1952 RCA 21T176 - Early Television Foundation

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3 s § TOP VIEW TUBE PLACEMENT CHART PAGE 5
ALIGNMENT INSTRUCTIONS 1. 2. 3. 4. 5. 6. 1. 8. 9. DUMMY ANTENNA Direct .005MFI Direct ALIGNMENT INSTRUCTIONS—READ CAREFULLY BEFORE ATTEMPTING ALIGNMENT The high voltage shock hazard may be eliminated by removing the horizontal oscillator tube, (V18), from its socket. VIDEO IF ALIGNMENT Connect the ends of a IOOOS1 potentiometer across a 7.5 Volt battery capable of withstanding considerable current drain. Connect the positive end of the battery to chassis. Connect the center arm of the potentiometer to the junction of R95 & R96. Connect the synchronized sweep voltage from the signal generator to the horizontal input of the oscilloscope for horizontal deflection. SIGNAL GENERATOR COUPtING High side to terminarA of L24. Low side to chassis. •• High side to pin 1 (grid) of 6AU6, (V3). Low side to chassis. High side to point F . Low side to chassis. SIGNAL GENERATOR FREQUENCY Not Used " " " " 44MC (10MC Swp) MARKER GENERATOR FREQUENCY 39. 75MC 41.25MC 47.25MC 43.7MC 45. SMC 41. BMC 42.15MC 45MC 45.75MC 46. SMC 42.25MC M.5MC 42.25MC 45MC 45.75MC CHANNEL 4 " Any channel which cau ses no interference. SOUND IF ALIGNMENT CONNECT SCOPE Use VTVM DC probe to pqint. Common to chassis. " " Vert. Amp. to point C^ Low side to chas- •sis. Vert. Amp. thru detector probe, (fig. 2) to pin 5 oteAUB (V3). Low side to chassis. Vert. Amp. to point ^^ Low side to chassis. Connect the oscilloscope across the speaker voice coil to use as an output indicator. Turn the trimmer A16 for minimum capacity. DUMMY SIGNAL SIGNAL CONNECT GENERATOR GENERATOR CHANNEL ADJUST ANTENNA VTVM COUPLING FREQUENCY . 005MFD High side to pin 1 (grid) of 6AU6, (V10). Low side to chassis. 4. SMC (4001. AM mod) Any DC probe to point. Common to chassis. A14 A15 ADJUST Al A2 A3 A4 A5 A6 A7,A8 A9.A10 REMARKS Set bias pot. to -IVolt. Adjust for MINIMUM deflection. Attenuate signal gen. to maintain -IVolt reading. Adjust for maximum deflection. Attenuate signal gen. to maintain 1 volt reading. Connect 330ft resistor across R37, R38 and terminals 'A* and 'F'of M6. Adjust for response curve similar to fig. I. Attenuate sweep gen. to maintain . 5 volt peak to peak response. Leave 330S2 resistors connected. Connect a 180fi resistorbetween pin 5 of V3 and junction ot R29 and C40. Adjust lor response similar to fig. 3. 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. REMARKS Adjust for maximum deflection on VTVM. Adjust signal gen. to obtain 10 volt reading. Adjust for MINIMUM 400ft. indication on scope. Repeal steps 10 and 11. F IG FIG DC probe to pcint. Common to chassis. A16 Check the voltage at polnt. If the voltage exceeds t 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 -1.5 volts with A15 adjusted for MINIMUM 4001. indication on scope. 14. See Fig. 6 High side to point A . Low side to chassis. 4. SMC (IMC Swp) USE SCOPE Vert. Amp. thru 10KSJ to poinKQ>. Low side to chassis. A17.A18 A19 ANTENNA MATCHING UNIT ALIGNMENT Adjust for maximum amplitude and symmetry as per Fig. 5. This unit has been properly aligned at the factory and is very stable. Alignment should not be attempted unless it has been definitely established that it is out of alignment and proper equipment is available to align it. The required equipment consists of a sweep generator capable of at least 1 volt output, and an oscilloscope with a sensitivity of at least .02 Volts per inch. Misalignment of this unit can cause serious attenuation of the signal especially on channel 2. Adjustment of the FM trap, (A43), however will not effect the alignment. In the event of replacement of the antenna matching unit, the entire tuner should be realigned. - Disconnect the FM trap, L8, from the channel selector switch. The free end of L8 is alignment 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: OR AND ALIGNMENT IDENTIFICATION PAG
Page 11 and 12: n. ALIGNMENT INSTRUCTIONS CCONTJ RF
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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