cDrJroNEEr{ Shot/,n tn thb photo b Model SX-7. ORDER NO. ARP-047-O COMPUTER CONTROLLED STEREO RECEIVER sx-7 sx-6 SX-s.SiX-EiL SX-,QISX-4L . The AM tuner of SX-4L wave-band tuner with MW LW (long wave). and SX-SL is a two (medium wave) and Model SX-7 (and SX-6, SX-5 and SX-4) are new types of receivers featuring microcomputers for easier operation. The AM/FM tuner stages incorpo- rate quartz PLL synthesizers for high stability, while the power amplifier stage is a non-switching amplifier which achieves class A quality with class B efficiency (not included in the SX-4 model). PIoNEEF| ELECTFICINTC CCtFtFCtFtATtCtN 1 chome. Mesu.o ku. rokyo 153. J5p5n U.a. tfcritlaF alaC?Flo|llca CC'FFC,;|AY|C|N a5 orro.d o. ve. Moonach e. New Je.sey O7O74, t)S A FlONaaE aL:ClFlC,l\IC ll(rFC'PC' N.V. Lu thasen Haven I 2O3O A..we.p Berg'um FroNaatl an.actFctNlca aua?FAl-ra ETY. LYo. 1 7a 1Ba Bound ro. s 31 95. aust.6r,€ F H O AUG.1981 Printed in lapan www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com BLOCK DIAGRAMS SX.4/KU FM FRONT ENO FM IF AMP A DETECTOR FM MPX STEREO OEMOOULATOR FREQUENCY OISPLAY - toon Fx l-- GNo ! IF AHP A DETECTOR IC ii#n i*---- l TUNING OETECTOR IC P06004 R6 R 7 v o o R 8 R 9 ,,o ffi R t l K O K I K 2 K 3 . ' I R Q P O bl P L L S Y N T H E S I Z E R C I R C U I T FT4,/AM S€LECTOR 8CO TO OECIHAL OECOROER ---4---r.:--]-: ItPx STEREo oEcoo€R Ic P O W E R A M P L I F I E R AUX / vroEo R . C H REC T F€lADAPToi PLAY FUXCTION SELECTOR i- X U T I N G CONTROL 3 9 . 6 d 8 A T r t H r + "rr r*S* _.Qp-q oFF TAPE,/AOAPT SW {I HOOE SW -----O t moro or LOU0llESS sw : SPEAKERS t" fr l pxoHes r-__+____zi I I f---)t' * # l + - f l t - R.cx J" lUN ER sEcrrofl E q A X P FUIClOli SELECTOR 2 A C l 2 O v 6 0 H r www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com SX-s/KU FH FROIIT EiTO FM IF AMP. A OETECTOR FREQUET{CY OISPLAY MPX STEREO o€cooER Ic LEO t{UTERIC OISPLAY IF AMP A OETECTOR IC ,L-' L-'nn I l_t l_t .l_t l_t I oerscron I I stGr{AL I METER I our TUNING OETECTOR IC P0500rr R t O R E S E T R r l K O r ( t K 2 K ! P I l R O P O d - _ -' stAlto.BY O l o : o! HUTE P L L S Y N T H E S I Z E R C I R C U I T PHONO EO. AMP F M l A M S E L E C T O R 8 C O T O O E C I M A L /E Y9 YO YI Y2 Y3 Y4 T! lux / vr0€o il P O W E R A M P L I F I E R 4 l . 3 d B A T t t X r L C X . Ic rElrcrnor 'LIY FutcTrofi s€L€cToR r-*:@* Pq OFF F steoxens P[1"'o*tt f1---=J )r | --|J l'.-___€ r c x r O POWER SUPPLY CTRCUIT cotTRoL c r l c u l T POWTR TRATSFORMER A C l z o v , 6 0 X t 3 AC OUiL EIS www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com SX-6/KU A M ANIENNA AM STEREO CONTROL C I R C U I T MEMORY I /sToP 1 rDowN l TUNING t u " { PRESET R€F. OSC tTC40498P) ; soorHt + ttt th IIt PRESEI ( STEP} tNo. - 4 2 d 8 { A T t t H r ) 'APE I l8trtk FUNCTION ( PA4008) it-- ? t l d, d) ^';"1* o suSsoN rc ouT/ {J LOUONESS ott o + 9 7 ? 6 J EALANCE - 8 3 TAPE I r?) (3) (4' {5t STATION IND LOCAL osc 1 I I t-l t-t t-t t- 1 t_t l_t.t_l t_l x tN x ouT (D OC 08 S 25tHr RESET 2 0 t 9 4 3 2 t 9 t 2 / l OISPLAY C IRCU IT 4 0 3 9 3 4 3 3 3 2 3 1 3 0 2 9 2 8 2 7 5 1 6 1 5 r 4 r 3 L l N J + t N l O U T - S O L O U T J CONTROL (PD6OO4) E tN/ tN/ xiar_ n-ESer nO STANO By r oUT r rOUT - roUT- 4 37 9 tO il t2 252423 222Ot9 t8 t7 34 t 2 3 4 5 6 7 MUTE I L t N ( L C T I L T2_ PROTECTION C I R C U I T + 4 . 9 V ( + 8 7 ) + 4 . 9 V ( + 8 8 ) OVERLOAO OETECTOR F ^ T O I *t.-.