General-Electric-Co-LF-116 电路原理图.pdf

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1、收音机爱 好者资料库 RadioFans.CN MANUAL OF 1942 MOST POPULAR SERVICE DIAGRAMS IF ALIGNMENT WITH OSCILLOSCOPE“FM” CHANNEL Step Input Signal Connected to Input Frequency Band and Pointer Setting Trimmer Adjustment Comments 1 6SG7 converter grid in series with 22 mmf. 4.3 MC & 200 KC Sweep “FM Band 42 MC C52 C5

2、3 Connect high side of oscilloscope in series with 470,000 ohm resistor to R19 at point “B.” Connect low side to chassis ground. Peak trimmers for resultant curve shown _. 2 6SG7 converter grid in series with 22 mmf. 4.3 KC & 200 KC Sweep FM” Band 42 MC C35 C36 3 Repeat Step 1 4 Repeat Step 2 5 6SG7

3、 converter grid in series with 22 mmf. 4.3 MC & 200 KC Sweep “FM” Band 42 MC C60 C58 Connect high side of oscilloscope in series with 470,000 ohm resistor to R36, point “A.” Connect low side to chassis ground. Peak trimmers for resultant curve shown in Fig. 4. COO is aligned when curve crosses midwa

4、y in vertical plane. Proper alignment of C58 gives straightest sides to curve near crossover point. Table II IF ALIGNMENT WITH METER“FM” CHANNEL Step Input Signal Connected to Input Frequency Band and Pointer Setting Trimmer Adjustment Comments 1 6SG7 converter grid in series with 22 mmf. Unmodu lat

5、ed 4.3 MC signal “FM” Band 42 MC C52 C53 C35 C36 Connect the 10-volt scale of a 20,000 ohm per volt voltmeter in series with a 470,000 ohm resistor between point “B” and ground. Peak all trimmers for maximum output using just enough input signal to give a satisfac- 2 Repeat Step 1 tory- output readi

6、ng. 3 6SG7 converter grid in series with 22 mmf. Unmodu lated 4.3 MC signal “FM” Band 42 MC C60 C58 Connect the 10-volt scale of a 20,000 ohm per volt voltmeter in series with a 470,000-ohm resistor between points “A and ground. With C60 purposely detuned, peak C58 for maximum meter reading. Align C

7、60 for the 0 voltage point where the meter reading changes from a positive to negative value. Use as low a signal input as necessary to give a satisfactory meter reading. Table III RF ALIGNMENT“FM1 CHANNEL Step Input Frequency Band and Pointer Setting Trimmer Adjustment Comments Direct to “FM” Anten

8、na Post Unmodu lated 49 MC signal “FM Band 49 MC C4 (Osc.) Connect the 10-volt range of a 20,000 ohm per volt voltmeter in series with a 470,000-ohm resistor to point 2 Direct to “FM Antenna Post Unmodu lated 49 MC Signal “FM” Band 49 MC C2 C30 “B.” The other side of the voltmeter lead connects to c

9、hassis ground. Peak trimmers for maximum meter reading using just enough signal input to give satis factory meter reading. X S 3 Direct to “FM Antenna Post Unmodu lated 43 MC Signal “FM” Band 43 MC C76 (Osc.) Direct to “FM” Antenna Post Unmodu- ulated 43 MC Signal “FM” Band 43 MC C75 C77 / Fig. 4 Di

10、rect to “FM” Antenna Post Unmodu- ulated 46 MC Signal FM” Band 46 MC Cl A 6 / 7 Repeat Step 2 v/ x- 1 Table IV IF, “BC,” and “SW” ALIGNMENT“AM” CHANNEL Step Input Frequency Bend and Pointer Setting Trimmer Adjuetment Comments i 6SG7 converter grid in series with .05 mfd. 455 KC Modulated “BC” Band 5

11、50 KC C50 C39 C34 C33 Connect 5.0-volt AC voltmeter across the voice coil of the speaker. Peak all trimmers for maximum out put. All RF alignments must be made with the chassis 2 Capacity Coupled 17.8 MC Modulated “SW” Band 17.8 MC C23* in the cabinet. When aligning the SW oscillator trimmer, use ma

12、ximum capcit peak. The image frequency should appear at “Rock gang condenser when making alignment. 3 Capacity Coupled 17.8 MC Modulated “SW” Band 17.8 MC 09* CU 4 Capacity Coupled 1500 KC Modulated “BC” Band 1500 KC C24 5 Capacity Coupled 1500 KC Modulated “BC” Band 1500 KC 07 C8 6 Capacity Coupled 580 KC Modulated “BC” Band 580 KC C25* A-FM COMBINATION RECEIVERS 7 Repeat Steps 4 and 5 Models LF-115 & LF-116 A-FM PHONOGRAPH COMBINATION RECEIVERS Models LFC-1118, LFC-1128 &. LFC-1228 COMPILED BY M. N. BEITMAN, SUPREME PUBLICATIONS 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN