Pioneer-SX-450-Service-Manual电路原理图.pdf

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3、12 tO! 2 xz Qror Rlor 33 93_or FU ocor250313R n n trr.vl n UXos - UIOB U3o8 DIAL INDICATOR EV 300mA x3 3 cr O .r- U) C)o 5cr- c- !- ASsy AWK - 069 Qo,r,Qos 2SCl3tSAxz 2gltQlxz ,0.6V SW 3H a1 Rll E2K .-* t S hF c eo R.,o(-uig I to = .s a = ADJUSTilENT c?os22P + c- E. $ o o E .J : O . -+ o , d Crn 22P

4、 d- = ADilUSTtlENT L2 11H Rzco l0 (llZWl shs1i+ Sfvcn (r 9 t r C) (r 5t c- !- RF Ass/ AWE o, HA1.l37 REC- i Li I VI : SIONAL VOLTAGE AT G mA : DC CURRENT AT NO V : DC VOLTAGE AT NO 6 3 o o t, o (ji LV STEREO IND 8V 50 mA a,e HAll o E a o o s ) o 9 c- ci r H* i T= H Y c - -A ttr C3 Qns 2SCl222 xz I -

5、l-r33.511 ) = 9, 9. t f, o. o ., c:, I I tAs J 2 I E o3o,250313R : N . E flK NK I uEdh+HtE l10Nlr0R I ffi 1M(85) t-249 J.U I Rzia iOoir v) ? 5t- tr- 3- EAKER OUTPUT 10.9V /EQ (lKHr) IGNAL Dto,l ll s tdt b 3 ?scl3 8+ Qrot 2sv D 6 Drs - Dror N-l50Ax+ DIAL INDICATOR 8V 300nrA x3 RF Ass7 AWE oro2 2SC535

6、 VCrlCr C,n4 P1-Jlc-#lF ll;ia LA vc, rct la,Qnz2SA?25 xz ozo3, T .Y (v E J r02 a- lo l d 5 a, lj l= J - h ) mA : DC CURRENT AT N0 V : DC VOLTAGE AT NO ( d o S: ? 9. ADJUSTMENT 9.1 AM SECTION 1. Through a 1k ohm resistor, connect an AM signal generator to the AM antenna terminal. Set for 40OHz at 100

7、dB and 3O% modulation. 2 Connect AC voltmeter to TAPE REC iack (L or R). Set FUNCTION switch to AM position. Set AM signal generator and SX-450 dial in- dication to point A (600kHz). Adjust T6 for maximum indication on AC voltmeter. Set AM signal generator and SX-450 dial in- dication to point C (1,

8、400kH2). 4 . sx-450 7. Adjust TC4 for maximum indication on AC voltmeter. 8. Again set AM signal generator and SX-450 dial indication to point A. 9. Adjust bar antenna core for maximum in- dication on AC voltmeter. 10. Return AM signal generator and SX-450 dial indication to point C. 11. Adjust TC5

9、for maximum indication on AC voltmeter. 12. Repeat steps 4-11 to eliminate variations in AC voltmeter indications at noint A and C. F q . ) 5. c). 1 AC voltmeter AM signal generator t r q 25 9.2 FM SECTION 1. Through 300 ohm dummy antenna, connect FM signal generator to the 300 ohm FM antenna termin

10、als and set for 4OOHz at 100dB and IO0% modulation. 2. Connect AC voltmeter and distortion meter to TAPE REC jack (L or R). 3. Set FUNCTION switch to FM and MUTING switch to OFF. 4. Set FM signal generator and SX-450 dial indication to point A (90MHz). 5. Adjust T3 for maximum indication on AC voltm

11、eter. 6. Adjust T5 lower core for center of scale indication on AM/FM meter. 7. Set FM signal generator for 9dB output and adjust T1 and T2 for maximum indication on AC voltmeter. 8. Set FM signal generator and SX-450 dial indication to point C (106MHz). 9. Adjust TC3, then TC1 and TC2 for *ui*rr- A

