Scribd
Upload
1K views39 pages

Pioneer sx-780 Complete SM

Receiver

Uploaded by

laurentiu
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
1K views39 pages

Pioneer sx-780 Complete SM

Receiver

Uploaded by

laurentiu
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
You are on page 1/ 39
Service: Manual AM/FM STEREO RECEIVER xX-780 MPIONEER' MODEL SX-780 COMES IN FOUR VERSIONS DISTINGUISHED AS FOLLOW: [te] Voltage Remarks KU 120V only US.A, model Ke 120V only | conaca mode! sic This service manual is applicable to the KU type, the additional service manual. CONTENTS 1, SPECIFICATIONS 2. FRONT PANEL FACILITIES 3. BLOCK DIAGRAM 4, CIRCUIT DESCRIPTION 4.1 Tuner Section. 4.2 Audio Section 5. DISASSEMBLY 6. PARTS LOCATION 6.1 Front Panel View 6.2 Front View with Panel Removed 63 Top View 6.4 Rear Panel View 7. DIAL CORD STRINGING . 8 ADJUSTMENTS 81 FM Tuner 82 AM Tuner ae 83 DC Balance of Power Amplifier 84 Meter Drive Circuit | | =e | s | __ntov, r20v, 220v, 240 (Switchable) Generel export model NOV, 120V, 220V, 240 {Switchable} " u 2 2 13 4 16 ” ” US. Miltary mode! 8. PACKING 10. EXPLODED VIEWS 10.1 10.2 11. SCHEMATIC DIAGRAMS, P. C. BOARD External Part . Internal Part PATTERNS AND PARTS LIST 4 na 13 na 5 16 7 8 19 Miscellanea. Schematic Diagram . P. C. Board Connection Diagram LED Assembly (GWx-191) . Headphone Assembly (GWX-192) Capacitor Assembly (GWR-110). . Fuse Assembly (AWR-169) Tuner Assembly (AWE-099) AF Assembly (GWK-118) When repairing the KC, S, $/G types, please see 19 a es 25 ss 33 388 - 33 - 34 37 — 1. SPECIFICATIONS ‘Semiconductors FETs eeTery eS eee 8 u Transistors... Tey 6 Diodes ...... see einen? Amplifier Section Continuous Power Output of 45 watts" per channel, min., at 8 ohms from 20 Hertz to 20,000 Hertz with no more than 0.057% total harmonic distortion, or 45 watts per channel at 4 ohms from 20 Hertz to 20,000 Hertz with no more than 0.08% total harmonic distortion. Total Harmonic Distortion (20 Hertz to 20,000 Hertz, from AUX) continuous rated power output « . 23 watts per channel power output, 8 ohms . 1 watt per channel power output, Bohms..... «= «No more than 0.03% Intermodulation Distortion (50 Hertz: 7,000 Hertz = 4 : 1, from AUX) continuous rated power output 23 watts per channel power output, BOWMS . eee e+ NO more than 0.03% 1 watt per channel power output, 8 ohms No more than 0.03% Damping Factor (20Hertz to 20,000Hertz, 8 ohms)... .30 Input (Sensitivity/Impedance) No more than 0.05% No more than 0.03% No more than 0.05% PHONO. 2.5mV/50 kilohms AUX. be eeseeeee ees 150mV/S0 kilohms TAPE PLAY 1 150mV/S0 kilohms TAPE PLAY 2 150mV/S0 kilohms PHONO Overload Level (IkHz, T:H.0.: 0.08%) .. 200mV ‘Output (Level/Impedance) TAPE REC 1. 150mVv TAPE REC 2 150mV. SPEAKERS A,B, AtB. HEADPHONES ‘ow impedance Frequency Response PHONO (RIAA Equalization) -20Hz to 20,000H2 +0.24B AUX; TAPE PLAY "Hz to 80,00082"9 8 Tone Coil BASS ... +8dB, —74B (100Hz) TREBLE . +74B, —64B (10kHz) Filter Low ‘1SHz (6dB/oct.) Loudness Contour (Volume control set at ~40d8 position) “+648 (100H2), +348 (10kHz) Hum and Noise (IHF, shortcircuited, A network, rated power) PHONO. OTA NOS. DI bale ‘AUX, TAPE PLAY 9548 FM Section Usable Sensitivity MONO 2.22.2 ee eee eee e ees 1034BF(1.8nV) $048 QuisingSestvty MONO ooo eee e cece 16.24BF (3.64¥) STEREO. 37.048 (39nV) Signal-toNoise Ratio at 6548 MONO . cece 8068 STEREO : 728 Distortion at 6548 100Hz, .... MONO shee OTe STEREO 0.15% ThHz 22. MONO 0.07% STEREO 2 2 sieeeiweney. anc 15K at f.. MONO | pres scout STEREO... 2... 2. 0.25% Frequency Response ....... . 30Hz to 15,000H2"3-3 dB Capture Ratio. . : 1048 Selectivity... rear ora es esa Spurious Response Ratio... 6508 Image Response Ratio... 2.6.00 + 65¢B IF Response Ratio. yi 9008 AM Suppression Ratio : S0d8 Muting Threshold 119.2486 (104V) Stereo Separation «458 (i 354B (30H2~1 SkH2) Subcarrier Production Ratio... 5548 SCA Rejection Ratio .... 6548, ‘Antenna Input « 300 ohms balanced 75 ohms unbalanced AM Section Sensitivity (IHF, ferrite antenna) 300uV/m (IHF, ext. antenna) . . suv Seboctivity. 175 cae suieed ead teed 2648 Signalto-Noise Ratio... ee S048 Image Response Ratio... 4048 IF Response Ratio... 4048 Antenna Built-in ferrite loopstic antenna Miscellaneous Power Requirements Power Consumption Dimensions . 