ff o'll ,r*:(' EefvicecVlanual S \-Ci,lO S T E R E OA M P L I F I E R ()rrroruEErl' to o This service manualis applicable the KU type. CONTENTS I.SPECIFICAT|ONS 2. FRONTPANELFACILITIES 3. DISASSEMBLY 4.PARTSLOCATION 5. BLOCKDIAGRAM 6.LEVELDIAGRAM T.CTRCUITDESCRIPTIONS... S.ADJUSTMENTS .......3 .....4 .... ......6 ......8 .......8 ...' ......10 9 6 P D 1 0 . S C H E M A T I C I A G R A M , . C .B O A R D P A T T E R N SA N D P A R T S L I S T 1 0 . 1M i s c e l l a n e a c 1 0 . 2 S c h e m a t iD i a g r a m D 1 0 . 3 P . C .B o a r dC o n n e c t i o n i a g r a m 10.4 PartsList of P.C.BoardAssembly . 11. PACKING '.-..'.14 15 18 21 ...... 22 ( S 9 . E X P L O D E D V I E W S A N D P A R T S L I . .T. . . . . 1 1 r siA-ci1 cl 1. SPECIFICATIONS Semiconductors lCs Frequency Response P H O N O( RI A A E q u a l i z a t i o n ) Transistors Diodes Amplifier Section ...... 27 18 20Hz 20.000H210.3d8 to T U N E RA U X ,T A P E L A Y1 . 2 , P 13dB . . 1OHz 60,000H2 to Tone Control BASS. ..t10dB(100H2) TREBLE ....t10dB(10,000H2) Filter . Subsonic . 15Hz (-6dB/oct) ( V o l u m ec o n t r o ls e ta t - 4 0 d B p o s i t i o n ) L o u d n e sC o n t o u r s , . . . . + 6 d B( 1 0 0 H 2 ) + 3 d B ( 1 0 , 0 0 0 H 2 ) H u m a n d N o i s e( l H F , s h o r t - c i r c u i t e A , n e t w o r k ) d PHONO . . .82dB TUNER,AUX,TAPEPLA,2. ., 1Y ... IOOdB C o n t i n u p 0 w e ru t p u tf 4 5 w a t t s *e rc h a n ous o p o n e l , i n .a t 8 o h m sr o m2 0 H e r t z 2 0 , 0 0 0 m , f o H e r t z i t hn o m o r eh a n . \ 3 % t o t a la r m o n i c w t0 h distortion. I Total HarmonicDistortion (20 Hertzto 20,000 Hertz, I o h m s ,f r o m A U X ) 22.5 watts per channel'power output . N o m o r et h a n 0 . 0 2 % Intermodulation Distortion(50 Hertz : 7,000 Hertz= 4 : 1 8 o h m s ,f r o m A U X ) continuous ratedpoweroutput . . No more than 0.03% 22.5 watts per channelpoweroutput No more than O.O2% DampingFactor (2OHertzto 20.000Hertz,S ohms) . . 50 I nput (Sensitivity/lmpedance) PHONO ....2.5mV/50kilohms TUNER 1 5 0 m V / 5 0k i l o h m s AUX. ....150mV/50kilohms T A P E P L A Y 1, 2 . . 1 5 0 m V / 5 0k i l o h m s P h o n oO v e r l o a d e v e l( T . H . D .O . O 5 o 1o 0 0 0 H 2 ) L / ., PHONO 130mV O u t p u t( L e v e l ) TAPERECl,2.. ... 150mV Speaker .... A,B,OFF Miscellaneous P o w e rR e q u i r e m e n t s AC 120V,60H2 PowerConsumption ...100W(UL) Dimensions . 4 2 O ( W x 9 4 ( H ) x 3 4 7 ( D )m m l 1 6 - 9 / 1 6 ( W )3 - 1 1 l 1 6 ( H ) 1 3 - 1 1 / 1 6 ( Dn x x i) W e i g h t( w i t h o u tp a c k a g e ) 6 . 9 k g( 1 5 l b 3 o z ) Furnished Parts Operatinglnstructions ........1 NOTE: Specifications and the design subject to possible modifications without notice due to improvements. * Measured pursuant to the Federal Trade Commission,s Trade Regulation rule on Power Output Claims for Amplifiers. 2 . F R O N TP A N E L F A C I L I T I E S SWITCH O POWER 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 the muting circuit has been actuated to suppress generated when the unpleasantnoise that is sometimes power is on and off . M @ POWER ETER This meter allows you to readout the rated power level with a on the fluorescentdisplay tube when speakers nominal impedanceof 8 ohms are connectedto the i a m p l f i e r ' ss p e a k etre r m i n a l s . IN @ FUNCTTON DICATORS S @ SPCETER ELECTOR the speaker system. to Usethis selector select f O F F : S o u n dn o t o b t a i n e d r o m s p e a k e r s . connectedto the A: Sound obtained from speakers A s p e a k etre r m i n a l s . connectedto the B: Sound obtained from speakers B s p e a k etre r m i n a l s . T h e T U N E R , P H O N O ,T A P E , A U X f u n c t i o n i n d i c a t o r s with the positionof the function light up in accordance se lector. S @ FUNCTION ELECTOR When set. to Use this selector selectthe programsource. the function indicatorabovethe meter panelcorrespondr i n g t o t h e p o s i t i o no f t h e f u n c t i o ns e l e c t ow i l l l i g h t u p . t tn T U N E R : S e t h e r ew h e n l i s t e n i n go b r o a d c a s os a t u n e r t c o n n e c t e do t h e T U N E R j a c k s . ( T h eT U N E R f u n c t i o ni n d i c a t o ri g h t s p . ) l u o P H O N O : S e t h e r e w h e n p l a y i n gr e c o r d s n a t u r n t a b l e to