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NotTaR of Television Sets : Interference when using VCR RF connectio..  
 Copyright © 1994-2007, Samuel M. Goldwasser. All Rights Reserved. Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: 1. This notice is included in its entirety at the beginning. 2. There is no charge except to cover the costs of copying. I may be contacted via the Sci.Electronics.Repair FAQ (www.repairfaq.org) Email Links Page.
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Interference when using VCR RF connection

(Some of these comments also apply to use of LaserDisc players, satellite receivers, video games, or other sources with RF modulator (Channel 3/4) outputs).

This may consist of patterns or lines in the picture.

If this only happens on the antenna or cable, it may be a problem with these sources or the tuner in the VCR rather than the TV. As a test, try the connecting the TV directly to the antenna or cable.

If it only happens on cable, there may be a (temporary) problem with cable transmission - contact your cable company.

If it happens on playback of good quality (commercial) recordings, then it could be a compatibility problem between the VCR and TV.

Make sure your patch cable connections are secure and that the cables are not damaged - in particular that the center pin is intact.

Try fine tuning if your TV has this capability. If this does not help, try switching the channel 3/4 selector on the VCR to the opposite position and try that channel, sometimes one will be better than the other particularly if one of these or an adjacent channel is active in your area.

If you have RCA baseband video inputs on your TV, try this connection to the VCR. These should work better in any case.

Confirm that it is not actually a problem with the VCR - try another TV if possible.

If you just changed your component placement, the VCR or TV may be picking up interference from another component. Turn off everything but the VCR and TV and see if that identifies the culprit. Move the TV away from the VCR so see if they are interfering with each other - the TV may be introducing interference into the VCR.

Occasionally, the particular patch cable or its length may affect reception quality - try another one.

If none of this helps, you VCR's RF modulator may be bad or slightly weak. Alternatively, the tuner in the TV may be faulty. If reception is generally noisy on all sources, AGC or RF/IF alignment may need adjusting. However, not all tuners are created equal. Your TV may simply be making the best of a marginal situation.

A light dimmer on the same circuit as the TV may result in similar symptoms. If you are tuning up your motorcycle (or automobile) in the same room, this may be spark ignition interference.

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