3 120V, 60Hz 150W (UL), 280VA (CSA) + 480(W) x 140(H) x 320(D)mm 18-7/8(W) x 5-1/2(H) x 12-5/8(D)in Weight . . Without package . 11.2kg (24Ib 1102) With package = 12.8kg (281b 302) SX-780 Furnished Parts FM T-type antenna . (Operating instructions 1 ‘Measured pursuant to Federal Trade Commission's Trade Regulation Rule on Power Output Claims for Amplifiers. NOTE: ‘Specifications and design subject to possible modification : without notice due to improvements. 2. FRONT PANEL FACILITIES POWER METERS. These meters allow you to read out the rated power level when speakers with a nominal impedance of 8 ohms are connected to the receiver's speaker terminals. NOTE. ‘These values are related to the impedance of the speakers and they vary according to the frequency. In order to find out the exact output level, connect an 8-ohm dummy load instead of the speakers. POWER SWITCH —__________ Set this switch to ON to supply power to the receiver ‘There will be a short delay when it is set to ON, because the muting circuit has been actuated to suppress the un: pleasant noise that is sometimes generated when the power is switched on and off. PHONES JACK Plug the headphones into this jack when you want to listen through your stereo headphones. Release both SPEAKERS buttons if you want to listen to the sound through your headphones only (This means that both buttons will be released) SPEAKERS swiTcHes | Depress the button corresponding to the speakers con: nected to the SPEAKERS terminals (A or B) on the rear panel. You can depress both of these buttons to listen to sound from two pairs of speaker systems at the same time. BASS AND TREBLE CONTROLS When turned clockwise from the OFF position, the response in the bass or treble range, respectively, is boosted. Turning counterclockwise attenuates the re- sponse. At the OFF position the tone control circuit is bypassed and frequency response is fat TAPE MONITOR INDICATOR With either of the TAPE MONITOR switches set to ON, the TAPE MONITOR indicator lights up. This lamp indicates the receiver is monitoring or playing back the tape on the tape deck connected to the TAPE jacks. SOURCE INDICATOR, With either of the TAPE MONITOR switches set to OFF, the SOURCE indicator lights up. This lamp indicates the receiver is playing the program source; AM broadcast, FM broadcast, record on the turntable, or another com: ponent connected to the AUX jacks. LOW FILTER SWITCH When this switch is set to 15Hz, a 6dB/oct attenuation ‘can be provided for frequencies below 15Hz. This means that you can cancel out noise in the ultra-low frequencies which is generated by low-pitched rumble from a turn: table and other forms of distortion. Although this noise cannot be heard, it can generate intermodulation distor tion and damage the speakers. FM MUTING SWITCH ———__—_—_—— When this switch is set to the upper position (On), the FM muting function acts to suppress unpleasant inter- station noise while tuning between the FM broadcasting stations. When the switch is set to the OFF position, the FM muting function does not act, thus enabling suitable reception of weak radio stations. DIAL POINTER This pointer indicates the broadcasting stations, STEREO INDICATOR ‘This indicator lights up when the receiver is tuned in to receive stereo broadcast. AM/FM TUNING METER | When tuning in to FM stations, position the meter pointer in the center of FM area for optimum reception. In the case of AM stations, tune for maximum meter deflection toward the right of the scale. FUNCTION SWITCH Use this switch to select the program source. For a second after the switch is selected, no sound will be heard. This is due to the operation of the muting circuit, which can suppress the unpleasant switching noise generated when the FUNCTION switch is elected. AM: When listening to AM broadcasting FM: When listening to FM broadcasting, The STEREO indicator lights up when the receiver is tuned in to an FM stereo broadcast. PHONO: When playing a record on the turntable con: nected to the PHONO jacks, AUX: — When listening to an audio component con: nected to the AUX jacks. TUNING KNOB Use this knob to tune in to broadcasting stations. Select the station and tune for optimum reception by ‘observing the dial scale and the AM/FM tuning meter 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 