Noblitt-Sparks-Industries-Inc-148101 电路原理图.pdf

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1、VOLUME R-21, MOST-OFTEN-NEEDED 1961 RADIO SERVICING INFORMATION ARVIN MODELS 30R12 30R18 CODE 1* 48102 FM TUNER J l.J. -L I20T8 (M 5&I MODELS 30R12 30R18 V2 .-. 1*5 0 TI y3 - TJrogvl “asfel w (M| 0 TI V3 i 18 . 1)005 .009 m i4tr *= 5 7 PC-2_|4 I 5 5 V j JOK Ja. 66V 820 v-VA _|0 17 e lie z paxtoh can

2、at rbquskt Tczi-i-T-r5TWr _4JlElW -0 * EXTERNAL CONNECTION TO PRINTED BOARD. | L VOLTAGES MEASURED TO 8- WITH A VTVM - 20%, NO SIGNAL TO. 1 | RESISTANCE VALUES ARE IN OHMS. K* 1,000 MEG 1,000,000 / Till SMALL X P. CAPACITANCE VALUES LESS THAN 0) ARE IN MICROFARADS (*), = Jlj ABOVE AND 1 AND VALUES O

3、F (i) OR GREATER ARE IN MICROMICROFARAOS (*.#, “T T7 CRITBB W UNLESS OTHERWISE INDICATED. . no. 2 ALIGNMENT PROCEDURE Detector and I. F. alignment ueing signal Generator and Oscilloscope. 1. Connect FM Generator, High Side, to grid (pin l) of 12BA6 2nd 1, F, tube through .01 mfd. dummy. 2. Set gener

4、ator frequency to 10.7 Me. modulated either 60 cycles or 400 cycles, 460 Kc sweep (240 Ke deviation) 3. Connect vertical input of scope across volume control of receiver (grounded terminal to B-, ungrounded terminal to high side of control). 4. Set scope switch for internal synchronisation and set h

5、orisontal oscillator to 2X fre quency of modulating voltage of generator. ()20 or 600 cycles) 5. Tune FM to high end of band. 6. Adjust frequency vernier of horizontal oscillator on scope until the pattern becomes stationary. 7. Adjust ratio detector primary slug No. A2 (outer peak) for maximum vert

6、ical sweep of the scope pattern. 6. Adjust ratio detector secondary slug No. A1 (outer peak) to center the cross-over point of the pattern. Pattern should look like Figure l, with the same amount of curve on both ends, and the cross-over point in the center. 9. Adjust 1, F. slugs A3.A4 (outer peak)

7、for greatest vertical sweep of the pattern, consistent with linearity. If the 1. F, slugs are adjusted for maximum sweep of the pattern, the pattern may become non-linear. Therefore, adjustment should bs made for the greatest sweep which can be obtained and still have all four ends of the X pattern

8、similar in sise and shape. 10. Connect generator to antenna screws on the back of the chassis. 11. Adjust tuner slugs AS, A6 for greatest vertical sweep consistent with linearity. 12. Check the alignment of the 1. F. and detector circuits by varying the signal genera tor frequency above and below th

9、e center frequency of 10.7 Me. If the receiver is perfectly aligned, two small x patterns of similar sise and shape will result, one on either side of the center frequency. See Figure 2. V6 V5 V2 V3 V4 -4700 *4700 Tz 01 1 HTCIO “X C7 _l.C8 gmu- X PAXTKW ABOVE AND B1&0V CENTER PREQUzNCT fA6l 7m o o 81 TOP A4 BOTTOM I1eAD R -snzn- W -ESEH- Qm BOTTOM VIEW OF FM TUNER TOP VIEW OF FM TUNER AI TOP A2 BOTTOM O -VI I a s 4 - / TlVls M lfC 4 yuoucr 21 TUNER SCHEMATIC 收音机爱 好者资料库 RadioFans.CN