SERIAL NO. 301 ONKYO. SERVICE MANUAL SUPER SERVO OPERATION INTEGRATED STEREO AMPLIFIER MODEL A-7040 ease ¢ © TABLE OF CONTENTS PAGE ONKYO. in COMPONENTS‘SPECIFICATIONS Power Outpt: 50 watts per chanel, min. RMS, Sigal to note ratio; PHONO: 80 dB IME A Newort) 2 3 ohme both chanel dive, TUNER: 90g lH A Netwos}) ftom 30'He 1020 Kis with'ao Loudness: (-40 48) "Sob a 100 He tom thar 90863 sal harmonies S3aR lous Seaton Range (Ind avid) aa Total Harmonic see » Dstorton" 0.026% at ted power Genera Oba wat Supa ower Spay Rating: AC 120 vols, 6 He (1200 mode) IMDitorton: 26% at ted poner ANC Li, 13099001240 Soca ote Thitees:t) Satta Sut Gateral moaeh Bcguncy Response 1556000 He 1 8) Outpt: SPEAKER A&B, PHONES RInA Deviation’ 20~ 2000 He 208 ¢0) TAPE REC 82 Damping actor Sat hms inp: Mono Ie Input Sent and TUNER npeusse””"™! muon 14 2: 22m, 504 TAN Lay 42 TUSER' ©” TSomv,SOkohms Semiconductors: 22 Tanto 10 1c, 19 Diodes TAETLAY 103 Binenon Stag} tt « 8b) mm isin, So kohne Toda ise e Soe hone Oven: 17OnV RMS. An DODGED We: Ske 0 Tone con Bass 210 48100 TREBLE lo gbat lone Seprietions and fests we abet to change without wghOt Flier Satie eblot) pele fo known SERVICE PROCEDURES 1. VOLTAGE CONVERSION (Universal model) This model is equipped with a universal power transformer to permit operation at either power source of 110, 120, 220 or 240V AC S0/60H2. To convert the unit toa different power source voltage, change the plug as illustrated in the drawing below. CAUTION. DISCONNECT POWER SUPPLY CORD FROM AC OUTLET BEFORE CONVERTING VOLTAGE. ®) 68) (8) @®) For 110V Operation For 120V Operation For 220¥ Operation For 240 Operation [Vortace sEtector Sy 2, REPLACING THE SPEAKER PROTECTION FUSE seaken Fuse I)Rontes er lng econ and bro 2) Ree ise its ye ans ts PREACAUTIONS 1. For continued protection inst fre hazard, eplace only with same type and same rating fuse. PARTS NO. AC fuse 4A) 252083 (110/120V model) BAT 252020 (220/240V model) Speaker protection fuse 4AT 252014 2. Replacement for power, complementary and driver transistors, if necessary, must be made from the same beta (he) sroup asthe orignal type. 3. Always disconnect the chassis from powerline when soldering. Tuming the power switch OFF is not enough. Powerline leakage passing through the heating element may destroy the transistors, 2BLOCK DIAGRAM wis) SHEREh / Hime Sal” CIRCUIT DESCRIPTION ‘Serivo Operational Amplifior In order to achieve a greater degree of fidelity in wave form transmission, and to remove the large capacitance capacitors (which have questionable effect on the quality of sound) from the NFB, DC amplifier designs are being more and more widely used in amplifiers today. The A-7040, however, has advanced even further by adopting the recently developed Servo Operational Amplifier which features a truly superb quality of sound, and performs considerably better than the now conventional DC amplifiers ‘The major circuit feature of the Servo Operational ‘Amplifier (See outline in Fig. 1-1) is the servo feedback loop which has no effect whatsoever on the main signal. In other words, if the signal feedback factor is ®, and the servo feedback factor fp, the 0 = 6, <6; €1 rela. tion holds true within the signal bandwidth, while Bs > 1 hholds true in the subsonic region down to DC. For this purpose, a servo feedback amplifier was necessary. And since it was also necessary to include a high-cut fier, and suppress signal amplifier drift at higher DC gain plus 1/F noise and other subsonic region components, @ ~64B/oct high-cut mirror integrating circut (See Fig. 1-2) has been employed. The Veer in Fig. 1-1 serves as the input voltage requited to keep the system output DC voltage at OV. In the block disgram for the actual Servo Operational Amplifier (see Fig. 1-3), RF and Rg constitute the signal feedback loop, while A2 and A3 form the servo feedback lo0p. ‘Assuming that Al, A2, A3 > 1, the input/output characteristics T(w) may be expressed as, Ry (Rit AD RE Re Me) Proves (Se rated apa {vais mle Ls NF ‘Serve operational Fig. 1.1 input vin] 1. ‘oureur Fig. 12The frequency response is a8 shown in Fit. 1-4. uy eine about O.3Hz ~ 2Hz. A3 is phase inveried in order 10 prevent positive feedback inthe DC region Hence, the subsonic frequencies are effectively cu just 45 if by coupling capacitor. But unlike capacitor, the ‘ourput impedance of the servo operational amplifler decreases at lower frequencies (coupling capacitor Impedance increases at corresponding frequencies) due to 2 greater amount of feedback. Since, however, in actual circuits the second stage is driven at a suitable impedance level, and the output impedance of the amplifier itself is sade sufficiently large enough (10 improve stability) by connecting resistance pin series, the output impedance is kept constant at 7%. With coupling capacitors, on the other hand, the increased impedance at lower frequencies naturally results in an increase in thermal noise (directly related to effective impedance) in the low frequency region ‘Although servo feedback circuit integrating capacitors of large leakage current, or high DC resistance and inductance are undesirable, the effects are nowhere near as serious as the insertion of a capacitor in the signal path. Output Indicator Driver Circuit Q701 and Q702 ate the power indicator drive ICs. The audio signal applied to pin no. 3 of Q701 is first amplified and then applied to the comparator. The LEDs connected to the IC output terminals pin nos. 9 ~ 13 are lit up in succession depending on the comparator level The connection from pin no. 14 to pin no. 1 in Q701 is part ofa feedback loop where the feedback resistor R721 (82KQ) determines the gain of the amplifier, and is con- sequently used in the adjustment of indicator level Input yl Rt AZ RI RG ma htt ft MatEEEE LBI416 EQUIVALENT DIAGRAM 5EXPLODED VIEW COMPONENT LOCATION 8B oo a a - (5) ge a MTs) OoEXPLODED VIEW — PARTS LIST er, No. PARTS NO. sag60121 210122 28191037 13639125, 27267048 27180038, 24320319, 13639128 272670898 27180037 28320318 24130062 28320308, DESCRIPTION Front panel at (2) Front panel Gas for indicator Power switch knob as'y (3-5) Power switch guide Spring Power switch knob Push switch knob sy (6-8) Pash switch guide Spring sh switch knob 3STS*6BQ, Tapping sor ‘Volume contol kaob COMPONENT LOCATION — PARTS LIST 120V model No. QISSUT—pantsNo. DESCRIPTION 12669540 NAAF-640, Pre. and main ampll pet, 12ss9se1 NASWESL, switch pcb, 12e68542 NABSGA2 Power sony 12669547 RASiL642 swith ph 12g69544 NAV, Volume control pen 12669545 NAME-6¢5, output indicator ares ped: 12669586 NADISE46, output indicator a504,0608 2211255 ,, BecisisiGR, Themoampl. Hideo | SCIIS(80) & tater 9507, 9607 3200995 ,,28C258010) , Baoossa * seaseory) ower ap (9508, 608 3201003, 28A1105{0) ,, Power amp, 3201004" 2$A1105(¥) "transtor PLooi 10087 ‘Too. 230286 PLB.SVO.1SAWIS Power NPT-S6ED, Power ane ‘coo 3504012 ULTDSV1034, UL capuctor ROOL,Roo2 