1952 RCA 21T176 - Early Television Foundation

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JCTIONS ORE ATTEMPTING ALIGNMENT tl oscillator tube, (V18), from its socket. of withstanding considerable current drain. Connect the positive end junction of R95 & R96. zontal input of the oscilloscope for horizontal deflection. •JNECT :OPE 'M e to pqinKg>. to chassis. ' ' ADJUST Al A2 A3 A4 REMARKS Set bias pot. to -IVoIt, Adjust for MINIMUM deflection. Attenuate signal gen. to maintain -IVolt reading. Adjust for maximum deflection. Attenuate signal gen. to maintain 1 volt reading. F IG.4 11, 18. ALIGNMENT IN If the tuner is operating and requires only touch up alignment the completely realigned pre-set all adjustments to the approximate Pre-set A26 so the screw head is approximately 3/8 inch above t Do not change any adjustments on the antenna matching unit. Disconnect the coax link from terminal" A" of L24. Connect a 39S2 Connect a clip lead from the tuner AGC terminal, (terminal 3) to During step 17 the signal generator is connected to the RF Amp. and the tube replaced in its socket. Connect the generator to the Set the fine tuning control 30 degrees clockwise from the mechan Connect the synchronized sweep voltage from the signal generat DUMMY ANTENNA 1500MMF See fig.e SIGNAL GENERATOR COUPLING High side to pin 7, (grid) of 6BQ7, (VI). Low side to chassis. Across antenna terminal SIGNAL GENERATOR FREQUENCY Not used Not used MARKER GENERATOR FREQUENCY 43. SMC (4001. mod) 227MC unmod) CHAN 2 8 A5 A6 19. 183MC (10MC Swp) 181. 25MC 185.75MC up. to point side to chas- A7,A8 Connect 330S2 resistor across R37, R38 and terminals 'A1" and V'of M6. Adjust for response curve similar to fig. I. Attenuate sweep gen. to maintain . 5 volt peak to peak response. 20. Not used 129MC 6 np. thru de- -obe, (fig. 2) of6AU6 (V3). ; to chassis. ASaAlO Leave 330J3 resistors connected. Connect a 180n resistorbetween pin 5 of V3 and junction of R29 and C40. Adjust for response similar to fig. 3. FIG.5 21. 22. " " 8 SMC (10MC Swp) Not used 83.25MC 87, 75MC Not used up. to point side to chas- Remove all damping resistors. Set IF bias to -6 volts. Check for response curve similar to fig. 4. If necessary retouch A4 and A5 for proper response. Retouch A6 only if absolutely necessary. Incorrect adjustment of A6 will interfere with trap action. 23. 24. " Repeat step 18. " 85MC (10MC Swp) 83.25MC 87. 75MC ator. 25. Repeat step 19. ADJUST A14 REMARKS Adjust for maximum deflection on VTVM. Adjust signal gen. to obtain 10 volt reading. 2*. Repeat step 23, If necessary repeat steps 16, 17, and 20 until no fur 27. see Fig. 8 Across antenna terminal. Not used 257MC 13 A15 A16 A17.A18 A19 Adjust for MINIMUM 4001 indication on scope. Repeat steps 10 and 11. Check the voltage at poinK^). II the voltage exceeds ± 1. 5 volts, adjust A16 for zero voltage on VTVM between positive and negative peaks. Repeat adjustment of A15 and A16 until VTVM reads less than 1 1. 