docCOLOR TELEVISION TRAINING MANUAL Chassis Series VB8B
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COLOR TELEVISION TRAINING MANUAL Chassis Series VB8B
Training Manual VB8B Chassis COLOR TELEVISION TRAINING MANUAL FILE NO. Chassis Series VB8B CIRCUIT DESCRIPTION > Scan Velocity Modulation Circuit (SVM) > Right and Left Unbalanced Pincushion Correction Circuit > Inner Linearity Compensation by Dynamic S-Correction > Dynamic Focus Circuit Note: The VB8B chassis series is used for flat screen televisions which includes models DS27910 and DS32920 and is similar to the VB7C chassis. This manual contains only the different circuit descriptions from the VB7C chassis. For the complete circuit descriptions refer to the VB7C training manual reference number TI780010. REFERENCE NO. -1- TI780011 Training Manual VB8B Chassis Table of Contents 1. Chassis Summary 2. Scan Velocity Modulation Circuit (SVM) 3. Deflection Circuit 3-1. Outline 3-2. Pincushion Correction 3-3. Right and Left Unbalanced Pincushion Correction Circuit 3-4. Inner Linearity Compensation by Dynamic S-Correction 4. Dynamic Focus Circuit -2- ANT 1 H-S IC801 CPU WITH CAPTION DECODER 2 V-S 38 12 35 7 6 5 4 30 13 11 MUTE S1-SW S2-SW PIP TV/AV PIP AV 1/2 MAIN AV 1/2 FIX/VAR IN SELECT 15 2 BEAM VOLTAGE DETECT. ABL-IN OUT SELECT Y OSD (R) OSD (G) OSD (B) OSD (BLK) RESET AFT S-CURVE POWER FAIL POWER ON/OFF D627 +16V +135V C Y Q627 12V SW. C1/C2 INT. VIDEO 13 Q202 BUFFER H-S V-S T401 H-DRIVE TRANS. -B SIDE PCC Q402 HORIZ. OUTPUT Q451 R L BALANCE 4 3 39 36 37 33 34 38 4 9 S2-SW 11 V2/Y2 14 C1/C2 Q721 -B OUT -G OUT -R OUT F/ V L F/ V R MUTE H L L H L H Q001 5 3 Y1 IN V1 IN C1 IN C1 IN S1/SW IC1002 SELECT AV 1/2 2 1 13 V2 IN 12 Y2 IN IC1001 SELECT V/Y + C1/C2 H D482 D428 (16V) R428 ANODE LEAK DETECT. Q900 PIX TUBE DEFLECTION YOKE 13 12 5 3 2 1 L L H L H EXT VIDEO D445 -B D483 V 11 14 9 4 10 15 MAIN AV1/2 Y H V2/Y2 V1/Y1 V1/Y1 15 S1-SW 10 MAIN AV 1/2 8 AFC 5 ABL 1 6/7 H.V. T402 HORIZ. FOCUS OUTPUT SCREEN TRANS. HEATER 9 V +B 3 LOW +B 11 Q711 T8801 R Q701 (7V) +26V B D429 G HOLD DOWN DETECT. L Q712 Q1706,Q1707,Q1708 Q1709,Q1711,Q1712 VELOCITY MOD Q722 L R AV 1 Q702 HOLD DOWN INNER PIN Q471 Q462 Q401 HORIZ. DRIVE IC501 9 SIDE PCC AMP. VERT. Q461 OUTPUT Q462 ABL H-PULSE IC3401 MTS DECODER 4.5MHz SOUND L164 X161 TRAP 36 33 26 30 40 17 18 19 2 37 5 56 VIDEO 75 Q135 BUFFER IC101 SIGNAL PROCESS FM DET. BUS INTERFACE VIDEO DET. VIDEO SW. V SYNC SEP. H HORIZ. DRIVER DELAY LINE RGB OUT CONT BRITE SHARP BLACK STRETCH BPA COLOR DEMOD 5V B9 RESET OSD SW. 32 R AV 2 AV 1 5 6 SCL 10 SDA 9 Y 52 49 C 54 Q208 VIDEO OUT 44 12 13 14 8 15 D801 AV 2 SDL SCL ACL X141 78/79 SAW FILTER RF AGC 77 11 5V B6 9V 12V B4 5V ALWAYS B9 Q1700 Q1701 Q1702 Q1705 VM Q1703 Q831 RESET Q498 5V REG. Q486 9V REG. IC681 5V REG. 3 1 7 SC H PULSE INT. VIDEO C1/C2 S CLOCK 3.58 +12V Q681 12V SW DRIVE 9 COMB FILTER 12 16 14 EXT. VIDEO STANDBY MODE ALWAYS +5V CONTROL SIF BLOCK DIAGRAM 31 33 32 34 28 FOR CONTINUED PROTECTION AGAINST A RISK OF FIRE, REPLACE ONLY WITH THE SAME TYPE 4A, 125V FUSE. ATTENTION: POUR MAINTENIR LA PROTECTION CONTRE LES RISQUES D' INCENDIE UTILISER UN FUSIBLE DE RECHANGE DE MEME TYPE 4A, 125V. RF AGC