to MIN. LOUDNESS SWITCH Set this switch to ON when listening at a low volume. The frequency response of the human ear varies according to the listening volume, and setting this switch to the ON position compensates for hearing response by emphasizing the bass and treble. BALANCE CONTROL Use this control to balance the volume of the left and right channels. First, however, set the MODE switch to MONO. If the sound appears to 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 ad- justing, return the MODE switch to STEREO. TAPE MONITOR SWITCH (1, 2) Set switch 1 to ON with a tape deck which is connected to the TAPE 1 jacks (REC and PLAY) when you want to monitor the playback or recording of a tape, The tape on a deck which is connected to the TAPE 2 jacks (REC and PLAY) can be similarly monitored by setting switch 2 to ON. NOTE: ‘Set the switches to the upper (OFF) position when listening to records or broodcasts. ‘_mopE swiTcH Use this switch for selecting mono or stereo performances. STEREO: Set to this position for normal stereo opera tion, MONO: When set to this position, the left and right channel signals will be mixed and repro- duced monophonically from both speaker systems. 0 3. BLOCK DIAGRAM |-|o" Pac ® |Srorecron? ed a 1 _[rcroan 4. CIRCUIT DESCRIPTION 4.1. TUNER SECTION AM Tuner (Fig. 1) ‘The tuner employs a 2-gang tuning capacitor, one IC (HA1197) and one AM ceramic filter. See page 24 for details of the internal structure of HA1197 which contains a Lstage RF amplifier, converter, 2-stage IF amplifier, detector, and AGC ireuit. Qo of the output circuit is a special AM muting circuit. This circuit is operated until the ‘AM tuner stabilizes immediately after the FUNC- TION switch has been set to the AM position, +B is supplied to Rys, thru C.,, and the base of Qi is, forward biased. Concequently, Qio is tumed on, and the AM output signal is shorted to ground during the time constant of Cra, Res FUNCTION of o - ANT. our Te scCHALIS7) wren Fig. 1. AM tuner circuit FM Front end ‘The FM front end consists of a 3-ganged tuning capacitor, a dual-gate MOS FET equipped 1-stage RF amplifier, a local oscillator and a mixer. The output of the local oscillator (a modified Clapp circuit employing a single transistor) is applied to the base of the mixer transistor. IF Amplifier and Detector ‘Three dual element ceramic filters are used as the selection elements, and one IC (HA1201) containing one differential amplifier and one FM IF IC (PA3001-A) are used as the amplification elements. The HA1201 compensates for the fil- ter insertion loss, and also limits the amplitude of the FM signal. ‘The PA3001-A performs IF amplification, am- plitude limiting and FM detection. It also drives the TUNING meter and controls muting. See the block diagram on page 24 for the internal structure of this IC. ‘Multiplex Decoder ‘The sub-carrier generator (PLL system), NFB demodulator, automatic pilot canceller, and stereo/mono automatic switch are also built in an IC (PA1001-A). With the addition of a few CR elements, a multiplex decoder of high S-N ratio and low distortion has been achieved (Again refer to page 24 for further details of this IC). ‘A major feature of the PA1001-A is the automatic pilot canceller. This circuit detects the level of the 19ktz pilot signal, and automatically adjusts to that level to cancel out the pilot signal completely. ‘This has made the designing of the low-pass filter in the following stage very much easier, and has further extended the frequency response at the high end. ‘The output signal from the multiplex decoder is passed on via the deemphasis circuit and AF amplifier (which serves as both low-pass filter and crosstalk canceller) to the FM muting gate. it connected to the output of the FM tuner serves as a muting circuit which eliminates unwanted FUNCTION selector switch- ing noise and FM interstation noise. This muting circuit is shown in Fig. 2 ‘At more than approximately +70kHz detuning or low input level (less than 104V antenna input), a DC voltage is produced at pin 12 of the FM IF IC (PA3001-A). At this time, if the FM MUTING switch is set to ON, pin 12 is connected to Qs base through Roi, Qsy comes on. As a result, the potential at point A will drop, followed by the FETs (Qz4, Qao) being tumed