-*l RcH + + _ ! { _ l t o R c H t ) HEAOPHONES L R L R A - S P E A X E R S - A 4 www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com N F uJ(L I o F { rc ooo lrJ F (L= It t! q J oH e lrJ a 6ts x 8 !! lrJ > o I (l P o UJ F trJ o 6 (L= t! $t-r_-r fr gl_r_-r" t ?,:,:_-e gr-,:,d* i-- E - F ll ci (l ro oz N F 9 g l EI el=l f - r t r : ; : 6E E tr9 = *2 5 L)() xo J La o 9 (r lrj N U) trJ I F z (n JJ o o-l iil l @ l o t r ) l =il ; e l (9 z F f= r-r E - \ i < 9 rg r rl 'i '1,[ ri ri rr ri ,. $l =l "gI EL e J(ts lHr F 8Ed t! o '-F f I Fr- tsa Hl =: = f l | E s oloJ o \ r I ]f) C D N o $ ( ' | F hlg ftl >l= sl a l F 3 l _ l z z l - - ( J l = = - L < |r) l.- G lrJ F f o o(r 9= ( ) F 83 J f r-r q3 t-l 9 9 = ! ..\ E'= g= ;b L = d o v - 8 8 B5l N l t-r 1l ;5 F=:i'l ? o r o = o r . - o S o I - J e'E (9 irl o = (L= r E (r lrJ co Jo- Io () zlrJ fo trJ G lr- r L . q - z r : ? E lgE :HF rsa L-l- ?'i o- l-i- o l P+ fi 2, = f H Jot Fzo() Lrl Fv) a ie-* !(') = .J z o o g u , ,-fi: o - q ipl o2 I = u A ooro f Y hxct) 5 www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com i * N A o @ o c 5 P dH IIJ F > lrJ o o za F() lrJ F (ln (r lrl F lrJ (r lrl=I F f(L F lo c lrJ G o J o- I o o z trJ o lrl E l! I Z F GI tt ta, r.t t (,= F E ( h @ F ' N t u c r N ( \ r tE2,: ( r . < " o c -t z 3 J dr E l F ( ) z t 8<.l () I J E UJ N ar't lrJ F z tn (ts u.l t!=& (r lrJ=o (L HE $* IJz f t- F o J an q, (It n $ lrs l(r > l1! ItE trl F l== (h 9 E & R t r t o 9 _ o b v I B pssaSlPElp 6 3 'x l=t'- o * * l * No t t \ l o - o o l! g d e e : = a s @ o t ) t - l ;?EE d i E S ( l ) i ' l ) u L ! = U ; - f l < f f d e l > F ' x g S 2 P F f(-) E() - L L lq (r LU= U' tt o F I = Jo EF c6 z(J 9r" F = (J? 3d uJ> a ./t ql = q 5 N @ - J ( n i l E 6 o I 3 9 : N R I c ! n o Y Y o ( D r ! l . l U() z J CD l- o -l E, -t -l Et zFh ?,^5 Cp E R " ' l 9 E E . n = J r L = _ J E : i (\l lrJ F s? >a z- U J . c _ a ; H H F : o 5_8 o o Et E - l t - @ : o5_8 { > o c -t N N U g IJ(L s Iu F= (n 9z (r Fo lrJ fr Jo(r Fzo (J J z (9( N I= F (D tt @ dro ct E @ d rO { o- o lrl ozo I (E lrj(9(, c F F lrl an lrl(r o Y ! 4 5H = 5 b 9 z t 3 P g @ = N r o s l : r l u t c i , J s aElq =r I g ''t o N . to ? . 6 . . E ( ) N > | r ) > o = t r i e3 L{}* 6 www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com CIRCUIT DESCRIPTIONS Outline of Main Stage The overall composition is outlined in the block diagnms on pp.2-6. r Tuner Stage o AM/FM Synthesizer Stage *MANUAL : Frequency changed in single steps each time the TUNING UP or DOWN hey is pressed. Frequencies scanned when pressed continuously, the scanning being stopped as soon as the hey is released. *STATION SCAN : Frequencies scanned. when either TUNING UP or DOWN key is pressed. Scanning pauses for 5 seconds when a broad.casting station b tuned, and stops altogether if the MEMORY/STOP key is pressed within that 5 second period. Otherwise, the scanning is resumed., *STATION SEARCH : Frequencies scanned when either TUNING UP or DOWN key is pressed, and stopped when a broadcasting station is tuned. sx-7 sx-6 sx-5 sx-4 l.D. MOS FET single-stage RF amplifier plus twin vari-cap tuning circuit (equivalent to 4-ganged tuning capacitor) in FM front-end. Same as SX-7 J-FET single-stage RF amplifier plus twin vari-cap tuning circuit (equivalent to 3{anged tuning capacitor) in FM front-end. Same as SX-S PLL lC stereo decoder stage Same as SX-7 Same as SX-7 Same as SX-7 Vari-cap tuning circuit (equiva- lent to 2-ganged tuning capaci- torl in AM tuning stage and AM tuner lC lLA1247l. Same as SX-7 Same as SX-7 Same as SX-7 sx-7 sx-6 sx-5 sx-4 lmproved S/N ratio achieved by pulse-swallow system for FM reception. S/N ratio 80dB(Mono) 75dB (Stereol Same as SX-7 S/N ratio 8od8(Monol 75dB(Stereo) Same