BUS SCL IIC SCL BUS SDA IIC SDA 10 9 19 20 17 42 41 40 39 25 3 29 27 D694 IC601 POWER REG. Q635 OVERLOAD PROTECT. Q693, Q695 F BLK CAUTION IF AGC 6 5 RC IN KEY IN X IN X OUT D612 PHOTO COUPLER D625 D624 T601 CONVERTER TRANS. D621 Q601 SW. Q604 OSC Q605 ERR. AMP. L 10 R C Y Y 4 3 1 SP901 (L) SPEAKER (L) F/ V OUT (L) F/ V OUT (R) SP902 (R) SPEAKER (R) IC1201 Q1201 1 Q1202 S2 IN AV2 S1 IN AV1 K1051 AUDIO IN (R) AUDIO IN (L) A/V 2 IN VIDEO IN AUDIO IN (R) AUDIO IN (L) A/V 1 IN VIDEO IN K1001 15 2 8 IC001 AUDIO 3 5 AMP. Q1211 F/ V 5 SELECT 9 10 Y1 IN C1 IN S1 SW C Q1212 Y2 IN C2 IN S2 SW g7yam -3- 4A 125V A101 UHF/VHF TUNER WITH PLL & BAND SW IC802 EEPROM A1901 RC PRE-AMP C809 X 801 RL601 RELAY D601 FULL WAVE RECTIFIER Q658 RELAY DRIVER +12V C808 LF601 LINE FILTER PS601 POSISTOR SW1901-1906 CONTROL KEYS F601 AC FUSE L901 DEGAUSING COIL AC120V 60Hz C601 4A 125V Fig. 1-1 Training Manual VB8B Chassis Part 1 Chassis Description 1. Chassis Summary Fig. 1-1 shows a fundamental block diagram of the VB8B chassis. Part 2 Circuit Description Training Manual VB8B Chassis 2. Scan Velocity Modulation Circuit (SVM) 2-1 Outline The SVM (Scan Velocity Modulation) circuit improves the picture resolution by changing the electron beam scan velocity to emphasize the brightness change of the contour of the picture. Increasing the scan velocity of the electron beam makes the activation period of the fluorescent face shorter, lowering brightness. Decreasing scan velocity, increases the period of activation and raises brightness. Because this system does not change the volume of the beam current itself, it does not degrade the focus quality. Fig. 2-1 shows the SVM circuitry of the VB8B chassis, Fig. 2-2 shows the functional waveforms respectively, and Fig. 2-3 shows the SVM block diagram. 2-2 Operation At the SVM circuitry, the input video signal with positive polarity (a) is amplified and inverted by Q1701. After passing through Q1702, the signal is differentiated by R1711 and L1701 and becomes (b). This 1st differential signal passes through Q1705 and is further shaped by C1708, C1709, L1702, and R1717, and amplified by Q1706. The result is the current waveform (c) which flows in the SVM coil. Q1707 and Q1708 compose a complementary-amplification circuit connected directly at the base. The base clipping provided by Q1707 and Q1708 VBE eliminates the fundamental noise generated as a result of primary differentiation and improves the signal-to-noise ratio. Q1709 and Q1711 compose a class B push-pull current-amplification circuit. The voltage at the connection points of the two output transistor collectors is balanced by half of the 130V source voltage. Direct feedback is applied to the two output transistors by R1736. In operation, when the negative direction modulation voltage is applied to the output circuitry, Q1709 conducts and current flows into the SVM coil charging C1722. At this time the deflection speed is increased and the brilliance decreases. Next, when the positive direction modulation voltage is applied to the output circuitry, Q1711 conducts and current flows through the SVM coil discharging C1722. At this time, the deflection speed is decreased