off. When the FUNCTION selector switch is at AUX, PHONO or AM position, Qs» will turn on due to +B being applied to its base via the FUNCTION switch, and FETs (Qzs, Qo) being tured off. When the FUNCTION switch is changed to the FM position, Qso will tum off due to +B being not applied to its base. The potential at the gate of FETS(Qz5, Q29) will consequently increase (at a speed determined by the Cys, R412 time constant) until FETs are tumed on, and muting condition terminated, 4.2 AUDIO SECTION Phono Equalizer Amplifier ‘This circuit is an NFB-type equalizer amplifier, with one IC (HA1457) in both L and R channels. ‘This IC is a low-noise type, and provide an open- loop gain of 824B. The main performance speci cations for this circuit include a voltage gain of 35.50B (at 1kHz), a phono dynamic margin or overload level of 200mV (RMS, at 1kHz, with 0.05% THD), and PHONO equalization within +£0.34B (20Hz—20kHz), Tone Control Circuit A CR-type tone control circuit is used in this unit. The signal is amplified to the necessary level by the flat amplifier (IC) with a voltage gain of about 31.4aB in front of the control circuit. When the BASS and TREBLE controls are in the center, position, the tone-control networks are automati- cally switched out of the signal path in order to give a perfectly flat frequency response. Power Amplifier (Fig. 3) The first stage consists of a PNP dual-transistor differential amplifier (Q;) which loads the current mirror circuit (Q)) to obtain a high stable gain even in the high-frequency range. The pre-driver stage (Qi1, @13) operates with the constant current, circuit (Qys) as the load, amplifying the voltage to the required level. With a hybrid IC (STK-0050) in the power stage, a power output level of 45W +45W/82. (20H2—20kHz, THD 0.05%) has been ‘obtained. This IC features a Darlington connection complementary circuit power stage integrated with the bias circuit. ‘The purpose of Q, is to equalize temperature changes in Q,. By keeping the input base poten of Q; at a constant OV, the Q; output neutral point potential will remain steady despite changes in temperature. Since this power amplifier is a DC amplifier, any DC voltages appearing at the Q, in- put base will be amplified and passed on to the output. In order to avoid this, the drop in poter tial across R23; due to the Q, input base current, is vepuoor-ar | [ oe- Emenasis [frre AMP | We (pa3001-8) designed to be absorbed by the Qs base current, thereby maintaining the R our Fucrion hase ae 3. PHONO 400K FONCTION Fig. 2 FM muting circuit Q; input base potential constant at OV. Fig. 3 Power amplif Protection Circuit (Fig. 4) The protection circuit featured in this equip- ‘ment employs an IC (PA3004) recently developed by Pioneer. This IC includes output DC voltage detection (a), +B voltage level detection (b), ~B voltage level ‘detection (c), AC voltage detection (d), Ct discharge switching (e), relay drive trigger switching (f), and constant current circuitry (g and h). This protection circuit is responsible for muting when the POWER switch is turned ON and OFF, speaker protection in case of an abnormal power amplifier neutral point potential, and speaker dis- connection in case of protection circuit failure due to abnormal voltage in the power supply to the protection circuit IC. ‘* Power Switch Muting ‘The delaying action employed when the POWER switch is turned ON is determined by the time constants of the timing capacitor (Ct) and the con- stant current circuit (g). When the POWER switch is turned ON, +B is passed via (g) to charge up Ct. ‘574-0080 vd DETECTION Te VOLTAGE LEVEL SXx-780 oureur cireuit When fully charged, switch (£) will tum on, and a base current will flow from circuit (h) to Qz., thereby turning the relay on. When the POWER switch is tumed OFF again, the AC voltage disappears immediately, resulting in switch (e) being tumed on by the AC voltage detector (d), thereby discharging Ct. Consequently, switch (£), Qs, and the relay will all be turned off. * Abnormal Power Amplifier Neutral-point Potential ‘The occurrence of any abnormality in the power amplifier neutral-point potential will be detected at (a), resulting in switch (e) being tumed on. Ct will thus be discharged, and switch (f), Que, and the relay all turned off. ‘© Abnormal Protection Circuit Power Voltage The power supply voltage level is detected by detectors (b) and (4). If the prescribed level is not attained, switch (e) will tum on, and switch (f), Qae, and the relay all turn off. al [be vourace erection (©) gerection ‘VOLTAGE LEVEL The VOLTAGE ‘) perecTion P8008 Fig. Protection cireutt 5. DISASSEMBLY Wooden Cover Remove the wooden cover by undoing the 4 screws (0-9). Bottom Plate Undo 10 screws (@— @® ) to remove the bottom plate. Front Panel Pull off all the knobs, and remove the 2 screws (® .