Westinghouse-Electric-Corp-H-716T5 电路原理图.pdf

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1、收音机爱 好者资料库 RadioFans.CN VOLUME R-20, MOST-OFTEN-NEEDED 1960 RADIO SERVICING INFORMATION WESTINGHOUSE Chassis V-2400-1, Continued Figure 4 Bottom view of printed circuit chassis with components shown symbolically 11 Bottom view of tuner printed circuit with components shown symbolically 154 收音机爱 好者资料

2、库 RadioFans.CN VOLUME R-20, MOST-OFTEN-NEEDED 1960 RADIO SERVICING INFORMATION WESTINGHOUSE Chassis V-2400-1 (Continued) ALIGNMENT 1. Connect two 100K ohm resistors from test point MCM to ground as shown in schematic. 2. Use VTVM connected as indicated in the FM alignment chart. 3. Use a signal gene

3、rator with output frequencies of 10.7mc and 80 to llOmc. Generator should have an adjustable output attenuator. 4. Set the volume control at maximum. 5. Keep the signal generator output voltage level low to avoid overload. 6. Sweep generator providing 10.7mc signal, 500KC sweep width for discriminat

4、or alignment. ANTENNA INFORMATION When the metal link, on rear of the receiver, connects the center and right hand antenna terminals, the receiver is using the built-in antenna. For best results the AC line cord should be stretched out rather than coiled. In weak signal areas or under adverse condit

5、ions, it may be necessary to use an outside FM antenna. In this case, the metal link should be removed from the center antenna terminal and the 2-wire lead-in (300 ohm), from the external antenna should be connected to the center and left hand terminals. CHASSIS REMOVAL 1. Remove screw from cabinet

6、bottom and two screws from , cabinet rear. 2. Remove control knob from left side of cabinet. 3. Separate cabinet front from cabinet back. The chassis is now exposed and ready forservicing. To replace chassis follow reverse of above procedure, being careful to cor rectly slide chassis into side groov

7、es on inside of cabinet rear cover. Connect Signal Generator to: High side of generator to pin #1 of 2nd IF Amp. Signal Generator Frequency LI Setting 10.7mc unmodulated Antenna terminals using network shown in figure 5. Antenna terminals with proper term ination see fig. 5 REMOVE THE TWO 100K OHM R

8、ESISTORS Min. 108.5mc unmodulated 106mc unmodulated VTVM Connection Adjustment Between points A” and *B” Secondary of T4 (top adj.) for zero voltage. Between point C” and ground Primary of T4 (bottom adj.) for max. Adjust generator output for VTVM meter reading of 5 to 6 volts. Between points A” and

9、 B Recheck T4 secondary and adjust for zero voltage if necessary. Between point C” and ground Primary and secondary of T3 and T2 for maximum. Reduce generator ourput to maintain 5 to *6 volt reading. Between point C” and ground C7 for maximum negative voltage. Tune for signal C4 for max. negative vo

10、ltage (rock in). REPEAT STEPS 6 AND 7 UNTIL NO FURTHER CHANGE IS NOTED, ALTERNATE DISCRIMINATOR ALIGNMENT PROCEDURE (OSCILLOSCOPE METHOD) Step Connect Marker and Marker Connect Adjustment Sweep Generators to: Frequency Scope to: 1 i Pin #1 of 2nd IF Amp. 10.7mc Between point C” and ground T4 primary

11、 (bottom) for symetrical response (see figure 6). Set generator output for 4-6 volt reading. Between point T4 secondary (top) for 10.7mc marker at center of B” and ground curve (see figure 6). 10.7 MC yMARKER 20 IMM0ANGC OP SWCCP CA0LC 10 Ml At 52 -A. 56 -A- 120 72 JV 85 JV 110 -A. Figure 5 Impedonce (notching network Figure 6 Discriminotor response curve 155 收音机爱 好者资料库 RadioFans.CN