as SX-7 S/N ratio 75dB(Mono) TOdB(Stereo) Same as SX-7 S/N ratio 75dB(Monol 70dB(Stereo) Frequency memory (presetting) capability for up to 8 stations in each band. Same as SX-7 Frequency memory (presettingl capability for up to 6 stations in each band. In models including two AM bands (LW and MW), any LW or MW frequencies may be stored in the 6 AM memories. Same as SX-5 3 tuning modes: MANUAL STATION SCAN STATION SEARCH Same as SX-7 2 tuning modes: MANUAL STATION SCAN only the sTATloN scAN tuning mode is available. www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com o Amplifier Stage o Display Stage sx-7 sx-6 sx-5 sx-4 Equalizer amplifier features low- noise twin FET ICL differential amplifier in first stage, and oper- ational amplifier (lC) in second stage for MC cartridges. S/N ratio 8OdB(MM) 67dB(MC) Equalizer amplifier features low- noise transistors differential amplifier in first stage. and oper- ational amplifier (lC) in second stage. S/N ratio 79dB Operational amplif ier (lC) euqalizer amplifier. S/N ratio 70dB Same as SX-S S/N ratio Microcomputer controlled elec- tronic switching lC (PA40O8l for function selector. Same as SX-7 Same as SX-7 Same as SX-7 Microcomputer controlled VCA lC(PA5O04) volume control features 32-step control, pre- settable levels and audio rnuting (-2sdBl. Same as SX-7 Conventional volume control with variable resistor. Same as SX-5 Non-switching amplifier em- ployed in power amplifier stage. Output power 60W+60W l2OHz-20kHzl Rated distortion O.009% Same as SX-7 Output power 45W+45W (20H2-20kHz) Rated distortion 0.OO9% Same as SX-7 Output power 30W+30W l2OHz-20kHzl Rated distortion O.O2/" Conventional class B ampli- f ier Output power 20W+2OW l2OHz-2Ok{zl Rated distortion O.O4% sx-7 sx-6 sx-5 sx-4 s-digit LED numeric display of tuned frequency. Same as SX-7 Same as SX-7 16-point scale LED display of tuned frequency. LED numeric display of elec- tronic volume control levels. Same as SX-7 Not featured in SX-5 Not featured in SX-4 LED numeric display of time (built-in quartz clock function). Not featured in SX-6 Not featured in SX-S Not featured in SX-4 6-point LED display of output power. Same as SX-7 Not featured in SX-5 Not featured in SX-4 3-point LED SIGNAL indicaror indicating signal strength of tuned frequency. Same as SX-7 TUNED indicator to show that broadcast station has been tuned. Same as SX-5 www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com Tuner Stage O I.D. MOS FET The FM front-end RF amplifier in model SX-? (and SX-6) features an I.D. MOS FET (ion-implan- tation dual gate MOS FET) - P001 manufactured by Pioneer Semiconductor Laboratory. The major features of this FET - P001 include high gain,Iow noise, Iow distortion and low IM (P.G. 25dB/ 100MHz, N.F. 2dBl100MH2, I.M. -54d8/107dBp) as a result of an extremely accurate short channel obtained by a "self aligning" operation involving a "local silicon oxidation" process. Furthermore, a O.4p narrow channel (1/3rd to 1/5th the width in normal components) has been achieved by the ion-implantation double diffusion construction. Use of this FET in the FM front-end greatly assists in improving sensitivity and reducing inter- ference. o Pulse-Swallow PLL Synthesizer When the VCO (Voltage Controlled Oscillator) frequency is very high and the CMOS progmmm- able divider operating frequency is exceeded, the PLL will cease to function. Two methods are presently available to resolve this problem. In one of these methods (the fixed divider system), an ECL (Emitter to Emitter Coupled