@ ) and 2 nuts (®, ®). Front panel Fig. 5 6. PARTS LOCATION 6.1 FRONT PANEL VIEW Wooden cover assembly AM-EM meter ‘AMM.072 ‘AAW.093 Front panel assembly: ANB oT cee jh) Knob (TUNING) AAW-092 % DA: nab (VOLUME) (o7 € ean st ‘RAB.I05, i he «¢ Knob (PowER)— af 4 Knob (LOUDNESS) AAD.139 ba AAD.138 Phone jack (PHONES) —— knob (BALANCE) AN 000 AAB.I76 Knob (SPEAKERS) Knob (TAPE MONITOR) ADATO RAD. 138 Knob (BASS) Knob (MODE) AABITe AAD.138 Knob (TREBLE). Knob (FUNCTION) AaB.75 AAB 175 Knob (LOW FILTER) Knob (EM MUTING) AD.138 RAD. 138 6.2 FRONT VIEW WITH PANEL REMOVED LED (SOURCE, green) LED (TAPE MONITOR, red)___AEL-308 LED (STEREO, red) AEL-307 AEL-307 Dial pointer assembly AAF-O74 Dial panel ———Ss AAG-161, A (VOLUME) ACV-161 fl ‘Variable resistor 1MD2 Lever switch (POWER) aan (BALANCE) Sleuth ete Lever switch (MODE) |_ ACTON (SPEAKERS) ask-144 Lever switeh ASG-139 Slide rotary switch (TAPE MONITOR} Variabie resistor 100KS2 (FuncTioN} ASK-145, (sass) ASE-107 ACV-193 — Lever switeh (FM MUTING) Variable resistor 100kS2 ask-144 (TREBLE) Lover switeh (LOW FILTER) ACV-194 ASK-144 Sx-780 63 TOP VIEW Lamp (wedge type) 8V 0.38 _ ole Acrylic: ‘ANR.036 Yr ae AF assembly wg g Gwk.118 Ee Tuner assembly — AWE-099 Tuning drum assembly— AXA-TI3 Capacitor assembly Power transformer Gwr-110 ATTSI12, 6.4 REAR PANEL VIEW Slide switch ‘Terminal (SPEAKERS) (DE-EMPHASIS) AKE-028 ASH.016 ‘Terminal (ANTENNA) AKA-002, Terminal (GND)_ AKE-O31 Terminal 6P Terminal 6P Lper antenna AC power cord AKBO38) — AKBO39.— ATB505 Abe-028 AC socket (AC OUTLETS) ‘AKP-004 12 7. DIAL CORD STRINGING 1. Remove front panel (See page 10). 2. Remove the tuning drum from the tuning capacitor shaft (Fig. 6). 3. Tie one end of the string to the peg on the in- side of the tuning drum (Fig. 6). 4, Set the tuning capacitor to its maximum ca- pacity (with the vanes fully meshed). 5, Attach the tuning drum to the tuning shaft so that the fixing screw head is pointing exactly upwards, 6. Draw the string out through the gap cut in the tuning drum, and after passing it half-way round the drum, thread it successively over the pulleys A, B, C. 7. Pass the string over pulley D after having would it around the tuning shaft three times (in a clockwise direction as viewed from the rear). 8, Tie the other end of the string to the hook on the spring, so that the string is tensioned, after passing it around the tuning drum twice Fig. 7), Set the tuning capacitor to its maximum capac- ity (with the vanes fully meshed). 9, Attach the dial pointer to the string at the start point (at the extreme left of the dial scale), and secure it firmly to the string. 10. Check that when the tuning shaft is turned, the dial pointer, tuning capacitor, etc., all move smoothly. 11. Paint-lock the knots on the string, and cut off ‘the excess string after painting. Tuning drum Tuning drum 13 Tuning drum 8. ADJUSTMENTS 8.1 FM TUNER ‘The tuning coil in the FM front end does not have an adjusting core. Consequently, tracking adjustments at 90MHz are performed by regulating the gap between the rotor and stator of the tuning, capacitors (VC,, VC;, VC;). The expression ‘“ad- just VC,” (VC,, VC;) found in the text means that the two outer rotor blades of each of these tuning capacitors are to be extended outwards with spatula (Part No. GGK-066) as shown in Fig. 9. Ti lo= an Rotor blade SOF Fig g Connect the test instruments as shown in Fig. a Set the FUNCTION switch to FM. ‘Turn the FM MUTING switch to OFF. Set the dial pointer of the SX-780 to 106MHz. Set the FM Signal Generator (FM SG) output to 106dB at 106MHz, with 100% modulation (75kE1z deviation) for 400Hz. This modulation setting should be used for all the following adjustments. 