Entertainment Center: TVs, Stereos, VCRs and DVDs - Zenith picture whitens with black broken lines
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10-28-01, 12:20 PM
Our 10 Year old Zenith 25-inch TV has a fine picture except when the program we are watching shows a scene with a light background. This makes our TV picture turn white with black broken lines going across. We can still see the scene through the whiteness, but it is annoying. When the program we are watching turns to a darker scene, the picture goes back to being just fine.
Thanks for your help,
Mike
Thanks for your help,
Mike
Smokey
10-29-01, 02:11 AM
Good Morning, MrTvLand:
The condition is called "Video Overload" and is most often caused by a change in the AGC (Automatic Gain Control) circuit of the television signal circuitry.
Television signals vary in strength between channels so the set electronically monitors the level of video being projected on the screen. If the video level is too high, you will get the overloaded condition you described with the lines (usually accompanied by a buzz in the sound) when a "high" white picture is displayed. Normally, the set compensates for this situation by electronically reducing the signal level within the set. In your case, it is not.
In some sets (not all), the level is adjustable by a level adjustment in the back of the set. In most of the newer sets, this system is so stable that it is no longer adjustable.
Changes in the operation of this circuit can be affected by several sources including a problem in the low voltage supply. Finding the actual cause of the failure will take a little troubleshooting and the repairs are not expensive
normally.
A quick fix that works (sometimes) is to put a two set coupler (splitter) in the antenna line. Connect the antenna wire to the splitter input. Leave one output disconnected. Connect the set to the other output. This reduces your incoming signal by one-half (3 dB). The couplers are available at Radio Shack for a couple of bucks.
Smokey ;)
The condition is called "Video Overload" and is most often caused by a change in the AGC (Automatic Gain Control) circuit of the television signal circuitry.
Television signals vary in strength between channels so the set electronically monitors the level of video being projected on the screen. If the video level is too high, you will get the overloaded condition you described with the lines (usually accompanied by a buzz in the sound) when a "high" white picture is displayed. Normally, the set compensates for this situation by electronically reducing the signal level within the set. In your case, it is not.
In some sets (not all), the level is adjustable by a level adjustment in the back of the set. In most of the newer sets, this system is so stable that it is no longer adjustable.
Changes in the operation of this circuit can be affected by several sources including a problem in the low voltage supply. Finding the actual cause of the failure will take a little troubleshooting and the repairs are not expensive
normally.
A quick fix that works (sometimes) is to put a two set coupler (splitter) in the antenna line. Connect the antenna wire to the splitter input. Leave one output disconnected. Connect the set to the other output. This reduces your incoming signal by one-half (3 dB). The couplers are available at Radio Shack for a couple of bucks.
Smokey ;)