sA-7cIa - Creapromedia
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1. Q409 6 2SA D4li 4ia 182076 92 3 MAI2000 AND PARTS LIST NOTES e When orderin the following examples Ex 1 When there are 2 effective digits any digit apar and 47k ohm tolerance is shown by J 5 and 5602 56 x 07 561 47ka 47 x 10 173 s 0 52 ORS 12 010 Ex 2 When there are 3 effective digits such as m hig tors y 562kn 562x10 5621 e The 5 mark found on some component parts indi safety factor of the part Therefore when replacin identical designation 9 1 MISCHELLANEA Miscellanous Parts CAPACITORS Part No Symbol amp Description CKDYF 473Z 50 C1 C4 n SEMICONDUCTORS Part No 2 Symbol amp Description 8 2SA1075 A G Q1 Q4 2SC2525 A G 02 3 OTHERS Part No Symbol amp Description A ATT 603 T1 Power transformer A AEK 403 FU1 Fuse 2 5A A ASK 515 11 Lever switch POWER P C BOARD ASSEMBLIES Part No Description Sa GWK 130 AF assembly GWX 335 SP switch assembly GWX 336 Headphone assembly amp GWX 337 Fuse assembly GWX 334 Terminal assembly GWX 333 Tape terminal assembly GWS 194 Switch assembly GWS 193 Mode assembly GWS 192 Muting assembly GWG 130 Volume assembly a GWG 129 Control assembly AWV 004 Indicator assembly 9 SCHEMATIC DIAGRAMS P C BOARD g resistors first con vert resistance values into co PATTERNS de form as shown in t from 02. e ee 56 ee Soti P a Ou 25K 34 m P a ta a ew 9 4 PARTS LIST OF P C BOARD ASSEMBLIES AF Assembly GWK 130 CAPACITORS Part No A ACH 212 ACG 004 CCDSL 050D 50 CCDSL 270K 50 CCDSL 470K 50 CCDSL 680K 50 CCDSL 221K 500 CKDYB 471K 50 COMA 473 50 COMA 473J 250 CCDSL 100K 50 COSA 271J 50 COSA 122G 50 COPA 183G 50 COPA 683G 50 CEANL 3R3M 50 CEANLNP 4R7M 50 CEANL 470M 16 CEANL 470M 35 CEA 010P 50 CEA 2R2P 35 CEA R47P 50 CEA 100P 16 CEA 100P 63 CEA 101P 16 CEA 101P 25 CEA 101P 35 CEA 331P 63 CEA 471P 6 CEA 102P 50 Note RESISTORS Part No RD PM J RD PM 0 RD PM OOO J A 1 RN4SO OOOO RS1P ODD J A RD4PM OOD J 5016 OOO J ACN 030 RS2P DJ 1 RDZPSF OJ Symbol amp Description C503 C504 C502 C505 C506 C311 C312 C409 C410 C413 C414 C401 C402 C405 C406 C407 C408 C415 C418 C305 C306 C319 C320 C421 C322 C411 C412 C425 C426 C301 C302 C509 C510 C315 C316 C313 4 C317 8 C303 C304 C403 C404 C321 C322 C307 C308 C325 C517 C511 C512 C419 C420 C513 C516 C515 C424 C323 C324 C507 C508 C309 C310 C514 C423 When ordering resistors convert the resistance value into code form and then rew
3. SPEAKER B SPEAKERS BA SUBSONIC 2 _ Phones FL TUBE TONE CONTROL PROTECTION LN circuit VN a INOICATOR Lel POWER DRIVE METER 7 TUNER tB PHONO FUNCTION AUX 1 t 1 I I PHONO 5 TUNER R CHANNEL SAME AS L CHANNEL O SPEAKER A SPEAKER B c swell RECTIFIER 1 POWER AMP a raes TAPE 1 POWER RECTIFIER VOLTAGE REGULATOR INDICATOR DRIVE FUNCTION INDICATOR LPLAY G AC LINE Dg rREC G POWER AMP VOLTAGE REGULATOR EO AMP TAPE 2 Le Lay G RECTIFIER TONE AMP VOLTAGE REGULATOR 4 CIRCUIT DESCRIPTIONS 4 1 PHONO CIRCUIT RF interference Filter Since the phono input circuit is extremely sensi tive it is adversely affected by radio freguency interference This interference is reduced by insert ing a resistor in series with the phono input circuit by setting the PHONO INTERFERENCE FILTER switch on the rear panel to the ON position Egualizer Amplifier The egualizer amplifier is a 3 stage direct coupled amplifier with emitter to emitter feed back An S N ratio of 86dB at 2 5mV input IHF A PHONO INTERFERENCE FILTER switch OFF has been achieved by using a ultra low noise PNP transistor 2SA978 at the first stage and reducing the signal source resistance and
4. e MEN 5 cee Service Manual STEREO AMPLIFIER A 708 U PIONEER Chome Meguro ku Tokyo 153 Japan U S PIONEER ELECTRONICS CORPORATION 85 Oxford Drive Moonachie New Jersey 07074 U S A PIONEER ELECTRONIC EUROPE N V Luithagen Haven 9 2030 Antwerp Belgium PIONEER ELECTRONICS AUSTRALIA PTY LTD 178 184 Boundary Road Braeside Victoria 3195 Australia PIONEER ELECTRONIC CORPORATION 4 1 Meguro 1 Printed in Japan ART 367 0 SA 708 Indicator Assembly AWV 004 Volume Assembly GWG 130 CAPACITORS Part No Symbol amp Description Part No Symbol amp Description ACV 181 VR1 Variable resistor 1 a i VOLUME CEANL OR1M 50 C102 RD 4PM 104J R111 R112 CEA 101P 16 C3 RD 4PM 123J R113 R114 CEA R47P 50 C4 CCDSL 271K 50 C101 C102 COMA 332K 50 C5 C6 COMA 473J 50 C103 C104 CKDYF 473Z 50 67 69 ASK 158 85 Lever switch LOUDNESS Note When ordering resistors convert the resistance value into code form and 4 RESISTORS then rewrite the part no as before Part No ___ Symbol amp Description RD APMF GOD J R1 1 Ne RDAPM OOO J 2 R4 ACP 078 VR1 VR2 SEMICONDUCTORS Part No CUI ET Symbol amp Description y 2 TA7318P A 01 a 74 73 HA12010 Q2 03 F JA OTHERS 1 E 4 1 Part No Symbol 8 Description AAV 004 V1 Fluorescent indicator tube 3 ATT 577 T1 Heater transformer 10 PACKING Key No Part No mu Description VR 7 1 A
