RCA-CTC4-Sams-314-9电路原理图.pdf

PHOTO FACT* Folder RCA VICTOR MODELS 21-CT-66OU 21-CT-661U, 21-CT-662U, 21-CT-663U, 21-CT-664U (Ch. CTC4, CTC4A) RCA Victor Model 21-CT-662U (Ch. CTC4A) TRADE NAME RCA Victor Models 21-CT-660U, 21-CT-661U, 21-CT-662U, 21-CT-663U, 21-CT-664U (Ch. CTC4 or CTC4A) MANUFACTURER Radio Corporation of America, RCA Victor Television Division, Camden, N. J. TYPE SET Color Television Receiver TUBES Twenty-six POWER SUPPLY HO-120 Volts AC-60 Cycles RATING 3. 6 Amp. 117 Volts AC TUNING RANGE-Channels 2 thru 13 VHF, 14 thru 83 UHF, Video IF 45. 75MC, Sound IF 4L 25MC (Intercarrier) INDEX Alignment Instructions 5 thru 9 Block Diagram 3 Drive Cord Stringing (UHF) 31 Disassembly Instructions 33 Miscellaneous Adjustments 20, 29 Parts List and Descriptions 22 thru 27 Photographs Cabinet-Rear View 33 Capacitor Identification 12, 17 Chassis-Top View 14, 15 Convergence Chassis 31 Printed Circuit Sub-Chassis (Sound IF) 10 Photographs (Cont) Printed Circuit Sub-Chassis (Video IF) 10 RF Tuner 21,28 Resistor Identification (R1-R142) 11, 18 Resistor Identification (R143-R232) 13, 16 Trans., Inductor heck all UHF channels for response similar to ator and bias supplies. rticular antenna matching er to connect output of matching unit at point Remove the first video IF amplifier tube lead to chassis. Adjust for -6 volts at the oscilloscope for horizontal deflection, sually 50 ohms. A20 A21.A22 Adjust for MINIMUM 400% Indication on scope. Remove .001MFD capacitor from point Op to grid of V5A. Connect a 300, i watt carbon resistor from point < to chassis. Use very short lead- Set sweep generator for maximum output. Adjust A21 and A22 for response curve similar to Fig. 7. Repeat steps 16, 17 and 18 until no further Improvement Is noted. A21 affects shoulder of curve (52MC point). Adjust A22 for maximum response at 53MC point. If dis- tortion of response Is affected by a second harmonic of sweep generator output, tune a (FM trap) for maximum Inductance while adjusting A19 thru A22. After final adjust- ments return A55 to its original position. Restore connection from L15 to channel switch. Replace V4 In its socket. no presetting of adjustments. When complete inals with a 39 ohm carbon resistor. jf the oscilloscope for horizontal deflection, usually 50 ohms. A24,A25. A26 REMARKS Preset A24 to read -3.5 volts at point . The limits of oscillator injection voltage are 2.5 volts minimum and 5.5 volts maximum. Set fine tuning control maximum clockwise.Adjust A25 for audible beat on frequency meter. Adjust A23 clockwise until beat note just begins to change, then turn one full turn in same clockwise direct- ion. Return fine tuning control to Its mechanical center of Its range. o channel 13 and adjust A27 for channel 13 oscillator icy. Switch to channel 13 and readjust A27 for channel ;es are noted. ) point le to A26,A39; A40 Couple signal generator loosely to antenna terminals to provide markers. Adjust scope gain for maximum and attenuate generator output for minimum signal Input. That will produce usable pattern on scope. Adjust for response similar to Fig. 8. A39 affects frequency of bandpass, A40 affects tilt. Adjust A26 to place markers at 100% on response curve. A26 also affects bandwidth. raits at point . Repeat steps 19, 20 and o point Ide to A41.A42Adjust for response curve similar to Fig. 8, Turn off generator and check oscillator In- jection at point 4 1 1 J. FIG.7 24 25 26 27 28. 