and the brilliance increases. The current is 2nd differentiated by the SVM coil and C1722. The SVM coil consists of two coils assembled in the DY/CPM (Convergence Purity Magnet), which is located on the CRT neck and positioned over the electron beam gun. One coil is positioned on the upper side of the gun and the other one is at the lower side of the gun. The current through the SVM coil generates a magnetic field at right angles with the electron beam and is added to the electromagnetic field produced by the horizontal deflection yoke. Thus the deflection velocity of the electron beam is modulated by the SVM magnetic field resulting in a change of brightness. The total horizontal deflection magnetic field applied to the electron beam results in waveform (d). The horizontal electron beam velocity changes as shown in (e) and the resultant brightness change is shown in (f). When OSD (On Screen Display) characters are displayed, including captions, the blanking pulse is added to transister Q1701 by Q1703 stopping the SVM so the characters will not be distorted. Note: This SVM circuitry is designed to be most effective at a frequency range of 3MHz to 4 MHz of the video signal where the resolution of the picture is most visible. -4- Training Manual VB8B Chassis C1748 C1705 16EM100 KZ0.01F Q1709 2SA 1837LB L1703 R1742 2SJ150 C1722 Q1711 2SC 160EM 4793LB 22BE 1 C1719 160EM 10BE C1717 FK4700 (D:BF) C1709 CJ56 CL Q1703 2SC1740SS: 2SC945AKA: 2SC1815GR: 2SC536G-NP Q1708 AC Q1712 AE C1724 KK270 C1716 KK820 Q1701 AC R1716 J R1707 1/10GJ 3.3KC R1706 1/10GJ 1.8KC C1706 25EM 100 C1701 FK0.015 (D:BF) D1701 TVR1B R1714 1/10 GJ 820C R1708 1/10GJ 3.3KC R1703 1/10GJ 68KC R1700 1/10GJ 4.7KC R1753 100 Q1700 AC D1708 R R1737 1/2DJ 39B R1720 1.8K 5V B6 R1723 R1722 120K 33K C1749 35EM100 R1725 100 R1724 39K Q1706 AE R1728 DJ47B C257 KK0.01 LZB <F.BLK> C1712 FJ0.012 (D:BF) C258 16EM 47 L256 J C1711 FK0.01 (D:BF) Fig. 2-2 Q1702 AE C1707 KK4700 LZB <SVM SW> R1729 J C1704 CJ270CL R1719 1/10GJ 560C R1711 Q1705 1/10 GJ AE 1KC L1701 L2B9100KN :L2E1100KN R1710 R1712 1/10 220 GJ 1.8KC C1714 KK820 R1736 12K R1733 100K R1744 1.2K C1740 EM1 L1702 L2B9330KN: L2E1330KN R1730 DJ1K Q1707 AE R1731 J C1715 200FK4700 (H:B) R1732 1/2DJ 1.2K D1707 SB07 -03N R1740 1/2DJ 2.7B R1735 1/2DJ 1.2K R1727 DJ10B K17C J10EA030N: J10KR030N C1708 CJ120 CL R1734 100K L1704 C1726 500 CK270GAA D1705 SB07 -03N L1705 L1703/1704/1705 ZZ0122: B4Z21B 0080N 3 R1738 1/2DJ 39B C1721 16EM 47 K17H V/M COIL 130V R1741 1/2DJ 2.2B R1702 1/10GJ 22KC R1705 1/10GJ 560C R1717 1/10GJ 470C L2B95R6KN: L2E15R6KN 2 Fig. 2-1 R1704 DJ100 L1706 1 R1718 1/10GJ 1.2KC R1709 J 9V Q208 AC C1713 KK680 15 53 R208 1/10GJ1KC <Y-OUT> 49 VCC amplitude IC101 LA76834NMP (a) Video input signal amplitude (b) Differentiated waveform current Current waveform in SVM coil (c) magnetic field Horizontal deflection magnetic field (d) velocity ++ + (e) - Current SVM Coil + - Velocity of horizontal deflection - Neck of CRT The brightness change of fluorescent substance on the CRT luminance (f) R G B Electron Gun time Video Buffer Signal Q1700 Fast Blanking SVM Pulse Mute Q1703 Video Signal Amplifier Q1701 1st Differentiate & Amplifier