Hoffman-ch140-Rider-TV-3-1电路原理图.pdf

CHASSIS 140, 142 ,146 MODEL 610DOORS OPEN CHASSIS 147 MAJOR COMPONENTS Model 610 Model 612 MODEL 612DOORS CLOSED J- POWER TV Chassis Speaker Cabinet 140 6 PM, Part #9062 Voice coil, 3.2 ohms at 400 cps Part #7532 Escutcheon Frame Part #2250 Filter Plate Glass Part #733 142 6 PM, Part #9062 Part #7533 Part #2277 Part #734 BLOCK DIAGRAM Picture Tube 10BP4, 10FP4 12KP4, 12LP4, 12QP4 Installation and service information on chassis 140 and 142 is given John F. Rider RadioFans.CN MODELS 6lO, Ch Ch. llj.6; 826, ELECTRICAL AND MECHANICAL DATA Range TV Channels 2 to 13 Intermediate Frequencies Video 26.1 Me Sound 21.6 Me Power Source Chasis 140, 142 -operate with RF-1, RF-2 or RF-3. . llj.0; 612, Gh. 12; 820, 821, 822. 82?, 828, Gh. ll|3; 912, 913, Gh. l4? TUBE COMPLEMENT (Less Tuning Unit) 2 6AU6 Sound IF V101, V102 1 6AL5 Ratio Detector V103 1 6AV6 1st Audio V104 1 6K6 Audio Output V105 2 6AG5 Video IF V106, V107 2 6AU6 Video IF V108, V109 1 6AL5 Video Detector VI 10 1 6AC7 Video Amplifier VI 11 1 6SN7 D.C. Restorer, Sync Sep. VI 12 1 6SN7 Sync Separator and Clipper VI 13 1 6SN7 Vertical Osc. and Output VI 14 1 6C4 A.F.C. Phase Splitter VI 15 1 6AL5 A.F.C. Phase Comparator VI 16 1 5U4G Low Voltage Rectifier V117 1 6SN7 Horizontal Oscillator VI 18 1 6BG6 Horizontal Output VI 19 1 1B3GT High Voltage Rectifier V120 1 6W4GT Damping Diode V121 Summary of Tube Complement 6AU6 4 6SN7GT 4 6AL5 3 6C4 1 6AV6 1 6BG6 1 6K6 1 1B3GT 1 2* 6AG5 2 6W4GT 1 6AC7 1 5U4G 1 2* * Chassis 143 or 147 TUNING UNIT 1 6AG5 RF Amplifier 1 6J6 Osc. and Mixer PICTURE TUBES The following kinescope tubes may be used interchangeably in the respective chassis which employ 10, 12, or 16 inch tubes. Slight circuit variations for specific tubes are noted in the text. 10BP4 10FP4 12KP4 12LP4 12QP4 15AP4 16AP4 0 Tl n 2 z H A 4 CONTROLS ON REAR OF 7 FOCUS V VERT / LIN CHASSIS TAJ/ r-*-y Of, / r itX. f) a / / 77 7 WIDTH ADJUSTMENT - -LU3 ( CHASSIS 140,14? a LH6 ( CHASSIS 143,147) HEIGHTV Rf,?-/ -HWtZ DRIVE HULU (CHASSIS 140.142 8146) HORIZ LIN (CHASSIS I43-M7) John F. Rider RadioFans.CN istRASTER CENTERING ADJUSTMENTS Vertical and horizontal adjustment of the raster position he within the picture mask is accomplished by means of the nt spring mounted screws on either side of the focus coil. Relative action of the two screws is indicated by the mark- ing on the set backboard, he AGC ADJUSTMENT Chassis 140 and 142 units below serial No. D903447 were shipped with a provision for optional AGC action on the Head End. In strong signal areas, it may be found that chassis of this type may produce a weak or washed out picture due to overloading of the first video IF stage. If this is the case, it will be necessary to provide AGC action on the Head End. This may be accomplished by moving the green and white lead from the Head End to the rear tie point on the AGC tie strip (See Figure 14). NOTE of X) nt in- ler In making the following adjustments a source of television signal, such as that from a station, should be available, and the set should be al- lowed to operate for at least 15 minutes before adjustment. HORIZONTAL SYNC ADJUSTMENT Normally, all sets should hold horizontal sync throughput the entire range of the horizontal hold control. In any case, ) the sync error at either extreme of the horizontal hold con- trol, when the channel selector is switched off channel and back again, should not produce more than 3 or 4 diagonal bands across the screen. If the sync error produces more than 3 or 4 bands, the horizontal frequency must be reset as follows: 1Set the contrast control for a weak picture, approximately et midway in its range. til 2Set the horizontal hold control to the extreme clockwise K- position. MODELS 610, 612, 820, 821, 822, 826, 82?, 828, 912, 913 3Switch the channel selector off channel and back again. 