Pioneer SPEC-4 Service Manual
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Pioneer SPEC-4 Service Manual

Pioneer SPEC-4 Service Manual

Stereo power amplifier
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STEREO POWER AMPLIFIER
SERVICE M A N U A L
flD
P I O N E E R

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Summary of Contents for Pioneer SPEC-4

  • Page 1 STEREO POWER AMPLIFIER SERVICE M A N U A L P I O N E E R...

  • Page 2: Table Of Contents

    S P E C - 4 MODEL SPEC-4 COMES IN TWO VERSIONS DISTINGUISHED AS FOLLOWS: Type Voltage Remarks 120V only U. S. A . model 110V, 120V, 220V and 240V (Switchablel General export model • This service manual is applicable to KU(p2—p40) and S(p41—p48) types.

  • Page 3: S P E C

    PACKING Additional Service Manual C O N T R A S T OF MISCELLANEOUS PARTS E X P L O D E D VIEW SCHEMATIC DIAGRAMS, P.C. B O A R D P A T T E R N A N D PARTS LIST 3.1 .

  • Page 4: Front Panel Facilities

    2, FRONT PANEL FACILITIES POWER SWITCH [-PEAK L E V E L METERS Set to ON position to energize SPEC-4. After setting to When speaker systems of 8ohm nominal impedance are ON, there is a brief delay before sound is obtained. This connected, these provide direct readout of the peak out­...

  • Page 5: Connection Diagram

    3 . CONNECTION DIAGRAM Before making the connections, check that the power is off. Also, make sure that you turn the power off if you want to change over the connections when the components are operating. Ground wire Convenience outlet (AC OUTLET)" UNSWITCHED: Power is always sup­...

  • Page 6: Block Diagram

    I PEC-4 4 BLOCK DIAGRAM...

  • Page 7: Circuit Description

    5. CIRCUIT DESCRIPTION 5.1 POWER AMPLIFIER This unit is a DC amplifier with an input coupling A power limiter circuit protects the power stage. capacitor. Generally, in direct coupled amplifiers, Di, D 2 , D 3 and D 4 , Ds, D 6 are drive voltage limiters 100% NFB is applied at the DC stage.

  • Page 8: Protection Circuit

    S P E C - 4 The input signal is divided by Ri, R2 and sent to 5.3 PROTECTION CIRCUIT the logarithmic compression -circuit. The loga­ This circuit protects the power transistors in case rithmic compression circuit is an audio IC of overload, the speakers in case of power amplifier (TA7136P2) and utilizes the rise characteristic malfunction, and also performs a muting function...
  • Page 9 Muting Operation the point A potential divided by Rd and RL When the power supply is turned ON, Q base is (load). Point D is connected to Q12 base and point reverse biased through D 2 and R22 • turning Q n OFF C to Q i emitter through R and Re...

  • Page 10: Power Supply Circuit

    S P E C - 4 and at Qs the collector current increases and the potential drops, causing current to flow through If the DC voltage is positive, Q collector current increases and the potential drops, while at Q collector current decreases and the potential rises. Current therefore flows through D«.

  • Page 11: Disassembly

    6. DISASSEMBLY Top cover Bottom plate Remove the 17 screws(C) at the bottom plate and Remove the 12 screws(A) to detach the top cover. lift off the bottom plate. Front panel Loosen the set screws of the 2 LEVEL knobs with an hexagonal wrench and remove all the knobs.

  • Page 12: Parts Location

    SPEC-4 7. PARTS LOCATION Front Panel View Knob (RIGHT L E V E L ) A A B - 1 5 3 Peak meter (RIGHT) Knob ( L E F T L E V E L ) Handle Handle AAW-068...

  • Page 13: Top View

    Top View Power amplifier assembly Power amplifier assembly A W H - 0 6 5 A W H - 0 6 5 Heat sink Heat sink E l e c t r o l y t i c capacitor 2 2 , 0 0 0 / i F / 8 0 V Electrolytic capacitor 2 2 , 0 0 0 / i F / 8 0 V A C H - 0 5 6 A C H - 0 5 6...

  • Page 14: Bottom View

    SPEC-4 Bottom View 5P housing A K X - 0 1 7 5P housing 6P housing A K X - 0 1 7 A K X - 0 1 8 — 6P housing Fuse 6 A A K X - 0 1 8...

  • Page 15: Adjustments

    Observe the wave­ form with the oscilloscope and adjust so that the waveform is symmetrical. A C Voltmeter Oscilloscope Distortion meter SPEC-4 L E F T R I G H T Dummy load 4 f 2 A F signal generator Fig.

  • Page 16: Meter Amplifier

    VRi (R channel) and V R 2 (L channel) so that the output meter indicates OdB. Meter amplifier Fig. 12 The position of V R i and V R 2 AC Voltmeter SPEC-4 LEFT RIGHT A F . Siqnal qenerator Fig. 13 Connection diagram for meter amplifier adjustment...

  • Page 17: Exploded Views

    9. EXPLODED VIEWS NOMENCLATURE OF SCREWS, WASHERS AND NUTS The following symbols stand for screws, washers and nuts as shown in exploded view. Symbol Description Description Symbol E type washer Brazier head tapping screw Flat washer Pan head tapping screw Spring lock washer Binding head tapping screw Countersunk head tapping screw...