6. Adjust TC; to give the maximum reading on the multitester (with DC 200uA range). Adjust the primary (lower) core of T; so that the AM-FM meter (the FM tuning meter) indicator needle reads dead center. 8. Set the FM SG output to 154B. 9. Adjust TC, and TC, to give the maximum reading on the multitester. 10. Set the SX-780 dial pointer to 90MHz. 11. Set the FM SG output to 106dB at 90MHz. 12. Adjust VC; for maximum reading on the multi- tester. 13. Set the FM SG output to 15dB, 14. Adjust VC, and VC; so that the multitester reading reaches a maximum. 15. Alternately repeat the adjustments of VCs, VC, and VC; when the dial pointer is at 90MHz, and of TC;, TC, and TC, when the dial pointer is at 106MHz, until adjustment at the one frequency requires no further re- adjustment at the other frequency. 16. Adjust the core of T, to give the maximum reading on the multitester. 17. De-tune the SX-780 (to a position at which only inter-station noise is heard), and adjust the primary (lower) core of T; so that the AM. FM meter indicator needle reads dead center. 18, Set the FM SG output to 664B at 98MHz, 19. Tune the SX-780 to a dial reading of 98MHz and check that the AM-FM meter is reading correctly at the center of the meter scale. 20. Adjust the secondary (upper) core of T; to give a minimum level of distortion. 21. Repeat the steps detailed in section 17 to 20 for the adjustment of the primary and second. ary cores of T; until both requirements are fully satisfied. jet the SX-780 dial indication and FM SG fre. ‘quency for 98MHz. 23. Set the FM MUTING switch to ON, and check the muting threshold. If the muting threshold is more than 284B, cut the jumper lead N. Multiplex Decoder 24, Connect an MPX Signal Generator (MPX SG) to the external modulator terminals of the FM SG. 25. Connect the 19kHz pilot output signal from the MPX SG to the X-plates (horizontal input) of an oscilloscope, and use a probe to connect the Y-plates (vertical input) to the No. 23 terminal. 26. Set the FM SG output to 664B, unmodulated. 27. Adjust VR, to freeze the motion of the result- ing Lissajous figure. Nore: Lissajous figure adopts the general form shown in Figure 10 due to the fact that the MPX SG 19kHz pilot signal ‘output is a sine wave, and the No. 28 terminal carries a 76kHz saw-tooth wave as determined by the adjustment of VR, 22, Fig. 10 Lissajous waveform SX-780 28. Tum the FM SG modulation mode setting to ‘external modulation. 29. Set the MPX SG to pilot signal (19kHz) only (7.5kE1z deviation). 30. Adjust VR; so that an AC voltmeter (REC terminal) shows minimum reading (19kH2 leak) Adjust the MPX SG modulation settings to kHz, L (R), 45% modulation (33.75kHz devia- tion), with’ 10% pilot modulation (7.5kH2 deviation). 82. Adjust the core of T, (within +90°) for mum distortion in the 1kHz demodulated out- put from L (R) channel 31. FM signal generator M3000 ANT REC PLAY 8 TAPE 7 tester Jumper lead N Oscilloscope eS - 00 00||/oo 0 0 = ‘our VERT. HORIZ, PILOT OUT Fig. 1 4s 7 L 2 i 3 10. EXPLODED VIEWS 10.1 EXTERNAL PART A ‘Screw 4x15 ABA-209 Wooden cover assémly wears i B a See the next page screw 396 crea Koo (SPEAKERS) Seria c Front pana seb. seid Koobanembly POWER) sews “ H itt Wates wo Knob (BASS). ‘o as : Knob (TREBLE) ae rab (LOW FILTER): ae Knob ( : AAD-138 LAA Fe wr 4 AAD-138 ae o @ | ABA-082 ACN31 Screw 3x6 ABADIG A Nylon rivet tos Meee 4 Gy: = ySefow 3x6 Hybrid 10 > BAGS STK-OO5OA e “Ceramic capacitor 0.01/260V Serew 3x18 \ac'oat ABA210 Ea a Cover : AEC. 2H) “se | go vonen gy 507 4 ial shat assembly Headphones assembly Screw 3x8 Sow 3x6 [~. aa /ABA-065, Serow 4x8 ABA‘ 3x8 2 Seren 3x6 ABAII6 AF assembly Gwk-i18 ° 8 6 row 3x6 — ABA.002 ee 11. SCHEMATIC DIAGRAMS, P.C. BOARD AND PARTS LIST 11.1. MISCELLANEA Miscellaneous Parts NOTE: When ordering resistors, first covert resistence 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%, ond K = 10%). PATTERNS Seon st ‘wars Seis iia ete ats Roars 693) ose one aanon k ee sip O1OK Bs2 Men heroic dg enh cr Mh rtaon met! rei tor Pohaa soon tot sot awuse sea e capacitor bein sta omen fete, symtoms Arai re | reel Acco ct weno ackoie shoo DC EMMA fecem fz tema Pow eC Ons) ACN-031 Rt Wire wound resistor 2208 Mgt st tome fe Stine ner sreosson 01,02 anna roots ‘ons ‘atti Lawes ano Fuses ‘oc Se nomarore rect, sytet nn sxasne Temi AELOM ——PLI-PL2 Lan ino) ne oan eee itis. a