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1、STEREO POWER AMPLIFIER SPEGI?, KCU (DrrroNEER RadioFans.CN 收音机爱 好者资料库 1. 2. 3. 4. CONTENTS SPEC|F|CAT|ONS . 3 FRONT PANEL FACILITIES . . . 4 CoNNECTION DIAGRAM . . 5 CIRCUIT DESCRIPTION 4.1 Power Amplifier 6 4.2 Peak Level Meter Circuit 7 4.3 Protection Circuit , 8 4.4 Surge Current Suppressor Circu
2、it . . 10 BLOCK DIAGRAM . . 11 ADJUSTING PROCEDURES 6.1 ldle Current Adiustment . 13 6.2 Current Limiter Sensitivity Adiustment . . . . 14 6.3 Meter Amplifier Adjustment . 15 D|SASSEMBLY . . . 16 PARTS LOCATTONS . 20 5. 6. 7. 8. 9. 10. EXPLODED VIEWS SCHEMATIC DIAGRAMS, P.C. BOARD PATTERNS AND PARTS
3、 LIST 10.1 Schematic Diagram and Miscellaneous Parts . . 30 10.2 Power Supply Circuit Assembly (AWR-093) . . 33 10.3 Power Amplifier Assembly (AWH-045) . -. . 37 10.4 Meter Amplifier Assembly (AWM-0811 . . 42 11. PACKING . . 47 12. PARTSLISTOFEXPLODEDVIEWS. .48 23 RadioFans.CN 收音机爱 好者资料库 EiPEC.E 1.
4、SPECIFICAT|ONS Semiconductors Transistors .55 Diodes . .75 Power Amplifier Circuitry . . Cascaded differential Amplifier, Push-pull drive, Triple push-pull, direct coupled OCL. Continuous Power Outout from 20 Hertz to 20,000 Hertz (Both channels driven) . . . . . . 250 watts per channel (g ohms) Tot
5、al Harmonic Distortion at20 Hertz to 20.000 Hertz (Continuous rated power output)o.1% (125 watts per channel power output,8 ohms) . .O.O5% (1 watt per channel poweroutput,8 ohms) . . . . . . . , . . . 0.Q5o/o lntermodulation Distortion (Continuous ratedpower output) . - O.lo/o (125 watts per channel
6、 power output, S ohms) . . -.0.05% (1 watt per channel power output, 8 ohms) . . . .O.O5% Frequency Response . 5 Hertz to 80,000 HertzlldB Input (Sensitivity/lmpedance) . . . . . . . 2Vl50k ohms Output Speaker. . 4ohmstoSohms Damping Factor (20 Hertz to 20,000 Hertz, S ohms) .,. 50 Hum and Noise (lH
7、F, short-circuited, A network) . . . . . . .110d8 Miscellaneous Power Requirements . . AC 120V 60 Hertz Power Consumotion . . . . . . .,. 500watts Dimensions .480(W) x186.5(H) x445(D) mm 19-5/16 x 7 x13-3116in Weight: Without Package . Furnished Parts 24.3kg; 54lb Connection Cord with Pin Plugs Oper
8、ating lnstuctions NOTE: Specificdtiotrt and the design subject to possible mod,fication without notice due to improuements. 2. FRONT PANEL FACILITIES PEAK LEVEL METERS When speaker systems of 8O nominal impedance are con- nected, these provide direct readout of the output power in Watts. NOTE: Speoh
9、er syotem impedance uaries occording to frequency. To obtoin o preciae medsurcment of the output poue remoue Spedher conectiotrs ond connect 8a dumtuy loods ocro4i the SPEAKERS termindls- POWER SWI CH Set to ON to energize the SPEC-2. Output will not be obtained until the PRoTEcTIoN indicator lamp S
10、oes out. This effect is due to the internal muting circuit and does not indicate malfunction. METER ZERO POINT ADJ USTMENT PROTECTION INDICATOR The lamp lights when the protection circuit functions. lf the lamp stays on during operation, turn off the POWER switch and check as described in the sectio
11、n Protection Circuit Operation. After identifying and correcting the source of difficulty, if the lamp still fails to extinguish, contact a Pioneer Authorized Service Center, INPUT LEVEL CONTROLS (LEFT rl tO C i O q1 o STEREO PRE-AMPLIFIER (e.s. Pioneer SPEC-1) SPEAKERS IMPEDANCE swilch St to malch
12、the nominal imDed- ance of the spoaker systms em- ployed with the SPEC-2. Be sure to turn otf the po!r before chenging this switch setting. For about 6 to 12 seconds 6tter changing the position o the IMPEDANCE swirch the PRO- TECTION lamp lights and sound is not obtained from the speaksr systems. Th
