Pioneer QX-949A F Service Manual Download

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Summary of Contents for QX-949A F

Page 1: ...4 H 4e qil ffiil F K t t j a 1 ilT 1 ui gtrg 4 r q ffi sffiffi eru ffiffiffiH ...

Page 2: ...it DISASSEMBLY 7 1 Wooden Gabinet 7 2 Bottom Plate 7 3 Front Panel ADJUSTMENTS 8 1 AM Section 8 2 FM Section 9 3 FM MPX Section C 8 4 Power Amplifier Section DIAL CORD STRINGING PARTS LOCATIONS 10 1 Front View 1 1O 2 Front View 2 10 3 TopView 37 10 4 Bottom View 39 10 5 Rear View 41 11 EXPLODED VIEWS 43 12 PACKING 52 13 SCHEMATIC DIAGRAMS P C BOARD PATTERNS AND PARTS LISTS 13 1 Schematic Diagrams ...

Page 3: ...Amplifier Assembly AWG 023 86 13 9 Power Supply Circuit A Assembly AWR 080 91 13 10 SwitchCircuitAssembly AWS 048 94 13 11 Power Amplifier Assembly AWH 027 gB 14 PARTS LIST OF EXPLODED VIEWS 102 NOTE THE MODEL QX 949A COMES IN TWO VERSIONS DISTINGUISHED AS FOLLOWS Round label on rear panel Voltage Type F KCU 110V 20V 130V 220V and 240V switchable 120V only General export model UL U S A and CSA Can...

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Page 6: ... connector Rotate connector 180 and re insert it Loosen screw to open cover CHANGING LINE VOLTAGE SETTING AND FUSE F MODEL To remove the fuse unscrew the fuse cap located in the center of the line voltage selector and withdraw it together with the fuse Next pull the line voltage selector plug out of its socket rotate it until the cutaway aligns with the appropriate line voltage marked on the back ...

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Page 9: ...Glx sl4slA 5 LEVEL DIAGRAM 1T rl ttlll tlr i tigmy 1 20ll Power boosting switch is set at 40ll trequency at lkllz c a oe o o 13 ...

Page 10: ...A1137 is at more than xTOkHz detuning and with an extremely low input level 2Cil TAPI Rtc PB 4Cll it PX OWPUI lux g_ a DC voltage is produced By setting the FM Muting switch to ON pin 12 is connected to pin 5 and the analog switch in HA1137 is operated ON OFF to perform muting Multiplex Decoder Demodulation is performed by switching detection with the circuit contained in the IC HA1156 depicted in...

Page 11: ...IUI ll 0 meter ex s 4slA L nr out 0tt t ott Switching signat 3gkllz lC HA1156 lC HA1138 Fis 4 15 ...

Page 12: ...CHANNEL signals as the difference signal is demodulated from a frequency modulated 30kHz carrier sub signal and the sum signal varies according to the cartridge output level though indirectly related level matching becomes necessaq In other than the CD 4 mode a fixed resistor replaces of the variable resistor to provide a fixed gain 35 6d8 at lkHz equalizer amplifier The inclusion of a balanced po...

Page 13: ...an Vr 13 becomes approximately equal to I and e reaches a maximum determined by the murimum gain of the AGC amplifier The amplifier gain can therefore be controlled by Vb in this manner Vb being obtained from a synchro nous detector FM Demodulator The block diagram of the PLL FM demodulator circuit is depicted in Fig 9 This circuit consists of a voltage control oscillator VCO phase com parator PC ...

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Page 15: ...ecessary components Left and right separation remains good since LF does not combine with RF and RF does not combine with LF If the sound source is CF center front or CB center back front to rear separation cannot be obtained since LF RF LB and RB all become the same volume The logic circuit is provided for improve this effect With CF crosstalk to LB and RB is at out of and since with CB crosstalk...

Page 16: ...variable resistance voltage control circuit Since these MOS FETs are P channel enhancement types equivalent internal resistance becomes in finite when gate voltage is zero By applying a negative voltage to the gate Fig 4 the equivalent internal resistance can be varied from infinity to several hundred ohms r _J Basic decoder GIX g4slA 2SK40V FET is employed for back blending With a CF sound source...

