AFT and remote control Circuits

Television 1 Jess Role @ Television 1 Jess Role @ UEAB2006UEAB2006

AFT and remote control AFT and remote control CircuitsCircuits


Importance of AFCImportance of AFC Receivers that have provisions for remote Receivers that have provisions for remote

tinning have no provision for remote fine tinning have no provision for remote fine tuningtuning

Color receivers that have provisions for Color receivers that have provisions for remote tuning to obtain the best color remote tuning to obtain the best color reproductionreproduction

Many customers found it difficult to adjust Many customers found it difficult to adjust the manual fine tuning control propertythe manual fine tuning control property

A very slight drift in the frequency of the A very slight drift in the frequency of the tuner oscillator causes a loss of color tuner oscillator causes a loss of color picture qualitypicture quality


AFT SectionAFT Section


Troubleshooting AFT circuitsTroubleshooting AFT circuits

Weak or no AFT performanceWeak or no AFT performance No picture no sound raster okNo picture no sound raster ok Large tuning errorLarge tuning error Moment to moment picture Moment to moment picture

variationsvariations


Ultrasound remote controlUltrasound remote control


Causes of AFT problemsCauses of AFT problems

A defective transistor or associated circuitsA defective transistor or associated circuits A defective transformer A defective transformer defective IC or associated circuits such defective IC or associated circuits such

as an open coilas an open coil Misalignment of the AFT tuned circuitsMisalignment of the AFT tuned circuits Incorrect power supply voltageIncorrect power supply voltage Defective varactorDefective varactor Incorect varactor voltageIncorect varactor voltage


AFT circuit that uses dc amplifier to AFT circuit that uses dc amplifier to drive the varactordrive the varactor


Large tuning error on channels that Large tuning error on channels that originates form the varactororiginates form the varactor

DC amplifier balance change caused DC amplifier balance change caused by the change in resistor anywhere by the change in resistor anywhere in the DC amplifierin the DC amplifier

Defective varactorDefective varactor


Remote control CapabilityRemote control Capability

Change channelChange channel Adjust volumeAdjust volume Adjust picture Adjust picture Adjust contrastAdjust contrast Adjust sharpnessAdjust sharpness Sound quality adjustmentSound quality adjustment Power switchPower switch


Remote controlsRemote controls

Ultrasonic TransmitterUltrasonic Transmitter– Acoustic transmitterAcoustic transmitter– Function by tune signals from receiver Function by tune signals from receiver

to transmitter to transmitter


Ultrasound Ultrasound remote remote controlcontrol


Kinds of remote control faultsKinds of remote control faults

Weak intensive response on all Weak intensive response on all functionfunction

Dead all functionDead all function Dead on some function but not allDead on some function but not all


Electronic memory remote controlElectronic memory remote control

Producing ultrasonic sound through Producing ultrasonic sound through electronic circuit controlled system.electronic circuit controlled system.


Three tone remote controlThree tone remote control


Infrared systemInfrared system

Using invisible infrared signalUsing invisible infrared signal Digitally modulated infrared signal Digitally modulated infrared signal

42 KHz sensed by infrared diodes.42 KHz sensed by infrared diodes.


Infrared remote controlInfrared remote control


AFT discriminator circuitAFT discriminator circuit


AFT CircuitAFT Circuit


Receiver Receiver


TransmitterTransmitter


Multifunction Remote ControlMultifunction Remote Control

AFT and remote control Circuits

Documents

Transcript of AFT and remote control Circuits