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Icom IC-T81A Service Manual

Other manuals for IC-T81A: Instruction Manual

Summary of IC-T81A

  • Page 1

    Service manual multiband fm transceiver.

  • Page 2

    Introduction danger ordering parts repair notes this service manual describes the latest service information for the ic-t81a/e at the time of publication. Never connect the transceiver to an ac outlet or to a dc power supply that uses more than 16 v. Such a connection could cause a fire hazard and/o...

  • Page 3

    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 . . . . . . ....

  • Page 4: Section 1

    M general • frequency range : * 1 specifications guaranteed 144 – 148 mhz, * 2 specifications guaranteed 430 – 440 mhz * 3 specifications guaranteed 440 – 450 mhz, * 4 not guaranteed • mode : fm and am (rx only), wfm (rx only) • no. Of memory channels : 124 (incl. 10 pairs of scan edges and 4 call c...

  • Page 5

    1 - 2 m receiver • receiver system : double-conversion superheterodyne • intermediate frequency : 1st 69.45 mhz (13.35 mhz: wfm) 2nd 450 khz • sensitivity* : (except spurious points; typical values) * fm and wfm are measured at 12 db sinad, am is measured at 10 db s/n. • squelch sensitivity : 50, 14...

  • Page 6: Section 2

    2 - 2 section 2 inside views • logic unit • rf unit if ic (ic701: ta31136fn) crystal filter (x1: cr-639 5.039mh) af power amplifier (ic201: ta7368f) af volume (ic202: m5222fp) af mute switch (q361: 2sj364) cpu (ic1: m38267m8lgp) bottom view vco circuit 1st mixer (ic601: µ pc2757t) wfm rf amplifier c...

  • Page 7: Section 3

    3 - 1 section 3 disassembly instructions a b chassis panel c e e d sealing rubber j1 logic unit d chassis panel f f logic unit f shield plate • removing the chassis panel 1 remove 1 knob a , and unscrew 1 nut b . 2 unscrew 2 screws c . 3 remove the chassis panel in the direction of the arrow. • remo...

  • Page 8: Section 4

    4 - 1 section 4 circuit description 4-1 receiver circuits 4-1-1 duplexer circuit (rf unit) the transceiver has a duplexer (low-pass and high-pass fil- ters) on the frist stage from the antenna connector to sepa- rate the signals into below uhf and shf signals. The high- pass filter (l51–l55, c41–c46...

  • Page 9

    4 - 2 • rf signals wfm band the wfm band signals are applied to the rf amplifier (q201) via the tunable band-pass filter (d202). The ampli- fied signals pass through the tunable bandpass filter (d203), and are then applied to the 1st mixer circuit (ic601, pin 1). Varactor diodes (d106, d107, d202, d...

  • Page 10

    4 - 3 4-1-8 2nd if and demodulator circuits (rf and logic units) the 2nd mixer circuit converts the 1st if signal to the 2nd if signal. A double conversion superheterodyne system (which converts receive signals twice) improves the image rejection ratio and obtain stable receiver gain. The fm if ic (...

  • Page 11

    4 - 4 (3) 440 mhz band the signals from the limiter amplifier (rf unit; ic301) changes the reactance of a diode (vco unit; d321) to mod- ulate the oscillated signal at the 440-vco circuit (vco unit; q321, q322, d321, d322, l322). The modulated signals are amplified at the buffer-amplifier (q323) and...

  • Page 12

    4 - 5 the apc sensor (r911) detects driving current from the drive voltage at the ygr (q138), drive (q921) and power (q922) amplifiers. The detected current is converted into dc voltage at q913, then applied to the apc control circuit (ic901, pin 2). The applied voltage is compared with a “pset” vol...

  • Page 13

    4 - 6 • pll circuit shift register prescaler phase detector loop filter programmable counter programmable divider x1 13.8 mhz q311, q312, d302, d311 144 mhz vco 50mhz rx vco buff. D802, d803 q807 q313, d312 3 4 5 pstb ic801 (pll ic) clk data to transmitter circuit to 1st mixer circuit (ic601, pin 1)...