Page 17: ...asses through the time constant circuit and is applied to the gates of MOS FETs for LB and RB gain control The front control voltage passes through the time constant circuit and is applied to the gates of the junction FET for back blend and the MOS FETs for LF and LB gain control As the junction FET is an N channel depletion type LB and RB are normally blended but the device becomes open when a ne...

Page 18: ... The equivalent circuit when cutting out low frequencies is shown in Fig 18 In this case the input signal is applied to Q9 through the parallel impedance of VR1 and C33 which is high in the low frequency range and suppresses the lower frequency signals High Frequency Control The high frequency control circuit is shown in Fig 19 and the equivalent circuit when boosting high frequencies is shown in ...

Page 19: ...to cut noise and distortion which occur when switching the power on and off The circuit is shown in Fig 22 and consists of a bridge type over current and overload detector a differential amplifier DC voltage detector and a power switch on off detector section Relay Driving Circuit Q7 Q9 in Fig 22 comprise the relay driving circuit In the normal condition reverse bias is applied to the base of Q7 a...

Page 20: ...lay switch turns on to automatically restore normal operation Fig 25 shows the equivalent circuit at the time of a negative half cycle In this circuit a potentiat is produced between b and e as above and Q1 is turned on Detection of DC Voltage This is a differential amplifier consisting of Qb and Q6 as shown in Fig 26 The bases of Qb and Q6 are connected to the junction points of the power amplifi...

Page 21: ...ASSEMBLY 7 1 WOODEN CABINET Unscrew the two screws holding each side then lift the back of the wooden cabinet upward place a rr 12 j1 2 t t 7 2 BOTTOM PLATE Unscrew a total of the 14 screws holding it in 26 ...

Page 22: ...obs For TUNING knob loosen the setscrews with a hexagonal wrench before remov ing it Unscrew the two screws in the upper edge of the front panel and the three nuts from the shafts Then pull the panel gently forward GIX g4gA N 27 ...

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Page 24: ... modu lator terminals 3 Connect the oscilloscope horizontal inputs to MPX sG s PILor our terminals and vertical inputs to No 18 terminal of tuner assembly 4 Tune unit and FM SG to g8MHz 5 Produce a Lissajous pattern on oscilloscope and adjust VRl to make the pattern still 6 Then set signal generator for modulation of L later R and pilot Adjust vR2 to obtain muimum channel separation Tuner assembly...

Page 25: ...IX g4gA amplifier has been come into operation a defect in the output transistors can be suspected Check the output stage 6 After approx 10 20 minutes of warming up time adjust VRB so that the voltage across terminals 1 and 2 of the power amplifier assembly becomes 20mV 7 In the same w y adjust VR4 to obtain 20mV voltage readings across the terminals 25 and 26 8 Next connect voltmeter between term...

Page 26: ... the tuning shaft 4 Lead the string around pulleys F and G then wind it 2 turns around the Tuning drum 5 Now tie the other end of the string to the spring on the Tuning drum Turn the tuning shaft and check for proper function Then trim the ends of the string 6 Turn the tuning shaft until the plates of the variable are all the way in Move the pointer to the left end starting point on the dial and f...

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Page 39: ...HA1137 FlVl tF lc HA1138 ArU rC HA1156 Fwr MPX lC GIX g 4slA 57 ...

Page 40: ... Bottom 1 pl CX 718D Index 2S8507 2SD31 3 25D525 2SC 1384 M51 651 P to il 12 t314t5 t6 t7 t8 tlJ 1j1 tr W cx 049 HA1 156 HA 1452 I9 tot ilz t3t4 zhtshbLlrn_ W A1 Index 25K4OV n D a t G A J E 25A679 2S8530 2SC 1 079 25D370 ffO C I ll z tli B rr d 2SK3OA 2SA725 2SA7 26 2SC461 2SC869 2SC7 17 25 C1312 2SC 1344 258527 258528 25D357 25D358 ffi3 2SC 1 682 ryE 2SC 1451 E c B E c B 515 415 315 215 t 15 515...