5. 15 43 Power Amplifier 6 9 2 Schematic Diagram 16 44 Indicator Circuit 7 9 3 P C Board Connection Diagram 19 45 Protection Circuit 8 9 4 Parts List of P C Board Assemblies 23 5 DISASSEMBLY KAE e KRE ci m ad DSS AE aa 9 10 PACKING W a a a a a a a a w a a a a w a w u w a nm on n a aa 25 11 SUPPLEMENTS FOR HA TYPE 25 on LINE VOLTAGE SELECTION 4 HR type Line voltage is factory adjusted at 240V HA type Line voltage is factory adjusted at 220V Line voltage can be changed with following steps 1 Disconnect the power cord 2 Remove the top cover refer to page 9 3 Reset the fuse 2 5A on the Fuse assembly to the correct place see Fig 1 4 Stick the line voltage label on the rear panel Part No 5 Description a 240V AAX 193 220V label Fuse AAX 192 240V label assembly Fig 1 1 SPECIFICATIONS Semiconductors PRI ee Aa 3 EE SS 2 GE A YW A HEARST SEO AY ES 41 31 Diodess RI E AR Nine Amplifier Section Continuous Power Output of 65 watts per channel min at 8 ohms from 20 Hertz to 20 000 Hertz with no more than 0 02 total harmonic distortion or 65 watts per channel at 4 ohms from 20 Hertz to 20 000 Hertz with no more than 0 03 total harmonic distortion Continuous Power Output at 1kHz both channels driven T H D 0 02 8ohms 70 watts per ch
6. 50 C221 C222 C225 C226 COMA 104J 50 C227 C228 CEA 100P 16 C209 C210 CEA 220P 25 C233 CEA 101P 10 C207 C208 CEA 101P 35 C231 C232 CEANLNP 010M 50 C229 C230 CEANL 2R2M 25 C217 C218 CEANL 3R3M 25 C223 C224 CEANL 3R3M 50 C201 C202 CEANL 4R7M 50 C213 C214 Note When ordering resistors convert the resistance value into code form and then rewrite the part no as before RESISTORS Part No Symbol amp Description RD 4PM OOO J R201 R207 R213 R214 R219 R236 R241 R243 RD4VS OOO J R208 R212 R215 R216 R239 R240 RS1P ODD R217 R218 A RD4PM 000 R237 R238 ACT 117 VR2 VR3 Variable BASS TREBLE ACT 118 VR4 Variable BALANCE SEMICONDUCTORS Part No Symbol amp Description 2SA978 0201 O202 2SC1919 0203 O204 2SC1400 2SA949 Q205 6 2SA905 SWITCH Part No Symbol amp Description wa 0 ASK 158 S6 S7 Lever TONE SUBSONIC Mode Assembly GWS 193 Part No 2 Symbol 8 Description RD PM 332J R109 R110 ASK 158 4 Lever switch MODE SP Switch Assembly GWX 335 Note When ordering resistors convert the resistance value into code form and then rewrite the part no as before Part No Symbol amp Description RS2P 000 J R601 R602 RD PM OOO J R603 R604 RS1P 000 J R605 R606 ASD 104 10 Rotary switch SPEAKERS Headphone Assembly GWX 336 Part No _ Symbol amp Description AKN 023 Phone jack PHONES Fuse Assembly GWX 337 Part No _ Symbol amp
7. 6dB 100Hz 3dB 10 000Hz Hum and Noise IHF short circuited A network RH OIN Ogee 86dB TUNER AUX TAPE PLAY o 100dB Hum and Noise DIN continuous power 50mW PEIONO E v es AD 70dB 60dB TUNER AUX TAPEPLAY 86dB 61dB MULLIN Bek o vc peu Fn 20dB Miscellaneous Power Requirements IiA modelles e sacre 5 220V 50 60Hz tiRomodelikes epe ce rr e 240V 50 60Hz S S G models 110V 120V 220V 240V 50 60Hz Power Consumption EAS HRImodelse e mo m meth t NF 600W SS Gtmlodel Sweeny dur e RES EM eee US 190W Dimensions 420 W x 150 H x 337 D mm 16 9 16 W x 5 7 8 H x 13 1 4 D in Weight without package 9 7kg 21 Ib 6 oz Furnished Parts OperatingsinstructiOns mane UH SERA 1 Fuse 2 5A S S G modelsonly 1 Fuse 5A S 5 6 models only 1 NOTE Specifications and the design subject to possible modifi cations without notice due to improvements Measured pursuant to the Federanl Trade Commision s Trade Regulation rule on Power Output Claims for Amplifiers L 3 BLOCK DIAGRAM 16 5dB 35 548 etx PHONO TAPE MONITOR PHONO hey y RFI Marr P FILTER TUNER O AUX 6 LOUONESS TAPE DUPLICATE 1 se prec Ge TAPE 1 rrec G TAPE 2 teray jl 1kHz MUTING VOLUME MODE Fi MW O SPEAKER A
