Toshiba TW40F80 manual White Peak Bending Correction Circuit, Outline, Operation Theory, Eht

Page 72

4-2. White Peak Bending Correction Circuit

4-2-1. Outline

White peak area in screen picture may sometimes cause bend- ing in picture. See figure below.

In TP48E60 series, correction signal which video ripple in video output circuit power supply 200V is input to pin 24 (Bending correction terminal) of Q501. This corrects white peak bending.

4-2-2. Operation Theory

Fig. 9-11 shows circuit diagram. Video ripple in video out- put circuit power supply 200V suffers DC cut by C475, and is inverted in Q470, then input to pin 24 of Q501 via C481. Pin 24 of Q501 is a bending correction terminal. The volt- age which is applied to this terminal, controls phase of video signal to correct white peak bending.

	Q501
						R379
	EHT	24
	EHT	24
Bending correction						C415
Bending correction
	terminal
	terminal
							BB91
	Receiving Board						BB91
	Receiving Board				93
	Power, Def board				93
	Power, Def board								9V
									9V

R481	R483		200V
R481

C481 Inversion		R478	D406
			3	T416
Q470			C475
	D470
R482	R484	D474	C466
R482

White peak

Bending by white peak

Fig. 9-11 White peak bending correction circuit

72

Image 72

Contents TW40F80 Contents Terminal FUNCTION, Description and Block Diagram Wide Aspect Conversion Circuit Failure AnalysisSection X Deflection Distortion Correction Circuit Section XI Digital Convergence CircuitSection Feature Improved ServiceabilityOutline Merits of BUS System Reduction of Parts CountSpecifications Chassis ModelFront View Video 3 InputsRear View IN-VIDEORemote Control View 100Chassis Layout Starsight Newosd FRO. SurrConstruction of Chassis Major Features Section II TUNER, IF/MTS/S. PRO Module Circuit BlockOutline RF AGCAudio Multiplex Demodulation Circuit A.PRO block diagram A.PRO Section Audio ProcessorConfiguration of the audio circuit and signal flow are given POP Tuner Terminal No NameOperation of Channel Selection Circuit Microcomputer SDA SCLMicrocomputer Terminal Function Microcomputer Terminal Name and Operation Logic Terminal Name Function In/Out Logic RemarksOn Screen Function EEPROMQA02SDA System Block Diagram Local KEY Detection Method Local key assignment FunctionRemote Control Code Assignment Code FunctionTo TV set Custom codes are 40-BFH TV set for North U.S.A Code Function Optional Setting for Each Model OPT0 OPT1 Models HEXEntering to Service Mode Test Signal SelectionService Adjustment Failure Diagnosis Procedure Contents to be Confirmed by CustomerExecuting Self Diagnosis Function Understanding Self Diagnosis Indication Self CheckClearing method of self diagnosis result Troubleshooting Chart TV does Not Turned onYES No Acception of KEY-IN No Picture Snow NoiseMemory Circuit Check No Indication On ScreenSection IV DVD Switch Circuit DVD Switch Block Diagram Outline Configuration Section V WAC Circuit OutlineCircuit Operation OperationWide aspect conversion unit block diagram PB6348 Pin Function Pin function of TC9097F QFP 80 pinNames and functions of TC9097F Name FunctionVFL2 Block Diagram TC9097F system block diagramWide Aspect Conversion Circuit Failure Analysis Procedures E2PROM OK?Adjustment Method Raster Horizontal OneSection VI Dual Circuit Outline Principles of OperationScreen multi-search process System Component Diagram of Dual Unit Video/Color/Deflection Process Section OSD Sub Screen Process Section Sub screen process sectionMain/Sub Screen Superimposing Section Main/Sub screen superimposing sectionMain IC Terminal FUNCTION, Description and Block Diagram DiagramQY01 MPC1832GTQY01 mPC1832GT pin layout QY03 TC9092AF internal block diagram QY03 TC9092AF pin layout QY03 TC9092AF pin list No Pin name Pin function CKWMRD1 QY10/QY11 M518221-30ZS internal block diagram Section VII 3-DIMENSION Y/C Separator Circuit Outline Configuration Circuit DescriptionCircuit Description Terminal description PZ01 Section Viii Vertical Output Circuit Outline Theory of OperationOutput Circuit Actual CircuitSawtooth Waveform Generation Circuit OperationOutput Output stage power supply voltage Linearity Characteristic Correction Protection Circuit for V Deflection StopCharacter Correction Up-and Down-ward Extension Correction Up-and Down-ward Linearity Balance+35V Over Current Protection Circuit Theory of OperationUZ22BSD UZ11BSBRaster Position Switching Circuit KetsuSignal Section IX Horizontal Deflection Circuit OutlineHorizontal Drive Circuit Basic Operation of Horizontal DriveOn period OFF period Signal DEF/POWER PCB Horizontal Output CircuitOperation of Basic Circuit FBTDescription of the basic circuit T1~t2 T2~t3T3~t4 T4~t6Amplitude Correction Linearity Correction LINCurve Correction S Capacitor Left-right Asymmetrical Correction LIN coil Linearity coilWhite Peak Bending Correction Circuit OutlineOperation Theory EHTBlanking Low Voltage Protection Gate ProtectorHigh Voltage Generation Circuit AFCABL High Voltage DPC Circuit Regulator1. +210V 2. +35VHigh Voltage High Voltage Circuit CR-BLOCKAnode Actual FBT CR-BLOCK E HED’ RAY Protection Circuit 23 X-RAY protection circuitOver Current Protection Circuit Functions and Features Block DiagramDiode Modulator Circuit OUTActual Circuit Basic Operation and Current Path Later Half Scanning PeriodFirst Half Scanning Period Later Half of Flyback Period First Half of Scanning PeriodP.T Section XI Digital Convergence Circuit Outline Reset MemoryProm PLLPicture Adjustment Service Mode Entering/Exiting ModeInitial screen First screen Second screenSfull Key function of remote control unit ENTOperation procedure Each Screen Adjustment MethodNormal/Full Theater Wide1 Theater Wide 269.5 When CRT is Replaced When Convergence Unit is ReplacedCase Study Troubleshooting Adjusting Procedure in Replacing CRTAdjusting Procedure in Replacing Convergence Unit/Main Def Convergence Output Circuit Convergence Block Diagram Convergence Troubleshooting Chart Main Unit