441723316 Sa 2¥, Mea one soot yoonsias, NSTI 108 , Power so02 HUI Naswaad ey, speaker selector switch Poot 2045086 NPLSPRBLIS, Tuner, Phono Land Phone ? input terminal 002,003 25085025 NPIAIPRBLO3, Tape input) output termina F008 2s0go008 Grou termina 3soasors LI 0H, Headphone jack Poos 006,007 28060029 NTMAPRMNOS, Speaker ‘erminal P008, Poo? 2s0s0032 STg4d#01, AC outlet POLO.OIT 35080004 Fusenolder POL, POLIa 252014, SAT Speaker fuse Foors"'"'* 35309 4A (STS) AC Tue wor 38099 ASC. bower supply cond Wools 370025 SIP 'Stainrelit oo 37110079 Front wacker aoa TTLISOA3A. Side bracket ‘Aus 37160052" Radiator ane Hod Ria Bracket Aart 273048 Bracket for power ane ann? amaonss ‘os2 noisy panel 0x8 4371500968 Shielded plate for equalizer er. REF partsno. —DescriPrion 1128320312 Tone contol knob 12 24320314 Selector nob 1328140126 Cushion 1428184081 Top cover 25140020 Cushion 1s 838440109 TTBFI0C(BC), Tap crew 16 834430062 38TS+6BQABO), Tapping sew 27170084 Bottom board 27175009 Leg 831130162 __3STW+16BQ, Tapping screw 831130082 —-3STW+8B0, Tapping screw 271900444 Holder 2228130073 Plate indicator Universal model REF. ciRcUIT ar ge PARTSNO. DESCRIPTION 1 12669540 NAAF.640, Pre, and main mph. pb, 2 12s69s¢1 NASW, Switch pc, 3 126708424 NARSO423, Powe ppiy 4 ssost RASinc4s swith neh 5 13e69544 NAVR‘844, Volume conirol cb, ‘ 12669545 Riane-645, output indicator rier prob 7 12569846 NADICS&6, Output indicator cb. 0808. 060s 2211255, BSCRISIGR 4, Therma amp 2211286" —28C181StBL) ° tansstor 9 807.0607 2300983 ,, 28C2S80(0) , Power amp 3200984°" 2895401) * tansitor 10 808,.Q608 3301003 ,, 28A1103(0) ,, Power ampli 2201004" 3SA11080¥) © wansior 1 PLoor 710087" PLE.SVO.41SAW1-S, Power Indicator lamp 12 Toot oast—_NISGEAD, rower tne 13 C0O1,C002 3500082 PMERTIYSIOCEE, 18 ‘aapacter 14 ROI, Roo? 441723314 3300, BW, Metal oxide fm eat ts S001 2soasost NPS 1-126" Power switch te S002 35030104 NRSW24E SY, Speaker ‘elector swith 17 Poot 25045086 NPF-GPRBL2S, Tuner, Phono Vand Phono 2'input terminal 18 P002,P003 25045025 NPJAPRBLOS, Tape Input) eutput termina ty rove 2sueoouy — Srounterminal 20 Roos 35043018 LI-LO0H, Headphone jack 21 Pons,roor 28080029 NIMAPOINOS, Sper 2 asosoois PAS, 3P init 23 potoa ports 25030008 Fuseholder 2 POLO 359014 HAT. Speaker fuse Fa ins AAT Ey aC is 352003, 3A. Acie 2 2808002) X17440, VS socket ® 27110079 Front bracket, By FTLISOAGA Side bracket 40 31160082" Radiator Et 22019 RICE, Bracket 2 Fi8dtee Becket Poter wane 2 aaonss acct FY 27120188 Back panel 38 37150096B ‘Shielded pate for equalizerSCHEMATIC DIAGRAM Node 4:7040 ONKYO CORPORATIONPRINTED CIRCUIT BOARD — PARTS LIST PRE., AND POWER AMPLI. PC BOARD. CIRCUIT NO. PARTSNO. DESCRIPTION (NAAF-640) — PARTS LIST Resistors rooeaaos SDE ntencanicsoxes2s ROUT ao, = PARTE © DEEORIPTION R310,R410 5148034 NIGRGMLICSOKBO3S- ice ile Slolors _ NientctooKwress 0101.0201 0301, Syoery ates? Rovere aisaigae kn iawar Q302,0401,0402, at RS13,R613 4000003 | D-22A, Themistor Qsoni9e09" azzsoz—_Nneasseox Reinet? ozs Niowia0gb, tears Rienes — isaize un 1aw Lor sonaso: ERMA sccases) Ravaes — Galeaitat Ski WMO Bier BEG or ROR — Maisnsia ison uawimor sona6e2 atlas decane) ; Eilttesr Sebineh) RSIERSZ3——agggo47 420, $W, Me plate 503.0603 BUS, HAO) ReaiRed® 451731008 109,20, Meul asososoe IRS BECO Revenese —Sloloset Sn, I, Seul Hse or SELIG Wooster aisasig eon, iswaMor esosqcos URS” REEBD ° bor Steusie Soniwsior Hassect 316d) suites 9506,0606 2200403, 2SA815(0)., sio1 Sosore?