8. IE Indicator assembly Control assembly L Volume assembly AWV 004 GWG 129 GWG 130 Rear Panel View Terminal INPUT a SPEAKERS AKB 055 AKE 038 Slide switch PHONO INTERFERENCE ASH 015 Terminal TAPE 1 1 SS A Recessed plug AC INLET AKB 054 AAKP OOB Connector socket 2 Terminal TAPE AKB O54 AKP 024 Key No Part No 1 ABA 069 A 2 ATT 603 A 3 AEK 403 4 GWX 337 5 6 7 ABA 025 8 9 6 10 ABA 069 11 12 8 13 AWV 004 14 GWX 336 15 GWG 129 TO issus A17 ASK 515 18 19 GWX 335 20 21 ABN 050 22 ABN 049 23 ABN 031 Description Screw 4x8 Power transformer Fuse 2 5A Fuse assembly Wire saddle P C Board holder Screw 3x4 Frame Foot assembly Screw 4x8 Angle Screw 3x6 Indicator assembly Headphone assembly Control assembly Lever switch POWER Cushion SP switch assembly Panel stay Union nut Union nut Nut M7 Heat sink Key No 25 31 32 33 34 A 35 36 37 38 39 40 41 42 43 44 45 Part No AEC 488 28C2525 A G 2SA1075 A G ABA 208 GWK 130 GWG 130 GWS 194 AKP 008 AKE 038 GWX 334 GWX 333 ABA 228 ABA 057 ABA 157 ABA 115 ABA 116 ABE 005 u Description Insulator spacer Transistor Transistor Screw 3x12 Frame AF assembly Volume assembly Switch assembly Frame Re
9. be accentuated When the volume is low the human ear finds it harder to hear the bass and treble than when the volume is high The loudness switch is thus designed to compensate for this deficiency By setting it to ON the bass and treble come through much more strongly and the sound takes on a punch even when the volume control is turned down VOLUME CONTROL Use this control to adjust the output level to the speakers and headphones Turn it clockwise to increase the output level No sound will be heard if you set it to 0 MUTING SWITCH Set this switch to 20dB to attenuate the audio output by 20dB There is no need to adjust the volume control if you use this switch when turn ing down the audio output temporarily and when changing over records or tapes HEADPHONE JACK Plug the headphones into this jack when you want to listen through your stereo headphones NOTE Set the speaker selector to OFF when listening only with headphones 4 3 POWER AMPLIFIER The first stage is a differential amplifier formed by twin transistor while the load circuit forms a current mirror circuit The current mirror serves to make this stage operate in push pull mode thereby eliminating the even numbered harmonics and doubling the gain The pre driver stage is a Darlington connection while the load circuit forms a constant current source thereby obtaining a high voltage gain The power stage is a D
10. such as 560 ohm K 10 RDwPs 4 RD APS AMG RN2H K RSIP OOK h precision metal film resis RN4SR 67 cates the importance of the g be sure to use parts of List of Changed Parts for Factory Modification List of changed parts information will be furnished when ever necessary and you are requested to amend parts number in this parts list Description Part No 1 2 r 9 2 SCHEMATIC DIAGRAM NOTE The indicated semiconductors are representative ones only Other alternative semiconductors may be used and are listed in the parts list 194 SWITCH Ay GWS TAPE TERMINAL Assy GWX 333 a m TERMINAL Ass GWX 334 ane AM An al S4 MODE MODE Assy GWS 193 sane VOLUME Assy Gv s D507 508 2 0507 508 a 60511514 18247 2569458 09 rs 5 MZ 140 0509 t 2SA904A F POWER SUPPLY CIRCUIT FOR EUROPE MODEL D401 404 6 D405 406 151555 Daig MZ 240 1 _ 8 7 1 4W 58 tolerance unless ed F i 18 G 23 K 10 tolerance capacity F voltage V unless zed p pF thout voltage is 50V except capacitor VENT voltage at 65 65W output lkH2 tage V at no input signal in s DC voltage at rated power route ing point found on some compone
11. Description A ACG 001 C501 Terminal Assembly GWX 334 Part No Symbol amp Description RD PM 222J R301 R302 ASH 015 58 Slide switch a PHONE INTERFERENCE AKB 055 Terminal INPUT Tape Terminal Assembly GWX 333 Part No Symbol amp Description RD PM 394J R101 R102 RD PM 104J R103 R104 AKB 054 AKP 024 Terminal TAPE Connector socket Switch Assembly GWS 194 Part No ___ Symbol amp Description u ASK 160 si Lever switch DUPLICATE ASK 160 2 Lever switch TAPE MONITOR Muting Assembly GWS 192 Part No 0555005 Symbol amp Description u RD 4PM 562J R107 R108 RD PM 473J R105 R106 ASK 158 S3 Lever switch MUTING