4If Step 3 throws the picture out of horizontal sync, LI 11 must be readjusted as follows: aRotate the core in the direction which reduces the number of diagonal bands on the raster. bThe direction of rotation under Step a. will usually be counter-clockwise. If it is clockwise, the adjust- ment must be carried beyond the sync pull-in range and back again, so that the pull-in setting is always approached from a counter-clockwise direction. Dur- ing clockwise rotation, switch off channel and back several times to release sync lock-in. 5Set the horizontal hold control to the extreme counter- clockwise position. 6Switch the channel selector off channel and back again. 7If the receiver will not pull in to horizontal sync with the horizontal hold set at the counter-clockwise extreme, it may be necessary to compromise the adjustment of LI 11 slightly; however, it is preferable to have best pull-in action at the extreme clockwise position. 8Set the horizontal hold control by observing the top portion of the picture and setting the control at the point at which there is no distortion of the vertical lines in this region. This should be near the center of the range of the horizontal hold control. 9If the above adjustments will not correct the horizontal sync pull-in, it is possible that LI 13 is misadjusted. The setting of LI 13 is normally fixed at from 60% to 100% of its maximum inductance and must be within this range for proper horizontal sync operation. This setting is in- dicated by a core stud extension of 1/2 or less (See Figure 4 for the location of LI 13). 10Set LI 13 within its normal range, and readjust LI 11 as in step 4. Fig. 3 MOUNTING OF 16 TUBE he se re ch as 014, azi Iff I5AP4 OR I6AP4 READ INSTRUCTIONS BEFORE REMOVINGTHIS TUBE RadioFans.CN HORIZONTAL LINEARITY ADJUSTMENT Chassis 140, 142, 146 Adjustment of the horizontal linearity on these chassis is most conveniently effected by means of C159, the horizontal drive condenser. Because of the nature of the horizontal AFC circuit used in this receiver, adjustments in the horizontal output circuit may affect the horizontal frequency (LI 11) and horizontal hold adjustments. Therefore, if it is necessary to readjust C159, it will also be necessary to recheck the horizontal sync adjustments (See above). Chassis 143, 147 On these chassis, no horizontal drive control is provided. Instead, R140 is available on the rear chassis apron as au external adjustment or horizontal linearity. The range of adjustment of linearity is varied by means of the core in LI 16, which is accessible through the extreme right hand opening in the rear chassis apron by removing the -set back- board (see Figure 4). Normally, the factory setting of LI 16 should not require readjustment in the field and it should be possible to make all necessary horizontal linearity adjustments by means of R140. However, if this is not the case, it may be necessary to reset LI 16 as follows: 1Turn the core stud until it extends about V4 out of the coil. 2Check the effect of adjustment of R140. 3Turn the LI 16 core stud about 5 turns counter-clockwise. 4Recheck the effect of R140. 5Repeat Steps 3 and 4 until the optimum setting of LI 16 core is found. As on Chassis 140, 142 and 146, readjustments of the horizontal linearity will require rechecking of the horizontal frequency (Llll) and horizontal hold (R181) settings (See Horizontal Sync Adjustment). WIDTH ADJUSTMENT Adjustment of picture width is obtained by means of the core in LI 12, which is available through the hole in the lower left hand rear corner of the high voltage shield can (See Figure 4). Clockwise rotation of the core slug increases picture width, and counter-clockwise rotation decreases it. On certain sets, it has been found difficult to obtain suf- ficient width, even with LI 12 core in the extreme clockwise position. In cases of this kind, the following remedies are recommended: 1Replace VI19, 6BG6G, Horizontal Output. 