Q1702,Q1705, R1711,L1701 Shaping C1708,C1709, L1702,R1717 Fig. 2-3 -5- Amplifier Q1706 2nd Differentiate & Output Q1707, Q1708 Negative Feedback Q1712 Q1709, Q1711 Training Manual VB8B Chassis 3. Deflection Circuit 3-1 Outline Fig. 3-1 shows the block diagram of the deflection circuit of VB8B Chassis. IC501 V-Output <LA7846N> 6 Fig. 3-1 Deflection Yoke 3 Vert. Coil IC101 IVCD <LA76834NMP> 30 25 V-Drive S-correction Capacitor Q411 H-Output Q401 C417 T401 Drive Trans T402 FlyBack Trans. Linearity Coil H-Drive ABL/ACL Horiz. Coil L413 L416 Dummy Coil 26 Pincushion Correction Q461 L414 Q462 Fo (dynamic) EW-Out 11 T8801 C477 C8804 Dynamic Focus Q451 Q471 Fv Fh Fo (static) Screen Inner Pincushion Right & Left Unbalanced Pincushion Correction Correction The horizontal drive pulse is output from pin 30 of IC101 (signal processor) and input to the horizontal output stage. The vertical sawtooth signal is output from pin 26 of IC101 and input to pin 6 of IC501. The vertical output signal is output from pin 3 of IC501. The signal processor (IC101) is controlled and compensated for V-size, S-correction, V-linearity, Pin distortion correction, H-size and H-shift by the CPU via the I2C bus. Pincushion correction (PCC) is accomplished by adding the east-west parabola pulse output from pin 25 to the horizontal output circuit. Inner pincushion correction (Inner PCC) and right & left pincushion unbalance correction are accomplished by using FETs in parallel with C417, the S-correction capacitor. Dynamic focus is also accomplished using T8801 in parallel with the S-correction capacitor C417. 3-2 Pincushion Correction In the PCC correction circuit, consisting of Q461 and Q462, the east-west parabola signal supplied from pin 25 of IC101 is added at the horizontal output stage and pincushion correction is performed by varying the DC bias. Further, the ABL and ACL voltage is fed back to the base of Q461 to compensate for the width change by the beam current. -6- R452 8.2K R451 1/2DJ 100K R454 820 R L UNBALANCE V6451 X R450 X R457 2SJ1.8K R456 2SJ1.8K R455 680 R453 1K PCC AMP Q451 TXXGA 000868N R459 2SJ3.9K R458 2SJ3.9K 1AA2HEA0206-Q462A C478 X R477 100 Q462 2SB1274 (QRA:RRA) C476 500KK 1000A Q471 TXXGA 000868N Q461 2SC3114 (R:S:T) R460 1/6NF 560 R476 2.7K C477 250MJ0.15 (AT:AP:AU) C472 63GJ 0.1V: HJ0.1 D463 1SS133 C479 KK4700 Q472 AE R468 56K R465 1/6NF120K D473 RD10EB2 :MTZJ10B D472 MTZJ10A C474 400GK 0.1P R474 470K C475 16PM10 R475 1SJ 47K INNER PIN R472 680 D462 1SS133 R473 5.6K R470 1/2DJ 100K FO T8801 L18B0450N K16P C8804 1000KK2200 (CRD:NHA) C8802 J C8803A 1000KK 2200(CRD:NHA) C8801 X DAF AFTER S V H Fig. 3-2 -7-B GND PCC H DEFLECTION-YOKE CRT COMPONENT K16V BEFORE S KP DAF KX1P KX3P KX4P KX5P KX J30B0250N :J30B1380N C445 25EM22 :EM22LBZA KX1P/.../KX5P KV AFTER S BEFORE S D446 MTZJ20A :RD20EB1 D445 EU1 R445 1SJ560 T402 L40B13100 F.B.T 11 10 8 3 7 6 LOW +B V+B SC FO HV HEATER AFC 9 5 2 4 1 C462 CJ 100CL <E/W> C463 FK0.015 (D:BF) R462 1/10GJ 4.7KC R463 1SJ3.3 C464 63GJ 0.15V: HJ0.15 C434 160PM 0.47D C417 250MJ0.18 (UAP:AT:AU) L413 L71B0250N C413 400NJ 0.012 EAQ R413 5SJ 3.9VCA C419 100GK2.2P L414 LM0045 :LM0045D :L26B0170N R434 :L26B0260N 27K