Logic) prescaler is positioned in front of the programmable divider. And when, for example, a 1/10 prescaler is em- ployed to obtain 25kHz step frequencies, the reference frequency will be 2.5kHz. This frequency is very low and cannot be adequately removed by the low-pass filter. As a result, signal components are leaked into the mixer leading to deterioration in the S/N ratio. This is one of the main dis- advantages of the fixed divider system. The other method available is the pulse-swallow system which employs a special frequency divider called a "two-modulus prescaler" instead of the prescaler used in the fixed divider system. In this method, a 25kHz step synthesizer will generate a 25kHz reference frequency and a 50kHz step synthesizer will generate a 50kHz reference frequency, resulting in a much higher S/N ratio than in the fixed prescaler system. The pulse-swallow system employed in the SX-7 is incorporated in an IC (M54922P) controlled by microcomputer. Amplifier Stage o Non-Switching Amplifier (SX-7, SX-6, SX-s) In non-switching amplifiers, the output stage transistor bias is controlled on the basis of class B operating point in order to maintain the operation within the operating region (between cutoff and saturation) and thereby suppress the generation of switching distortion. The basic non-switching amplifier circuitry is outlined in Fig. 1-2. To simplify the diagram, transistor Vgn and diode Vg, E1 and E2 are assumed to be 0.6V and the transistor base current is disregarded. While no input signal is applied, the voltage drop across R5 and R6 may also be dis- regarded. And if the voltage across R1 and R2 due to idle current is ignored, the voltages at different positions will be as shown in the diagram. When an input signal is applied, a voltage will be generated across Rt by NPN stage (Q1/Q3) oper- ation during the positive portion of the signal. This voltage is applied to the Q5 emitter-follower (voltage gain of about 1) resulting in almost the same voltage being generated across Rb. This voltage is then added to the output stage bias voltage. Hence, the PNP stage (Q2/Q4) maintains the same bias conditions as when no signal was applied, which means there is no cutoff. Likewise, the NPN stage maintains the same bias conditions during the negative portion of the signal as when no signal was applied, again eliminating any cutoff. Fis. 1-1 Pulse swallow system I Fig. 1-2 Basic circuitry of Non Switching Amplifier www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com Gontrol Stage The incorporation of microcomputers in these receivers has further simplified operational procedures. The PD6007 (SX-7) and PD6004 (SX-6, SX-5 and SX-4) ICs are both basically the same 4-bit microcomputer (with 2k-bit memory capacity), the main difference lying in the software program. Whereas the PD6007 incorporates a clock function, the PD6004 features a 2 band (LW/MW) AM tuner switching function. The PD6007 and PD6004 pin configurations are shown in Fig. 1-3. E X l o l X l o l REEEi tRo so s l scz ro T' r o P r P 2 P r O o O l O z U 3 O 5 O 6 V3s KI K 2 K l KO STBY Fia R r 5 R r 2 H t l Rto R e R E R7 R6 d5 R4 R 5 R 2 R r RO Fig. 1-3 Pin configuration of PD6007 (PD6004) iSET rRo SF 5U fp" I I P . I l"' LPo l-xo Il*' l*' LKo TC Rl3 Rt2 [-n,r I I R'o 1"" LRe t l-nz I LR6 R5 R. AF MUTE IND R3 VOL. MEMORY R2 VOL. lND. R r f"o VOL. OATA I ^- our PUT | "' l o " l o o Lo. fo. DArA l^- our PUT | "' l o ' Loo EXTAL CLOCK INPUT KEY INPUT CLOCK INPUT (5OOHz) SCAN STOP MUTING OtIT P.O.DATA / o)4.,, INPIJT 5-TH DIGIT o o R 5 ol _ _ M54s22P ! | 5""i'- aM/ AJ cPs RE.ET PA4@€l c4 Fil C 3 A M c2 PHOilO C { A'XIVID€O i]"",, : ,.':,,," .," FUIICTION SELECTfi IC 1 0 Fig. 1-4 System diagram of control section (SX-7) www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com o Synthesizer Control Fig. 1-5 outlines the tuner-related computer operation command input key matrix. Key description 9k/10k : AM-MW band frequency step switch. ON for 9kHz steps, and OFF for 10kHz steps. 