2Disconnect one end of LI 12. 3Add an .02, 600 V paper condenser across terminals 5 and 6 of T107. Horizontal Output Transformer. VERTICAL LINEARITY AND HEIGHT ADJUSTMENTS The vertical linearity and height adjustments on Chas 140, 142, 143, 146 and 147 are conventional potentiome adjustments located on the rear chassis apron. For a gig of the height control, counter-clockwise rotation of i vertical linearity control compresses the top half of the p ture, and decreases the overall picture height. Clockw rotation of the height control increases the vertical size the picture uniformly. TEST EQUIPMENT For complete and thorough servicing of any TV recei the following test equipment is considered essential. In ticular, no alignment of a receiver should be underta without this equipment. 1RF Sweep Generator meeting the following minirr requirements: aFrequency Ranges 18 to 30 Me, 10 Me sweep width For Head End alignment, the following is also ne sary. 50 to 90 Me, 15 Me sweep width 170 to 225 Me, 15 sweep width bOutput adjustable with at least 0.1 volt maxim 2Cathode-ray Oscilloscope with a sensitivity of the o of O.lV/inch. 3Signal Generator to provide the following crystal i trolled or crystal calibrated frequencies: 21.6 Me Sound IF and Sound Traps 26.1 Me Video IF Carrier In addition, picture and sound RF carrier frequencies r be provided as required for Head End alignment (See Ser Data No. 18). 4DC Voltmeter 20,000 ohms per volt or vacuum tube with high voltage multiplier probe to permit readine 15 KV. 5(Optional) Heterodyne Frequency Meter for Head alignment, providing crystal calibrated frequencies as quired The picture tube in the television receiver may also be sidered a tool in the servicing of the receiver, since the dition of the information on the screen, together with c indications often serves to establish or at least localize trouble in a receiver in need of repair. The following sections of this publication are devotd data pertinent to the use of the above equipment in the sej ing of Hoffman Chassis 140, 142, 143, 146 and 147. OSCILLOSCOPE PATTERNS Following is a tabulation of waveforms taken at vat points in the circuit of Chassis 140, 142, 143, 146 and together with pertinent data on methods of connecting oscilloscope. /%W V RadioFans.CN MODELS 6lO, 6l2, 820, 821, 822, 826, 82?, 828, 912, 913 OSCILLOSCOPE PATTERNS VIDEO AMPLIFIER OUTPUT PIN 8 VI 1 1 O.H.F. 30 CYCLES FIRST SYNC SEPARATOR OUTPUT PIN 2 V112B O.H.F. 60 CYCLES SECOND SYNC SEPARATOR OUTPUT PIN 2 V113A O.H.F. 60 CYCLES PARTIALLY INTEGRATED VERTICAL SYNC JUNCTION R157, R158 O.H.F. 60 CYCLES. SINGLE HORIZONTAL SYNC PULSE PIN 7 Vll 5 O.H.F. 15,750 CYCLES PHASE COMPARATOR PULSE PINS 1 readings taken on 5,000 ohm per volt meter, .dings taken on vacuum tube volt meter. c voltages vary with signal. These values for general guidance only, isured to transformer center tap. tages measured between pins 7 and 8. lliance and contrast controls at minimum. Iliance at minimum, contrast at maximum, liance at maximum, contrast at minimum. ; ALIGNMENT, METHOD II Connect the sweep generator to pin 5 of the 6J6 mixer tube in the Head End, through an input filter of the type described under Step 1 above. Connect the voltmeter and oscilloscope as in Step 5 above. Set the AGC voltage at 3 volts as described in Step 3 above. Turn off the sweep in the sweep generator and adjust center frequency for maximum voltmeter reading