Zenith-19M20-Sams-259-16电路原理图.pdf
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1、PHOTO PACT* Folder ZENITH CHASSIS 19M20, U, Z, 19M21, U, UZ, Z VOLUME CONTROL ON-OFF SWITCH ZENITH MODEL CHANNEL SELECTOR SWITCH M1800R TRADE NAME Zenith i MODELS M1800E, M1800R, R1800EZ, R1800RZ, R1812EZ, R1812RZ M1800EU, M1800RU, R1800EUZ, R1800RUZ, R1812EUZ, R1812RUZ. M1800EZ, M1800RZ M2228R, M22
2、29E, M2229R, M2230E, M2230R, M2230RZ2, Ma249E, M2249R, M2250E, M2250R, M2252E, M2252R, R2229EZ, R2229RZ, R2230EZ, R2230RZ, R2249EZ, R2249RZ, R2250EZ, R2250RZ, R2257EZ, R2257RZ, R2258EZ, R2258RZ . M2228RU, M2229EU, M2229RU, M2230EU, M2230RU, M2249EU, M2249RU, M2250EU, M2250RU, M2252EU, M2252RU, R2229
3、EUZ, R2229RUZ, R2230EUZ, R2230RUZ, R2249EUZ, R2249RUZ, R2250EUZ, R2250RUZ, R2257EUZ, R2257RUZ, R2258EUZ, R2258RUZ M228RZ, M2229EZ, M2229RZV M2230EZ, M2230RZ, M2249EZ, M2249RZ, M2250EZ, M2250RZ, M2252EZ, M2252RZ , M2250RUZ CHASSIS 19M20 19M2OU 19M20Z 19M21 19M21U 19M21Z 19M21UZ MANUFACTURER Zenith Ra
4、dio Corp. , 6001 Dickens Ave. , Chicago 39, Illinois TYPE SET Television TUBES Nineteen Receiver POWER SUPPLY 110-120 Volts AC-60 Cycle RATING 1. 6 Amp. (a 117 Volts AC TUNING RANGE Channels 2 Drive Cord Stringing thru 13 VHP, 14 thru 83 UHF, Video IF 45. 75 MC, Sound IF 41. 25 MC INDEX 6, 7 Photogr
5、aphs (Cont) (Intercarrier) , . . , 23 Trans. , Inductor Si Alignment Identification Horizontal Sweep Circuit Adjustments 11 Servicing in the Field Parts List and Descriptions . Photographs Cabinet-Rear View Chassis-Top View RF Tuner Resistor Identification 15 thru 18 Schematic (Alternate Tuner) Sche
6、matic (TV) 11 Trouble Shooting Aids 4 , 9 Tube Failure Check Chart . 3 Tube Placement Chart (Bottom View) 10, 21 Tube Placement Chart (Top View) . 14, 19 12, 20 8 22 13 2 21 5 R 5 -o to N N -i I is c- w c N N N HOWARD W. SAMS chart lists tubes whose failures are most likely to produce the indicated
7、symptoms. Refer to tube placement chart for location and type of tube. POWER SUPPLY FAILURE No raster, no sound - V18 LOSS OF PICTURE OR SOUND No pic, no sound, has raster - V2, V3, V4, V5, V6 No pic, no sound, has snow - VI, V2, V3 No pic, has sound, has raster - V6, V7, V19 Has pic, no sound - V8,
8、 V9, V10 Overloaded picture -V7 SYNC FAILURE No vert, sync - VJ, Vll Nohoriz. sync -Vll, V13, V14 No vert, or horiz. sync - Vll SWEEP FAILURE No raster, has sound - V14, V15, V16, VI7, V19, Fuse (Ml) No vertical deflection - V7, V12 Poor vert, linearity or foldover - V7, VT2 Poor horiz. linearity or
9、 foldover - V14, V15, VI6 Narrow picture - V14, V16, V17, V18 Vert, off freq. - V7, Vll Horiz. off freq. -Vll, V13, VM i 10 N H - I K) c - NC V* N N SET 259 FOLDER 16 PAGE 5 RadioFans.CN ALIGNMENT INSTRUCTIONS 1. 2. 3. 4. The high voltage lead should be securely taped and kept away from the chassis.