9k/1k (PD6004) : AM-LW band frequency step switching. ON for 9kHz steps, and OFF for lkHz steps. TUNING AUTO/MANUAL : ON for auto tuning (x1), and OFF for manual tuning. SCAN/SEARCH : ON for short-time hold search (x2), and OFF for operation according to TUNING AUTO/MANUAL switch (*6). FM : Display of tuned frequency by single push (*3), and pin 16 of synthesizer IC (M54922P\ switched to L level (x4). AM : Display of tuned frequency by single push (*3), and pin 16 of synthesizer IC (M54922P) switched to H level (x{). LW/MW (PD6004) : LW-MW switching with each push. M1 - M8 : T\rned frequency presetting keys. Cor- responding STATION indicator lights up (*5). TUNING UP, DOWN : Frequency tuning keys. MEMORY/STOP : Memory store enable key. STATION indicators (1 to 8) and the PRESET STEP indicator blinks on and off for 5 seconds when pressed once. A broadcasting station and volume step may be stored in memory during this 5 second period. And when pressed during frequency scanning, the scann- ing operation is halted. EL,E2 : Switching for different regions (USA, Europe etc.) Wired up according to region without switching. 81, B2 (PD6004) : FM IF offset adjustment. (*1) Station search where frequencies are scanned by pressing ?UN/NG UP or DOWN key once. Scanning stops when broadcast station frequency is tuned. (*2) Station scan where frequencies are also scanned by pressing TUNING UP or DOWN key once. Scanning pauses for 5 seconds when broad,casting station frequency is tuned. Scanning will be resumed after the 5 second pause unless the MEMORY/STOP hey is pressed. (*3) 16-bit serial d.ata from the SO pin is sent to the frequency display d,riuer IC (TD6301P), conuerted to 7-segment decimal data by transfer cloch (output from Pg and P1 pins) for driuing the LED numeric display. LOCK SW. NON-LOCK SW. IlnAnjJ Fig. 1-5 Switch key matrix for synthesizer control (*4) The data transfened to M54922P contains 2O bits. These are diuided into 5 groups of 4 bits each by the 4 pins Rg to R1y The transfer output clock is obtained from R6 and R7. The first 4 data items (16 bits) are used in programmable diuider frequency diuision, while the Sth data item (4 bifs) is used for operation mode designation. (*5) BCD encoded data from pins Og - Og is applied to the BCD to decimal decoder IC (M74LS42P). Pins I to 9 (excluding pin 8) correspond. to Ml to M8, and are switched to L leuel resulting in the LEDs being lit up. (*6) Actual circuits are wired so that the K6 line to the SCAN/SEARCH switch is cut when the AUTO/ MANUAL switch is in the MANUAL position. The SCAN/SEARCH switch will be operatiue only when in the AUTO position. NON - LOCK SW. www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com r Function Selector Control The computer operation command input key matrix for function selector control is outlined in Fig. 1-6. Key description PHONO : Pin 10 of the IC (M74LS42P) refened to above (*5) is switched to L level (*7), and volume steps are displayed (00 - 31) in the LED numeric display. AUX : Pin 11 of IC (M74LS42P) switched to L level (x8), and volume step