13、is is du6 to the built- in muting circuit, RIGHT CHANNEL LEFT CHANNEL SPEAKER SYSTEMS 4. CIRCUIT DESCRIPTION 4.1 POWER AMPLIFIER The SPEC-2 is a high power design, employing a cascoded differential amplifier first stage, push-pull drive, and darlington triple push-pull circuit with all stages direct
14、 coupled (OCL). The circuit diagram is shown in Fig. 2. Q1 and Q2 form the differntial amplifier. The input signal is applied to Q1 and NFB from the output stage applied to Q2 base. These two transistors are con- nected in common base circuits with Q3 and Q4, forming a cascode amplifier. Since the c
15、ommon emitter circuit (Q1 when at 4Q, RL4, RL6 and RL3). Because of RL4 off, output circuit of the power amplifier becomes open, and the stages beyond the predriver are stopped operation completely by RL5. RL2, RLg and RL6 are for changing the trans- former secondary taps when the impedance switch i
16、s selected and determining the value of the current control circuit in the power amplifier. They are thus not directly related to the protectiorr func- tion. Zener diodes D2 and DB fix the operating poten- tials of Q29 and Q30, and the difference in their starting points prevent misoperation. Power
17、Switch ON Muting This circuit also includes a delaying function when the power switch is set to ON. The delay time is determined by R8 and C1 in the Q29 and Q30 base circuits. Immediately after the power switch is turned ON, Q27 and Q28 are reverse biased by -B1 and -B2, and switched OFF. Point B po
18、tential from+B3 passes through R8 and rises as Cl charges. The rise time is determined by the time constant of C1 and R8. When the potential exceeds D3 (zener diode) zener voltage, Q30 is switched ON and current flows in the relay circuit connected to Q30. In the same manner, when the potential at p
19、oint B exceeds D2 zener voltage, Q29 is switched ON and current flows in RL5. Correct voltage is thus applied to the power amplifier. Fig. 6 Block Diagram of the Protection Circuit Power Switch OFF Muting Since +B3 normally passes from R7 to R6 and flows to -B.2, Q28 base is maintained at cut off po
20、tential. When the power switch is tumed OFF, -B2 immediately ceases, since its time constant is smaller than +83. Consequently, +83 passes through Dl and is applied to Q28 base, tuming Q28 ON. Point B potential then falls rapidly, tuming Q27 and Q30 OFF. lmpedance Selector Muting When the impedance
21、selector switch (S1) is changed from 8Sl to 4Sl, uncharged capacitor C2 is introduced into the - 82 circuit, temporarily reducing -B2 voltage. This causes Q28 to switch ON, C1 to be discharged, and Q29 RL1: PRIMARY SURGE CURRENT CONTROL RL2, RLs : SECSNDARY SURGE CURRENT CONTROL AND VOLTAGE SELECTOR
22、 RLn: P0WER SUPPLY CUT_ OFF RELAY RL5: MUTING RELAY Rh CURRENT LIMTER SENSITIVITY CONTROL PEAK LEVEL METE R L EFT 1 TPUT + RIGH 6- + I PEAK LEVEL METER t B? Schematic Diagram PO$/ER nNe Ass) AwH - 04$ 2SCt58Sxi CONTROL 0r.Qe, Qrz 2SD6l0A + c?60P C3 INPI.JT L C F I | tr/trt TI t; rt 16s n, | .1;= 2 l
23、 r0 20v , 9 tH o,Dr,Ds,os,Dr,Dro lS24?3 xs POWER N1P ASSy AWH - 045 Rr i:ri, rj:, :nji.:.iir! .:i+ e:,er,0s,0c 6 2SA?25+ i RrlK(2i) Drs 3 3l ri sPEC-e Cl58*xi LEFT PO9ER $mY ASSy AWR - 093 - A RIqHT rs: A t6T 9N 050 i$ ktos Rs. ? RELAYS RLI PRII4ARY SURGE CURRENT CONTROL RELAY RLz.3 SECONOARY SURGE
24、CURRENT CONTROL ANO VOLTAGE SELECTOR RELAYS RL+ OUTPUT CUT-OFF RELAY RLs NUTING RELAY AC r20V 50-60 Hr cURRENT LIilITOR SENSITIVITY CONTROL RELAY l-l SIGNAL v0tTAGE NECESSARY FOR OBTAINING 250fv,/6Q oUTPUT POWER (lKHz) : DC VOLTASE AT NO INPUT SIGNAL. :i;l : OC VOLTA$S AT 25OfV/EQ OUTPUT POWER DC CU
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