Sylvania TV Screen Wavy Looking

Old 01-22-04, 01:25 PM
compaqguy200's Avatar
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Sylvania TV Screen Wavy Looking

When I change stations with the remote control the picture on the screen is crystal clear for about two seconds and then the picture or any words on the screen becomes wavy. If I change to another channel it is clear for two seconds and becomes wavy again. Any suggestions the TV is around 11 years old..Thanks for any help
Old 01-22-04, 02:14 PM
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Possibly it's a problem with the local oscillator or AFC control in the tuner module. When you cange channels the LO probably changes to the correct frequency and then drifts. It is possible that something in the AFC circuit has failed and cannot keep the LO on the correct frequency.

If you have a video input port you can try viewing something through this. If the picture is good then this will also indicate a problem like this.

Another possibility is a faulty line or field scan circuit. For normal operation the scanning operation must be synchronized to the sync pulses in the video. If if cannot synchronize then you could see this effect. How the synchonization is achived depends on the design of your particular model. I believe some use a phase locked loop (PLL) to achieve this.

Last edited by rav12; 01-22-04 at 08:55 PM.

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