 0 001 C70 0 001 Q202 UN9115 C197 0 001 C304 0 001 C513 0 001 D52 MA2S077 D51 MA2S077 C73 0 001 C141 0 001 C171 0 001 C180 0 001 R158 3 9 K C901 0 001 R919 4 7 K C912 2...

Page 51: ...001 R3 4 7 K C94 0 001 C875 0 001 C873 0 001 C871 0 001 C869 0 001 C867 0 001 C726 7 P C895 0 001 R895 33 K C894 0 001 C897 6 P R892 4 7 K D805 MA2S077 L809 22 nH R889 220 C888 0 001 C889 0 001 C882 0...

Page 52: ...ne 425 454 8155 Fax 425 454 1509 URL http www icomamerica com Customer Service Phone 425 454 7619 Glenwood Centre 150 6165 Highway 17 Delta B C V4K 5B8 Canada Phone 604 952 4266 Fax 604 952 0090 URL h...

Page 53: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan A 5566I S 1 1999 Icom Inc...

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