connected the PHONOjacks. ( T h eP H O N Of u n c t i o ni n d i c a t o ri g h t s p . ) l u T A P E 1 : S e t h e r e w h e n p l a y i n gt a p e so n t h e t a p ed e c k to connected the TAPE 1 jacks. (TheTAPE function indicatorlightsup.) AUX: Set here when listeningto a programsource w h i c hi s c o n n e c t e t o t h e A U X j a c k s . d ( T h eA U X f u n c t i o ni n d i c a t o ri g h t s p . ) u l @ B A S SA N D T R E B L EC O N T R O L S Use these controls to adjust the bass and the treble. control lf you set the tone switchto ON and turn the bass to right from its center position, you will be able to C r e m p h a s i z eh e s o u n d i n t h e l o w - f r e q u e n c ya n g e . o n t versely, turning the bass control to the left from the , t c e n t e rp o s i t i o n y o u w i l l a t t e n u a t eh e s o u n d . You can use the treble control to adjustthe soundin the range. high-frequency r sA-Ci1cl i I i coNTRoL O volurvrE Use this control to adjustthe output levelto the speakers and headphones. Turn it clockwiseto increase output the l e v e l . o s o u n dw i l l b e h e a r di f y o u s e t i t t o , , 0 . , ' N swtrcH @ LouolrrEss When listening a performance to with the volumecontrol turned down, set this switch to ON and the bassand treblewill be accentuated. W h e nt h e v o l u m e i s l o w , t h e h u m a ne a r f i n d s i t h a r d e r to hear the bassand treble than when the volumeis high. The loudness switch is thus designed compensate to for this deficiency.By setting it to ON, the bassand treble come throughmuch more stronglyand the soundtakeson a punchevenwhen the volumecontrol is turneddown. JA @ n C R o p H o N E cK Plug the headphones into this jack when you want to listen through your stereo headphones. NOTE: Set the speakerselector to OFF when listening only with headphones. S ) su e s o N t c F TL T E R WT T C H @ rnpe 2 swrTcH Set this switch to the ON position when monitoring a tape performance on a tape deck which you have connected to t h e T A P E 2 j a c k so r w h e n m o n i t o r i n g a r e c o r d i n g . NOTE: Set the switch to the upper (OFF) position when tistening to records or broadcasts, etc. selected by the function selector. I I f' When this switch is set to the 'l 5Hz position,the subsonic filter with a cut-off frequencyof 15Hz is actuated.The subsonicfilter serves attenuatefrequencies to lower than 15Hz in a 6dB/oct slope. lt is therefore effective in suppressing ultra-low-frequency noise which is generated by record warp and other causes. You cannot actually hear this noise but it is a factor in the generationof intermodulation distortion and it may damage your speakersystem. Set this switch to the 1SHz position during recordplay for the besteffect. coNTRoL @ BalarucE Use this control to balancethe volume of the left and r i g h t c h a n n e l sl.f t h e s o u n da p p e a r t o b e l o u d e ro n t h e s r i g h t , i t m e a n st h a t t h e v o l u m eo f t h e r i g h t c h a n n e li s higher. Turn the balance control to the left and adjust. Conversely, the soundappears be louderon the left, if to it meansthat the volume of the left channel is higher. Therefore, turn the balancecontrol to the right and adjust. swtrcH @ rorue Set this switch to ON when adjusting the bassand treble controls.When set to the upper (OFF) position,the tone control circuits are disengaged frequencyresponse and is flat. This function is convenient checkingphono carfor tridge and speaker tone quality and listening room acoustics. r @ powentNDtcAToR When the power switch is set to ON this lamp lights up, i n d i c a t i n gh e a m p l i f e r i s t u r n e do n . t i t- 3. DISASSEMBLY Bonnet Case Removethe four screws o . Front Panel Removethe four screws e . Bottom Plate Removethe six screws O. \o..oo/o' Bonnet case Front panel 4. PARTS LOCATION FrontPanelView o The !i, marh found on some component parts indicates the importance of the safety factor of the part. There' fore, when replacing, be sure to use parts of identical designation. m (t .J!g!r.