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NAD T742 Service Manual
Summary of T742
Page 1
Nad t 742 s u r r o u n d sound receiver t 7 4 2 s u r r o u n d s o u n d r e c e iv e r s e r v ic e m a n u a l www.Electronicsrepair.Net.
Page 2: Service Safety Precautions
2 service safety precautions 1. Replacing the fuses caution: for continued protection against the risk of fire replace only with same type of fuse. Reference no part number description m270 *ah 5120-0200-0 5a time-lag 5x20 ul/csa m271 *c 5120-0024-0 3.15a time-lag 5x20 vde-semko m272 *ah 5120-0052-0...
Page 3: Specifications
3 specifications power amplifier and preamplifier section (all channels stated 8 ohms) rated distortion (thd 20hz-20 khz fl/c/fr) ≤ 0.08% (thd 20hz-20 khz sl/sr) ≤ 0.3% input sensitivity (ref. 8 ohms, 1 khz) 180+/-30 mv s/n ratio (a-wtd, 1khz, 1w, 8 ohm) ≥ -78 db (a-wtd, 1khz, 80w, 8 ohm) fl/fr/c ≥ ...
Page 4
4 am tuner section input level is expressed as the reading in open-circuit of 75-ohm source impedance signal generator usable sensitivity (999/1000khz) ≤ 30 dbµ s/n ratio (5mv in) ≥ 38 db thd (5mv in) ≤ 3% if rejection (450 khz) ≥ 45 db image rejection (f+2xif) ≥ 28 db selectivity ≥ 17 db output 130...
Page 5: Rear Panel / Front Panel
5 rear panel / front panel rear panel front panel 1. Fm & am antenna 2. Tape 1 & cd inputs 3. 5.1 channel inputs 4. Dvd - sat vcr - video 4 (audio & video) 5. Digital audio inputs 6. Audio pre outs / subwoofer out 7. Monitor out 8. Speakers: front, center & sur- round speakers 9. Soft clipping 10. I...
Page 6: Disassembly Instructions
6 disassembly instructions 1. Remove machine screws m 4.0 x 6.0 ( 1 to 6 ) from the side panels. Remove tapping screw 3.0 x 8.5 ( 7 )from the back panel. Refer to figure no.1. Figure no.1 2. Pull both sides of the top cover slightly outwards 8 and tilt approx. 35˚ and then remove in the direction as...
Page 7
8 7 p702 p701 power switch pcb j401a ac3 pcb j203b j101a j604b j601b j208a j208b j203a j206a j207a j207b secondary pcb j701a j202b j206a jp210 jp211 j702b jp210 j602b t201a t202a jp207 jp206 m704b c230 jp209 jp203 j206b jp204 jp205 c221 p261 p260 p262 j101b j203b j202a j201b p264 psu pcb p266 p265 d...
Page 8
9 10 osc rf vt block diagram coaxial x2 optical x1 74hc153 4053 74ls157 m62446fp s-v ideo selector cd4052 tempera ture protection tuner l tuner r power down detect pin. For spk of f, mute on, vfd of f. Fl t rigger out ir in fl out2 out3 out1 out4 fr center sl sr sub fr center sl sr sub v ideo pin 1 ...
Page 9
11.
Page 10: Alignment Procedures
12 alignment procedures amplifier section idle current step item connection adjustment adjust for 1 front left channel voltmeter to m714 on main board vr7703 1mv±0.2mv 2 front right channel voltmeter to m713 on main board vr7702 1mv±0.2mv 3 center channel voltmeter to m712 on main board vr7701 1mv±0...
Page 11: Important Notes
13 fm/rds section - fm mono: 1khz, 75khz devi., 60db/µv - fm stereo: 1khz, 67.5khz devi., 60db/µv pilot signal 19khz 7.5khz devi. Outputs - connect the non-inductive type resistor of 8 ohms to the all speaker terminals unless otherwise noted. Item fm if/rf stereo distortion stereo separation muting ...
Page 12: Pcb Layout
14 pcb layout s-video board video-5 board volume board.
Page 13
15 video board tuner board.
Page 14
16 surround amplifier board primary board secondary board.