R418 2SJ2.7K D471 R C422 250GJ 2.2P C414 630NJ 0.022 EAQ TP50 D406 ERB44-04 C493 100PM 2.2X X H-OUT Q402 2SD2645YB T401 AD0008 :AD0008C R491 DJ1K X R494 DJ390K C406 500KK 470A L401 L26B 0800N R406 L402 R416 1/2DJ DJ33 L3004 5.6K J407 C407 J 500KK 2200A <ABL> TP51 L403 ZZ0208 D407 ERD07 -15L R485 R492 18K 1/6NF 33K R276 12K C412 C411 1500MH 1500MH L416 7100 L26B0770N: 6500 L26B4090N (XK:AN) (XK:AN) R471 1/10GJ 180KC D487 S5277B :ED0445 :MPG06D :ERA15-02 <ACL> R493 DJ180K Q401 2SC2271 (D-C:E-C :D:E) R408 1SJ15K C408 160EM 4.7BE R407 2SJ6.8K Training Manual VB8B Chassis Fig. 3-2 shows a deflection circuit diagram of VB8B chassis Training Manual VB8B Chassis 3-3 Right and left unbalanced pincushion correction circuit 3-3-1 Outline The DY and CPM are adequate for landing the electron beam on the fluorescent screen after passing through the shadow mask. However, as for the pathway of the electron beam, unbalance of right and left occurs because of pincushion distortion. Particularly in the flat face CRT, the unbalanced pincushion distortion can stand out as shown in Fig. 3-6-1. This is because the migration length of the electron beam is different between the central part and the corner parts of the CRT face. Generally, conventional pincushion correction circuitry can correct the isometric distortion, but it cannot correct pincushion distortion that is right and left unbalanced. This unbalanced pincushion correction circuit is constructed with a FET (field effect transistor) and a resistance circuit which are connected in parallel with the S-correction capacitor to resolve the unbalanced pincushion distortion. 3-3-2 Operation Fig. 3-3 shows the diagram of the right and left unbalanced pincushion correction circuit. When the S-correction capacitor is charged by the horizontal deflection current ia in the polarity as shown by the arrow in Fig. 3-3, a positive voltage is impressed between G (gate) and S (source) of the FET by the bias circuit. The FET turns ON between D (drain) and S (source) and current flows according to the voltage across the S-correction capacitor. When the S-correction capacitor begins to discharge and the bias voltage between gate and source of the FET becomes lower than the threshold level the FET turns OFF. Fig. 3-4-1 and Fig. 3-4-2 show the waveforms of the horizontal deflection current during the horizontal scan period. In the scanning interval last half the horizontal deflection current decreases so that the discharge current from the S-correction capacitor flows towards the FET, and amplitude of the upper part of horizontal deflection current becomes less. Fig. 3-5-1 and Fig. 3-5-2 show the waveforms of horizontal deflection current in the vertical scan period. When the voltage impressed across the S-correction capacitor is high due to the horizontal deflection current being high, the FET current will become high. This results in the greatest amount of correction. Therefore, the middle of the envelope of the upper part of horizontal deflection current becomes dented as shown in Fig.3-5-2. Because of this, deflection of the right side of the image becomes less, and the middle of the right side of the image