12. HA 187 Side pad 2 ARB 328 Operating instructions ENGLISH 3 AHD 698 Packing case 11 SUPPLEMENTS FOR HA TYPE Model SA 708 HA is the same as the SA 708 HR with exception of description in this supplements Contrast of Miscellaneous Parts Part No Symbol Description Remarks P HR type HA type L 4 AC socket AC OUTLETS AKP 026 Operating instructions ARD 137 GERMAN FRENCH MODEL SA 708 COMES IN FOUR VERSIONS DISTINGUISHED AS FOLLOWS Type Voltage Remarks HR 220V and 240V Selectable U K and Oceania model HA 220V and 240V Selectable Europe model 5 110V 120V 220V and 240 Switchable General export model L S G 110V 120V 220V and 240V Switchable U S Military model d This service manual is applicable to the HR and HA types When repairing the S and S G types please see the additional service manual ART 368 CONTENTS e 1 SPECIFICATIONS 3 6 PARTS LOCATION 10 2 FRONT PANEL FACILITIES 4 7 ADJUSTMENTS uu uu 12 3 BLOCK DIAGRAM 4 6 8 EXPLODED VIEW 13 4 CIRCUIT DESCRIPTIONS 9 SCHEMATIC DIAGRAM P C BOARD 4 1 Phono Circuit L L ses 6 PATTERNS AND PARTS LIST 4 2 Tone Controls Non FA a et sik 6 9 1 Miscellanea aig fap ude E y m W Mee Ws sak Sl Oude a Hoa Se eee T
13. annel Total Harmonic Distortion 20 Hertz to 20 000Hertz 8 ohms from AUX continuous rated power output No more than 0 02 32 5 watts per channel power output AEAF No more than 0 0296 1 watt per channel power output No more than 0 0296 Intermodulation Distortion 50 Hertz 7 000 Hertz 4 1 8 ohms from AUX continuous rated power output No more than 0 02 32 5 watts per channel power output Se ROL REN crane a No more than 0 02 1 watt per channel power output No more than 0 02 Damping Factor 20 Hertz to 20 000 Hertz 8 ohms 35 Input Sensitivity Impedance PHONO me arr cee mo O mwa 2 5mV 50kilohms DUNE WN A 150mV 50kilohms 150mV 50kilohms A cd TAPE PLAY n eee 150mV 50kilohms TAPE PLAY 2 DIN connector 150mV 50kilohms Phono Overload Level T H D 0 01 1kHz PHONO ES teal te ki ae te eee tee eee y 200mV Output Level Impedance WAPEAR ECH eer e atenn etr a 150mV 1kilohm TAPESREGOD ue sen 407 150mV 1kilohm TAPE REC 2 DIN connector 30mV 80kilohms Speaker uen y A B A B 4 16ohms Freguency Response PHONO RIAA Equalization TUNER AUX TAPE PLAY 10Hz to 50 000Hz 1dB 20Hz to 20 000Hz 08 SA 708 Tone Control BASS atc tae ah een 7 5dB 7 5dB 100Hz EREB EET 7 5dB 7 5dB 10 000Hz SUBSONMICIE tel ISR 15Hz 6dB oct Loudness Contour Volume control set at 40dB 6 position
14. ar panel Recessed plug AC INLET Terminal SPEAKERS Terminal assembly Tape terminal assembly Screw 3x6 Screw 3x8 Screw 3x8 Screw 3x10 Screw 3x6 Washer Terminal GND 8 SA 708 8 EXPLODED VIEW NOTE e_ Parts without part number cannot be supplied e The A mark found on some component parts indicates the importance of the safety factor of the part Therefore when replacing be sure to use parts of identical designation Key No Part No Description Key No Part No _ Description 1 ABA 079 Screw 4x8 7 AAB 204 Knob 2 ANE 235 Top cover 8 AAB 202 Knob 3 ANB 747 Front panel assembly 9 AAB 203 Knob 4 M45 086 Washer 10 Bottom plate 5 B71 004 MEN 11 ABA 048 Screw 3x6 6 AAD 183 Lever knob 12 AEC 525 Rivet 13 B22 017 Washer 7 ADJUSTMENTS Idle Current Adjustment 1 Turn the VOLUME control down to minimum level turn the power on and wait about 10 minutes 2 Connect a DC voltmeter to the TP terminals L ch TP4 and TP3 R ch TP1 amp and TP2 of the GWK 130 3 Check that the voltage between TP4 and TP3 L ch lies within the DV DC 4mV 50mV range Then make a similar check for the R ch between TP3 and TP4 If the voltage is less than 4 4mV cut jumper A L ch and jumper B R ch If the voltage exceeds 50mV check for circuit failure TP4 TP3 TP2 TP1 en 1 Jumper A Jumper B Fig 7 1 Output Indic