5 volts with A15 adjusted for MINIMUM 4001 indication on scope. Adjust for maximum amplitude and symmetry as per Fig. 5. lent should not be attempted unless it has been definitely established required equipment cons sts of a sweep generator capable of at least nch. Misalignment of this unit can cause serious attenuation of the will not effect the alignm ;nt, mid be realigned, of L8 is alignment Poin \Sy, as shown on the schematic. mp. thru detrobe to >, Low side A17 A18 A19.A20 Adjust for MINIMUM 400^ indication or scope. Adjust for MINIMUM 400% indication or scope. Connect a 3000 resistor from Point^to chassis. Adjust for response curve similar to Fig. 7. A19 controls the placement of the shoulder. A20 is adjusted to give maximum amplitude of .53MC marker consistant with curve shape shown in Fig. 7 . Repeat steps 14, 15 & 16 until no further improvement can be made. 300-r BALANCED L-WV FIG.6 TO 300j 28. 29. 30. 31. 33. Repeat Step 20 Repeat Step 19 See Fig. 6 Across antenna terminal. 213MC 211.25MC (10MC swp.) 215.75MC 207MC 205.25MC (10MC swp.) 209.75MC 201MC 199.25MC (10MC swp.) 203.75MC 195MC 193.25MC {10MC swp.) 197.75MC 189MC 187.25MC (10MC swp.) 191.75MC 183MC 181.25MC (10MC swp.) 185.75MC 177MC 175.25MC (10MC swp.) 179.75MC 85MC (10MC swp.) 79MC (10MC swp.) 69MC (10MC swp.) 63MC (10MC swp.) 83.25MC 87.75MC 77.25MC 81.75MC 67.25MC 71.75MC 61. 25MC S5.75MC 55.25MC 59.75MC 57MC (10MC swp.) 32. See Fig. 6 Across antenna terminal. Not used 257MC Remove 39SJ Resistor and reconnect from V 251MC 12 245MC 11 239MC 10 233MC 9 227MC 8 221MC 7 129MC 6 123MC 5 113 MC 4 107MC 3 link 101MC tuner. Recheck 2 step FM TRAP If interference from an FM station is encountered adjust the FM in the area, they should be checked to make sure the trap is not 13 12 11 10 9 8 7 6 5 4 3 2 13 F IG.8 F IG. 3
n. ALIGNMENT INSTRUCTIONS CCONTJ RF ALIGNMENT If the tuner is operating and requires only touch up alignment the following pre-setting adjustments should not be performed. If the tuner is to be completely realigned pre-set all adjustments to the approximate center of their range with tie following exceptions. Pre-set A26 so the screw head is approximately 3/8 inch above the chassis. Turn A9 fully counter-clockwise. Set A23 one quarter turn from tight. Do not change any adjustments on the antenna matching unit. Disconnect the coax link from terminal" A" of L24. Connect a 39fi carbon resistor across the open end of the link. . Connect a clip lead from the tuner AGC terminal, (termina 3) to chassis. During step 17 the signal generator is connected to the RF Amp. grid by means of a piece of small diameter wire slipped over Pin 7 of the tube, and the tube replaced in its socket. Connect the generator to the free end of the wire. Set the fine tuning control 30 degrees clockwise from the mechanical center of its range. Connect the synchronized sweep voltage from the signal generator to the horizontal input of the oscilloscope for horizontal deflection. DUMMY ANTENNA 1500MMF SIGNAL GENERATOR COUPLING High side to pin 7, (grid) of 6BQ7, (VI). Low side to chassis. SIGNAL GENERATOR FREQUENCY Not used MARKER GENERATOR FREQUENCY 43. SMC (400% mod) CHANNEL 2 CONNECT SCOPE Vert. Amp. to point
Page 1 and 2: PHOTO FACT* Folder RCA MODELS 21T17
Page 3 and 4: 4TH VIDEO IF ©6CB6 HORIZ SYNC AMP
Page 5 and 6: CHASSIS TOP VIEW PAGE 3
Page 7 and 8: OR AND ALIGNMENT IDENTIFICATION PAG
Page 9: ALIGNMENT INSTRUCTIONS 1. 2. 3. 4.
Page 13 and 14: HORIZ. INEARITY CONTROL WIDTH HORIZ
Page 15 and 16: PAGE 12 CHASSIS BOTTOM VIEW-RESISTO
Page 17 and 18: WIDTH LINK HIGH VOLTAGE SUPPLY RF T
Page 19 and 20: i} ITEM No. C50 C51 C52 C53 C54 C55
Page 21 and 22: SCRIPTIONS (Continued) ESISTORS IDE

1952 RCA 21T176 - Early Television Foundation

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