becomes dented as seen in Fig. 3-6-2. In this way the distorted image, which is right and left unbalanced as shown in Fig. 3-6-1, is corrected as shown in Fig. 3-6-2. Note: Since correction of the right and left unbalanced pincushion will make the right side of the image smaller than the left side, additional consideration should be given to the linearity coil. -8- Training Manual VB8B Chassis Q411 H-Output Horiz. Coil D407 L416 ia L413 Linearity Coil ib ib' = ib - ic ( at Q451=ON) ic R459 D C417 S-correction Capacitor R452---R455 Fig. 3-3 1H Horizontal time Q451 G S Right & Left Unbalanced Pincushion Correction ia = - ib Blanking time R456 R451 1V Scanning time ib t ia Fig. 3-4-1 ta tb Fig. 3-5-1 Horizontal Deflection Current ic ib' ib t ia Fig. 3-4-2 Fig. 3-5-2 a Fig. 3-6-1 -9- b a=b>c c Fig. 3-6-2 Training Manual VB8B Chassis 3-4. Inner Linearity Compensation by Dynamic S-Correction 3-4-1 Outline Generally, a flat picture tube has a geometric error that is called “inner pin distortion.” Inner pin distortion is a geometric error resulting in a different cross hatch width between the sides and the center of the image as shown in Fig. 3-8-1. Compensating for this error is almost impossible by conventional PCC circuits. This inner pin distortion can be overcome by adapting the value of the S-correction capacitor during a certain interval of the scan time. In this way an improved S-shaped deflection current can be realized to compensate for the above mentioned error of any picture tube. 3-4-2 Operation Fig. 3-7 shows the diagram of the inner pincushion correction circuit. Perfect horizontal linearity can be realized by a continuous adaptation of the deflection current during the horizontal scan. Creating a more linear deflection current during the start and end of the scanning time can be realized simply by increasing the value of the S-correction capacity during these scan intervals. This is accomplished by switching another S-correction capacitor (C477) in parallel with C417 during the proper scan interval or duty cycle. Generally, the horizontal width is dependent on the voltage across the S-correction capacitor. Therefore, by modulating this voltage the envelope of the horizontal deflection current becomes parabola shaped. At the vertical scanning time of the top and bottom corners the voltage across the S-correction capacitor is low. At the vertical scanning time of the center part the voltage across the S-correction capacitor is high. When the voltage across the S-correction capacitor C417 is low, D472 is OFF, Q451 is OFF, Q471 is ON and C477 serves as the additional S-correction capacitor, and the horizontal width is widened. When the voltage across the S-correction capacitor C417 is high, D472 is ON, Q451 is ON, Q471 is OFF and C477 is removed, and the horizontal width is not changed. In this way the inner linearity can be fully compensated over the complete picture by modulating the duty cycle as a frame period. Fig. 3-9-3 shows the horizontal deflection current with the inner Pincushion correction circuit and Fig. 3-8-4 shows the picture after geometrical adjustment. -10- Training Manual VB8B Chassis Horiz. Coil Linearity