10、 Do not remove the horizontal oscillator tube (V14) to disable the high voltage . VIDEO IF ALIGNMENT Connect the negative lead of a 2 volt bias supply to the ungrounded side of C31. Connect the positive side to chassis. Connect the synchronized sweep voltage from the sweep generator to the horizonta
11、l input of the oscilloscope for horizontal deflection. DUMMY ANTENNA 470MMF SWEEP GENERATOR COUPLING High side to pin 1 (grid) of 6CB6 (V5). Low side to chassis. High side to point . Low side to chassis . SWEEP GENERATOR FREQUENCY 43MC (10MC Swp) MARKER GENERATOR FREQUENCY 39.75MC 45.75MC 39.75MC 41
12、.25MC 47.25MC 42.75MC .OMC 45.75MC CHANNEL Any non interfer- ing channel CONNECT SCOPE Vert. Amp. thru 10KSJ to point . Low side to chassis ADJUST A1.A2 A3.A4, A5 A6, A7, A8,A9 REMARKS Attenuate generator output for 3 volts peak to peak on scope. Adjust for response curve of maximum amplitude and sy
13、m- metry similar to Fig. 1. Remove bias battery. Use maximum scope gain to amplify trap region of response curve as in Fig. 2. Adjust for MINIMUM marker amplitude. Reconnect bias supply. Attenuate sweep generator output to maintain not more than 3 volts peak to peak on scope. Alternately adjust A6 t
14、hru A9 to obtain response similar to Fig. 3. A6 affects the high side and A7 affects the low side of the response curve. OSCILLATOR ALIGNMENT The master oscillator adjustment, A10, is to be made only if the individual channel oscillator adjustment fails to bring the channel within the range of the f
15、ine tuning control. If channels 2 thru 6 fall within the range of the fine tuning control but the higher channels do not , slight adjustment of A10 may be necessary to bring in the higher channels , Connect the negative lead of the bias supply to the ungrounded side of C31. Connect the positive lead
16、 to chassis. Adjust for -1 volt at C31. Turn up the scope gain so that the sound trap notch in the response curve becomes visible,. Connect the synchronized sweep voltage from the sweep generator to the horizontal input of the oscilloscope for horizontal deflection. The sweep generator output lead s
17、hould be terminated with its characteristic impedance, usually 50 ohms. Set the fine tuning control to the mid-position of its range. DUMMY ANTENNA Two 120S2 Carbon Resistors SWEEP GENERATOR COUPLING Across antenna ter- minals with 120S2 in each lead. SWEEP GENERATOR FREQUENCY 57MC (10MC Swp 63 MC (
18、10MC Swp 69MC (10MC Swp 79MC (10MC Swp 85MC (10MC Swp 177MC (10MC Swp 183MC (10MC Swp 189MC (10MC Swp 195MC (10MC Swp 201MC (10MC Swp 207MC (10MC Swg 213MC (10MC Swp MARKER GENERATOR FREQUENCY 59.75MC 65.75MC 71.75MC 81.75MC 87.75MC 179.75MC 185. 7 SMC 191.75MC 197.75MC 203.75MC 209.75MC 215.75MC CH
19、ANNEL 2 3 4 5 6 7 8 9 10 11 12 13 CONNECT SCOPE Vert. Amp. thru lOK.fl to point . Low side to chassis ADJUST All A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 REMARKS Adjust to place sound marker in trap notch as in Fig. 4. FIG.FIG.2FIG.3FIG.4 PAGE 6 RadioFans.CN ALIGNMENT INSTRUCTIONS (cont) HF AND M
20、IXER ALIGNMENT Remove the bias supply from C31 and connect a jumper from the tuner AGC lead (yellow) to chassis. Connect the synchronized sweep voltage from the sweep generator to the horizontal input of the oscilloscope for horizontal deflection. The sweep generator output lead should be terminated
21、 with its characteristic impedance, usually 50 ohms. DUMMY ANTENNA Two 120S2 Carbon Resistors SWEEP GENERATOR COUPLING Across antenna ter- minals with 120S2 in each lead. SWEEP GENERATOR FREQUENCY 69MC (10MC Swp) 201MC (10MC Swp) MARKER GENERATOR FREQUENCY 67.25MC 71.75MC 199.25MC 203.75MC CHANNEL 4
22、 11 CONNECT SCOPE Vert. Amp. thru 10KS3 to point . Low side to chassis. ADJUST A23, A24, A25 A26, A27, A28 REMARKS Adjust for response similar to Fig. 5. Adjust A26 and A27 for symmetrical response similar to Fig. 6. Adjust A28 for proper band width. Repeat steps 5 and 6 until best overall symmetric
23、al response is obtained. Remove jumper from tuner AGC terminal to chassis. SOUND IF ALIGNMENT Connect an attenuator Zenith part #3-17203 or equivalent) in series with the receiver antenna. Tune in a tone modulated TV signal and adjust the attenuator until the signal falls below the limiting level of
24、 the 6BN6 limiter detector, as evidenced by a hiss similar to superregeneration. Adjust the sound take-off transformer (A29, A30) the sound IF transformer (A31) and the quadrature coil (A32) for maximum sound of best quality. Adjust the buzz control (R9) for minimum intercarrier buzz. II the interca
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- Zenith-19M20-Sams-259-16 电路原理图 Zenith 19 M20 Sams 259 16 电路 原理图