racak evinaa AKE.O31 ‘Terminal (GND} Arties Fun-rua Foo ve saa eee aecico ru Faan cons nett P. BOARD ASSEMBLIES Eee List of changed parts ntrmatin wl be fried when nt “AF snsembty number in this parts list. Gaeiwe Guaeraventy Gree seahnecanty ‘AWE-099, Tae A List of Changed Parts for Factory Modification auniee Pan eer Se) Pette | Dinin wes! td +— orwens futsal nn asc) atc | 23 External Appearance of Transistors and ICs 280750 mcr a 7 saeco E samo CBE 2sc1885 : a" qt ea Met: 28a7268 Ee CBS 2sa060 250898, ¢ E 250025 c 8 8 ci 250979 Ee 2scass 8. ‘2805354 8 fe scr 8 Ce Ee 2a —~ iss ao (3 asa? ces Block Diagram of ICs PAI001-8 ov s ea sae tee Ww Lat tet SNe gM TPP ELE) i) ple it Ciro I $ 8x80 ho , aa WURERRE io vant = er les Ee a ls a = 1 876543 1 [ea ‘Sratf fe" ‘PA3004, = Pastas wer estar Mae an oye a ae rs eu” ES fesece? z : = We 1W OSC, H SCN MER INN 7A et Bt t 1 4 1 Bee RESISTANCE VALUE CODES ‘Nominal rsinance | Significant figure Multiplier | Resistance ‘ah cove igus) 108)” | value code Code numbers of resistors used in Pioneer ipment are expressed in the following way:— mh ao ee rele os y ie 502 562 soe | 8R62 10 100 10R0 Code number > RD % PS.473.4 NL oS 2 Abe Feacrveusise 110 110 xi? | 1100 tk lie soot Power rating {000 1 aU oa Shape (tubuler) 1 100 x10 | "1961 Resistance (code valve) << Thy toto? | t00e z 336K Tolerance 28, 336 mio | 9962 Low-noise marking 12K Ae moet tis Furthermore, in the list of parts found in the {Ho00000) 100 x10 1004 Service Manual, the resistance (code value) part of Pee the above code number is expressed as DDO or (1560000) = pn a coon. Resistors included in the Service Manual list of Ex. 2 For OOD Codes parts | eeeseees Deano When ordering resistor components, first ascer tain the actual resistance value from’ the circuit Significant sia diagram, and then convert it into code no. form as shown in the following examples. Ex. RD%PSGo0 JNL Multiplier (10%) * Resistors with fractional valu For further details on code numbers, refer to OMe. 6 “Tuning Fork” VOL. 1 Significant figures Ex.1 For 0000 Codes ex.2 Nominal resistance | Significant figure Multiplier | Resistance + General resistors ar "rtworigres "(Os | vive code go 090 os 06 os: 15 16 1RS Significant figures Muttiptier (10%) 1 a us 2 220 33 331 * Resistors with fractional values 10 102 G.70--o ooro cy x10 862 Significant figures Decimal point oa x10? 63 82 xo a2 10 x10! 108 i tea x10! 225 Significant figures Decimal point sia 1 L 2 3 11.2 SCHEMATIC DIAGRAM a [99995] 7 I NOTE: ‘The indicated only. Other alt fare listed in the parts lst. 12 tors are representative ones Wconduetors may be used and Sx-78 7 I 2 11.3. P.C. BOARD CONNECTION DIAGRAM. 7s UNBALANCE: A rae 300 fen Sota. Lenono | ter aw Leonor TUNER ASSEMBLY AWE-099 B ef ic a ‘DER D 7 L 2 29 LESS SFE, sus PLAY REC PLAY REC a Len nen Lyare1 — PLAY REC PLAY REC ten! fen L yare2 SxX-7; 7 ay 8 I 9 rowen tc 320090) = Vie & C4 Shag vy np Sy sage {— sussee | Ph ‘| |ele! me iat eSmivaTio " 8 200m Srna] Hen Gite * [HEADPHONE ASSEMBI (GWX-192 * noe -s ae Seren f o Oia Gnae SPEAKER B a SPEAKER A : 7 I 8 a 2 10 L iW I 12 6 CAPACITOR ASSEMBLY GWR-110 2.2m Siw 6,001 ac faov son 2 s, = SWITCHED POWER UNSWITCHED. 10OW MAX B00" MAX me acettoa ey FUSE ASSEMBLY AWR-169 [ 10 rE u I 2 Sx-780 11.4 LED ASSEMBLY (GWX-191) 11.6 CAPACITOR ASSEMBLY (GWR-110) On AEL-307 (STEREO) REO Qn AEL-308 (SOURCE) GAN 10x) AEL~ 307 (TAPE MONITOR) RED Note: When ordering resistors, convert the resistance value into code form and ‘then rewrite the part no. as before. PartNo. ‘Symbol & Description AeL907 021,023 LED EL 208 2 LED PartNo. ‘Symbol & Description ROKPS.ooDs R601, R502 acHo82 501,502 Eleetroiytic 000/50V 11.5 HEADPHONE ASSEMBLY (GWX-192) 11.7 FUSE ASSEMBLY (AWR-169) ere eae FU 1A q 8 Part No. & Description PartNo, ‘Symbol & Deseristion AKRO13 Fuse clip AKN-009 Phone jek ‘acG-003 a Ceramic 0.01/125 33 11.8 TUNER ASSEMBLY (AWE-099) Parts List ‘TRANSFORMERS AND COILS part symbol & estotion on symbol & Desovion ares FMurt ceaanmeas 060,028 reo 12 Ftd anor cenanarso cot aro) 13 AMtomea Sxovr zaazs0 ond Connzac so” ose sataxe LeU Rr choke col'2248 exove tank 0 c80 Arwoze Ur ehnecotl 27H cen tori cr.cr2.078 ae FM cone iter coswaeo G7 frrose Aco Ceoxt coors crs arrose outer Note: When ordering reat, convert the capacitors Teoutace elt ao code form: and RESISTORS then murs the prt noob before fare Symbol & Daeotion or mol Dsroton noeat2 Veiner mewn = Tea arame emer FROMPS 000) RI, R3—RB,RID—RO4,ROG—RAt, RAD abe ccous 120% 1 fRouvS 200) Ra, RO RI2,R42~RA8, RED-RSA eos 220K 80 G2 fwksa occa F Rae EXDVE 109250 G2~C5,c8, C14, 16,617, C29, C24 Sxove ase 80 Geo cro, C78 ncrois VR Samitnod 47k cou! 180K 80 cb novos V2. Samide 2k 08. 