29 30 31 32 33 34 35 36 VHF TUNER ALIGNMENT (Cont). DUMMY ANTENNA TWO soon carbon resistors TwolSOC Carbon testators SWEEP GENERATOR COUP1ING Across antenna terminals with 300n in each lead. Connect frequency meter as in step 19. Across antenna termi- nals with 13012 in each lead. SWEEP GENERATOR FREQUENCY 183MC (10MC Swp) 213 MC (10MC Swp) 207MC (10MC Swp) 201MC OOMC SWP) 195MC (lOMC Swp) I89MC (10MC Swp) 183MC (10MC Swp) 177MC MMC Swp) Not used 85MC (10MC Swp) MARKER GENERATOR FREQUENCY 181.25MC 185.75MC 2U.25MC 215.75MC 205.25MC 209.75MC 199. 2 SMC 203.75MC 193.25MC 197.7SMC 187.25MC 191. 75MC 1B1.25MC 185.75MC 175.25MC 179.75MC Freq. meter to 129MC 83.25MC 37.75MC CHANNEL 8 13 12 11 10 9 8 7 6 CONNECT SCOPE Vert. Amp. to point q . Low side to chassis . Not used Vert. Amp. to point . Low side to chassis. ADJUST A26,A39 A40 A34 A43, A44 REMARKS If necessary retouch A26, A39 and A40 to obtain desired response(Fig.S). If A40 required adjustment turn off generators and switch back to channel 13 and check injection voltage AS in step 22. Repeat steps 23 and 24 until proper response is obtained. Check for response curve similar to Fig. 8. Check oscillator injection voltage for each channel at point . If markers fall below 85% of maximum on any one channel retouch A26 and A39 thru A42 to obtain response curves within proper limits as in Fig. 8. Set fine tuning control to its mid-range posi- tion. Adjust A34 for an audible beat on frequency meter. Adjust for response curve similar to Fig. 8. Check oscillator injection voltage as in step 22. Readjust A24 If necessary. If A24 required readjustment switch receiver and generator to channel 8. Readjust A40 for response similar to Fig. 8. Recheck A23 and A25 for proper oscillator frequency as in step 19. TwolSOSJ Carbon leslstors Two 130! Carbon Resistorf Two 130n Carbon Resistors Across antenna termi- nals with 130Si in each lead. Connect frequency meter as in step 19. Across antenna termi- nals with 120S1 In each lead. Across antenna termi- nals with 130ft In each lead. 85MC (10MC Swp) 79MC (10MC Swp) 69MC OOMC Swp) 63MC (LOMC Swp) 57MC flOMC Swp) Not used Not used 183MC (lOMC Swp) 213MC (lOMC Swp) 85MC (lOMC Swp) 83. 2 SMC 87.75MC 77.25MC 81. 75MC 67.25MC 71. 75MC 61.25MC 65.75MC 55.25MC 59.75MC Freq. meter to 257MC 251MC 245MC 239MC 233MC 227MC 221MC 129MC 123MC 113MC 167MC 101MC 213MC (4001,Mod.) 85MC (4001Mod) 181. 25MC 185.75MC 211.25MC 215.75MC 83.25MC 87.75MC 6 5 4 3 2 13 12 11 10 9 8 7 6 5 4 3 2 13 6 8 13 6 Vert. Amp. to point . Low side to chassis. Not used Vert. Amp. to point . Low side to chassis. Vert. Amp. to point . Low side to chassis. A27 A28 A29 A30 A31 A32 A33 A34 A35 A36 A37 A38 A45 A46 A47 A48 A49 Check for response curve similar to Fig. 8. Check oscillator Injection voltage on each channel at point <Q . If markers fall below 85% on any one channel SLIGHTLY retouch A43 and A44. If unable to obtain correct MINIMUM tilt on channels 5 thru 2 knife colls (by expanding or compressing coil turns) L39 thru L42 and L47 thru L50. Adjust individual channel oscillator slug for audible beat on each channel. Recheck oscillator Injection voltage on each channel at point to verify that the voltage Is within ( 2 volts MINIMUM and 5. 5 volts maximum) limits. Connect the negative lead of a variable bias supply to ungrounded side of C76. Positive lead to chassis. Adjust for -6 volts at ungrounded side of C76. Remove short from tuner AGC at point . Connect negative lead of a second bias supply to point ra . Positive lead to chassis. Adjust tor -IS Volts at point . Set scope for maximum gain. Adjust lor MINIMUM 4001- Indication on scope. Reduce bias to -3 volts at point . Adjust A47 for maximum amplitude between two peaks on response curve. Adjust A48 for maximum amplitude between two peaks on response curve. A48 is adjusted by expanding or compressing coll turns. RepeatBtepa 33 and 34. Increase bias at point to -3 volts and again repeat steps 33 and 34 . Adjust A49 for maximum