15. arlington connection pure complementary SEPP circuit employing an high speed transistor The high speed transistor is a kind of IC consisting of a number of small transistor being connected in parallel via an emitter resistor This provides excellent high freguency characteristics comparable to those of a small signal transistor Furthermore because there is no time constant in the NFB circuit in the low freguency region amplification is possible down to DC DC inputs will be cut off however by the input coupling capacitor of the power amplifier The circuit features described above provide an extremely wide power freguency range 65W 65W 20Hz to 20kHz THD 0 02 822 4 4 INDICATOR CIRCUIT The SA 708 output power and function indi cators feature fluorescent indicator tube FL tube In this tube thermionic emissions from the cath ode are accelerated into the fluorescent substance of the segmental anodes resulting in the emission of light This tube is used to indicate numerals letters and other symbols ic TA 7318P 72 00 a DETECTOR 8 SIGNAL IN 0 oerecron EC 00 DC I HHA SA 708 An outline of the FL tube drive circuit is shown in Fig 4 1 The output circuit signal is applied to pin no 6 4 of the IC TA7318P A The IC con tains a detector circuit compressor 40dB and peak hold circuit for both left and right channels The dynamic range of the s
16. ator Adjustment 1 Set the TONE switch OFF position 2 Set the SPEAKERS selector to the A position yiri 0000 and connect an 89 resistor and AC voltmeter TWE i to the speaker output terminals ol ual 3 Set the FUNCTION switch to the AUX posi a tion and apply a 1kHz 150mV signal to the amp vR AUX input terminals 4 Adjust the VOLUME control so that the volt age on the output terminals SPEAKERS read 9 9V AC 1 5 Adjust VRI L ch and VR2 R ch of the Panel stay indicator assembly so that the output power indicator read 10 watts Fig 7 2 Ass y GWX 337 EERE am HEAD PHONE Ass y SP SWITCH Ass y GWX 335 o gt GWX 336 48 os amp 3 89 TE e 15 Raca 8 o mA Si 9 e 3 Roog 30 NN e e LI N w w a pan l l Ela a n ee xm WP RFPS SES 8 6 8 ES 85 25 8 8 5 5 o 1 a a fe A E NT o 18 o 4 m G 88 7 ge m ca a P LAB demi 8 hE 65552 9 5 5 2 8 rf je xx mi 3 te W e 8 1 9 eam i i NDICATOR Ass y AWV 004 10 L an 12 SP SWITCH Assy HEADPHONE Assy GWX 336 1 8 9 SP AT SPEAKER A 2 7 CONTROL i C A a Assy Gws i29
17. ective digits such as in high precision metal film resis tors 5 62ka2 562 x 10 5627 7 a Si demanti RN4SR 9 7 e The N mark found on some component parts indicates the importance of the safety factor of the part Therefore when replacing be sure to use parts of identical designation 9 1 MISCHELLANEA Miscellanous Parts CAPACITORS List of Changed Parts for Factory Modification Part No Symbol amp Description List of changed parts information will be furnished when ever necessary and you are reguested to amend parts CKDYF 4732 50 61 4 number in this parts list sewmconpucrons 7 7 Pe SEA fo Part No Symbol 8 Description 2SA1075 A G Q1 04 2SC2525 A G 02 3 OTHERS Part No mE Symbol amp Description A ATT 603 Ti Power transtormer A AEK 403 FU1 Fuse 2 5A ASK 515 S11 Lever switch POWER P C BOARD ASSEMBLIES Part No Description 0 e 9 GWK 130 AF assembly GWX 335 SP switch assembly GWX 336 Headphone assembly GWX 337 Fuse assembly GWX 334 Terminal assembly GWX 333 Tape terminal assembly GWS 194 Switch assembly GWS 193 Mode assembly GWS 192 Muting assembly GWG 130 Volume assembly e GWG 129 Control assembly AWV 004 Indicator assembly Miu 555 11 2 Ass y GWX 337 HEAD PHONE Ass y SP SWITCH Ass y GWX 335 GWX 336 T7 wou 4 e gen um nng 2 z P
18. egualizer element impedance The 2nd stage load has been reduced a large ag FL HEATER output voltage obtained and the output impe dance lowered by using an emitter follower at the output stage Metal film resistors having a tolerance of 1 and polypropylene film capacitors having a toler ance of 2 are used on the NFB circuit to obtain an equalizer deviation of within 0 2dB over the 20Hz to 20000Hz range The maximum allowable input of this circuit is 200mV at 1kHz THD 0 01 4 2 TONE CONTROLS The tone amplifier is a 3 stage direct coupled amplifier with emitter to emitter feedback Tone control BASS TREBLE is accomplished by providing the tone amplifier NFB circuit with a frequency characteristic The NFB circuit is changed to a flat frequency characteristic when the TONE switch is in the OFF position 9 BASS AND TREBLE CONTROLS Use these controls to adjust the bass and the treble If you set the tone switch to ON and turn the bass control to right from its center position you will be able to emphasize the sound in the low reguency range Conversely turning the bass control to the left from the center position you will attenuate the sound You can use the treble control to adjust the sound in the high freguency range TONE SWITCH Set this switch to ON when adjusting the bass and treble controls When set to OFF the tone con trol circuits are disengaged and frequency response is