180K 807,22 orien wae sewIcONDUCTORS cost or 80 cto (CGB RA7K 500 C11 core ‘Semel terion ceocn 300% 0 C12 askeayoran at och eon 0 E13 saemey oon, coos ton 6018 o32 moa a CKOYF 4732 60 C18—C21, C25, C26, C29, C30, C33, C62 id = CKDYF 473250 065 = re cEAznare0 ca? CeAotorso — cat.cnt chao | 1s apap nm, 2SA726S-F orG 7,08 (asa7e0 or) cas si1s80 cae CSZAGREMG = C37 ee = CEANL Vor Gam cH cKOYB.821K 60 C39 aecedee A or O10, COMA473K'50 C42 aria ts2078 1,02 ceamrie cae CEA 221P 16 C44, C53, — (CKDYA 472) 60 C45, C46. _— exove eax 60 GH7, 648 GxovesriKeo cH 680 cstcs2 cst cee, cs8 csr. es8 co Fano 0 182076 ‘2507268? 1 T 2 I 3 11.9. AF ASSEMBLY (GWK-118) anaes? = T36PI yy. ua 2SCIT7OAN? roan, SazacibaR BT [ poesia «1 SP 9s SOL Cy EKA) Tel af tap Pecos | Fam Banna | ote Sepa |p | SF, haa San] TEE ‘Eilon PA G t82076.2 + wystH- 005018) : ouatsiss6x2 | aa2sagren: “see, cousaesonzsn 2428012 pa By Dowie fad SX-780 Parts List of AF Amplifier Assembly (GWK-118) SWITCHES PartNo. ‘Symbol & Descriotion for No. Symbol & Description ASE107 81 Slide rotary (FUNCTION) CEA 100 16 C218, 05. ASKS 82 Liver (TAPE MON 1) ERATOR IG C319 ASKS 83 Liver (TAPE MON 2) asks st Lier (MODE Ac 000 €320-C323 Ceramic 0.047/150V Ask188 86 Lier (LOUDNESS) CEARATP 50 CAD1—Ca0 cEAzIP6 —caDS as148 86 Lever (LOW FILTER) a RESISTORS Note: When ordering resistor, convert the 486-139 se Dual push (SPEAKERS) preienes Vataa‘e Oak ferred ae S, fetens then rewrite the part no. os before. Far Ne. ‘Symbol & Descriotion CAPACITORS acv-ie1 VR1 Variable 1004-8 (VOLUME) art No. Symbol & Deszription Act.019 VR2 Variable 1M (BALANCE) SS rae VRS ——_Varlable 100k (BASS) Coost. 151K 50. 101, c102 ov-198 VR4 Variable 100k (TREBLE? CEA Ni 2AZP 50 C103, C104, 6117, C118, 0229, 6230 aceon VRS, VRE Semifixed 150% CEAaTiPG C105, C108 GCOS 101K 50 C107, C108, 6235, C236, C241, C242 cs2049 \VR7, VR8, Semifixed 10k CDSE 101K 506312, C313 {CCDSL 220K 50 C109, C110 ROKPS O00) RIO1-AI24, R20T—R242 R2I9—AIAZ ROKPS 000) R247, R248, R261, A252, R257, A258, cara 103660 c111,c112 207-916, R19 COPA 353650 c113,c114 ROMPS.OCs R920, AI24--RI26, AIBO-RII5, A4OT—RAS COMA 32150 C115, C116 ROMPSF 000.4 R243 R246, R249, R250, 25D, AIA, CEAAR7P35 C201, 0202, c324~C327 R250.—R262, R267, A268 CKDYB 391K 50 6209, C204, C215, C216 ROKPSF 00D RIO1—R306, ABI, ATG, A321 coma 220K 60. ¢208, 206 RSIP.OD0J R286, R266, A269, A270, A923, A326, R327 CEA NL O10? 50 C207, C208 RS2P O00) CCOSL 560K 50 C200, 0710, 6235, 234 ‘ACN.030 R269-R266Wire Wound 0.22/20 CeOst 0500 50. C211, c212 CeAavor6 C213, C214 SEMICONDUCTORS CEA NLAR7P 25 217, C218 COMA 123/50 C219, 6220, PartNo. ___ Symbol COMA 273K 60 0221, 6722 Description Casa sesso. Ga, erat Tare aa.at Comaszasso C28, 6220 Bera 08.08 par 97.08 (CEA NLR22M 50 227, 0228 CCDSL 121K 50 6231, C232 COSI 100K 500 6237, 6238 NA '473K 50 6239, 6240 CEA 10125 C301 -C304 28C2201-F 0G 09,010 2SCI775A€ of F_a11,012 2SC1885R or $19,014 DSAVIZAorS 15,016 28C1984.R of Q 017,026 (2sc1735-0 orc) CEA 470P:35 ©3085, 6306 CEA 101 50 307, C308 GEA 2R2P 50 308, €310, CEA10116 © c311 CEAanIP6s C314 2SABS0D orc a8 (280912.8 oF 0} 2S0926R-D or E19 258506. 0M 020 CEA2zP6s C315 (25A968.0 or ¥) CEAa70P50 C316 CEA 30°16 C317 2sa850-Derc a18 (2sa912.8 o a) ae PartNo. Symbol & Description List of Changed Parts for Factory Modification 2sagoinr az (25A8994-€ 0° 0} Symbol Part No. Description 28K34C oD 023,024 T 20712C 0rd a25 A008 027 | 2K34CorD 028,029 (28K117,¥ or GR) | 181555 bios | (182473) z-140 04 | (wz-140) | 182471 0s | 1062 6-09 (sisot-02) SRSAMS, p10-019 24K 261 14, 015, 017, 018 182076 016,019 (182473) z.061 20 (wz.061) OTHERS PartNo. ‘Symbol & Description ‘763.000 L1L2 AF choke colt ANH-203, Heat sink ABAAIG Screw 336, ABN028 Union nut ABN047 Union nut 871.010 Nuc M7 871.004 Nut MO ABE-001 “Toothed lock wathar MO ABE-006, “Toothed lock washer M7 40 PIONEER ELECTRONIC CORPORATION «1. .Jea.re |

You might also like