  • Page 14

    Pin port description number name pin port description number name 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 vin remote sd ctcin lockv thermc sbatt cont ctcout beep bpcpi noise pda2/ul pda1/ul dast iost plst2 plst1 cloneout input port for the over-voltage detec- tion from connected battery pack...

  • Page 15: Section 5

    5 - 1 ad-92sma optional sma–bnc adaptor 1/8" (3.5 mm) 3-conductor plug 68 k Ω - + to [sp] jack audio generator ac millivoltmeter power supply 13.5 v / 3 a to [mic] jack fm deviation meter attenuator 40 db or 50 db rf power meter 10 w/50 Ω frequency counter standard signal generator caution: to the a...

  • Page 16

    5 - 2 5-2 pll adjustment the following adjustment must be performed at “adjustment mode”. Pll lock voltage reference frequency detecter output voltage adjustment adjustment adjustment condition measurement value point unit location unit adjust 1 2 3 4 5 6 7 8 1 1 • displayed frequency : 51.000 mhz •...

  • Page 17

    5 - 3 pll lock voltage check point (for 50 mhz rx, wfm and 144 mhz) 12lv vlv 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 voltage adjustment •...

  • Page 18

    5 - 4 5-3 receiver adjustment the following adjustment must be performed at “adjustment mode”. 50 mhz sensitivity wfm sensitivity am sensitivity vhf sensitivity adjustment adjustment adjustment condition measurement value point unit location unit adjust 1 2 1 2 1 2 1 2 • displayed frequency : 50.000...

  • Page 19

    5 - 5 • logic unit top view 50 mhz, wfm band, air band and 145 mhz sensitivity check point sd.

  • Page 20

    5 - 6 receiver adjustment (continued) the following adjustment must be performed on the normal mode after “sensitivity adjustment” in section 5-3. *this output level of the standard signal generator (ssg) is indicated as ssg’s open circuit. S-meter (50 mhz band) (wfm band) (144 mhz band) adjustment ...

  • Page 21

    5 - 7 s-meter (440 mhz band) (1200 mhz band) squelch level adjustment adjustment adjustment condition measurement value point unit location unit adjust 9 10 11 12 13 14 1 • displayed frequency : 445.000 mhz [usa-1] 435.000 mhz [other] • connect the ssg to the antenna connector and set as: level : 0....

  • Page 22

    5 - 8 output power (50 mhz) (144 mhz) (440 mhz) (1200 mhz) adjustment adjustment condition measurement value adjustment unit location 1 2 3 4 5 6 7 8 • displayed frequency : 51.000 mhz [eur], [uk], [ita] 52.000 mhz [aus], [sea], [usa-1] • output power : high • transmitting • output power : low • tra...

  • Page 23

    5 - 9 transmitter adjustment (continued) the following adjustment must be performed after “reference frequency adjustment” in section 5-2. Fm deviation (50 mhz) (144 mhz) (440 mhz) (1200 mhz) dtmf deviation (aus, sea, usa-1 only) tone call deviation (eur, uk, ita only) ctcss deviation (50 mhz) (144 ...

  • Page 24: Section 6  Parts List

    S.=surface mount ic1 1140008110 s.Ic m38267e8gp [usa-1] only 1140008100 s.Ic m38267m8l-230gp [other] ic2 1130009160 s.Ic x24320s8i-2.5t4 ic3 1110004890 s.Ic xc6371a500pr ic4 1130006220 s.Ic tc4w53fu (te12l) ic5 1110004530 s.Ic m62368gp 70ed ic141 1180001720 s.Ic s-81332hg-kc-t1 ic142 1110004540 s.Ic...

  • Page 25

    S.=surface mount r245 7030005080 s.Resistor erj2gej 823 x (82 k Ω ) r246 7030005310 s.Resistor erj2gej 124 x (120 k Ω ) r247 7030005090 s.Resistor erj2gej 104 x (100 k Ω ) r248 7030005170 s.Resistor erj2gej 474 x (470 k Ω ) r249 7030005110 s.Resistor erj2gej 224 x (220 k Ω ) r250 7030005090 s.Resist...