near 24 Me. Adjust the sweep generator attenuator for a voltmeter reading of 2 volts. Loosely couple the signal (marker) generator to the mixer stage. The exact method of coupling used will de- pend on the output impedance and signal level produced by the signal generator. In some cases an insulated wire, inserted between the mixer tube and its shield will pro- vide sufficient coupling when connected to the output of the signal generator. In other cases it may be necessary to use direct resistive coupling to the sweep generator input network. In any case sufficient coupling must be used to provide good readable markers on the oscilloscope, but the coupling must not pull or detune the mixer stage. Set the sweep generator sweep width at 10.0 Me, and the signal generator markers at 26.1-Me and 22.3 Me. Adjust pass band characteristics using the curve in Figure 12 as a guide. Repeat Steps 4, 5 and 8. IReferring to the composite IF curve shown in Figure 12, it may be seen that the overall IF response is a function of the additive effect of the individual stagger-tuned coils. Thus the particular coil or coils requiring adjustment to correct errors in the overall response curve may be selected and reset. After final adjustment, the curve shape must approximate that shown in Figure 12C and the markers must be within the ranges specified. SOUND IF AND DETECTOR ADJUSTMENT Connect the sweep generator as in Step 1 under Video IF Alignment, Method II. Connect point W of the isolation network shown in Figure 11 to pin 5, V103. Disconnect one end of C108. Connect the oscilloscope and voltmeter to point X of the isolation network. Loosely couple the signal (marker) generator to the sweep input as in Step 7 under Video IF Alignment, _ Method II. Turn off the sweep on the sweep generator. Adjust the sweep generator for maximum meter reading near 21.6 Me. Set the signal (marker) generator at 21.6 Me. Set the sweep generator attenuator to give a reading of 3 V on the voltmeter. 0Set the sweep width at approximately 1 Me. 1Adjust T100 top, T100 bottom and T101 bottom to produce a response curve similar to that shown in Figure 13, with the 21.6 Me marker located as shown. MODELS 610, 612, 820, 821, n 822, 826, 82?, 828, 912, 913 12Move point W of the isolation network (Figure 11) to the junction of C107, R104 and R107. Leave the os- cilloscope connected to point X, but remove the volt- meter. 13Reconnect C108. 14Adjust T101 top to locate the 21.6 Me marker in the center of the discriminator S curve as shown in Figure 13. Some dissymetry in the non-linear portions of the S curve will probably appear, due to AGC action. Do not attempt to correct this dissymetry with the T101 top adjustment. 15Recheck the Sound Trap Adjustments and repeat Steps 2 through 10 (above). Z Fie. 17 VIDEO IF RESPONSE WAVEFORM 22.3MC _ 22 PIX CARRIER 26.1 MC BANDWIDTH CURVE IMPROPERLY SHAPED 22.3 MC 26 I MC BANDWIDTH CURVE IMPROPERLY SHAPED 60% 26 I MC MARKER SENSITIVITY CHECK As an overall check of receiver performance, the relative sensitivity of the receiver may be compared to that of another receiver of the same model, by observing comparative performance of the two sets on a weak signal input. If convenient, it is suggested that this sensitivity check be performed on all sets which have been completely realigned as a final overall measure of the performance of the receiver. Other intormation relative to band pass, sync operation, linearity, etc. may be checked by observing the test pattern of a station known to be good in all respects. RadioFans.CN Fig. 13 SOUND IF AND DETECTOR RESPONSE 21.6 I.HD BOTTOM VIEW SHOWING PLACEMENT OF PARTS ON CHASSIS ,. a. PLUG is INSTALLED ON ilS AND WIRED IN P* WITH LINE INPUT RECEPTACLE. z o m OJ