User manual PIONEER SX-450

[. . . ] For servicingof the other types, please refer to the additional servicemanual. CONTENTS 1 . F R O N TP A N E L F A C I L I T I E S , . B L O C KD I A G R A M C I R C U I TD E S C RP T I O N S I 4. 1 4. 2 4. 3 4. 4 4. 5 4. 7 4. 8 6. P o w e rI n d i c a t o C i r c u i t . [. . . ] The output power indicator segments of the FL tube are driven by the HA12010 ICs (one for each channel) equipped with 12 pairs of differential amplifiers. These amplifiers are biased at increasing levels, so each amplifier will commence to operate separately as the input level increases. And since these amplifiers apply the voltage to the out" put power indicator segments, each successive segment will light up in tum as the input level rises. 8 P R O T E C T I O NC I R C U I T In order to protect both the amplifier and the speakers, the SX-450 has been equipped with a protection circuit which is opened and closed automatically by a relay in the output circuit. 4-11, this circuit consists of 3 main component parts. F )c (fafatSP) O ET E C I O R t/2 fD I FLUORESCEN ] N D I C A I O R T Ug E a c 7. 4-9 Powerindicatorcirclrit The relay drive circuit controls relay operation, delaying relay closure when the power is switched on, opening the relay quickly when the power is tumed off, and a. lsoopening the relay in response to instructions from each detector circuit. When the power is first switched on, C4 is charged up via R8, thereby increasing the potential difference across the capacitor terminals. Once this potential difference exceeds the zener diode, Q6 is turned on due to the forward biasing, thereby closing the relay contacts. When the power is switched off, C4 is discharged rapidly via Db and R7, resulting in Q6 being tumed off and the relay contacts being opened. The overload detector circuit outlined in Fig. 410 below consists of a Wheatstone bridge with the load RL forming one of the arms. Passthe cord out through the small opening in the circumference of the tuning drum (see diagram), and then take it over pulleys A, B, and C in that seouence. Wind the cord around the dial shaft 3 times. Pass it over pulley D, wind it around the tuning drum 2 times, and finally tie it to the spring hook O so that it is tensioned. T\rm the dial shaft, and check that the cord moves smoothly. Tum the dial shaft counter-clockwise as far as it will go. Align the dial pointer with the starting point of the dial scale, and then passthe cord over it. Check that the dial pointer is in line with the starting point of the dial scale. Finally apply the locking paint to the cord securing positions (stud O and spring hook O ) and the dial pointer connection. T u n i n gd r u m D ial shaft Startingpoint \ Dial pointer D i a lp o i n t e r F i g . 7 - 1 D j a lc o r ds t r i n g i n g Y 8 . Connect the FM SG (FM signal generator) to the FM antenna 300O terminal. o The tuning coils in the FM front end does not have an adjusting core. Consequently, tracking adjustments at 90MHz are performed by regulating the gap between rotor and stator of the tuning capacitors (VC-1, VC-2, and VC-3). [. . . ] , , R 2 0 1 R 2 2 8 R 2 3 1 -R 2 3 4 R 3 0 r R 3 0 6 . , F 3 1 1 R 3 ' f , R 3 2 7 , U 3 2 A R 3 4 1 . R 3 4 2 . 6 , R345, R346 R 3 r9 , R 3 2 0 R r 0 2 , R 1 0 3 , R 2 2 9 , R 2 3 0 R 3 0 7 R 3 '0 , R 3 1 7 - R 3 2 4 t R 3 2 5 , R 3 2 6 R ' t2 4 , B l 2 5 R121, R122 R329 R330, R337 R340 R 3 3 1 , R 3 3 2 R333 R336 0 . 22lzw Svmbol & Dscription ACH-215 ACG, 004 C E A R 4 7 M5 O L c E A 0 1 0 t \5 0 L 4 C E A4 7 O Mi O L cEA 470t\4 25L C E A4 7 O M 0 L 5 C E A1 0 1 M 0 L 5 cEA 221lvt35L C E A2 2 1 M5 O L cEA 331tV1 L 10 CEAN lOOM 0 L 5 C E A N 2 R 2 M5 0 L C E A N 4 R7 M 5 0 L C E A4 R 7 M 5 0 L C E Al O O M 0 L 5 C E A2 2 O M 5 L 2 3 C E A1 0 1 M 5 L c c D S L 1 5 0 J5 0 ccDs L 050D 500 c c D s L 1 0 0 D5 0 ccDsl 470J 50 ccDSL 560J50 c c o s L 1 0 1 J5 0 c c o s L 1 8 1 K5 0 0 682J 50 cot\, , 1A C101C102 E ectrolytic , C 1 1 7C 1 1 8 C e r a m i c , cl11, Cl12 cl15, C221. C224 c 11 0 c108 c 1 0 5 , c 1 0 6 , 1 1 6 c c 1 0 3 , c 1 0 4 , 1 1 4 c c119 c107 c113 c231 , C232 c201 . c202 c 2 1 7 , C 2 1 8 c229, C230 c211, C212 c203. [. . . ]