19. el signals and reproduces them monophonically SA 708 FUNCTION SELECTOR Use this selector to select the program source When set the function indicator above the meter panel corresponding to the position of the func tion selector will light up TUNER Set here when listening to broadcasts on a tuner connected to the TUNER jacks The TUNER function indicator lights up PHONO Set here when playing records on a turntable connected to the PHONO jacks The PHONO function indicator lights up AUX Set here when listening to a program Source which is connected to the AUX jacks The AUX function indicator lights up TAPE DUPLICATE SWITCH Use this switch when employing two tape decks to duplicate recorded tapes or edit tapes This switch is otherwise kept at the OFF position 1 2 When playing back the tape on a deck con nected to the TAPE 1 jacks and recording duplicating on a deck connected to the TAPE 2 jacks OFF Set to this position when not duplicating 9 1 When playing back the tape on a deck con nected to the TAPE 2 jacks and recording duplicating on a deck connected to the TAPE 1 jacks TAPE MONITOR SWITCH Use this to select the program source which is being reproduced 1 Set here to monitor a recording or a tape being played back on a tape deck which is connected to the TAPE 1 jacks OFF Set here whenever you are not playing back a tape or monitoring a recording i e when you
20. flat This function is convenient for checking phono cartridge and speaker tone quality and listening room acoustics BALANCE CONTROL Use this control to balance the volume of the left and right channels First however set the mode selector to MONO and adjust so that the sound appears to come from somewhere exactly be tween the two speakers If the sound appears to a be louder on the right it means that the volume of the right channel is higher Turn the balance control to the left and adjust Conversely if the sound appears to be louder on the left it means that the volume of the left channel is higher Therefore turn the balance control to the right and adjust After adjusting return the mode selector to ST 42 SUBSONIC FILTER SWITCH When this switch is set to the 15Hz position the subsonic filter with a cut off freguency of 15HZ is actuated The subsonic filter serves to attenuate freguencies lower than 15Hz in a 6dB oct slope It is therefore effective in suppressing ultra low freguency noise which is generated by record warp and other causes You cannot actually hear this noise but it is factor in the generation of intermodulation distortion and it may damage your speaker system Set this switch to the 15Hz position during record play for the best effect MODE SELECTOR Use this selector for selecting the performances ST Set to this position for normal stereo re production a MONO Mixes left and right chann
21. have set the function selector to PHONO or TUNER or AUX for an alter native program source 2 Set here to monitor a recording or a tape being played back on a tape deck which is connected to the TAPE 2 jacks 2 FRONT PANEL FACILITIES D POWER SWITCH Set this switch to ON to supply power to the amplifier There will be a short delay when it is set to ON because the muting circuit has been actuated to suppress the unpleasant noise that is sometimes generated when the power is on and off SPEAKER SELECTOR Use this selector to select the speaker systems OFF Sound not obtained from speakers A Sound obtained from speakers connected to the A speaker terminals B Sound obtained from speakers connected to the B speaker terminalis A B Sound obtained from Speakers connected to both A and B speaker terminals G POWER METER This meter allows you to read out the rated power level on the fluorescent display tube when speakers with a nominal impedance of 8 ohms are connected to the amplifier s speaker terminals FUNCTION INDICATORS The TUNER PHONO AUX function indicators light up in accordance with the position of the function selector NOTE The function indicator will not EO off when the tape monitor switch is set to position 1 or 2 LOUDNESS SWITCH When listening to a performance with the volume contro turned down set this switch to ON and the bass and treble will