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Page 45: ...embly AWX 054 RESISTORS Switch circuit ass y No 13 Realy Switch circuit ass y No 1 1 Relay Fg RzJ Rr 150 150 150 2W QW QW Symbol Description Part No R1 R2 R3 R4 Metal oxide 150 Metal oxide 150 Metal oxide 150 Metal oxide 150 2W 2W 2W 2W RS2P 151K RS2P 151K RS2P 151K RS2P 151K OTH E RS Symbol Description Part No Phone jack FRONT Phone jack REAR AKN OO2 AKN OO2 ...

Page 46: ...if ier assembly No 3 Power transformer V LT co o t o o o o too o o g roo o C I o Cz e l 0 01 Dz ca Cs Cr o l 0 01 DI SR3A M o l l SR3AM r F 0 0 I Ds 0 01 D4 SR 3AM SR3AM Do Ds C6 SR3AM C5 SR3AM o l DB e Jl 0 o 1o H 0 01 D7 SR3AM Ce SR3AM e ct 0 ol o F 0 01 lR 3 3K I 3w cs 10 000 50 R6 ls sK t3w c8 10 000 5c oRo 3 3K 3W 1 Co 10 000 5c rR sK gw c 10 000 5c zCH 4CH ss 2CH 4CH Power transformer V LT P...

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Page 54: ... O J J t k LU D L 1 r r r 1 r O s L I O z r I ylt 6LU vLt eru YL LIU 0l zz 0tJ tati q o cJ l a S Itl f i yL 8e I 2 d i t 13 7 PROTECTTON CtRCUtT ASSEMBLY AWM 079 q cf 2 I c c i E 9 5 _ t di c t n o 4 N r r n O d CI d E t O 5 L l I i I I i t 0 r za 0 0l OIILL OL otlzz otJ a3 ...

Page 55: ... 2 Power amplifier assembly A No 26 Power amplifier assembly A No 25 Power amplifier assembly B No 26 Power amplifier assembly B No 25 Power supply circuit A assembly No 9 Relay coils I Fower supply circuit A assembly Nos 20 21 Sg 3 S8 c s o o Y E n7v g Y 13 t c lvt o 7v o l i3 9V Sg e nnr 3 11 e lll o o ANt EE dK e w Eg I rurrt rtfr E e At raAA gEd 9 o t EF effFrrGg J i r rru ov oi1 s F G sEt 4F ...

Page 56: ...ilm 4 1k Carbon f ilm 1 5k Carbon f ilm 1 5k Carbon film 82 Carbon film 82 Carbon film 5 6k Carbon f ilm 15k Carbon f ilm 15k Carbon f ilm 91k Carbon film A 2k Carbon film 5 6k Carbon film 56k Carbon film 1Ok Carbon film 27k Carbon film 22 Metal oxide 91 1W RD PM 332J RD PM 332J RD PM 332J RD74PM 332J RD 4PM 332J RD74PM 332J RDz PM 332J RD PM 332J RD74PM 153J RDY4PM 153J RD PM 153J RD PM 153J RD74...

Page 57: ...C cn O a O t rt J R s Rst t o J o t F 6 1 l 11a l5K 131 lul 15 vl E c6ro 01l O 11 OM n cD a Y 22175 O tr f c 6 J cl R4s 5 6K I a co O J k Rzr 12 K 0I l qt Cs 100P L cY 7 c21 3o0P R z a I r _ t l _ D cl ja t CZ cJa i r l0 R c 3 c op D_ C Y O tta vl an I ne2 R C o CY u Czs rO iO _ R a __J 86 ...

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Page 60: ...2 0 01 D3 sIBot 02 Lr o 9 O c14 2200 63 FUSE oo SlB0l 02 o 25D3l3 as 2SBSOTP 1A cO A crs 100 80 as 2SA 20A O cO Or 9 t 6 O tr o I s J I t_ D6 wz t30 cs qo 16 Y f q C V O 99otl crd c d J o_ O O O d Re 82 2SCt3t8A Crs LI ct _ I R 4J 1W O Lr O Ctl C 6 14V Se O I9 O O 1 J 4 6u c2i 1000P 5 9 A c D A B b c D 91 ...