  • Page 26

    S.=surface mount c307 4030013850 s.Ceramic ecue1e102kbq c308 4030014500 s.Ceramic ecue1h121jcq c309 4030009000 s.Ceramic c2012 jb 1c 224k-t-a c310 4030014220 s.Ceramic ecue1e471kbq c311 4550005980 s.Tantalum temsva 1a 475m-8l c312 4030014220 s.Ceramic ecue1e471kbq c313 4030006880 s.Ceramic c1608 jb ...

  • Page 27

    S.=surface mount q826 1590001910 s.Transistor un911d (tx) q827 1590001970 s.Transistor un921e (tx) q828 1590001910 s.Transistor un911d (tx) q829 1590001970 s.Transistor un921e (tx) q901 1590001150 s.Transistor un9211 (tx) q902 1540000350 s.Transistor 2sd2216-s (tx) q903 1520000460 s.Transistor 2sb11...

  • Page 28

    S.=surface mount l143 6200006770 s.Coil eljre 1n5z-f l201 6200008730 s.Coil eljnd r10j 0.1u l202 6200008730 s.Coil eljnd r10j 0.1u l205 6200008730 s.Coil eljnd r10j 0.1u l206 6200008730 s.Coil eljnd r10j 0.1u l301 6200007750 s.Coil lqn21a 56nj04 l302 6200007750 s.Coil lqn21a 56nj04 l303 6200007720 s...

  • Page 29

    S.=surface mount r351 7030005300 s.Resistor erj2gej 150 x (15 Ω ) r401 7030007300 s.Resistor erj2gej 332 x (3.3 k Ω ) r402 7030005120 s.Resistor erj2gej 102 x (1 k Ω ) r403 7030007300 s.Resistor erj2gej 332 x (3.3 k Ω ) r404 7030005060 s.Resistor erj2gej 333 x (33 k Ω ) r409 7030007270 s.Resistor er...

  • Page 30

    S.=surface mount c6 4030014090 s.Ceramic ecue1h060ccq c7 4030014170 s.Ceramic ecue1h330jcq c8 4030014120 s.Ceramic ecue1h100ccq c9 4030014420 s.Ceramic ecue1h0r5bcq c10 4030014090 s.Ceramic ecue1h060ccq c12 4030014100 s.Ceramic ecue1h070ccq c13 4030014420 s.Ceramic ecue1h0r5bcq c14 4030014020 s.Cera...

  • Page 31

    S.=surface mount c321 4030014180 s.Ceramic ecue1h470jcq c322 4030013850 s.Ceramic ecue1e102kbq c323 4030014020 s.Ceramic ecue1h020bcq c324 4030013850 s.Ceramic ecue1e102kbq c325 4030014110 s.Ceramic ecue1h080ccq c326 4030013980 s.Ceramic ecue1h010bcq c327 4030014080 s.Ceramic ecue1h050bcq c341 40300...

  • Page 32

    S.=surface mount c895 4030013850 s.Ceramic ecue1e102kbq c896 4030014050 s.Ceramic ecue1h030bcq c897 4030014090 s.Ceramic ecue1h060ccq c898 4030013850 s.Ceramic ecue1e102kbq c899 4030013850 s.Ceramic ecue1e102kbq c900 4030014020 s.Ceramic ecue1h020bcq [aus], [sea], [usa-1] 4030014090 s.Ceramic ecue1h...

  • Page 33

    S.=surface mount r314 7030005290 s.Resistor erj2gej 682 x (6.8 k Ω ) r315 7030004980 s.Resistor erj2gej 101 x (100 Ω ) r316 7030004990 s.Resistor erj2gej 221 x (220 Ω ) r317 7030005070 s.Resistor erj2gej 683 x (68 k Ω ) r318 7030005300 s.Resistor erj2gej 150 x (15 Ω ) r319 7030004980 s.Resistor erj2...

  • Page 34: Section 7

    7 - 1 section 7 mechanical parts and disassembly screw abbreviations a, b0, bt: self-tapping ph: pan head fh: flat head bih: bind head ni: nickel sus: stainless zk: black ref. No. Oder no. Description qty. J1 6510020650 connector sma-r224 1 s1 7600000210 encoder tp70n00e20-15f-1903 1 sp1 2510000960 ...

