horizontal hd picture hold

[jpw711]

Hi, I've got a 622 and have a problem. When I'm watching HD, occasionally, the picture will "roll". About 20 years ago, TV's had horizontal and vertical hold knobs that would stop this. Of course, they were analog.

It seems to happen with mainly white backgrounds, during commercials mostly, on A &E, TLC, and HGTV, but also occurs on NBC NFL football games OTA (85% signal strength). On football games, it only happens when the lower score bar and upper stat bars are shown on the screen.

Has anybody else seen this problem? Don't know if it is the 622 or my TV, and I only have one HDTV (Hitachi). I'm at the point of calling Dish, but wanted some more info before I do.

Thanks

Joe

 

[KAB]

Nothing like this has been reported AFAIK. Sounds like your TV or connections. How are you connected...HDMI, Component?

 

[tempVAdish]

Is your TV a CRT? Sometimes problems in the power supply will cause tearing on the picture @ really bright areas...

 

[jpw711]

component, and crt. I fooled with the cables last night, didn't help, but I can always plug in some new ones.

Power supply theory is interesting, however, on the football issue, I can see, what looks like very fast refresh static that is dark. Would not be surprised if it turned out to be the TV, as it is 6 or 7 years old. I just went HD Feb 07, and OTA last fall. NBC football has been an issue since then.

 

[jpw711]

changed the cables, no difference

 

[RTCDude]

Hi, I've got a 622 and have a problem. When I'm watching HD, occasionally, the picture will "roll". About 20 years ago, TV's had horizontal and vertical hold knobs that would stop this. Of course, they were analog.

It seems to happen with mainly white backgrounds, during commercials mostly, on A &E, TLC, and HGTV, but also occurs on NBC NFL football games OTA (85% signal strength). On football games, it only happens when the lower score bar and upper stat bars are shown on the screen.

Has anybody else seen this problem? Don't know if it is the 622 or my TV, and I only have one HDTV (Hitachi). I'm at the point of calling Dish, but wanted some more info before I do.

Thanks

Joe

It's definitely your CRT TV, not Dish. Modern CRT TVs have automatic sync circuits and better timebase generators that eliminate the need for manual vertical and horizontal adjustments. That said, a TV can still malfunction.

What you said about a bright scene, or graphics at the top/bottom of the screen (I assume bright) tells me that you may be having something going wrong with what is called the "DC restoration circuit".

Without going into too much detail, modern CRT TVs are still built around the same circuitry concepts that has been use for analog TV signals since CRT TVs were first sold to the public. This is known as NTSC. Part of this standard is a set of pulses between each horizontal video line (the horizontal sync pulse), and one between each video frame; 525 video lines (the vertical sync pulse).

The DC restoration circuit creates a voltage reference to separate the sync pulses from the video information; sync pulses below the voltage reference, and video information above the voltage reference. The peak of the sync pulses are suppose to always be that same voltage value below the voltage reference, while the video information varies in voltage value (above the reference) by how bright is the video is (at the voltage reference is black, and above the reference is white).

If the DC restoration process isn't occurring correctly, the automatic sync circuits may have a hard time recognizing sync pulses. This is because a bright scene has the effect of moving a malfunctioning voltage reference down halfway or more into the sync pulses. This makes it look like to the automatic sync circuits that the sync pulses are much smaller, or have completely disappeared. This will make the automatic sync circuits lose sync lock and go into "hunt" mode looking for the sync pulses. In your case, it would appear that the vertical sync pulse is getting lost, and you see this "hunt" process as vertical scrolling of the screen.

You can get this repaired, but getting older CRT TVs is more and more expensive these days. Honestly, what you spend in repairs might be better spent getting a new flat panal TV that fit in better with the coming digital TV transition.

Hope this helps.

 

[Barry Erick]

Definately a cap in HV circuits or power supply. You might find a shop that can fix that, or simply buy that 62 inch set you've wanted and put this one at the curbside for someone who knows how to fix them to take.

 

[jpw711]

Thanks RTCDude, You have allowed me to use the Electrical Engineering degree I got 20 years ago for the first time in a long time., and I agree with you Barry, except my wife wants the new TV to fit into the old cabinet, so that leaves me with a 37"

 

[8bitbytes]

I have a 19" widescreen lcd upstairs that I beam tv2 output to wirelessly. If I am watching an HD channel, it rolls but if I watch an SD channel, it does not. Weird, especially since it's an LCD tv.

 

[whatchel1]

sync control

Thanks RTCDude, You have allowed me to use the Electrical Engineering degree I got 20 years ago for the first time in a long time., and I agree with you Barry, except my wife wants the new TV to fit into the old cabinet, so that leaves me with a 37"

It is a sync control issue. Built in cabinet? Could be as simple as solder joints going bad. If something more than that in a set that age isn't worth fixing. If not then maybe it's time to maybe it's time to say something like "wifey" wouldn't you like to have a newer prettier cabinet that holds the new components of the system. Then you figure out what TV and after that go shopping w/ the wife for the new cabinet.

 

[jpw711]

yeah, except her brother built it for a wedding gift.

 

[KAB]

yeah, except her brother built it for a wedding gift.

Have him build you a bigger one.