Page 61: ...o 1 4 otection circu it assembly N o 3 Power transformer OR Power transformer B LU Power transformer G R N Power transformer G R N Tuner assembly No 20 st 215 7 CD 4 assembly No 7 12 11 to vr t Rr6 lK lw 1C0 16 r trru o RrS 33K f 8lluo HA r o 17 t8 19 20 21 Ct zzoolaz sIB0l 02 R3 2 2 ffi HAA o o o4 q Ro roK T h o uo J i 0 01 R 180 bW J TCe I o ot 2SCl3l8A 8z e 2sc945 ITB gjH 1000P 311 o_1F I Cr 10...

Page 62: ...1O3Z 50 CKDYF 1O3Z 50 RESISTORS Symbol Description Part No R1 R2 R3 R4 R5 R11 R12 R13 R14 R15 R16 R6 R7 R8 R9 R10 Carbon film Carbon f ilm Carbon film Wire wound Carbon film Carbon film 10k Carbon film zJk Carbon film 16k Carbon film 16k Carbon film 18 Metal oxide 47 Carbon film 8 2k Carbon film 2 2k Carbon film 16k Carbon film 33k Metal oxide 1k 18 68 2 2 180 5W 4 7k 1W 1W RD PS lBOJ RD 4PS 68OJ ...

Page 63: ...r c C N N CY o C r C r il l I oo rw x 1 fl o l I I U b I rt ct tI l jl cr3l OC c N TT cr61 2 I st I O i I _ts I ii f a rq ca i iijl C l C l tD L Y I c J o r 0l o co O 0 _ I I I l r l__ A AI U Ll l Z O f O ___l t O YL a LL u r l I I I l I I _o Ja rC r co cL OIT Z LIj L I _ JL LU o_ S_ I _ d I I t t I r L_ r_r MZ Ogtl u i AZ 0El orE MZ Oqt zi u i 3r I l l i i A c D A C D ...

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Page 65: ...14 R15 R16 R17 R18 R t9 R20 R21 R22 R23 R24 Carbon film 180k Carbon f ilm 180k Carbon ilm 18Ok Carbon film 180k Carbon film 22k Carbon f ilm 22k Carbon f ilm 22k Carbon f ilm 22k Metal oxide 150 Metal oxide 150 2W 2W 150 2W 150 2W 75 1W 75 lW 75 1W Metal oxide Metal ox ide Metal oxide Metal ox ide Metal oxide Metal oxide Carbon film Carbon film Carbon film Carbon f ilm 75 12k 12k 12k 12k 1W w w Yr...

Page 66: ...1 8v O n O g U 0 0 25C10 3 Y ct o I Y ea n O Lz2 26 z2 23 25 Rs 10 2V Qrs 2SA6 I9 9O oa c N E 74 45V 36v 40 o T ft Y c o cta oa 19V Qr Qs sA t26 Q3 O c O O Rrr C5 2 2V A41l3s O y np izN crs zP O I t1 O O O I E L 6i t Y i t b O O Y r TY l9v 02 Q zSA t26 Q Ra 39K Q D LZ0 u4l Cr 100P R 18 041 35 Y O I aa L O I I O oa O O a n izr Cro 12 P O O O O tl z d Yo Y ct R38 4 l K Y C N d C2287P 2 2 3 3 A B c D...

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Page 69: ...PIC NEEFI ELECTFIONICS COFIPOFIATION 75 Oxfond OAive Moonachie New Jensey O7O74 J S A PIONEEFI ELECTFION C EUFIOPEI N V Luithagensteenweg no 3 2O3O Antwenp Belgium T IONEEFI ELECTFIONICS AUSTFIALIA PTY LTEI 178 184 Boundany FoFd Bnaeside Victonia 3195 Austnalia o AUG 1975 Printed in Japan ...

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