Page 15
17 audio board psu board.
Page 16
18 multi-channel board - component side.
Page 17
19 multi-channel board - solder side.
Page 18
20 main board.
Page 19
22 21 ac3 board - component side ac3 board - solder side.
Page 20
23 24 key board digital board speaker board led board power switch board.
Page 21
26 25 schematic diagram ac3 / dts note: 1. Resistors, are carbon film 5% 1/10w unless otherwise specified. 2. Ceramic capacitors, are 50v 10%. Unless otherwise specified..
Page 22
27 28 main note: 1. Resistors, are carbon film 5% 1/8w unless otherwise specified. Mf-metal film 2. Ceramic capacitors, are 50v 10%. Unless otherwise specified..
Page 23
30 29 ( from ac3 j601b ) out1 out2 out3 out4 avdd swin gnds srin slin gndc cin gndr rin gndl byr byl dvdd clk data latch dgnd agnd swout srout slout cout rout lout avss1 avss2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 lin u60...
Page 24
31 32 keyboard note: 1. Resistors, are carbon film 5% 1/8w unless otherwise specified. 2. Ceramic capacitors, are 50v 10%. Unless otherwise specified..
Page 25
34 33 tuner note: 1. Resistors, are carbon film 5% 1/8w unless otherwise specified. 2. Ceramic capacitors, are 50v 10%. Unless otherwise specified..
Page 26
35 36 3 4 5 2 1 m501 s_v2 in 3 4 5 2 1 m502 s_v1 in 3 4 5 2 1 m503 s_v3 in 3 4 5 2 1 m504 s_v3 out 3 4 5 2 1 m505 mon out 5 4 3 2 1 6 7 8 9 10 j715b 10pin 5 4 3 2 1 6 7 8 9 10 j716b 10pin c501 47u/10v c502 47u/10v c503 47u/10v c504 47u/10v c505 47u/10v c506 47u/10v c507 470u/10v c508 470u/10v c509 2...
Page 27
38 37 q7701 a56 q7707 a06 c7701 10u/50v q7713 2sc1845 q7714 2sc1845 r7701 10k r7711 680r r7714 470r r7720 10r r7723 6k2 c7711 100p c7712 100p c7717 220u/50v r7726 5k1 z7701 10v r7729 33k d7701 1n4148 d7702 1n4148 r7737 120r r7740 2k2 r7743 1k8 vr7701 1k q7724 a13 c7720 47p q7708 a06 q7727 2sc5197 q7...
Page 28
39 40 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 u302 tc9273 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 u301 4053 video3 out video4 out video2 in video1 in video3 in video4 in fr gnd fl +12v -12v v5_r cd_r t_r t_i_r t_o_r v5_l cd_l t_l t_i_l t_o_l t_mon dgnd latch data cl...
Page 29
41 q203 a56 q204 a06 c201 10u/50v q201 2sc1845 q202 2sc1845 r201 10k r202 680r r205 470r r206 10r r204 6k2 c202 100p c203 100p c205 220u/50v r203 5k1 z201 10v r245 33k d201 in4148 d202 in4148 r209 120r r208 2k2 r207 1k8 vr201 1k q205 a13 c204 47p q207 a06 q208 2sc5198 q206 a56 q209 2sa1941 c206 10u/...
Page 30
42 psu note: 1. Resist ors are carbon film 5% 1/8w unless other wise specified. Mf - met al film 2. Ceramic cap acit ors are 50v 10%. Unless other wise specified. 3. Components marked “ ” are safety critical p a r ts..
Page 31: Ic Block Diagram
43 ic block diagram ac3 board u101: 74hc153 14 7 9 a 2 1 6 5 4 3 15 b 1g 1c0 tg tg tg tg tg tg tg tg tg tg tg tg 1c1 1c2 1y 2y 1c3 10 11 12 13 2c0 2c1 2c2 2c3 2g 1 1g vcc 16 2 b 2g 15 3 1c3 a 14 4 1c2 2c3 13 5 1c1 2c2 12 6 1c0 2c1 11 7 1y 2c0 10 8 gnd 2y 9 ac3 board u102: 74hc157 4 1y 7 2y 9 3y 12 4...