Coil Fig. 3-7 Additional S-correction Capacitor L413 C474 S-correction Capacitor C417 C475 R475 Q471 R476 R470 C477 D C476 R474 R472---R473 D472 G Q451 D473 Without Inner Pincushion Correction (the best adjustment) corner = straight center = pin 1H S R477 Inner Pincushion Correction 1V Fig. 3-9-1 Fig. 3-8-1 Without Inner Pincushion Correction Horizontal Deflection Current Fig. 3-9-2 corner = barrel center = straight Fig. 3-8-2 With Inner Pincushion Correction The corners are widened. Fig. 3-8-3 After Geometric Adjustment Fig. 3-8-4 -11- Fig. 3-9-3 Training Manual VB8B Chassis 4. Dynamic Focus Circuit 4-1 Outline The migration length of the electron beam is different between the central part and the four corners of the screen. This difference is further increased in a flat face CRT compared to a conventional round shaped CRT. The most suitable focus voltage is usually different according to the migration length of the electron beam. Therefore, it is necessary to change the focus voltage according to the beam landing position to achieve optimum focus. This is called “DAF” (Dynamic Astigmatism Focusing). The optimum focus voltage waveform is a parabola shape in the horizontal and vertical periods (Fig. 4-2). Dynamic focus is realized by superimposing the amplified deflection current wave upon the focus electrode. 4-2 Operation The parabola voltage of the horizontal period is impressed across the S-correction capacitor C417 and coupled by C8803A and C8804 to the primary of T8801. Any DC voltage component is blocked by C8803A and C8804. The parabola voltage is boosted up to approximately 1000V at the secondary coil of the step-up transformer T8801. The parabola voltage is supplied to FBT T402 pin 11 and superimposed upon the DC voltage through the coupling capacitor in the FBT. The static focus voltage and the dynamic focus voltages are supplied to their respective focus electrodes of the CRT. Note: The vertical parabola correction function is not used in the VB8B chassis. For example, on the specification of CRT A68ERF031X013, the dynamic focus voltage is as follows: Line parabola (screen edge-to-edge) on Vdyn = typ. 800V ---horizontal focus voltage Frame parabola on Vdyn = typ. 350V ---vertical focus voltage Because the specification for the CRT shows the voltage for effective image screen, it is different from the actual voltage and is more than 1000V as horizontal parabola voltage. -12- Training Manual VB8B Chassis G6 G5 G4 G3 G2 G1 Example of Electron Gun (1)Gfoc (2)Gdyn Static Focus Fig. 4-1 Dynamic Focus T402 Flyback Trans. 1H 1H Horiz. Coil Linearity Coil L413 Dynamic Focus C8803A T8801 11 Dynamic Focus Input C8804 C417 Fv Fh Static Focus Screen S-correction Capacitor Cathode Video Fig. 4-2 t H Effective Screen 1H (edge to edge) Dynamic Focus Line Parabola 1V 1H Specification of CRT V t 1V Frame Parabola t Note: These waveforms are the ideal concept of dynamic focus, not actual. -13- t Training Manual VB8B Chassis For parts or service contact SANYO Fisher Service Corporation 21605 Plummer Street Chatsworth, CA 91311 (U.S.A.) 300 Applewood Crescent, Concord, Ontario L4K 5C7 (CANADA) July / 2002 / SMC Printed in U.S.A. -14-