— NRswe143.3528 Hooineer 3845188 1 2 . 0507,0607 3200993, 38C2S8K0) ,, Sistsis2 25035118 NPS-222-L80 Hrovssst 3Scasany) Rey esongcos — Ho1ean,, Heaitown musot Bolioasa wetarsavers03 Holoeor 3SAUGEV} or Q801,0803, BIBS or FRIESE or SWITCH PC BOARD (NASW-641) — 802 2211395 ,, 28A970(GR) PARTS LIST Biuaecr Shares) sro. 2so3si09 — wwsimau74 ae Biase, SSCIBISY) oy zai12ss 15(GR) POWER SUPPLY PC BOARD (NAPS-642) — oot 300664 og HSEISIEO) PARTS LIST (120V model) 902 Soets, dsasteto),. eoi-ba04 223863 «GPAODL, Dade Boocraer SRE} Cooscoor® —Sottie Tsou 30 ec expats Pinta enol Sols) sens Fasmotder psorpeor B62 osze2 S02D503.0602 295105 sisss POWER SUPPLY PC BOARD (NAPS-642a) — pene -D801,D802 oases Gp08B PARTS LIST (Universal model) Bes | RR | psoin9es 238633001, Sion dade Bas yee gia Cooecoor Satie Tso, Sov ee Colts SWITCH PC BOARD (NASW-643) — PARTS vsotueor — SHOon S138 x List cons cinco SB, aye soy. Sin.si72si01 03814 xpsaz2L19 Gioveaoe§—Szraanay Hak ov, Fe Sioseios SERGE Tear VOLUME CONTROL PC BOARD (NAVR-644) Gloiganr—sonesonay 2B, SOV. ~ PARTS LIST Cloveant MBN St, 3, et : . Gioeeing —Ssunsourt aur a8, bese furRare —SITANSS—_NAURGLAICIOORSTPISM, Gizeats —Ssatatoot Tope ev, tse | Gunes 3Sizeono, Isr dav Bese - HGH SRR! BLAS METER DRIVER PC BOARD (NAMES45) esoreeot S270 aie 10V ba P Gsineero | Sawoet Ee Sov i groin. 7539 —taiai6.te Csizest2—SS2781011 Tabu SOV, Bes Brovsvon —3sstos SSS Seon ide Sunes sot : rane bros Buea gaze C613,C614 345071002 L0pF2%, SOOV, C¢ €701,C702 352751001 10uF, 2SV, Elect. EIS sranzerssearnareton.s0V.0E FONG ERA teks fev Bese See 392853307 33uF, 25V, LL €708--C708 352750471 4,7uF, 25V, Elect cant 352722011 2204F 63V, Het. Restore a Sau pw gb nna MIB sen, w, wore Cooncgny Sarees Babu 4 DISPLAY PC BOARD (NADIS-646) — PARTS Coiocart ——sansioit loo. asv- ee List Crzets—SS20s0n11 gh 25V. Est oir SSzrei0a1 100s 16, Bec. Dri-pms asia GL-anGs9. LED Coleco Ss2700331 | SSureSOV. Het B34 25029 GLPR.LED Cures Samoan aur Sov. eect cL PRI, CAUTION: Replacement for power, complementary and driver transistors, if necessary, must be made fom the same beta group (ire) a the ong type NOTES: — Capacttons LL: Low leakage cucent type electrolytic capacitor DE:_ Nonsnductive polyester fim epactor Resistors: MOF: Metal oxide is restor nPACKING PROCEDURES REFNO. PARTSNO. DESCRIPTION 29100036 850 $S0mm, Poly bg 1 2 Bassas Seo Sonn: Feet ae 3 Bison Get oma 85) fee” Gitoa Seay es ution abel (084) & 29090398 Pad . 523080265 Citon box a ‘comer bg compete S.A model Beasts 2o3es006 dyssaoo2 $s i 39100006 350. 35omm, Poly bag Univeral model 2H tnataction manu 2 fonversion PE Bs2008”A'ST 6 Fase 29100002 180 86 mm, Poly bas for fue 35100008 280° $S0mm, Poly bas Germany model 25340316 "Instruction manuat ‘Jesesogs-1 Warrenty card aD 2100006 | 280'x'5dmm, Poly bag 9 13010203 Powersupply cord (UU) 253089” ASAVDEC, Power supply cord (G) 35380038 Voltage tag (UU), (CP NOTE: (USA): US.A. model (UU) Universal model (6) Germany model ONKYO CORPORATION Insertion Division: No. 24 Mori Bids, 235, Schome, Nishi Shinbashi, Mineto-ku, Tokyo, span Telex: 2423851 ONKYO J. Phone: 09-432.6081, ONKYO US.A. CORPORATION Eastern Office 42.07 20th Avenue, Long Island City, New York 11106, US.A. Phone: (212) 728-4699 Midwest Office 895 Sivet Drive, Woodéale,tlinls 60191, USA. Phone: (312) 695:2970 (ONKYO DEUTSCHLAND GMBH, ELECTRONICS £8036 Minchen-Germering,Indusretaste 18, West Germany. Telex: 621726. Telefon: (0691-84-5041 Printed in Japan 1904