12、 | / indication on AC voltmeter. 10. Again set FM signal generator and SX-450 dial indication to point A. 11. Adjust T3, then T1 and T2 for maximum indication on AC voltmeter. 12. Repeat steps 8-11 to eliminate variations in sensitivity at points A and C. 13. Adjust t4 for maximum sensitivity. 14. D

13、etune to noise only and adjust T5 lower core for center of scale indication on FM meter. 15. Set SX-450 dial indication to point B (98MHz) and adjust FM signal generator for center of scale indication on AM/FM meter. 16. Set FM signal generator output to 60dB and adjust T5 upper core for minimum dis

14、tortion. 17. Repeat steps 14-16 eliminate variation in mini- J a mum distortion position. tl ACvoltmeter Distortion 0*- f T2 T1 TC1 l t FI a) FM signal generator t r 9.3 MPX SECTION 1. Through 300 ohm dummy antenna, connect FM signal generator to 300 ohm FM antenna terminals. 2. Connect multiplex si

15、gnal generator to extemal modulation terminals of FM signal generator. 3. Connect oscilloscope horizontal input to MPX signal pilot output and vertical input via probe to TP (No. 13) of circuit board. sx-450 4. Set SX-450 dial indication to 98MHz and adjust FM signal generator for center of scale in

16、di- cation on AM/FM meter. 5. With FM signal generator unmodulated, adjust VR1 so that lissajous pattern on oscilloscope becomes stationary as shown in Fig. 12. 6. With MPX signal generator modulation lkHz, L + R 67.5kHz deviation and pilot 7.5kHz deviation, adjust T4 for minimum distortion. tl a t

17、I I r| l II I II I I I I i AC voltmeter Distortion meter FM signal generator Dummy load Oscilloscope MPX signal generator Fig.12 9.4 POWER AMPLIFIER SECTION (IDLE CURRENT 1. Set BASS and TREBLE controls ro center a r position. 2. Nothing should be connected to the INPUT jacks of SX-450 and an 8 ohm

18、dummy load should be connected across the SPEAKER terminal. 3. A DC voltmeter should be connect across between terminal number 19 1+;, 20 (-) for Left channel and 18 1+1, l7 (-) for Right channel. 4. Cut the jumper lead, if the voltage less than 15mV. fi j* i t a fNt # DC Voltmeter e d )10. DrAL COR

19、D STRTNGTNG Remove the Front panel (See page 14, 15). 1. Turn tuning drum fully clockwise (as viewed from X direction in Fig. 13). 2. Tie one end of cord to stud on inner section of tuning drum (more easily performed by loosen- ing setscrew and temporarily removing tuning drum from shaft). 3. Pass c

20、ord through pulley opening, make a half tum around the pulley, then route in the sequence: pulley A-Dial needle-pulley B-C. 4. Wind cord clockwise (as viewed from rear panel) 3 turns around dial shaft, then route to pulley D. 5. Wind 3 tums around dial pulley and tie to spring so that the cord is un

21、der tention. 1 6. Turn TUNING knob and confirm normal cord- motion. then trim off excess cord. I t 7. With tuning capacitorblades fully closed, move dial needle to starting point (left edge of scale). 8. Apply laquor to tied ends of cord. Spring hook Tie to spring hook sx-450 DIAL NEEDLE INSTALLATIO

22、N CAUTION Metal portion of dial pointer is plated. If this section is touched directly by hand or fingerprints and other impurities, it is difficult to remove dirt from aventurine finish. As this is not desirable in terms of both appearance and anti- corrosion, take exteme care not to touch the metal section when handling the dial needle. Dial needle . . - r l , . l I I Pulley C End: Stud Start: Fasten on end of the cord to startFis.13 Pulley D Tuning drum Dial shaft 29