  • Page 35

    7 - 2 unit abbreviation (c): chassis parts, (l): logic unit (rf): rf unit, (v): vco unit mp7 (c) mp23 (c) mp1 (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)...

  • Page 36

    Section 8 semi-conductor information 8 - 1 2sa1588 gr (symbol: zg) 2sc4117 bl (symbol: cl) b e c 2sb1132 r (symbol: barb) b c e 2sb1201 s (symbol: b1201) b e c 2sb1462 r (symbol: br) e c b 2sc3356 r25 (symbol: r25) e c b 2sc4215 0 (symbol: qo) b e c b e c b e c b e c 2sc4226 r25 (symbol: r25) b e c ...

  • Page 37

    9 - 1 section 9 board layouts 9-1 logic unit • top view ds1 d58 d59 d53 d52 d51 d55 d54 d57 d56 d61 r29 d141 q141 q151 q341 d151 r326 r327 r338 r325 q305 q306 q309 q304 c103 c101 r340 r321 r331 r337 r323 r332 d152 r151 r35 r141 c102 r153 r154 r305 r322 r18 r19 c321 r329 c322 r330 c328 r339 c320 r328...

  • Page 38

    • bottom view 9 - 2 c76 c2 r334 r210 c209 r209 c208 q7 c1 r203 c17 c207 q8 c75 q201 q308 l3 q202 r205 r204 r342 c162 r208 r207 r211 r343 d3 c205 l1 ic3 j1 c6 c709 ic701 d2 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 r31...

  • Page 39

    9-2 rf unit • top view 9 - 3 c981 c964 c971 c970 c967 l933 c951 c966 c969 l921 q905 l931 q912 c170 l142 l123 l801 q826 d919 r8 q5 l342 q341 r9 q904 l304 q902 d901 l306 q343 c954 l1 l6 l56 l57 l58 l202 q202 l205 l59 q910 d602 l201 l13 q923 r928 r949 c960 c961 c962 c963 l910 l909 l143 d801 d810 q819 q...

  • Page 40

    • bottom view 9 - 4 d5 l723 d721 c863 q828 q827 c864 q342 l804 q824 l811 q135 q136 q132 l110 q823 q822 l808 l137 l124 q131 l121 q9 q804 q805 q81 1 l724 l725 q821 l807 l135 q133 q134 l139 l134 q803 q812 q817 l341 l806 q816 q503 l507 l810 l809 l125 q91 1 d106 l109 d902 l924 q925 l108 l102 l925 q926 d9...

  • Page 41

    9 - 5 c374 r330 r368 r322 r329 c331 r303 c309 r304 c305 r316 r317 c318 c320 c332 c312 r31 1 r318 r323 c329 c327 c330 c325 c367 r308 r362 c362 c31 1 c301 d352 c360 r361 c326 r325 c314 r314 c369 c366 r365 c372 r367 r366 r363 c373 c368 q351 l332 q323 q313 q321 l321 l313 l301 q311 q322 c370 q350 l330 l3...

  • 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

    Q132: 2sc5454 q131: 2sc5195 d804: ma2s077 d805: ma2s077 d806: ma2s077 d807: ma2s077 q135: 2sc5107 q824: 2sc5195 q823: 2sc5107 tx-lo frequency: 1200mhz band rx-lo frequency: 1200mhz band q323: 2sc5195 q354: 2sc5195 vco board q321: 2sc5195 q322: 2sc5195 d321: ma2s077 d322: hvu350 q351: 2sc5195 q311: 2...

  • Page 44

    Tx/rx frequency d51: ma2s077 d52: ma2s077 d402: ma2s077 d403: ma2s077 q922: 2sk3075 q138: mxr9745 q136: 2sc3356 tx frequency: 430mhz band tx frequency: 1200mhz band q132: 2sc5454 q131: 2sc5195 d804: ma2s077 d805: ma2s077 d806: ma2s077 d807: ma2s077 q135: 2sc5107 q824: 2sc5195 q823: 2sc5107 tx-lo fre...

  • Page 45

    Tx/rx frequency d51: ma2s077 d52: ma2s077 d402: ma2s077 d403: ma2s077 q922: 2sk3075 q138: mxr9745 q136: 2sc3356 tx frequency: 430mhz band tx frequency: 1200mhz band q132: 2sc5454 q131: 2sc5195 d804: ma2s077 d805: ma2s077 d806: ma2s077 d807: ma2s077 q135: 2sc5107 q824: 2sc5195 q823: 2sc5107 tx-lo fre...