Page 32
Vcc data outputs o0 - o7 oe, ce and program logic y decoder x decoder output buffers y-gating identification cell matrix gnd vpp oe ce a0 - a18 address input 44 amplifier 1 output inverting input non-inverting input v – amplifier 2 v + output inverting input non-inverting input 1 2 3 4 8 7 6 5 + – –...
Page 33
45 rxp rs422 receiver clock & data recovery de-mux audio serial port registers mux mux vd+ dgnd va+ va+ filt agnd mck m3 m3 m2 m1 m0 sdata sck fsync c u verf cs12/fck sel c0/e0 ca/e1 cb/e2 cc/f0 cd/f1 ce/f2 ref cbl rxn 9 10 13 16 6 5 4 3 2 27 25 15 28 14 1 11 12 26 23 24 18 17 19 21 20 22 8 7 ac3 bo...
Page 34
46 1 1a 14 vac 2 1y 13 6a 3 2a 12 6y 4 2y 11 5a 5 3a 10 5y 6 3y 9 4a 7 gnd 8 4y ac3 board u114: 74hcu04 1 y 1b 2 y 0b 3 y 1c 4 z c 5 z 0c 6 e 7 v ee 16 v dd 15 z b 14 z a 13 y 1a 12 y 0a 11 s a 10 s b 8 v ss 9 s c e s c s b s a level converter y 0c y 1c z c y 0b y 1b z b y 0a y 1a z a audio board u3...
Page 35
47 2 s1 1 v ss 26 v dd 27 s1 3 s2 26 s2 4 s3 25 s3 5 s4 24 s4 6 s5 23 s5 7 s6 22 s6 8 s7 21 s7 9 s8 20 s8 10 s9 19 s9 11 s10 18 s10 12 s11 13 gnd 14 ck 15 data 16 resister 17 s11 (l-ch) 10bit latch circuit level shift + shift resister circuit (r-ch) 10bit latch circuit (same as l-ch circuit) audio b...
Page 36
48 dout ack word address buffers start/stop logic control logic state counters slave address comparators a0 a1 a2 scl wp sda vss vcc xdec data in storage high voltage/ timing control e 2 prom column decoders sense amps shift registers vcc a0 8 1 wp a1 7 2 scl a2 6 3 sda vss 5 4 key board u202: eepro...
Page 37
49 amplifier 1 output inverting input non-inverting input v – amplifier 2 v + output inverting input non-inverting input 1 2 3 4 8 7 6 5 + – – + multi-channel board u601, u602, u606, u607, u609: njm5532 u603, u608: njm4558d u701-u703: njm4558m 1 2 l-s1 vss shift register level shifter level shifter ...
Page 38
50 tuner board u902: lc72723m vdda 3 reference voltage antialiasing filter data decoder vref 1 vref flout 5 cin 6 pll (57khz) clock recovery (1187.5hz) + _ vddd 11 vssd 10 rdda 14 rdcl 15 mode 12 rst 13 rds-id/ready 16 vssa 4 mpxin 2 test 7 test 57khz bpf (scf) smoothing filter osc clk(4.332mhz) 9 x...
Page 39
51 s-video assembly u501: 4052 3 13 logic level conversion binary to 1 of 4 decoder with inhibit b 10 c 9 in h 6 v dd 16 v ss 8 v ee 7 tg tg tg tg common x out/in tg tg tg tg common y out/in 3 2 1 0 13 15 11 12 x channels in/out 1 5 2 4 0 1 2 3 y channels in/out a 11 v dd 16 7 4 6 2 5 5 4 1 3 12 2 1...
Page 40: Electrical Parts List
52 ac3 assy pc board pcb-n0a40c-ac3 pcb assy ac3 n0a40c pcb 1000 1725-570c-0000 pcb ac3 t742 capacitor c1111,c1138,c1201,c1204,c1206,c1209, 150d-224k-j-bd cc 16v 0.22µf 10% 0805 c1306,c136,c1405,c149 c102,c1112,c129,c138,c140,c142 150e-104m-j-bd cc 25v 0.1µf 20% 0805 c1133,c1135,c1139 150f-100j-j-bd...
