[Maginnis1951]

Lately, I've noticed a white, jagged line at the top of the screen whenever I'm watching TV. This is on both HD and regular digital. It seems to be mainly on ABC, and normally, only during the commercials. Although, I've also noticed it on Sportsnet HD.
Has anyone else noticed this?

SA8300 HD PVR
Panasonic TH42PX50

 

[57]

Sometimes people see white dots across the top of their screen, I've seen it occasionally on ABC when it's 4:3 upconverted programming.

Usually only happens if you have your overscan set too low (less than 3%) or you have "lowered" the TV image.

Have you checked your overscan with a setup DVD?

 

[Maginnis1951]

No. How would I go about doing that? I watched "Lost" last night, and, while the program looked great (lousy sound, though), it was in the commercials that I really noticed the choppy white lines at the top of my screen.

 

[james99]

I had this problem on a few HD channels (when upconverted). I simply raised the image and the problem went away.

Consult your owners manual for your tv for overscan and image positioning.

 

[57]

How would I go about doing that?

You need a setup DVD. See the Digital Home FAQ "What you need to do to your new HDTV".

If it's a new TV, you can perhaps call for service.

 

[JohnnyG]

Have you checked your overscan with a setup DVD?

Remember that you'd have to check this with the same resolution that you're having a problem with, so you'd need an upconverting DVD player.

 

[Maginnis1951]

Sometimes people see white dots across the top of their screen, I've seen it occasionally on ABC when it's 4:3 upconverted programming.

Usually only happens if you have your overscan set too low (less than 3%) or you have "lowered" the TV image.

Have you checked your overscan with a setup DVD?

Bay Bloor Radio spoke with Panasonic and, big surprise, they've never heard of this problem. !!
They are going to get a technician to come out and take a look at it.

 

[Maginnis1951]

You need a setup DVD. See the Digital Home FAQ "What you need to do to your new HDTV".

If it's a new TV, you can perhaps call for service.

Panasonic is having a technician come out tonight to take a look at it. He said that he would put a generator on it. Have you heard of that?
Eric

 

[57]

I assume that a signal generator can put up various test patterns on the screen. One of these may be the overscan pattern.

 

[tat2]

Those white dots (4 or 5 static dots on the left and alot of "moving" ones on the right) are usualy just the closed caption and v-chip information on line 21. (Field 1 CC, Field 2 Vchip). Mind you HD captions work differently so for try HD signals I'm not sure what it would be.

 

[johnnysmoke]

If the HD image is an upconvert of a standard definition signal, the closed caption information may also get upconverted. Adjusting overscan or horizontal position on your set will move this up and out of the active picture area.

 

[querty-m4n]

VBI

Short for vertical blanking interval, the part of a television transmission signal that is blanked, or left clear, of viewable content, to allow time for the television's electron gun to move from the bottom to the top of the screen as it scans images. This blank area is now being used to broadcast closed caption and HTML -formatted information.

http://www.webopedia.com/TERM/V/VBI.html

 

[tat2]

Yes, line 21 is in the VBI.

 

[Maginnis1951]

The technician checked the tv and found out that it was calibrated perfectly. Obviously, the problem lies with the STB. Question: if I was to swap out this 8300HD PVR for another one, would the problem go away?

 

[57]

Many people have already commented that the signal from the SA8300HD is actually "higher" than need be.

Check out Channel 24 (CP24) to see how things are displayed using the SA8300HD and perhaps compare it to putting the cable directly to the TV's tuners. I believe you'll find that the STB is actually "higher" than the signal direct to the TV.

Did the technician put up an overscan test pattern to see what the overscan on the TV is at the top/bottom/sides?

I suppose the calibration for the HD signals could be different than for the SD signals, so perhaps CP24 may not be a perfect gauge of how the SA8300HD sends HD signals, although you could set the SA8300HD to output 1080i only and view CP24.

Can you take a picture of the problem?

 

[JohnnyG]

I was quite certain this wasn't VBI related, and I couldn't think of anything else, so I kept out of it. VBI just didn't sound right to me. Most HDTVs clip this information completely. With the digital processing and scaling that's done with digital displays, why bother wasting memory on stuff you're not supposed to see anyway?

57, if the 8300HD image is higher, then that makes VBI all the less likely, right?

 

[Maginnis1951]

Did the technician put up an overscan test pattern to see what the overscan on the TV is at the top/bottom/sides?
Can you take a picture of the problem?

The technician put up the overscan test pattern and it was perfect on the tv. Not out of alignment at all. He also put up the Weather Network (191) through channel 3 on the tv, and there were no data lines showing. (On the weather channel, the data lines are coloured and show up down the left or right side of the 4:3 box.)
I also taped some golf on an HD channel (the golf was upconverted) and the data lines at the top showed up on the taped version as well. This indicates that the problem is with the STB, and not the tv.
I would hate to have to have the technician come back and tweak the tv due to a problem with the STB.
When you say "take a picture", you mean...?

 

[57]

57, if the 8300HD image is higher, then that makes VBI all the less likely, right?

Yes, but I have seen the "white dots" on 4:3 upconverted programming a while back - I believe it was ABC. I rarely watch this type of programming, (preferring instead to record/watch the equivalent SD channel)

1. The technician put up the overscan test pattern and it was perfect on the tv. Not out of alignment at all.
2. He also put up the Weather Network (191) through channel 3 on the tv, and there were no data lines showing.
3. I also taped some golf on an HD channel (the golf was upconverted) and the data lines at the top showed up on the taped version as well. This indicates that the problem is with the STB, and not the tv.
4. When you say "take a picture", you mean...?

1. I didn't ask about alignment, I asked about the %overscan - was it 3%, 6%, 10%???
2. Through channel 3 is meaningless if this is an HD input issue.
3. I have seen the dots on one channel. Do you see them on any other channels? If it only happens on one channel, perhaps that channel is to blame, not the STB.
4. Take a picture of the problem with a digital camera.

 

[Maginnis1951]

Sorry for my confusion. I did not see a screen that looks like the overscan one shown on various web sites. I have called and left a message with the technician. As well, I have contacted Panasonic to find out what the overscan percentage should be on this particular set.
This has shown up on a number of channels. (Weather Network, which is never HD, Sportsnet HD, ABC HD)
I can take some digital pictures tonight.
BTW, this set does not have any adjustments for overscan, or image positioning.

 

[57]

BTW, this set does not have any adjustments for overscan, or image positioning.

It may not be user adjustable, but there are probably adjustments in the service menu.

Did you compare CP24 via the STB and via the TV's tuner yet? Do you see the white dots/lines on the TV's internal tuner? Just hook up the cable temporarily to "ant1" or whatever it's called (Cable in?) to test...