- K n o b( B A L A N C E I AAB.223 Leverknob ( L O U D N E S S ,A P E2 ) T AAD.2OO 6 siA-610 Front View with Front Panel Removed F l u o r e s c e n ti n d i c a t o r t u b e AAV-O06 V a r i a b l er e s i s t o r( B A S S .T R E B L E ) ACT-127 Slide rotary switch (FUNCTION) A S X - I1 3 sl ide rota ry r*i t"tr -------]-=---.' (SPEAKERS) : I" ASE-oo3 I L e v e rs w i t c h ( P O W E R ] | ,, ll '!'tlr ' I o L:---Variable r e s i s t o r( V O L U M E ) 'l I tu " V a r i a b l er e s i s t o r( B A L A N C E ) ASK.520 Headphones .jack AKN-023 ACT-130 -Lever s w i t c h( T A P E2 ) ASK.172 Leverswitch ( LOUDN ESS) ASK-171 f L e v e rs w i t c h ( S U B S O N I C , O N E ) T A S K - 17 1 Top View with Bonnet Removed rl|r j Powertransformer ATT-667 A F a m p l i f i e ra s s e m b l y GWK.144 Switch assembly GWS-215 Switch assembly GWS-216 Volume assembly GWX459 t- t Headphones ssembly a GWX460 Tonecontrolassembly GWG-138 I AC socker AKP.O32 RearPanel View 1i Power code ADG-023 T e r m i n a l{ I N P U T ) AK8.064 T e r m i n a l( T A P E 1 ) AKB-063 Strein reliel AEC-327 Terminal(SPEAKERS) AKE-051 5. BLOCK DIAGRAM swtrcHEs: st Fu&trox luxEP-M-raPEI-AUX 32 t3 54 55 s6 se fAPE? ouoils Su6oirt(t5Hrl SPEAXERS &sR ioilE ON - 6F ox - gll Ox - 6 O'F-A-' ox -!Il or _lI! 6 . L EV E L DI A G RA M l}.tlJ"roo't (eo) xeai pnone AUX /TUNER 15OmV siA-61 cl n 7 . C I R C U I TD E S C R I P T I O N S Equalizer Amplifier The 54,-610 features a 3-stage direct-coupled equalizer amplifier for greater reduction of noise and distortion. Besides the use of an ultra low-noise transistor (25C26O2) in the first stage, the adoption of low impedance input resistance and equalizer circuit has contributed to an S/N ratio of at least 82dB (at 2.5mV input, IHF-A). Power Amplifier This all stage direct-coupled pure complementaly SEPP circuit features a current mirror load differential amplifier in the first stage, and incorporates the tone control circuit in the NFB loop. Although the incorporation of the tone control circuits in the power amplifier stage reduces the number of elements that the signal has to pass through, and thereby further reduces noise, distortion, and cost, the power stage does require a higher gain and a higher degtee of stability. In the SA-610, this high gain and high stability are achieved by a cunent mirror load differential amplifier in the first stage and by the use of a constant current circuit for the load of the predriver stage. Furthermore, the tendency for the pre-driver stage capacitance impedance load to cause deterioration in the high end frequency responseis suppressedby inserting a capacitor (C) between the emitter of the pre-driver stage (Q2) and the baseof the constant current circuit (Q1) as shown in Fig. 7-1. At frequencies where the reactance of this capacitor may be ignored, the push-pull action of Ql and Q2 servesto counteract the high end frequency response deterioration. The power amplifier stage is a complementary 2-stage' Darlington connection, resulting in an output power rating of 45W + 45W (8Q, 20Hz2OkHz\, harmonic distortion of less than O.O37o (20H2 20kHz at rated output), and output power bandwidth of 5Hz - 50kHz (0.O3% THD). Certainly a superb performance for an amplifier of this classis obtained. /. Constant circuit current rl I !f' Protection Circuit Besides protecting the speakers if a DC voltage should happen to appear at the power amplifier stage outputs, this circuit also mutes the signal path when the power switch is turned on and off (SeeFig. 7-2). If for any reason a DC voltage (in excess of about tbV) should happen to appear in the output of the power amplifier stage, it is detected immediately by either Q23 or q24. qn is turned on by a positive voltage, and Q24 by a negative voltage. In either case,Q25 is also turned off, thereby opening the relay contact to disconnect the power amplifier stage from the speakers. , The muting action when the power switch is turned on is achieved by delaying the rise of the Q25 base potential by means of the R95/C77 time constant circuit. When the power switch is turned on, C77 is charged up via R95, thereby increasing the voltage across both ends of this capacitor. When this voltage exceeds the zener voltage of the D15 zener diode, Q25 is biased in the forward direction, and is thereby tumed on to close the relay contact. When the power switch is turned off., C77 dischargesrapidly via D18, resulting in Q25 being turned off, thereby opening the rela ...