Sony-TA-F3A-Service-Manual电路原理图.pdf

RadioFans.CN 收音机爱 好者资料库 GENERAL Weight: Power Requirements: 120V ac, 60 Hz (US, Canadian Model) 220 V ac, 50160 Hz (AEP Model) 240 V ac, 50/60 Hz (UK Model) 120 or 220V ac adjustable. 50/60 Hz (E Model) Power Consumption: Dimensions: SPECIFICATIONS 85 W (US Model) 140W Canadian Model) AMPLIFIER SECTION 210W (AEP, E Model) 240W (UK Model) Continuous RMS Approx. 435 (w) x 145 (h) x 370 (d) mm Power output: 17 1/8(w) x x inches (Less than 0.5% THD) (US, Canadian Model) Approx. 410 (w) x 145 (h) x 370 (d) mm x x (AEP, UK, E Model) inches Including projecting parts and controls Power Bandwidth (IHF): SAFETY-RELATED COMPONENT WARNING! Damping Factor: COMPONENTS IDENTIFIED BY SHADING AND MARK ON THE SCHEMATIC DIAGRAMS, EXPLODED VIEWS AND IN THE PARTS LIST ARE CRITICAL TO SAFE OPERATION. REPLACE THESE COMPONENTS WITH SONY PARTS WHOSE PART NUMBERS APPEAR A8 SHOWN IN THIS MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY. Harmonic Distortion: IM Distortion: (60 Hz: 7 kHz = 4:1) ATTENTION AU COMPOSANT AVANT RAPPORT Approx. Approx. Approx. 10.5 kg (23 lb 2oz). net 12.5 kg (27 lb 9 oz), in shipping carton (US, Canadian Model) 9.5 kg (21 lb), net 11.5 kg (25Ib 6oz), in shipping carton (AEP, UK, E Model) Both channels driven simultaneously At 1 kHz 5OW+5OW At 20 Hz-20 kHz According to DIN 45500 (AEP, UK, E Model) 52W+52W 10 Hz-25 kHz 30 Less than 0.5% at rated output Less than 0.1 % at 1 W output Less than 0.5 % at rated output Less than 0.1% at 1W output RadioFans.CN 收音机爱 好者资料库 1-2. CIRCUIT DESCRIPTION PROTECTION CIRCUIT Two kinds of protection circuit are employed in this power amplifier. One is a power-transistor protection circuit and the other is a speaker pro- tection circuit. 1. Power-transistor Protection Circuit To protect overloaded power transistors from destruction, a protection circuit is employed. The fusible resistors are inserted in each of Q704, 4705 (L-CH) and 4754, 4755 (R-CH) collector and emitter circuits. When the excessive current flows into the power transistors, these fusible resistors break faster than the transistors and thus protects the transistors from destruction. Speaker Protection Circuit (See Fig. l-l and Fig. 1-2) When the excessive current flows into the power transistors, B+ voltage decreases. Therefore, 4301 turns on, biasing the base of Q302, and Q302 conducts. This removes the bias voltage at the base of Q306 and Q306 turns off. The relay is not activated by off state of Q306. According- ly, the speaker is cut off from the amplifier circuit. When the positive dc component presents at the speaker output terminal, C310 is charged up as shown in Fig. l-2. Q303 turns on, Q306 turns off and the relay RY301 is not activated (4304 re- mains in off condition). Also, when the negative dc component presents, C3 11 is charged up. This turns 9304 on, Q306 off and RY301 is not activated (9303 remains in off condition). 3. . Muting Circuit (See Fig. 1-3 and Fig. 1-4) This muting circuit prevents the loud “pop” (due to initial current flow) or click noises produced just after turning the POWER switch to on or off. These transients might damage a delicate high- fidelity speaker system. When POWER Switch turned on: C308 commerces to charge through R309. At the same time, the base voltage of Q306 gradually rises in accordance with charging voltage of C308. It takes about 3 seconds until Q306 is turned on. Accordingly, the speaker output terminal is cut off by the relay RY301 for about 3 seconds after the POWER switch is turned on. This protects the speaker from the destruction caused by the “pop” noises. . When POWER Switch turned off: Fig. 1-2. The reverse voltage (about - 1.7 V) that turns off Q306 immediately reduces, and the positive poten- tial is applied to the base of Q305. Q305 turns on and Q306 turns off, cutting off the operation of RY301. Therefore, no pop noise presents on the speaker output. POWER Switch :ON Fig. l-1. -4- Fig. 1-3.