Toshiba TW40F80 manual Actual Circuit

Page 83

3. ACTUAL CIRCUIT

In the actual circuit, the resonant capacitor is split into two as shown in Fig. 10-7. One, C440, is inserted between the collector of the H. OUT transistor and ground and another C444 inserted between the collector and emitter. In Fig. 10- 5, C440 is expressed as C1 and C444 as C2, and the resonant current path for the flyback period is shown by arrows.

In a conventional circuit, when brightness of a picture tube varies, high voltage current varies and the high voltage also varies. As a result, horizontal amplitude also varies.

However, in this circuit, the horizontal amplitude variation can be suppressed to near zero if the high voltage current varies with variation of the high voltage.

When the scanning period completes, the energy stored in the deflection yoke LDY is transferred to the resonant ca- pacitor in a form of current IY. In this case, the current is split into two; IY1 passing through C1, C3 and IY2 passing through C2. In the same way, the energy stored in the pri- mary winding of the FBT is transferred to the resonant ca- pacitor in the form of IP. In this case, the current (path) is also split into two; IP1 passing through C1 and IP2 passing through C2, C3. Concequently, the current differences be- tween IY1 and IP2 (IY1-IP2) passes through C3.

When the high voltage current IH reduces with a dark pic- ture, the current IP in the primary circuit decreases, so IP1 and IP2 also decrease. However, a current flowing into (IY1- IP2) increases as IP2 decreases. As a result, the pulse devel- oping at the point B increases and the voltage Vm at Csm also increases as shown in Fig. 10-8. That is, when a dark picture appears, the voltage across S-curve capacitor CS in- creases as shown in Fig. 10-8, the high voltage rises, and the horizontal amplitude is going to decrease. But, as VS in- creases, the deflection yoke current increases and this works to increase the horizontal amplitude. Accordingly, if the brightness of picture changes, the horizontal amplitude is maintained at a constant value. This is one of the fine fea- tures the circuit has.

H.

OUT

IP1	IP2			FBT
C1
			LDY	IH
			LDY	IP
IY1		IY2	CS
		IY	CS
		IY	VS
			VS
		C2
				VB
			Lm
	IP2		C3	Vm
	IP2

	IY1		Csm
	IY1

Fig. 10-5

VB

VS

0

Vm

Fig. 10-6

83

Image 83

Contents TW40F80 Contents Wide Aspect Conversion Circuit Failure Analysis Terminal FUNCTION, Description and Block DiagramSection XI Digital Convergence Circuit Section X Deflection Distortion Correction CircuitReduction of Parts Count Section FeatureImproved Serviceability Outline Merits of BUS SystemChassis Model SpecificationsVideo 3 Inputs Front ViewIN-VIDEO Rear View100 Remote Control ViewStarsight Newosd FRO. Surr Chassis LayoutConstruction of Chassis RF AGC Major FeaturesSection II TUNER, IF/MTS/S. PRO Module Circuit Block OutlineAudio Multiplex Demodulation Circuit A.PRO Section Audio Processor A.PRO block diagramConfiguration of the audio circuit and signal flow are given Terminal No Name POP TunerOperation of Channel Selection Circuit SDA SCL MicrocomputerMicrocomputer Terminal Function Terminal Name Function In/Out Logic Remarks Microcomputer Terminal Name and Operation LogicSDA On Screen FunctionEEPROMQA02 System Block Diagram Local key assignment Function Local KEY Detection MethodTo TV set Remote Control Code AssignmentCode Function Custom codes are 40-BFH TV set for North U.S.A Code Function OPT0 OPT1 Models HEX Optional Setting for Each ModelService Adjustment Entering to Service ModeTest Signal Selection Executing Self Diagnosis Function Failure Diagnosis ProcedureContents to be Confirmed by Customer Self Check Understanding Self Diagnosis IndicationClearing method of self diagnosis result YES Troubleshooting ChartTV does Not Turned on No Picture Snow Noise No Acception of KEY-INNo Indication On Screen Memory Circuit CheckSection IV DVD Switch Circuit DVD Switch Block Diagram Outline Operation ConfigurationSection V WAC Circuit Outline Circuit OperationWide aspect conversion unit block diagram PB6348 Pin function of TC9097F QFP 80 pin Pin FunctionName Function Names and functions of TC9097FVFL2 TC9097F system block diagram Block DiagramE2PROM OK? Wide Aspect Conversion Circuit Failure Analysis ProceduresRaster Horizontal One Adjustment MethodScreen multi-search process Section VI Dual Circuit OutlinePrinciples of Operation 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 SectionMPC1832GT Main IC Terminal FUNCTION, Description and Block DiagramDiagram QY01QY01 mPC1832GT pin layout QY03 TC9092AF internal block diagram QY03 TC9092AF pin layout CKW QY03 TC9092AF pin list No Pin name Pin functionMRD1 QY10/QY11 M518221-30ZS internal block diagram Circuit Description Section VII 3-DIMENSION Y/C Separator Circuit OutlineConfiguration Circuit Description Terminal description PZ01 Theory of Operation Section Viii Vertical Output Circuit OutlineCircuit Operation Output CircuitActual Circuit Sawtooth Waveform GenerationOutput Output stage power supply voltage Up-and Down-ward Linearity Balance Linearity Characteristic CorrectionProtection Circuit for V Deflection Stop Character Correction Up-and Down-ward Extension CorrectionUZ11BSB +35V Over Current Protection CircuitTheory of Operation UZ22BSDKetsu Raster Position Switching CircuitBasic Operation of Horizontal Drive SignalSection IX Horizontal Deflection Circuit Outline Horizontal Drive CircuitOn period OFF period FBT Signal DEF/POWER PCBHorizontal Output Circuit Operation of Basic CircuitT4~t6 Description of the basic circuit T1~t2T2~t3 T3~t4Curve Correction S Capacitor Amplitude CorrectionLinearity Correction LIN Linearity coil Left-right Asymmetrical Correction LIN coilEHT White Peak Bending Correction CircuitOutline Operation TheoryBlanking Gate Protector Low Voltage ProtectionHigh Voltage DPC Circuit Regulator High Voltage Generation CircuitAFC ABLHigh Voltage 1. +210V2. +35V Anode High Voltage CircuitCR-BLOCK ED’ ActualFBT CR-BLOCK E H 23 X-RAY protection circuit RAY Protection CircuitOver Current Protection Circuit Block Diagram Functions and FeaturesOUT Diode Modulator CircuitActual Circuit First Half Scanning Period Basic Operation and Current PathLater Half Scanning Period P.T Later Half of Flyback PeriodFirst Half of Scanning Period Section XI Digital Convergence Circuit Outline PLL ResetMemory PromPicture Adjustment Entering/Exiting Mode Service ModeSfull Initial screenFirst screen Second screen ENT Key function of remote control unitNormal/Full Operation procedureEach Screen Adjustment Method Theater Wide1 Theater Wide 269.5 Case Study When CRT is ReplacedWhen Convergence Unit is Replaced Adjusting Procedure in Replacing Convergence Unit/Main Def TroubleshootingAdjusting Procedure in Replacing CRT Convergence Output Circuit Convergence Block Diagram Convergence Troubleshooting Chart Main Unit