RAY Protection Circuit, X-RAY protection circuit | Toshiba TW40F80

7. X-RAY PROTECTION CIRCUIT

7-1. Outline

In case picture tube using high voltage, when high voltage rises abnormally due to components failure and circuit mal- function, there is possible danger that X-RAY leakage in- creases to affect human body. To prevent it, X-RAY protec- tion circuit is equipped.

7-2. Operation

Figure 9-23 shows the circuit diagram. Supposing high volt- age rises abnormally due to some reason, pulse at pin 9 of T461 also rises, and detection voltage ED rectified by D471 and C471 in X-RAY protection circuit rises. When ED rises, emitter voltage of Q464 divided by R459 and R462 becomes higher than [zener voltage (6.2V) of D458 + Q464 VBE ]. This causes Q464 turns on to supply base current to Q463.

Then Q463 turns on. By this Tr6 and Tr6 turn on to make ON/OFF pulse at pin 7of QA01 in low level, Q846 and Q845 turns off, then relay SR81 turns off. Tr6 and Tr7 are in thy- ristor-connection, and 5V of power holds protection opera- tion until main power switch is turned off. During circuit operation, power LED near main power switch blinks turn on and off in red.

Caution:

• To restart TV set, repair failure first.

5V

Z801

15
R9
R10		12V
Tr7
		Q463
R19	C894	Q464	R459

RELAY	Q846	Tr6		14
RELAY
SR80	16	R12	C1			R462
	16	R12	C1		D459	C458
					D459
		Tr5		R879	R468
		Tr5			R468

			R458
Q845	R11	R467	D458
Q845		R467

C459

17

ED

R472 T461

9

D471 C471

Fig. 9-23 X-RAY protection circuit

79

Image 79

Toshiba TW40F80 manual RAY Protection Circuit, X-RAY protection circuit

Contents

TW40F80 Contents Wide Aspect Conversion Circuit Failure Analysis Terminal FUNCTION, Description and Block Diagram Section XI Digital Convergence Circuit Section X Deflection Distortion Correction Circuit Reduction of Parts Count Section FeatureImproved Serviceability Outline Merits of BUS System Chassis Model Specifications Video 3 Inputs Front View IN-VIDEO Rear View 100 Remote Control View Starsight Newosd FRO. Surr Chassis Layout Construction of Chassis RF AGC Major FeaturesSection II TUNER, IF/MTS/S. PRO Module Circuit Block Outline Audio Multiplex Demodulation Circuit A.PRO Section Audio Processor A.PRO block diagram Configuration of the audio circuit and signal flow are given Terminal No Name POP Tuner Operation of Channel Selection Circuit SDA SCL Microcomputer Microcomputer Terminal Function Terminal Name Function In/Out Logic Remarks Microcomputer Terminal Name and Operation Logic EEPROMQA02 On Screen FunctionSDA System Block Diagram Local key assignment Function Local KEY Detection Method Code 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 Model Test Signal Selection Entering to Service ModeService Adjustment Contents to be Confirmed by Customer Failure Diagnosis ProcedureExecuting Self Diagnosis Function Self Check Understanding Self Diagnosis Indication Clearing method of self diagnosis result TV does Not Turned on Troubleshooting ChartYES No Picture Snow Noise No Acception of KEY-IN No Indication On Screen Memory Circuit Check Section IV DVD Switch Circuit DVD Switch Block Diagram Outline Operation ConfigurationSection V WAC Circuit Outline Circuit Operation Wide aspect conversion unit block diagram PB6348 Pin function of TC9097F QFP 80 pin Pin Function Name Function Names and functions of TC9097F VFL2 TC9097F system block diagram Block Diagram E2PROM OK? Wide Aspect Conversion Circuit Failure Analysis Procedures Raster Horizontal One Adjustment Method Principles 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 Section Main/Sub screen superimposing section Main/Sub Screen Superimposing Section MPC1832GT Main IC Terminal FUNCTION, Description and Block DiagramDiagram QY01 QY01 mPC1832GT pin layout QY03 TC9092AF internal block diagram QY03 TC9092AF pin layout CKW QY03 TC9092AF pin list No Pin name Pin function MRD1 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 Outline Circuit Operation Output CircuitActual Circuit Sawtooth Waveform Generation Output 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 Correction UZ11BSB +35V Over Current Protection CircuitTheory of Operation UZ22BSD Ketsu Raster Position Switching Circuit Basic Operation of Horizontal Drive SignalSection IX Horizontal Deflection Circuit Outline Horizontal Drive Circuit On period OFF period FBT Signal DEF/POWER PCBHorizontal Output Circuit Operation of Basic Circuit T4~t6 Description of the basic circuit T1~t2T2~t3 T3~t4 Linearity Correction LIN Amplitude CorrectionCurve Correction S Capacitor Linearity coil Left-right Asymmetrical Correction LIN coil EHT White Peak Bending Correction CircuitOutline Operation Theory Blanking Gate Protector Low Voltage Protection High Voltage DPC Circuit Regulator High Voltage Generation CircuitAFC ABL 2. +35V 1. +210VHigh Voltage CR-BLOCK High Voltage CircuitAnode FBT CR-BLOCK E H ActualED’ 23 X-RAY protection circuit RAY Protection Circuit Over Current Protection Circuit Block Diagram Functions and Features OUT Diode Modulator Circuit Actual 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 Prom Picture Adjustment Entering/Exiting Mode Service Mode First screen Second screen Initial screenSfull ENT Key function of remote control unit Each 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