Page 41
53 j604b 2102-031s-004 3 pin st. Wafer j101a 2102-101s-004 wafer 10p p2.5 st. J601b 2102-121s-004 12p st.Wafer crystal m101 2300-3060-0 x'tal 12.288mhz +/-20ppm screw 2704 2954-2606-0000 screws bt 2.6x6 2702 2954-3008-0000 tapping 3x8mm b-tite ic u131 3130-0890-0 ic njm4558d dual op amp. U123 3130-2...
Page 42
54 r194 4720-335j-j rmg 1/10w 3.3m 5% 0805 r172 4720-471j-j rmg 1/10w 470r 5% 0805 r121,r1301,r1305,r173,r197,r199 4720-472j-j rmg 1/10w 4.7k 5% 0805 r1101,r113,r116 4720-473j-j rmg 1/10w 47k 5% 0805 r104 4720-680j-j rmg 1/10w 68r 5% 0805 r115,r118 4720-750j-j rmg 1/10w 75r 5% 0805 r114,r117 4720-82...
Page 43
55 c205,c213 157c-227m-5-kw ce 10v 220µf 20% rl 6x12 c201,c206,c207,c209,c214,c215 157f-106m-5-iue ce 50v 10µf 20% rl 5x11 c223,c224 157i-477m-5-w&a ce 63v 470µf 20% rl 12.5 c220,c221 8910-0112-0 ce 63v 8200µf 20% rl coil l201,l202 1804-0540-0 spring coil 1mh wafer m704b 2101-9400-0 jm2422-3m wafer ...
Page 44
56 transistor q221 485c-123j-5 tr dtc123jsa rohm q201,q202,q210-q212,q220 4860-0190-5 tr 2sc 1845 (f.E) rl q208,q218 4860-5210-5 tr 2sc5198-0 hfe 80-160 q209,q219 4860-5220-5 tr 2sa1941-0 hfe 80-160 q204,q207,q214,q216 4860-8890-0 tr mps a06 vce 80v ns q205,q215 4860-8900-0 tr mps a13 vce 100v q203,...
Page 45
57 diode z301,z302 4837-7b51-2 dz 1/2w 7.07~7.45v rohm transistor q301 485c-144e-5 tr dtc144es rohm dig assy pc board pcb-n0a40c-dig pcb assy dig n0a40c pcb 1725-634a-0000 pcb digital n0a40c capacitor c702,c707 150f-102k-2-fc cc 50v 1000pf 10% at 3.5 c703 150f-103k-2-fc cc 50v 0.01µf 10% at 3.5 c706...
Page 46
58 diode d701 4837-4b71-2 dz 1/2w 4.55~4.80v rohm transistor q702,q703 4851-9230-5 tr 2sc1923-0 hfe 70-140 wire j203a 7705-1080-2004 conn.Assy awg26 5p p2.5 miscellaneous 1062,1065 4811-f32r-3 light rx unit gpif32r key assy pc board pcb-n0a40c-key pcb assy key n0a40c pcb 2000 1725-569b-0000 pcb key/...
Page 47
59 r207,r208,r209 4701-182j-c rcf 1/8w 1.8k 5% ats r210,r211,r212 4701-222j-c rcf 1/8w 2.2k 5% ats r228-r231,r262 4701-223j-c rcf 1/8w 22k 5% ats r284 4701-392j-2 rcf 1/8w 3.9k 5% at r220,r221 4701-471j-c rcf 1/8w 470r 5% ats j213,r213,r214,r219 4701-472j-c rcf 1/8w 4.7k 5% ats r222,r247,r248,r249,r...
Page 48
60 led d208 3700-2489-g led 3mm green sp main assy pc board (ah/titanium ah) pcb-n0a4xc-main pcb assy main t742(ul) (ce/titanium ce) pcb-n0a40c-main pcb assy main n0a40c pcb 1000 1725-568c-0000 pcb main n0a40c capacitor c7711-c7716 150f-101k-2-fc cc 50v 100pf 10% at 3.5x c701 150f-104k-2-fc cc 50v 0...