amplitude between two peaks on response curve . Switch tuner thru all VHF channels and observe the response on scope, as in steps 25 and 29. The dip at mid-point between two peaks on response curve should be 85% of maximum. If dip exceeds this limit it will be necessary to knife coils L22 thru L26 and LIT thru L20 to correct dip. Always knife coils starting with the highest frequency (channel 13 thru 2) and continuing to the lowest. Remove all test equipment and bias supplies. F IG.9 FIG.F IG.I2FIG.13 F IG.I4 PAGE 7 RadioFans.CN ALIGNMENT INSTRUCTIONS UHF TUNER ALIGNMENT (cont) 37 38 39. 40 41 42 43 Turn the change over switch to UHF position. To make the RF adjustment of the UHF tuner, the UHF tuner unit will have to be removed from the set. IF and oscillator adjustments may be aligned without removing UHF tuner. Connect a lOCXli carbon resistor from the center conductor of IF cable to chassis (point on schematic). If the oscilloscope does not have a sensitivity of 5 millivolts per inch, a suitable preamplifier may be used. Fabricate a test dial with markers scribed on its circumference at 0, 5 and 164 degrees. The test dial should be made to fit over the split gear on the tuner shaft for accurate alignment. Locate the 0 degree reference point with the capacitor plates fully meshed, The stop pin on the tuner should be against the stop plate on the gear assembly when the plates are fully meshed. Connect the high side of a VHF marker generator thru a lOOOfc carbon resistor to point . Insert resistor lead (insulate lead) through aperture provided for crystal removal. Connect low side 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 with its characteristic impedance, usually 50 ohms. DUMMY ANTENNA TWO soon Carbon Resistors SWEEP GENERATOR COUPLING Across UHF antenna terminals with SOOn In each lead. SWEEP GENERATOR FREQUENCY 887 . SMC (Use max. sweep width) 473. SMC (Use max. sweep width) MARKER GENERATOR FREQUENCY 41.25MC 43 . SMC 45.75MC 887. 5MC 41. 25MC 43. SMC 45. 7 SMC 473 . SMC CHANNEL 83 164degrees on tuning dial) 14 5 degrees on tuning dial) CONNECT SCOPE Vert. Amp. (thru preamp. if needed) to point thru detector (detector lead of Fig. 3). Low side to UHF tuner chassis. ADJUST A50, A 51, A52 A53, A 54 REMARKS Use low VHF and UHF marker generator output. If UHF sweep generator has no built-in marker, couple separate marker generator loosely to antenna terminals to provide UHF marker (887. 5MC). Adjust A 50 and A51 for maximum amplitude over- coupled response curve centered at 887. 5MC similar to Fig. 9. Adjust A52 until the 43.5 MC marker coincides with the 887. SMC marker. The 41.25MC and 45.75MC markers should be symmetrically located on top of response curve as in Fig. 9. Leave marker generators connected as In step 37. Adjust A53 until 43. SMC marker coincides with 473. SMC marker as in Fig. 10. If A53 has insufficient range adjust A 54 by repositioning coil until markers coincides. Repeat steps 37 and 38 until proper responses are obtained. Tune thru the entire UHF range and check tracking. If the 41.25MC and 45.75MC markers fall below 85% on any UHF channel it will be necessary to bend the RF plates to correct mlstracklng. The plates may be bent by using a knife blade with the shield cover removed. Knife the plates while tuning lower in frequency so that tracking above the point of knifing will not be disturbed. A check of which requires knifing may be made by touching the plates with the knifing tool while noting the effect on the response curve, then knifing the proper section or both sections if re- quired. Connect the DC probe of VTVM to point . Common to chassis. Tune thru the entire UHF range, at the same time noting the reading