also displayed in LED numeric display. FM: Pin 16 of IC (M54922P) switched to L level as described above (x9). AM: Pin 16 of IC (M54922P) switched to H level as described above (x9). LW/MW (PD6004) : AM band switching. CLOCK (PD6007) : Time displayed in LED numeric display when pressed 1x19;. Display- ed time is adjusted by TUNING UP and DOWN keys while the CLOCK key is depress- ed. In the SX-7, time is displayed as long as the POWER switch is left in the STD-BY position. (*7) L leuel here results in PHONO indicator being turned on, and the PHONO channel of the elec- tronic switch (PA4008) used by the FUNCTION selector aleo being turned on. (*8) L leuel here results in the AUX indicator plus the IC (PA4008) AUX channel being turned on. (*9) Depending on whether pin 16 of IC (M54922P) is at L leuel or H leuel, and the leuel of pin 10 (L leuel for PHONO) and, pin 11 (L level for AUX) of IC (M74LS42P), the AM-FM switching circuit is actiuated, the AM or FM indicator tumed on, and the IC (PA4008) AM or FM channel switched ON. (*10) A 500H2 pulse signal obtained by diuiding the crystal oscillator signal (source of the synthesizer reference signal) appears at pin 17 of IC (M54922P), and is applied to the TC pin of PD6007 to actiuate the cloch functions. r Volume Control (SX-7 and SX-61 Models SX-7 and SX-6 have been equipped with an electronic volume control IC (PA5004). This IC has the following 4 functions. 1. The gain is changed from -90d8 to OdB by changing the voltage on the VOL terminal (pin 12) from 0 to 3.2V. 2. The balance is changed continuously from right channel only (-bV) to center (0V) and left channel only (+5V) by changing the voltage on the BAL terminal (pin 9) from -bV to +5V. 3. Audio muting of approximately -25dB is applied when the MUTE terminal (pin 11) is switched to L level. Fig. 1-6 Switch key matrix for function selector Fis. 1-7 Switch key matrix for volume control www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com 4. Loudness as determined by a twin T-shaped filter connected between pin 3 (6) and pin 5 (14) is activated when the LOUD terminal (pin 7) is switched to L level. The operation command input key matrix for the VOLUME control is outlined in Fig. 1-7. Key description VOLUME UP, DOWN : Increase and decrease of 5-bit electronic volume control data (*11). 32 positions are available (00 to 3 1 ) . MUTING : Audio muting switch (*12). VOLUME PRESET : Memory switch for the elec- tronic volume control steps positions (32 positions from 00 to 31). MEMORY/STOP : Memory store enable key. A single push enables VOLUME position and STATION frequency to be stored in memory during a 5 second period. (*11) The S-bit output data from Oa - OZ and Rgpins is conuerted f'rom digital to analog data by ladder resistor and applied to pin 12 of PA5004. (*12) The Rg pin is switched alternately to H and L leuels each time this switch is pressed. This H/L leuel is applied to pin 11 of PA50O4, the L leuel resulting in actiuation of the muting circuit. o Other Terminals R4 Switched to L level when the electronic volume control position (00 - 31) is display- ed. The VOLUME indicator is controlled by this signal (SX-? and SX-6). Switched to L level when the VOLUME PRESET key is pressed once, and when the MEMORY/STOP key is pressed, L level and H level are switched alternately for a 5 second period. The PRESET STEP indicator is controlled by this signal. Switched to L and H level alternately each time the MUTING key is pressed. The PA5004 audio muting operation (-25dB) and the MUTING indicator