Philco-Radio-and-Television-Corp-TC-47 电路原理图.pdf

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1、VOLUME R-20, MOST-OFTEN-NEEDED 1960 RADIO SERVICING INFORMATION SCHEMATIC NOTES PHILCO TRANSISTOR - CLOCK RADIO MODEL TC-47 PANEL (CHASSIS) REMOVAL 1. Remove the followingTuning and volume control knot* batteries, two tri-mount fasteners at speaker end of panel, battery contact and retaining board.

2、2. Open the positive battery terminal lead from LI tie lug on panel. Open the speaker connections. 3. Remove the pane from the cabinet by first lifting up on the speaker end of the panel. SERVICE NOTES When signal tracing, inject signal at transistor col lector and limit input to keep signal across

3、speaker below 0.275 volts. T-I542 T-1504 2NDI.F CAUTIONDue to 2nd I-F transistor variations, the value of resistor R8 must be selected, within limits for optimum performance. When transi tor T-1504 (or T-1542) is defective and must be replaced, resistor R8 must also be changed unless the original pr

4、ovides the proper resistor operating characteristics. The value of R8 is selected to allow the 2nd I-F transistor collector to draw 2 milliamps and will be between 18,000 to 33,000 ohms. This is checked by measuring the voltage across R10, the 560-ohm collector return resistor. This voltage should b

5、e 1.12 volts, with a 10% tolerance ( .12 volt). All resistors are % watt, 10%, carbon, except R8 which is 5%. Coil resistances read with coil in circuit. Voice coil impedance 14 ohms. Voltages measured to ground with a 20,000 ohms/volt meter under no signal conditions. T-I503 1ST IF T-I502 CONV *R10 -j U H ROVfnS T-1505 AUD. OUTPUT Composite Bottom View 2ND IF SEE NOTES T-1504 r- T-1542 1ST IF T-1503 CONV T 1502 9ft W T-1505 AUD OUT lOOOJ 80R 4 CLOCK tiOuSiNC CLOCK MOTOR Schematic Diagram of Model TC-47 106 收音机爱 好者资料库 RadioFans.CN