View Full Version : Can somebody tell me what this is?
swhite
11 Nov 2007, 12:14 AM
I just bought a Pioneer Elite 42" plasma. The picture is great! However somtimes I see a small thin black and white band at the top of the picture that runs across the entire length of the screen, but only on some tv broadcast and only on some digital channels. I can either zoom this out of the screen or I can use the picture position option to raise it slightly and it goes out of the picture. Or somtimes it goes away by itself.
Now, everybody Ive talk to including the cable teck and a tv teck tells me that it is in the stations broadcast and I tend to believe that but has anyone else experienced this? I never see it on DVD video or HD broadcast. When I switch the channel to that stations anolog channel that band is not there.
Comcast says that the station is doing somthing to the signal to try and make it look better on the digital channel when the program is not in HD.
Anybody ever heard of that.
RFBurns
14 Nov 2007, 04:33 AM
Howdy!
This is a common problem in some wide screen sets, plasma or lcd based.
It is simply the default settings for vertical hight and sometimes the horizontal width adjustment, which should be accessable via the customer accessable controls/settings. However some sets hide these adjustments into the service mode, which requires the unit's remote control and punching in a certian key sequence to activate the service mode.
The lines are the vertical pulse in the video signal, and if the scan of the display is slightly off..in this case the vertical hight, it will display the vertical blanking pulse onto the screen. The black and white spots you see in that line is the closed caption data pulses embedded within the vertical blanking pulse.
This may occur with certian signals depending on what their native resolution is. For example...lets say your tv has the display to default at a native resolution of 1080p, but your set is recieving a 720p signal. The set not only has to up-convert the 720p to 1080p for it to fill the screen, it also must re-create the timing pulses for the video signal along with the video information. Some factory settings might be slightly off center and does not hide the timing pulses effectively. Again this can be adjusted out either with the customer controls or via the service mode.
Sometimes it is necessary to go through the adjustments for every resolution capability of the tv so that anytime it gets a non-native resolution signal, it will properly display them after the up-converting process.
If these adjustments cannot be done via the customer controls, contact the manufacturer for tech support. They can walk you through the adjustment procedure. Make sure you have the set's original remote as universal remotes or combo remotes often cannot access the service mode menus correctly.
Hope this helps.
:toast:
pfloyd
14 Nov 2007, 05:43 AM
Do you have any speakers nearby?
RFBurns
14 Nov 2007, 06:47 AM
Unlike the old CRT display that requires a deflection yoke to make the beams scan across the screen, a plasma display and lcd display does not require a deflection coil. The deflection coil is just an electromagnet coil wrapped around a large ferrite core that slips over the neck of the old CRT tube. The coil has both horizontal and vertical wound wire, each being fed by the pulses produced by the horizontal and vertical circuits, producing a magnetic field that is porportional to the video frame, thus causing the beams emitted by the CRT gun assembly within the neck of the tube to "deflect" and move from side to side, which produces the image on the CRT screen.
Some may remember when the old tv's deflection circuits went out, either a flat line going across the entire screen in the middle (loss of vertical deflection) or the famous bright dot in the center of the screen (loss of both horizontal and vertical deflection).
A plasma and lcd set does not have this circuitry. Thus are not affected by nearby speakers. The worst that would happen with a plasma set is the color may become distorted...ie color may change with the magnetic field. But it will not affect the scan of the display (deflection because there is no deflection involved).
:toast:
swhite
14 Nov 2007, 09:56 AM
Pfloyd:Yes , I have speakers next to the set but they are sheilded speakers.
RFBURNS: I will call Pioneer and ask them about it.
Thanks
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