  • Page 18: External Part

    SPEC-4 EXTERNAL PART NOTE: Parts indicated in green type cannot be supplied.

  • Page 19: Internal Part

    INTERNAL PART NOTE: Parts indicated in green type cannot be supplied. Panel Stay Block...
  • Page 20 Center Chassis Block NOTE: Parts indicated in green type cannot be supplied.
  • Page 21 S P E C - 4 N O T E : Rear Panel Block Parts indicated in green type cannot be supplied. Power Amplifier Block...

  • Page 22: Schematic Diagrams, P. C. Board Patterns And Parts List

    10. SCHEMATIC DIAGRAMS, P. C. BOARD PATTERNS AND PARTS LIST 10.1 SCHEMATIC DIAGRAM AND MISCELLANEOUS PARTS Miscellaneous Parts List NOTE: • Capacitors: in pj? unless otherwise noted p:pF SWITCHES • Resistors: in a !4W unless otherwise noted k:ka, M:Mn Symbol Description Part No.
  • Page 23 NOTE: Schematic Diagram The indicated semiconductors are representative ones only. Other alternative semiconductors may be used and are listed in the parts list. External Appearance of Transistors and IC 2SD424 (2SD555) 2SB554 (2SB600) 2SB628A 2SB536 2SD608A 2SD381 2SA858 2SA893A (2SA834) 2SC1775A 2SC1890A 2SC1439...
  • Page 24 10.2 METER AMPLIFIER ASSEMBLY (AWM-113)
  • Page 26 Parts List of Meter Amplifier Assembly (AWM-113) RESISTORS Symbol Description Part No. Symbol Description Part No. Carbon film 4.7M RDUPS 475J Semi-fixed 6.8k-B ACP-060 Carbon film 4.7M RDUPS 475J V R 2 Semi-fixed 6.8k-B ACP-060 Carbon film 1.2k RDUPS 122J Carbon film RDUPS 563J Carbon film...
  • Page 27 Symbol Description Part No. Symbol Description Part No. Transistor 2SC1384-R Electrolytic C E A 2R2P 50 (2SC1384-Q) Electrolytic C E A 2R2P 50 (2SC1166-Y) Electrolytic C E A 3R3P 50 (2SC1166-0) Electrolytic C E A 3R3P 50 Electrolytic C E A 4 7 0 P 1 6 TA7136P2 TA7136P2 Electrolytic...
  • Page 28 S P E C - 4 Symbol Description Part No. Diode 1S2473 (1S1555) Diode 1S2473 (1S1555J Zener diode XZ-235 Zener diode XZ-235 Thermistor 31D27 Thermistor 31D27 OTHER Symbol Description Part No. Heat sink ANH-117 List of Changed Parts for Ractory Modification Description Part No.

  • Page 29: Power Amplifier Assembly (Awh-065)

    10.3 POWER AMPLIFIER ASSEMBLY (AWH-065)
  • Page 31 Parts List of Power Amplifier Assembly (AWH-065) RESISTORS AND POTENTIOMETERS Symbol Description Part No. Symbol Description Part No. Thermistor TH101-2 Metal oxide RS2P 100J Thermistor TH101-2 Carbon film RDUPSF 4R7J Carbon film RDUPSF 4R7J Semi-fixed 470-B ACP-033 Carbon film RDUPSF 101J Semi-fixed .
  • Page 32 S P E C - 4 OTHERS SEMICONDUCTORS Symbol Description Part No. Symbol Description Part No. — A F choke coil 1.1JIH ATH-012 Transistor 2SA798-G Relay ASR-035 Transistor 2SC1775A-E Heat sink ANH-340 (2SC1775A-D) 5P plug AKM-019 Transistor 2SC1775A-E 6P plug AKM-020 (2SC1775A-DI * hfe of these transistors (Q2, Q3) should have the same value.

  • Page 33: Fuse Assembly (Awr-143)

    10.4 FUSE ASSEMBLY (AWR-143)
  • Page 34 S P E C - 4 Parts List of Fuse Assembly (AWR-143) CAPACITORS Symbol Description Part No. Mylar 0.01 400V C Q M A 1 0 3 K 4 0 0 Ceramic 0.01 125V ACG-003 SEMICONDUCTORS Symbol Description Part No. Diode SI B01-04 Diode...

  • Page 35: Power Supply Assembly (Awr-139)

    10.5 POWER SUPPLY A S S E M B L Y (AWR-139) Foil side Parts List of Power Supply Assembly (AWR-139) RESISTORS SEMICONDUCTORS Symbol Description Part No. Symbol Description Part No. Metal film 8.2k R S 1 P 8 2 2 J Diode S5151 Metal film...

  • Page 36: Power Supply Assembly (Awr-140)

    S P E C - 4 10.6 POWER SUPPLY ASSEMBLY (AWR-140) Foil side Parts List of Power Supply Assembly (AWR-140) SEMICONDUCTORS RESISTORS Symbol Description Part No. Symbol Description Part No. Metal film 8.2k R S 1 P 8 2 2 J Diode S5151 Metal film...
  • Page 37 11. PACKING...

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