Philco-Radio-and-Television-Corp-E-976 电路原理图.pdf

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1、100 收音机爱 好者资料库 RadioFans.CN VOLUME R-17, MOST-OFTEN-NEEDED 1957 RADIO SERVICING INFORMATION PHILCO Model E-976 (Continued from the preceding page at left) signal AM ALIGNMENT PROCEDURE OUTPUT INDICATOR Connect either an a-c volt meter or an oscilloscope across the voice coil terminals. SIGNAL GENERA

2、TOR Use an AM r-f generator with modulated output 1. Connect generator, through a .05 mfd condenser, to grid, pin 7, of the AM converter, S-3. Connect ground lead to chassis. 2. Set generator to 455 kc, tuning gang fully closed and adjust, in order given, TC14, TC13, TC12 and TCll for maximum output

3、. Repeat until no further gain is indicated Connect generator to radiating loop. Set generator to 1600 kc Set receiver to 1600 kc as indicated by pointer Adjust VC-2B for maximum. Set generator to 1400 kc. Tune receiver to signal and adjust VC*2A for maximum. FM ALIGNMENT PROCEDURE 1. Calibrate the

4、scope for 2 volts P/P. 2. Connect the scope, through a 100,000 ohm isolating resistor, to junction of Rl2 and C26. Scope ground lead to chassis. 3. Connect the signal generator to bottom of Tl second ary (junction of Tl with Rl and C5). Generator ground lead to chassis. 4. Inject marker signal, 10.7

5、 me (unmodulated). 5. Inject sweep signal, 10.7 me, approximately 150 kc total deviation (do not over sweep) 6. Adjust cores TC8, TC7, TC6, TC5, TC4 and TC3 S3 I2BE6 AM-CONV 3. 4. for maximum amplitude, symmetrical curve with the 10.7 me marker at top of curve. Adjust input signal to maintain output

6、, as shown on scope, below 2 volts peak during alignment Repeat step 6 until no further gam is obtained. 7. Calibrate the scope for 5 volts P/P. 8. Change the scope connections to LlO (FM audio output to function switch). 9. Remove sweep signal Inject 10.7 me, 30% AM modulated signal. Adjust TC10 fo

7、r minimum indi cation between peaks. See note below 10. Inject 10.7 me sweep signal and adjust TC9 for maximum symmetrical output 11 Touch up cores as in Step 6 plus TC9 for a sm- metncal, maximum amplitude, discriminator curve. To check alignment, discriminator curve should not shift in frequency w

8、ith an increase in signal input (below overload). If a shift does occur, the I F is not properly aligned, particularly the first stage, TC3 and TC4. 12. Inject 108 5 me 30% AM modulated signal, through an antenna matching network to the receiver antenna terminals 13. Open tuning condenser Insert a 6

9、 mil, non-metallic, shim between stator and rotor of the FM gang and close gang against shim Adjust VC3 for minimum indication between peaks 14. With tuning condenser fully closed, inject 87.75 me, 30% AM modulated, signal and adjust TC2 for minimum indication between peaks See note below. 15. Injec

10、t 91 me, sweep signal and with tuning gang tuned to 91 me, adjust TC 1 for maximum output. VC2B VC2A L4 y L3 I L6 L,5 35C 5 AUD OUT Top Hw Showing Alignment Points, Tube Locations and Tie Lugs ,op TC14top T C 7 bo t A M y. 7 . IDENTIFICATION OF PRINTED PANEL TIE LUOS LI Filament lead from pin 4 of S

11、-7 (35C5) to pin 5 of S-l (12AT7) L2 Filament lead from pin 3 of S-2 (12BA6) to pin 3 of S-3 (12BE6) L3 Green lead to junction of R19, C40, bottom of VR1 and arm of VR2 from C41 L4 Yellow lead from high Bide of VR2 to C32 L5 Red lead (B -f-) from lug 5 of S-2 to screen of S-7 and terminal 6 of N1 L6

12、 Yellow lead from arm of VR1 to terminal 2 of N1 L7 Blue lead from audio output, T-5, to plate, pin 7 of S-7 L8 Bare wire from panel ground to chassis ground L9 Yellow lead. AM audio to lug 1 of S2 from junction of Rll, C28 RIO and R18 LlO Orange lead. FM audio to lug 3 of S2 Lll Brown lead to AC in

13、terlock and two white leads to pilot lamps L12 Red lead (B -f-) from lug 4 of S2 to AM con verter screen, pin E, and Z3. TCl3bo. LI3 Loop antenna return to A.V.C. L14 Blue lead from plate, pin 5 of S2. to 2nd FM I-F transformer, Z2 L15 Red lead (B + ) from lug 5 of S2 to R7 LI6 Red lead from junction of R24 and C37A to audio output. T5 L17 Brown lead from audio output, T5, to R23 L18 Orange lead (B + ) to Cl8 feed through 101 收音机爱 好者资料库 RadioFans.CN