Emerson-Radio-and-Phonograph-Corp-844 电路原理图.pdf

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1、VOLUME R-17, MOST-OFTEN-NEEDED 1957 RADIO SERVICING INFORMATION Emerson Ttadio MODEL 844 CHASSIS 120309 MODEL 847 CHASSIS 120328 JS. BATTERY JS. 9 VOLTS RESHTOR* * NOTE; IF OME OF THESE TRANSISTORS Q-5 OR Q-6 BECOMES OEFECTIVE REPLACE BOTH OF THEM WITH A NEW MATCHED PAIR (PT. NO. 8lSOI4) RESISTANCE

2、READINGS FOR CHASSIS 20323 0-3 END I.F AMP. r / X RCStSTORS IN OHMS (R*lOOOI, ? CAMCITORS IN MFOS UNLESS OTHERWISE NOTED. 0-4 * 0-5 AND 0-6 DRIVER PUSH PULL / AUDIO OUTPUT / (MATCHED PAIR) SYMBOL TERMINAL B TERMINAL C TERMINAL E Q1 165KO 3.3K*fl 15000 Q2 4KQ 3800*Q 3300 Q3 3.3K*a 10000 Q4 4.2KO soon

3、 3.4KO Q5 3K*Q 220 2.9K*0 06 3K*Q 18 2.9*KO CONDITIONS FOR VOLTAGE AND RESJSTANCE READINGS * NOTE: IF ONE OF THESE TRANSISTORS 0*8 OR 0-6 BECOMES DEFECTIVE REPLACE BOTH OF THEM WITH A NEW MATCHED PAIR. (PT, NO. 015014) Figure 1 - TRANSISTOR AND BATTERY LOCATION DIAGRAM 1. Voltages indicated we posit

4、ive d.c., resistance is ohms. Figure 1 TRANSISTOR AND BATTERY 2. Measurements made with voltohmyst or equivalent. 3. All measurements taken between points and chassis, unless otherwise indicated. 4. Before toking resistance measurements, turn on-off switch to the off” position (or disconnect botteri

5、es). Then remove transistors. 5. Volume control ot moximum, no signal applied for voltage measurements. 6. Nominal tolerance in component values makes possible a voriation of t. S% in readings. 7. K is Kilohms, MEG is megohms. ALIGNMENT INSTRUCTIONS 9 CO Volume control should b# ot moximum; output o

6、f signal generator should b# no highor than necessary to obtoin on out- j put roading with e 30% audio modulatod R.F. Uso an insulatod alignment scrowdrivor for adjusting. lU Adjust for maximum output starting with T3. K. DUMMY ANTENNA SIGNAL GENERATOR COUPLING SIGNAL 1 GENERATOR ; FREQUENCY RADIO D

7、IAL SETTING OUTPUT METER .1 mfd. High side to junc tion of L-l & C-2. Low side to chassis. 455 KC. Tuning con denser fully open. Across voice coil. Use a loop set per pendicular and about 20 from center of bar loop ant. in set. 1650 KC. Tuning con denser fully open. Across voice coil 1400 KC. Tune f

8、or maximum output. Across voice coil. 600 KC. Tuning con denser set for 600 KC. Across voice coil. C-3A (osc. trimmer) See note below C-2A (Ant. trimmer) Tuning con denser fully open. Fashion loop of several turns of wire snd radiate signal into bar loop of re ceiver. Adjuat for maxi mum output. Adj

9、ust for maximum output. Rock the variable cond. each side of 600 KC while adj. osc. slug for maximum re sponse. If readjustment is neces sary repeat steps 2 to 4 until no further improve ment is noted. NOTE: C-3A is the oscillator trimmor capacitor, physically located on tho bottom side of tho tuning capacitor when the chassis is mounted in its case. Both C-3A and C-2A can bo reached (see Fig. 1.) C-3B is tho alter nate oscillator trimmer capacitor and is factory adjusted for minimum trimmor capacity requirements. 27 收音机爱 好者资料库 RadioFans.CN