Page 49
61 u722 3130-3800-0 ic upc79m12hf regulator u723 3130-8190-0 ic njm78m56fa 5.6v u701 3131-4850-0 ic njm5532m jrc (smd) u726 3131-9110-0 ic 74hc08 and gates(sop) relay m7702 4500-0900-0 relay 24vdc,250vac,10a m7701 4500-0910-0 relay 24vdc,125va,3a resistor r7720-r7722 4701-100j-c rcf 1/8w 10r 5% ats ...
Page 50
62 transistor q7732 4850-992f-5 tr 2sa992 hfe 300-600 q7734,q7735 485c-123j-5 tr dtc123jsa rohm q7713-q7723 4860-0190-5 tr 2sc 1845 (f.E) rl q724 4860-0660-5 tr 2sa1015 (g.R.) rl q7727,q7728,q7733 4860-5210-5 tr 2sc5198-0 hfe 80-160 q7729,q7730,q7731 4860-5220-5 tr 2sa1941-0 hfe 80-160 q7707q7712 48...
Page 51
63 c617,c618,c639,c640,c642,c649, 157d-335m-5-ii ce 16v 3.3µf 20% rl 5x5 c655,c662,c669,c675 c619-c622,c702,c706,c710,c712,c740 157d-475m-5-iu ce 16v 4.7µf 20% rl 5x11 c629-c632,c681,c682 157d-476m-5-im ce 16v 47µf 20% rl 5x7 c6100,c6101 157f-106m-5-gm ce 50v 10µf 20% rl 4x7 c645,c648,c652,c659,c661...
Page 52
64 r701,r713,r715,r723,r740 4720-000j-j rmg 1/10w 0r 5% 0805 r702,r710,r724,r728,r743 4720-101j-j rmg 1/10w 100r 5% 0805 r6016,r6109 4720-102j-j rmg 1/10w 1k 5% 0805 r704,r709,r717,r722,r742 4720-104j-j rmg 1/10w 100k 5% 0805 r703,r712,r718,r725,r744 4720-121j-j rmg 1/10w 120r 5% 0805 r706,r707,r719...
Page 53
65 capacitor c277 150f-103k-5-ii cc 50v 0.01µf 10% rl 5x5 c276 150f-223k-2-fd cc 50v 0.022µf 10% at c275 157e-227m-5-pu ce 25v 220µf 20% rl c278 8910-0091-0 cc 400v 0.01µf +-20% rl transformer t260 1806-2311-0 ei-35 transformer 12v/ac wafer j203b 2102-051s-004 5p st.Wafer j201b 2102-071s-004 wf t8 d...
Page 54
66 secondary assy pc board pcb-n0a40c-sec pcb assy secondary pcb 2000 1725-572c-0101 pcb spk pho sec pri psu capacitor c260,c262-c264 150f-104k-2-fc cc 50v 0.1µf 10% at c281,c282 153i-104j-5-nmn cm 63v 0.1µf rl (7.5x7) wafer j206a 2101-9400-0 jm2422-3m wafer j202b 2102-041s-004 4p st.Wafer resistor ...
Page 55
67 s-video assy pc board pcb-n0a40c-svd pcb assy s-video n0a40c pcb 4000 1725-571c-0000 pcb avd/muti/tun/vd/svd capacitor c528 150f-104k-2-fc cc 50v 0.1µf 10% at c525-c527 150f-223k-2-fd cc 50v 0.022µf 10% at c501-c506 157c-476m-5-gm ce 10v 47µf 20% rl 4x7 c507,c508,c510 157c-477m-5-ou ce 10v 470µf ...
Page 56
68 diode d501-d507 4804-1480-c diode 1n4148 ats z503 4837-4c20-2 dz 1/2w 5.0-5.2v at z501,z502 4837-7c51-2 dz 1/2w 7.29~7.67v rohm transistor q518-q525 485a-933s-5 tr 2sa933s hfe 120-560 q512,q513,q516,q517,q526 485c-114e-5 tr dtc114es q501,q507 485c-123j-5 tr dtc123jsa rohm q509 485c-144e-5 tr dtc1...
Page 57
69 c901 (ce/titanium ce) 150f-223k-2-fd cc 50v 0.022µf 10% at c916 150f-331k-2-fc cc 50v 330pf 10% at 3.5x c985 150f-561k-2-fc cc 50v 560pf 10% at 3.5x c991 153f-102j-5-im cm 50v 1000pf 5% rl 5x7 c961,c962 (ce/titanium ce) 153f-152j-5-jm cm 50v 1500pf 5% rl c970 153f-223j-5-lq cm 50v 0.022µf 5% rl c...
Page 58
70 ceramic filters m902,m904 2701-0010-1 cf10.7 +-30 m903 (ce/titanium ce) 2701-0010-1 cf10.7 +-30 m911 2701-0680-0 cf 450 +-1 ic u901 3130-8180-0 ic la1837 am/fm if u903 3131-3760-0 ic lc7218 pll freq u902 3131-9040-0 ic lc72723m rds resistor j991 (ah/titanium ah) 4701-000j-2 rcf 1/8w 0r 5% at r911...
Page 59
71 svr r956 4756-1036-3-06 svr 10k h3 7x7.6 rh0615c r941 4756-2236-3-06 svr 22k h3 7x7.6 rh0615c diode d901 4837-4c20-2 dz 1/2w 5.0-5.2v at d902 4837-7c20-2 dz 1/2w 9.1-9.5v at transistor q902 4851-9230-5 tr 2sc1923-0 hfe 70-140 q903,q945 485a-114e-5 tr dta114esa rohm q901 (ce/titanium ce) 485c-945p...
Page 60
M401 2113-1776-0 jack rca 4p yl nickel- ic u401 3131-4100-0 ic mc14051bcp motorola resistor r402,r408,r419,r421 4701-102j-c rcf 1/8w 1k 5% ats r405,r406,r407 4701-103j-c rcf 1/8w 10k 5% ats r410,r414,r417 4701-151j-c rcf 1/8w 150r 5% ats r409,r411-r416 4701-203j-c rcf 1/8w 20k 5% ats r403,r404,r428,...
Page 61
73 note: - the components identified by mark are critical for risk of fire and electrical shock. Replace only with part number specified. - : usa, canadian model only. - : european model only. - capacitors : cp-polystyrene, cm-mylar, ce-electrolytic, cc-ceramic, ctc-npo. - resistors : rmf-metal film...
Page 62: Exploded View
74 exploded view 123 0144 0104 0313 0303 0310 0310 0315 0319 0168 0317 0301 0307 0176 0159 0137 0166 0302 0167 0161 0315 0163 0304 0314 0310 0310 0178 0160 t002 0141 0149 0104 0146 0157 0110 0158 0106 0122 0112 0108 0210 0113 0193 0131 0130 0189 0119 0120 0121 0205 0154 0154 0129 0116 0124 0105 0107...
Page 63: Exploded View Parts List
75 0101 1403-5164-1 chassis t742 nickel 1 0102 (ah/titanium ah) 1403-5178-2 rear panel t742ah nickel 1 0102 (ce/titanium ce) 1403-5179-2 rear panel t742c nickel 1 0103 (ah/ce) 1404-5201-0 top cover t742 nickel 1 0103 (titanium ah/titanium ce) 1404-5202-0 top cover t742 nickel 1 0104 1404-5301-0 subf...
Page 64
0134 (ah/titanium ah) 7009-3100-2 ac cord 18awgx2 1 0134 (ce/titanium ce) 7009-3110-0 ac cord (semko) 1 0136 5400-9052-0 heat sink t-741 1 0137 4134-0121-0 bracket, htsk mount 2 0138,0301,0309 4152-0451-0 l-bracket 4 0139 2600-4008-0973 flat washer m4x0.8x9.7 4 0140 2607-4010-0703 spring washer m4x1...
Page 65: Packing Diagram
77 packing diagram 0002 0018 add on both sides 0006 0009 0008 0012 0007 0016 0002 0010 0017 0011 0014 0013 1 manual item part no. Description q’ty 0002 1490-3854-0 polyfoam endcap t741 2 0006 3000-9337-0 label serial number t742 1 0007 1450-2520-0 white paper a3-size 1 0008 1436-0701-0-3 carton box ...