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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.'.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 '.-.'.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

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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
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 - 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( 0 H 2 ) + 3 d B ( , 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 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 mH e r t z , 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 t 0 h distortion.
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. % Intermodulation Distortion(50 Hertz : 7,000 Hertz= 4 : 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 0 m V / 5 0k i l o h m s AUX.150mV/50kilohms T A P E P L A Y 1, 2. 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 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. O ( W x ( H ) x 7 ( D )m m l - 9 / ( W )3 - l ( H ) - / ( 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( 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

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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.

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.

@ 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

3. DISASSEMBLY

Bonnet Case Removethe four screws o. Front Panel Removethe four screws e. Bottom Plate Removethe six screws O.

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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.

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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

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 '

o L:---Variable

r e s i s t o r( V O L U M E )

"

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

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

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
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 t55 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

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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
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 relay contact.

L CH SP OUT R CH SP OUT

Fig. 7-2 Frotectioncircuit

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\Pre-driver
stage Fig. 7-1 Pre-driver

8. ADJUSTMENTS

8. 1 I D L E C U R R E N TA D J U S T M E N T 1. Set the SPEAKERS selector to the A position, and connect an 8Q resistor to the speaker output terminals. 2. Turn the VOLUME control down to minimum level, turn the power on, and wait about 10 minutes. 3. Connect a DC voltmeter to the TP terminals (Lch; TP4 and TP3, Rch; TP2 and TP1) of the AF Amplifier Assembly (GWK-144). 4. Check that the voltage between TP4 and TP3 (Lch) lies within the DC 4mV-50mV range then make a similar check for the Rch (between TP2 and TP1). If the voltage is less than 4mV, cut jumper wire A (Lch), and jumper wire B (Rch). If the voltage exceeds 70mV, check for circuit failure. 8.2 OUTPUT INDICATOR ADJUSTMENT 1. Set the TONE CONTROL to the center position. 2. Set the SPEAKERS selector to the A position, and connect an 8O resistor and AC voltmeter to the speaker output terminals. 3. Set the FUNCTION switch to the AUX position, and apply a 7kHz, 150mV signal to the AUX terminals. 4. Adjust the VOLUME control so that the voltage on the output terminals (SPEAKERS) read 9V (AC). 5. Adjust VR1 (Lch) and VR2 (Rch) of the indicator assembly so that the output power indicator read 10 watts.

AF Amplifier Assembly (GWK-144)

@ Jumperwire A Jumper

F.L MeterAssemblye
F i g.8 - 1 A d j u s t m e np o i n t t
V 9. EXPLODED IEWS AND PARTS LIST

ExteriorComponent

PartsList
NOTE: c Parts without part number cannot be supplied. o The A marh found on some component parts indicates the importance of the safety factor of the part. Therefore, when replacing, be sure to use parts of id.entical designation.
Key No. Part No. Description Bonnet case Screw Lever knob Front panel assembly Knob Knob Knob Screw Bottom plate Screw
1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
ANE.269 ABA-079 AAD.2OO AN8.847 AAB.222 AAB.223 AAB.221 ABA-186 AB4-066

InteriorComponent

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- - 36,2ssl-

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Key No. Part No. Description Power transformer Wire clip Frame Switch assembly Lever switch Capacitor Headphones assembly Tone control assembly F.L. assembly Cushion LED socket Switch assembly Volume assembly Cushion rubber LED Panel stay Heat sink AC socket Rear panel Power code Strein relief Terminal Terminal(GND) Fuse AF amplifier assembly Key No. Part No. Description Lever switch Lever switch Variable resistor Terminal Terminal Frame Foot assembly Screw Screw Screw Screw 1t spacer Nut 9@ Washer Screw Screw Remote wire Nylon rivet P. C. B.h o l d e r I nsulator spacer

l\ 1. 2. 3. 4.

4rT-667

GWS-215

A s. A e.
7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. A rg. 19. Azo. 21. 22. 23. Azc. 25.

AsK-s2o Acc-ool

GWX460 GWG-I38 AWV{07
26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 4't. 42. 43. 44. 45. 46. 47. 48.
ASK-I71 ASK-172 ACT-130 AKB-063 AKB-064
AEC-672 ABA-107 484-066 ABA-234 A84-026 M45-O86 871-004 ABE-005 ABA-240 ABA-198 AEC-352 AEC-488

GWS-216 GWX-459 AEL-320

AKP-032 ADG-o23 AEC-327 AKE-O51 AEK-Ioo GWK-I44
2SA1108/A/Oor R T r a n s i s t o rt h f e s h o u l d h a v et h e 25C2588/A/OorR T r a n s i s t o rJ s a m er a n k Screw ABA-145
A 1 O.S C H E M A T I CD I A G R A M. P. C. B O A R D A T T E R N S N D P PARTS LIST
1 0. 1M I S C E L L A N E A