  • Page 46

    198ns 3.2v c: 3.2 c: 12.6 c: 13.5 c: 13.2 c: 0.6 c: 3.2 t: 0 r: 3.4 t: 3.2 r: 0 t: 3.2 r: 0 t: 0 r: 3.2 c: 13.2 c: 12.7 r338 50 k r337 470 k mod q309 2sj364 q q307 un9214 r324 33 k q304 2sj364 q r327 50 k r323 56 k c322 0.001 q306 2sj364 q r330 470 k q305 2sj364 q +3c ic201 ta7368f ic202 m5222fp q30...

  • Page 47

    T: 0 r: 3.4 .2 c: 5.0 c: 2.5 c: 3.3 c: 13.2 r338 50 k r337 470 k mod q309 2sj364 q 4 364 q r327 50 k r323 56 k c322 0.001 q306 2sj364 q r330 470 k q305 2sj364 q l1 5ca-395kn-0369aq spremote ic3 xc6371a500pr i g o r342 10 k r343 27 k +3c r2 100k ab c162 0.001 r208 10k c917 0.001 c909 0.001 c912 0.001...

  • Page 48

    198ns 3.2v c: 3.2 c: 12.6 c: 13.5 c: 13.2 c: 0.6 c: 3.2 t: 0 r: 3.4 t: 3.2 r: 0 t: 3.2 r: 0 t: 0 r: 3.2 c: 13.2 c: 12.7 c: 5.0 c: 2.5 c: 3.3 c: 13.2 r338 50 k r337 470 k mod q309 2sj364 q q307 un9214 r324 33 k q304 2sj364 q r327 50 k r323 56 k c322 0.001 q306 2sj364 q r330 470 k q305 2sj364 q l1 5ca...

  • Page 49

    Vlv vhfout gnd ulv shift gnd vhvco3 uvco3 uhfout 12vcoout vlvco3 12vco3 gnd gnd gnd l301 0.82 µ h q301 2sc5195 q302 2sc5195 q322 2sc5195 l321 0.82 µ h q323 2sc5195 l322 15 nh c312 0.001 c319 0.001 c330 0.001 d312 1ss364 q311 2sc5195 q312 2sc5195 q313 2sc5195 r301 270 k r302 1 k r303 47 r304 220 r305...

  • Page 50

    Chg + - 50mhz wfm vhf 400mhz 1200mhz 50m 00m 1200m uhftx 50tx vhftx vhftx uhftx vcc +3c txc 12tx 6m 50tx vhf vhftx uhf txc uhftx 1200 12tx vcc txc pset r+3 1200 r+3 uhf 800 r+3 300 agc +5v tune r+3 chgc hv vcc bdet hv vcc w3 vhf r+3 6m vggc 50tx vc vhftx 12tx c124 0.001 l101 0.15 µ c201 0.01 c322 0....

  • Page 51

    Vlv vhfout gnd ulv shift gnd vhvco3 uvco3 uhfout 12vcoout vlvco3 12vco3 gnd gnd gnd l301 0.82 µ h q301 2sc5195 q302 2sc5195 q322 2sc5195 l321 0.82 µ h q323 2sc5195 l322 15 nh c312 0.001 c319 0.001 c330 0.001 d312 1ss364 q311 2sc5195 q312 2sc5195 q313 2sc5195 r301 270 k r302 1 k r303 47 r304 220 r305...

  • Page 52

    Introduction danger ordering parts repair notes communication equipment himmelgeister str. 100, d-40225 düsseldorf, germany phone : 0211 346047 fax : 0211 333639 url : http://www.Icomeurope.Com unit 9, sea st., herne bay, kent, ct6 8ld, u.K. Phone : 01227 741741 fax : 01227 741742 url : http://www.I...

  • Page 53: Service

    Service manual 1-1-32, kamiminami, hirano-ku, osaka, 547-0003, japan a-5566i-s- 1 © 1999 icom inc. Multiband fm transceiver.