+35V Over Current Protection Circuit, UZ22BSD | Toshiba TW40F80

3-1. +35V Over Current Protection Circuit

The over current protection circuit cuts off the power supply relay when it detects abnormal current increased in the +35V power line due to failure of the vertical deflection circuit.

3-1-1. Theory of Operation

Fig. 8-11 shows the circuit diagram of the over current protection circuit. When the load current of the +35V line increases, the voltage across a resistor of T370 will also increase.

When the voltage increases across R370. and the voltage developed across R371 becomes higher than the Vbs of Q370, Q370 turns on and a voltage develops across R374 due to the collector current flowing. When this voltage increases to a value higher than about 7V, Z801 operates, thus cutting off the power relay. When the circuit operates, a power LED provided will turn on and off in red.

C303

	R370
		+35V
R372		C310	D302
		C310

	R371
	C370
D421
UZ22BSD		Q370
		Q370
		2SA933SQ
	R373	D370
	R373	UZ11BSB
		UZ11BSB
			R375
		C371
	R374

R327

FBT pin 6

To pin 14 (GATE) of Z801

Fig. 8-11

64

Image 64

Toshiba TW40F80 manual +35V Over Current Protection Circuit, Theory of Operation, UZ22BSD, UZ11BSB

Contents

TW40F80 Contents Terminal FUNCTION, Description and Block Diagram Wide Aspect Conversion Circuit Failure Analysis Section X Deflection Distortion Correction Circuit Section XI Digital Convergence Circuit Section Feature Improved ServiceabilityOutline Merits of BUS System Reduction of Parts Count Specifications Chassis Model Front View Video 3 Inputs Rear View IN-VIDEO Remote Control View 100 Chassis Layout Starsight Newosd FRO. Surr Construction of Chassis Major Features Section II TUNER, IF/MTS/S. PRO Module Circuit BlockOutline RF AGC Audio Multiplex Demodulation Circuit A.PRO block diagram A.PRO Section Audio Processor Configuration of the audio circuit and signal flow are given POP Tuner Terminal No Name Operation of Channel Selection Circuit Microcomputer SDA SCL Microcomputer Terminal Function Microcomputer Terminal Name and Operation Logic Terminal Name Function In/Out Logic Remarks EEPROMQA02 On Screen FunctionSDA System Block Diagram Local KEY Detection Method Local key assignment Function Code Function Remote Control Code AssignmentTo TV set Custom codes are 40-BFH TV set for North U.S.A Code Function Optional Setting for Each Model OPT0 OPT1 Models HEX Test Signal Selection Entering to Service ModeService Adjustment Contents to be Confirmed by Customer Failure Diagnosis ProcedureExecuting Self Diagnosis Function Understanding Self Diagnosis Indication Self Check Clearing method of self diagnosis result TV does Not Turned on Troubleshooting ChartYES No Acception of KEY-IN No Picture Snow Noise Memory Circuit Check No Indication On Screen Section IV DVD Switch Circuit DVD Switch Block Diagram Outline Configuration Section V WAC Circuit OutlineCircuit Operation Operation Wide aspect conversion unit block diagram PB6348 Pin Function Pin function of TC9097F QFP 80 pin Names and functions of TC9097F Name Function VFL2 Block Diagram TC9097F system block diagram Wide Aspect Conversion Circuit Failure Analysis Procedures E2PROM OK? Adjustment Method Raster Horizontal One 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 Main IC Terminal FUNCTION, Description and Block Diagram DiagramQY01 MPC1832GT QY01 mPC1832GT pin layout QY03 TC9092AF internal block diagram QY03 TC9092AF pin layout QY03 TC9092AF pin list No Pin name Pin function CKW MRD1 QY10/QY11 M518221-30ZS internal block diagram Configuration Circuit Description Section VII 3-DIMENSION Y/C Separator Circuit OutlineCircuit Description Terminal description PZ01 Section Viii Vertical Output Circuit Outline Theory of Operation Output Circuit Actual CircuitSawtooth Waveform Generation Circuit Operation Output 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 UZ11BSB Raster Position Switching Circuit Ketsu Signal Section IX Horizontal Deflection Circuit OutlineHorizontal Drive Circuit Basic Operation of Horizontal Drive On period OFF period Signal DEF/POWER PCB Horizontal Output CircuitOperation of Basic Circuit FBT Description of the basic circuit T1~t2 T2~t3T3~t4 T4~t6 Linearity Correction LIN Amplitude CorrectionCurve Correction S Capacitor Left-right Asymmetrical Correction LIN coil Linearity coil White Peak Bending Correction Circuit OutlineOperation Theory EHT Blanking Low Voltage Protection Gate Protector High Voltage Generation Circuit AFCABL High Voltage DPC Circuit Regulator 2. +35V 1. +210VHigh Voltage CR-BLOCK High Voltage CircuitAnode FBT CR-BLOCK E H ActualED’ RAY Protection Circuit 23 X-RAY protection circuit Over Current Protection Circuit Functions and Features Block Diagram Diode Modulator Circuit OUT 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 Reset MemoryProm PLL Picture Adjustment Service Mode Entering/Exiting Mode First screen Second screen Initial screenSfull Key function of remote control unit ENT 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