NOTE: When ordering resistors,first conuert resistance ualues into code form as shown in the following examples. Ex. 1 When there are 2 effectiue digits (any digit apart from 0), such as 560 ohm and K = 10Vo). and 47h ohm (tolerance is shown by J = SVo, RDVTPSE@IilJ. 56Oa-56x10t-561 RD|/tPSAABJ.' 47ha-47x103-473 R N 2 H@ E E K._ 6.Sa-1RS.8SrP@[0@/(. ta-010 c Ex. 2 When there are 3 effective digits (such as in high precision metal film resistors). '. RN7ISrB tr@gm ,F 5621. 562 x 10' 5.62ha o The A mark found on sotne component parts indicates the importance of the safety factor of the part. Therefore, when replacing, be sure to use parts of identical designation.

Miscellaneous Parts

ASSEMBLIES
Part No. GWK-144 GWG-138 GWS-215 GWS-216 GWX459 GWX460 AWV-007 Symbol & Description AF amplifier assembly Tone control assembly Switch assembly Switch assembly Volume assembly Headphones assembly F.L. assembly

OTHERS

Part No. Symbol & Description
A 4TT-667 7\ ner-t oo ASK-520 A nrpoez

T1 F1 SB

Powertransformer Fuse Leverswitch (POWER) AC socket
Power code Front panel assembly Terminal(SPEAKERS)

A nocozs

ANB-847 AKE451

SEMICONDUCTORS

Part No.
List of Changed Partsfor FactoryModification

Symbol & Description

2sA1108/A/o 021,422\ 2sc2s88/i;5 019,o2o I
ntesnoura thesame have rank
parts informationwill be furnished List of changed whenever necessary and you are requested amend parts to numberin this partslist.
Symbol Part No. Description

AEL.32O CAPACITOR

D1 LED

A ACGOO1

Capacitor 0.01/250V
D 1 0. 2S C H E M A T I C I A G R A M
o': l---ot o"t'' (1/2) GW-K-144

REc f l

s2:' aPEz-

l:#i i-iI";+ II

l-r'E--l I @ H'l "' it---1 i "'o" I

I too47/25

i 17 |

I l_UI

lffil {.i''#,,ffiff l.AUX J"'"1 illlF'-._'* i"*,'''rt5i l:;; ::iHEi-Tf l 1\Jn*'ffii l l{----l l-::: llll _H ll

r 3l |

|IIp-]]*_|."::.F I IIIl'"::'""-#"I $"il | Lry
ffiN llll---.-. I"""-", J i t*41+.t_|dr{::::,:^f{.",","u"1*,,oIr R o L A s s. v ( 2 , 2 , G ||Hl fd h | l |

L-,=:i

S WI T C HE S : s t,7: S : 56 58. : Z : : : FUNCTION T A p E ? O N LOUDNESS SUBSONIC (15 Hz ) S P E A K E R S POWER TONE

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TUNER O ON ON PHONO F F OFF OFF TAPE I AUX
O F F - A - B ON _ ON OFF OFF
T h e u n d e r l i n e di n d i c a t e s h e s w i t c h p o s i t i o n. t
R5l 2.2k D3 rs2075 c39 o.ot/ 500

PartsList of Tone ControlAssembly (GWG-I3b)
PartsList of SwitchAssembly (GWS-216)
Part No. Symbol & Description 56 Slide rotary switch (FUNCTION)

ASX-13 |

coMA 303J 50 coMA 124K50 cosA 270KsO CQMA 122K50 coMA 562K50
c63, C64 c65, C66 c67, C68 c69, C70 c73, C74 When ordering resistors, conuert the resistance ualue into code form, and then rewrite the part no. as before. Symbol & Description VR3. VR4 Variable resistor R - R ,R 1 , 0 R
PartsList of VolumeAssembly (GWX-4S9)
Part No. Symbol & Description VR2 V a r i a b l e r e s i s t o r( V O L U M E )

ACV-184

RESISTORS
PartsList of Headphones (GWX-460) Assembly
Part No. Symbol & Description H e a d p h o n e sj a c k

ACT-127 tr RDT4PMD qJ

AKN-023
PartsList of Switch Assembly (cWS-215)
ASE.OO3 R S l P1 J RDlzrPM 563J
55 Sliderotaryswitch(SPEAKERS) R96, R97 R98, R99

11. PACKING

Key No. Part No. Description Operating instructions Packing case Side pad

1. 2. 3.

ARB.351 AHD.754 AH4.239

PICINEEFI

ELECTFICINIC

CCIFIPCIFIATICIN

4-1, Mesuno 1-chome, Mesuno-ku. Tokyo 'l 53, Japen
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