22. ignal is thus contracted by 40dB to obtain a peak held DC voltage The output power indicator segments of the FL tube are driven by the HA12010 ICs one for each channel eguipped with 12 pairs of differential amplifiers These amplifiers are biased at increasing levels so each amplifier will commence to operate separately as the input level increases And since these amplifiers apply the voltages to the output power indicator segments each successive segment will light up in turn as the input level rises The function indicators are lit up as a result of a voltage being applied to the corresponding func tion indicator segment according to the selected positions of the FUNCTION switch 4 5 PROTECTION CIRCUIT The purpose of this circuit is to protect the speakers and the power amplifier The relay in the output circuit is automatically opened in any of the following cases 1 During the transient operations power supply is turned on and off Upon detection of an overload caused by a short circuit in the load Upon detection of a DC voltage in the output caused by component failure or accident when the 2 3 1C HA 12010 LEV aw e We we p tm Ed OFFSET com EN s TEF FLUORESCENT TUNER HN O PHONO FUNCTION FILAMENT AUX Fig 4 1 INDICATOR TUBE Indicator circuit The A k found nent parts indicate
23. l 2 Men SIGA Ra e oil 2 s See 5 255 58 855 2 EEO 5 N NDICATOR Ass y AWV 004 10 l 11 ao L l 12 19 1 2 L 3 9 3 P C BOARD CONNECTION DIAGRAM 1 TAPE TERMINAL Ass y GWX 333 Riot bs TAFE 1 o o 7 6 08 7 MODE Ass y VOLUME Ass y GWG 130 GWS 193 MUTING Ass y 153 Lis LOUDNESS METING f s 00 12K 3 A aL E 7 I ee Ri 7 4 3 CONTROL Ass y GWS 129 07 ane eit Care 322 P wi ton qu flan JO Bass Ria TERMINAL Ass y 334 men N GWX 1 A AV 42 i SIG 4 m 5 cr gt W TUNER i 8 92 gt a 58 52 0 Z og ne clau Rass 172 801 Raa 0 72 OW POWER Tr e i i ok S 0 1 E FE 0 You e 5 W rire P wn kk E vw 7 YN 1 nine LS ov ois 3 A CM Om SA3AM 4 ak 85834M 4 2 D 1 5 0 det E Dos SRBAM 4 Di SR5 AM 4
24. nce Q will tum on and the relay will become de energized thus causing the output circuit to open POWER OO AMP er ee 8 m j 1 2 2R3 59 E 02 7 03 04 mr FRI 3 ave rk zs S RELAY i u i DRIV x R2 3 E 4 E Mn Y i mon a 1 0 ION a 6 a4 DS lt B2 gt 06 07 R4 0 t OA L AA rk os wert e 8 Me Ies RSS mc OLE pt me 3 A Overload detector B DC voltage detector OPower OFF detector Fig 4 2 Protection circuit 3 m Q2 RE N Ri w D2 J i Bi T Fig 4 3 Overload detector SA 708 5 DISASSEMBLY Top Cover Remove the two screws A on each side of the top cover Bottom Plate Remove the seven screws B and the rivet C to detach the bottom plate Front Panel Remove the all control knobs Remove the four nuts D Top cover Front panel Bottom plate SA 708 Top View Tape terminal assembly GWX 333 A Power transformer i ATT 603 0 ba AF assembly wa Oir GWK 130 MUI wid 1 n cr DDU 001 use 2 5A A AEK 403 YEE Fuse assembly Switch assembly GWX 337 GWS 194 SP switch assembly Muting assembly GWX 335 ES GWS 192
25. nt parts importance of the safety factor Therefore when replacing be arts of identical designation ic schematic diagram but the actual y due to improvements in design SATE 1 2 SQURCE 2 1 JR 1 QFF 2 OFF 20dB STEREO MONO OFF ON OFF ON OFF ON AFERENCE OFF ON TUNER PHONO AUX OFF A B A B OFF on indicates the switch position External Appearance of Transistors and ICs 2SA733A 2SC945A Type No hre 2SA798 Type No Lot No TA7318P 2SA968 2SC2238 250313 Type No hre 2SA904A 2SC1914A Suffix Lot No Type No hFE 1 1 0 a 2SA949 2502229 Type N pi Pup ki ll li li 1 U 2SA1075 A 2SC2525 A 2SA978 2SA1100 2SC1919 2SC2575 Type No 2SA726S _ Dot Lot No Type No hr 2SB507 Type No hre Lot No Type No 2SC1400 Type No 18 LI 9 SCHEMATIC DIAGRAMS P C BOARD PATTERNS AND PARTS LIST NOTES e When ordering resistors first convert resistance values into code form as shown in the following examples Ex 1 When there are 2 effective digits any digit apart from 0 such as 560 ohm and 47k ohm tolerance is shown by J 5 and K 10 5602 56 x 10 561 RDAPS 7 7 47ka 47 x 10 423 9 insi RD4PS 3 J a 0 52 ORS ES RN2H K 7 12 RSIP OO K E Ex 2 When there are 3 eff
