Toshiba TW40F80 manual On period OFF period

Page 67

(4)To shorten the storage time and the falling time, a suf- ficiently high reverse bias voltage must be applied to allow a heavy reverse current to flow. This operation also stabilizes operation of the horizontal output tran- sistor.

+

0

-

+

ib

0

V-

(a)

Fig. 9-2

On period

OFF period

t Input waveform (b)

Forward current

t Base current (c) Reverse

current

Falling time

Storage time

3-2. Circuit Description

In the N5SS chassis, the off drive system is employed.

(1)When Q1 inside Q501 is turned on, Q402 base is for- ward biased through 9V ® pin 22 of Q501 (H. VCC)

® pin 23 of Q501 (H. Out) ® R411/R410 resistor di- vider, and then, Q402 collector current flows through 125V ® R416 ® T401. In this case, the H output tran- sistor Q404 turns on with the base-emitter reverse bi- ased because of the off drive system employed.

Q501

H. Vcc

22

(2)On the contrary, when Q1 inside IC501 is off (pin 8 is 0V), base-emitter bias of Q402 becomes 0V and Q402 turns off, and a collector pulse as shown in Fig. 9-3 develops at the collector.

The voltage is stepped down and Q404 is forward bi- ased with this voltage, thus turning on Q404.

(3)In this way, by stepping down the voltage developed at primary winding of the drive transformer and by ap- plying it to Q404, a sufficient base current flows into Q404 base, thereby switching the Q404.

T401

H drive

transistor

C431	C417

Q1

R411

23

R410

Q402

H drive

transistor

9V

Fig. 9-3

1

3

R415

		Q404
		H output
2	4	transistor
2	4

C413

	+	V1
	+	V2
	R416	V2

C416

+125V

VCP

Q402 Q402

OFF ON

0V

0V

67

Image 67

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 LogicEEPROMQA02 On Screen FunctionSDA System Block Diagram Local key assignment Function Local KEY Detection MethodCode Function Remote Control Code AssignmentTo TV set Custom codes are 40-BFH TV set for North U.S.A Code Function OPT0 OPT1 Models HEX Optional Setting for Each ModelTest Signal Selection Entering to Service ModeService Adjustment Contents to be Confirmed by Customer Failure Diagnosis ProcedureExecuting Self Diagnosis Function Self Check Understanding Self Diagnosis IndicationClearing method of self diagnosis result TV does Not Turned on Troubleshooting ChartYES 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 MethodPrinciples of Operation Section VI Dual Circuit OutlineScreen 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 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 Configuration Circuit Description Section VII 3-DIMENSION Y/C Separator Circuit OutlineCircuit 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~t4Linearity Correction LIN Amplitude CorrectionCurve Correction S Capacitor 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 ABL2. +35V 1. +210VHigh Voltage CR-BLOCK High Voltage CircuitAnode FBT CR-BLOCK E H ActualED’ 23 X-RAY protection circuit RAY Protection CircuitOver Current Protection Circuit Block Diagram Functions and FeaturesOUT Diode Modulator CircuitActual Circuit Later Half Scanning Period Basic Operation and Current PathFirst Half Scanning Period First Half of Scanning Period Later Half of Flyback PeriodP.T Section XI Digital Convergence Circuit Outline PLL ResetMemory PromPicture Adjustment Entering/Exiting Mode Service ModeFirst screen Second screen Initial screenSfull ENT Key function of remote control unitEach Screen Adjustment Method Operation procedureNormal/Full Theater Wide1 Theater Wide 269.5 When Convergence Unit is Replaced When CRT is ReplacedCase Study Adjusting Procedure in Replacing CRT TroubleshootingAdjusting Procedure in Replacing Convergence Unit/Main Def Convergence Output Circuit Convergence Block Diagram Convergence Troubleshooting Chart Main Unit