on VTVM. Readings between .03 and .4 volts should be obtained. If voltages outside this limit are obtained, it indicates low B+ voltage, low or high crystal Impedance or an oscillator tube outside its allowable limits. This voltage may be varied by repositioning L3 (UHF osc. coupling coll. Connect DC probe of VTVM to point . Common to chassis. Readings between .75 and 3.5 volts should be obtained. Readings outside this range will cause crystal currents beyond allowable limits and in such cases the oscillator tube should be replaced. If the oscillator tube is replaced steps 37 and 38 should repeated, allowable limits and In such cases, the oscillator tube should be replaced. If the oscillator tube is replaced steps 37 and 38 should be repeated. FM TRAP ALIGNMENT Tune in a local TV station in which interference is noticed, adjust A55 for minimum interference in the picture. FIRST VIDEO AMPLIFIER AND BANDPASS AMPLIFIER ALIGNMENT Remove the G-Y,R-Y demodulation tube (V25) from its socket Connect the negative lead of a variable bias supply to pin 6 of AGC clamper tube (6T8/V11A). Connect the positive lead to chassis, Adjust for -2 volts bias at pin 6 of VILA. Connect a second bias supply to the ungrounded side of C76. Connect the positive lead to chassis. Adjust for -6 volts at ungrounded side of C76. DUMMY ANTENNA Direct Direct SWEEP GENERATOR COUPLING Connect signal generator and video sweep modu- lator across antenna terminals. (See remark Connect signal gener- ator and video sweep modulator across an- tenna terminals. (See remarks-step 1) SWEEP GENERATOR FREQUENCY SMC (3MC Swp) MARKER GENERATOR FREQUENCY 3.0MC 3.58MC 4. IMC 3. CMC 4. IMC CHANNEL 4 CONNECT SCOPE Vert. Amp. of wide band scope to point di . thru detector (detector lead of Fig. 3). Low side to chassis. Vert. Amp. of wide band scope thru de- tector (detector lead of Fig. 3). To ter- minal B of L80. Low side to chassis. Vert. amp. ofwide band scope thru detector (detector lead of Fig. 3) to terminal F of L87. Low side to chassis . Vert. Amp. of wide band scope thru 2MMF capacitor and detector (detector lead of Fig. 3) to pin 1 (plate) of R-Y demodulated (V25B) . Low side to chassis. ADJUST A 56 A57, A58 A59 REMARKS Signal generator should provide channel 4 video carrier frequency (67.25MC) with crystal accuracy. Connect DC probe of VTVM to pin 2 (grid) of 6CL6 (V7). Common to point . With zero video sweep modu- lation adjust signal generator output (67.25MC) for 1.5 volts on VTVM. Remove VTVM and apply video sweep modulation, being careful not be overload. Couple VHF signal generator loosely to pin 6 (grid) of 1st, video IF amplifier tube (V4) to provide 45.75MC marker. To set the local oscil- lator exactly on frequency adjust fine tuning control until a beat pattern is obtained on scope. Remove VHF generator from pin 6 of V4A. The response on scope should be similar to Fig. 11. Remove bias supplies. Connect a 330S2, 1 watt resistor across terminals A and B of bandpass primary coll (L80). Connect negative lead of a bias supply to pin 9 (grid) of burst keyer tube (V9B) . Connect negative lead of a second bias supply to junction of R168 and R169. Connect positive terminals of both to chassis. Adjust for -7 volts at both bias points. Adjust A56 for correct response curve simi- lar to Fig. 12. Remove 330J2 resistor from terminals A and B of L80 and connect to terminals C and F of demodulator transformer (L87) for adjustments In step 42. Connect both bias supplies as in step 41. At pin 9 of V9B Increase bias to -9 volts. At junction of R168 and R169 increase bias to -15 volts. Adjust A57 and A58 for response curve similar to Fig. 13. If necessary, make SLIGHT readjustment of A7 for desired re- s