26. operates and the output muting on the power amplifier will be removed When the power supply is tumed off B will abruptly decay and Q will conduct owing to the residual component of B As a result C will rapidly discharge O will cease to conduct where upon the relay will become de energized and restore muting Overload Detector The overload detector circuit incorporates the load RL in one side of a Wheatstone bridge see Fig 4 3 The base and emitter of a sensing transis tor Q are connected to the opposite corners of the bridge so if RL decreases Q will become forward biased If RL falls below a prescribed value 9 will turn on thereby passing a current through R and D Due to the voltage difference generated across R Q will become forward biased and conseguently turn on C will rapidly discharge As conseguence Q will turn on and the relay will become de energized thus causing the output circuit to open DC Voltage Detector The output circuit is connected to the Q emit ter and Q base via a low pass filter R4 C Any DC voltages appearing at the output circuit of the power amplifier will be applied to the G emitter and the Q base If the voltage is negative Q turns on Due to the voltage difference generat ed across R4 Q will become forward biased and consequently turn on C will rapidly discharge If the voltage is positive Q and O turns on C wil rapidly discharge As conseque
27. rite the part no as before Symbol amp Description R303 R316 R325 R334 R337 R401 R404 R407 R418 R423 R426 R429 R436 R443 R446 R451 R454 R503 R510 R512 R514 R419 R422 R317 R322 R323 R324 R447 R450 R511 R335 R336 R427 R428 R501 R502 R439 R442 R515 R516 R437 R438 SEMICONDUCTORS Part No 2SA978 28 9 2SC1400 2SA949 2SA798 G 2SC2291 2SA726S 28C2229 28A968 Y or O 28C2238 Y or O SA 708 an Symbol amp Description 0301 2 0303 Q304 Q305 O306 0409 O410 Q401 Q402 Q403 Q404 Q405 Q406 Q407 Q408 Q415 Q416 Q411 Q412 Q413 Q414 hfe of 0411 0414 should have the same value 25K34 25D712 250313 2SB682 2SB507 2SC945A 2SC2575 2SA733A 2SA1100 28A904A 2SC1384 152076 181555 151555 STV3H Y A 2 SIBO1 02 MZ 240 WZ 240 SR3AM 4 MZ 177 WZ 177 MZ 150 WZ 150 A 182471 MZ 140 WZ 140 OTHERS Part No ASD 118 ASR O23 Q501 O502 Q503 O511 Q504 Q505 Q507 O508 Q506 Q509 Q510 D401 D404 D411 D414 D405 D408 D409 D410 D415 D505 D508 D416 D501 D504 D509 D510 0511 04 D515 Symbol amp Description 59 Rotary switch FUNCTION RL1 Relay 23 Control Assembly GWG 129 CAPACITORS Part No Symbol 8 Description CCDSL 100D 50 C205 C206 CCDSL 270K 50 C215 C216 CKDYB 681K 50 C211 C212 CQMA 392J 50 C219 C220 COMA 223J
28. s 6 PARTS LOCATION 5 He ne f eri ele of the part There fore when replacing be sure to use parts of identical Front Panel View designation Lever knob Front panel assembly AAD 183 Knob ANB 747 AAB 202 Knob Leve knob ng 3 PF AAD 183 AAB 204 Lever knob ere 4 pA cd AAD 183 a 3 TR Knob Lever knob AAB 204 AAD 183 Lever knob J Knob AAD 183 AAB 203 Knob Lever knob AAB 204 AAD 183 Front View with Panel Removed Lever switch LOUDNESS ASK 158 Variable resistor VOLUME ACV 181 Fluorescent indicator tube AAV 004 d gt pey Rotary switch SPEAKERS Aj g 1 ASD 104 Da Lever switch MUTING ASK 158 r 4 Lever switch POWER ASK 515 di kai Phone jack n Lever switch TAPE AKN 023 ASK 160 Variable resistor BASS TREBLE LL Rotary switch FUNCTION ACT 117 ASD 118 Lever switch TONE Lever switch MODE ASK 158 ASK 158 Variable resistor BALANCE li Lever switch SUBSONIC ACT 118 ASK 158 Muting Operation When Power Supply is Turned On and Off With reference to Fig 4 2 when the power sup ply is turned on Q turns off due to B and B If there is no input DC on Q and Q they will be off and the timing capacitor C charges up through R and D and thus Q turns on When Q conducts the relay
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