are both con- trolled by this signal. Switched to L level during time display by PD6007. The colon (:) in the time display is controlled by this signal (SX-7). And with the PD6004, this pin is switched to L and H levels alternately during frequen- cy scanning operations, the signal being used to turn the TUNED indicator on and off (Sx-5 and SX-4). R5 : Switched to L level when 50kHz unit included in the FM tuning frequency (during tuning mode where FM frequencies are changed in 50kHz steps). This signal controls the "0" and "5" in the 5th digit position (10kHz unit) in the FM frequency display. And with the PD6004, this pin is switched to L level when the LW band is selected (in models equipped with 2-band AM tuner section). R6 : Synthesizer IC (M54922P) control output (data transfer clock I). Data transfer is commenced by the trailing edge of this signal (i.e. the moment that the pin is switched to L level). R7 : Synthesizer IC (M54922P) control output (data transfer clock II). Data reading timing signal. The M54922P reads data by synchro- nizing with the trailing edge of this signal. R8, R9, R10, R11 : Data output and key inputs applied toM54922P. RL2 : Muting output. Switched to L level for about 1 second when PHONO, AUX, FM and AM (LW/MW) key is pressed. Also switched to L level (for about 0.7 seconds) when the Ml to M8, TUNING UP or TUNING DOWN key is pressed. These signals control the electronic switching IC (PA4008) in order to suppress switching noise. Rl-3 : Scanning operation stopped when an H level input signal is applied during STATION SCAN or STATION SEARCH tuning mode. Input of detector signal from tuner section tuning detector circuit. Memory Hold Model SX-7 is equipped with an auxiliary power supply circuit used to supply the microcomputer with power irrespective of the POWER switch position. In this way, the microcomputer RWM (read write memory) contents can be preserved for about 2 weeks when the AC mains power is completely switched off. The clock function is inhibited in this case. If the AC mains power is left off for more lhan 2 weeks, the RWM contents will disappear, and will therefore have to be rewritten if the memory is to be used again. The RWM hold period in the SX-6, SX-5 and SX-4 models when the POWER switch is left off is about 3 days. When two new size "AA" dry batteries are used, however, memory contents can be maintained for several vears. R1 R2 R3 www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com The RWM hold period in the SX-7 has been extended by inhibiting the microcomputer (con- sumption current is less than 10pA). And in the SX-6, SX-5 and SX-4, the battery life has likewise been extended in much the same way. This inhibition operation is controlled by the I-EQ- and STBY terminals. The switching sequence involved in switching to inhibit mode must follow the order shown in Fig. 1-8. Normal memory functions are lost once the inhibit mode Vcc drops below 2.5V. Note that the RIESET terminal has to be at H level during inhibit mode. Furthermore, approximately lmA of current is consumed until cessation of the clock pulse input (Extal). Although the switch on sequence during restart has not been specified, the reset signal is applied only after all prescribed values have been retumed to normal. Fig. 1-8 Power supply sequence for inhibit mode www. xiaoyu163. com QQ 376315150 9 9 2 8 9 4 2 9 8 TEL 13942296513 9 9 2 8 9 4 2 9 8 0 5 1 5 1 3 6 7 3 Q Q TEL 13942296513 QQ 376315150 892498299 TEL 13942296513 QQ 376315150 892498299 http://www.xiaoyu163.com