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AFT and remote control Circuits

AFT and remote control Circuits. Importance of AFC. Receivers that have provisions for remote tinning have no provision for remote fine tuning Color receivers that have provisions for remote tuning to obtain the best color reproduction

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AFT and remote control Circuits

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  1. AFT and remote control Circuits

  2. Importance of AFC • Receivers that have provisions for remote tinning have no provision for remote fine tuning • Color receivers that have provisions for remote tuning to obtain the best color reproduction • Many customers found it difficult to adjust the manual fine tuning control property • A very slight drift in the frequency of the tuner oscillator causes a loss of color picture quality

  3. AFT Section

  4. Troubleshooting AFT circuits • Weak or no AFT performance • No picture no sound raster ok • Large tuning error • Moment to moment picture variations

  5. Ultrasound remote control

  6. Causes of AFT problems • A defective transistor or associated circuits • A defective transformer • defective IC or associated circuits such as an open coil • Misalignment of the AFT tuned circuits • Incorrect power supply voltage • Defective varactor • Incorect varactor voltage

  7. AFT circuit that uses dc amplifier to drive the varactor

  8. Large tuning error on channels that originates form the varactor • DC amplifier balance change caused by the change in resistor anywhere in the DC amplifier • Defective varactor

  9. Remote control Capability • Change channel • Adjust volume • Adjust picture • Adjust contrast • Adjust sharpness • Sound quality adjustment • Power switch

  10. Remote controls • Ultrasonic Transmitter • Acoustic transmitter • Function by tune signals from receiver to transmitter

  11. Ultrasound remote control

  12. Kinds of remote control faults • Weak intensive response on all function • Dead all function • Dead on some function but not all

  13. Electronic memory remote control • Producing ultrasonic sound through electronic circuit controlled system.

  14. Three tone remote control

  15. Infrared system • Using invisible infrared signal • Digitally modulated infrared signal 42 KHz sensed by infrared diodes.

  16. Infrared remote control

  17. AFT discriminator circuit

  18. AFT Circuit

  19. Receiver

  20. Transmitter

  21. Multifunction Remote Control

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