White scrolling lines on my cable tv...

[pyrate83]

Hi everybody...(Hey Dr. Nick). Sorry just sounded right but I have a new problem that I thought you might be able to help with. I am getting some white scrolling lines on one of four tv's in the house. The cable to this room is the longest run I'm sure. The cable guy said it's interference from something not a decrease in signal. I have put an amp. on the main line and it has helped the picture but the lines remain. It's not the ground wire, I checked that and I also ran the cable to my tv through my home theater surge protector which helped a little but the lines still scroll. The white lines are actually worse on the lower(local channels) than the higher numbers up aroun 60 to 100. Any suggestions on what could be causing it? I also checked my ceiling fan but that wasn't it.
Thanks.

[teegee420]

You ought to get a DC block from Radio Shack. They're pretty cheap.

[sitlet]

if its worse on the lower channels, its most likely a weak signal. a booster would probably solve this, but you said you already tried an amp. can you turn up the gain at all?

[pyrate83]

I've got the gain turned up as much as I can before the picture gets lines on it. It does look a lot better in picture quality...almost near perfect which is good for having run this cable from the basement to the attic and then down into the second story. I may try a DC block. BTW the amplifier is a bi-directional for the internet but I'm not sure if it's signal quality since I tried hooking the amp. up to the line running to this tv and still got the scrolling lines so I just kept the amp hooked to the main line coming in so all tv's could benefit from the boost. Let me know of any other suggestions.
Thanks again.

[flaninacupboard]

try disconnecting all your other TV's and vcrs and dvdr, anything with an RF output. could be a vcr output resting on a similar channel to the station that's upset.

[pyrate83]

DC block was a BIG help. Still some scrolling lines but much much less noticeable.

[sitlet]

maybe its something wrong with the signal coming into your house. do any of your neighbors have this same problem?

[Capmaster]

I've seen that sort of interference before when there's an open in the shield. Check the RF connectors on every cable. If there's even one that isn't making electrical contact you'll get over-the-air transmissions and other electrical noise getting into the center conductor of the cable and causing the interference you see.

[Doramius]

I agree with Cap. I've had the same problem, especially on a long run of wire, because I didn't check it thouroughly and it was kinked in areas. Later I found the kinked areas had damaged the shielding and that's what caused the problem.

This may not be your case, but you might want to see how your cables are running through your home. To save money and time when wiring cable, some people run the rooms in series with Y Jacks. It's usually best to have one main area (like in your garage or a single room) and then branch it to the other different rooms to avoid signal weakness.

[pyrate83]

I got another idea of what may be causing the lines I see. Could it be a ground loop issue? Like I said before it's just on this line but I found http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-1110 which I'm not sure will be a good thing to install on any of the coaxial lines. Would this help eliminate the white lines because when I ran the coaxial cable through my home theater surge protector the lines faded away somewhat however some of my channels were all messed up so I don't think the frequency range was high enough. But this little surge protector has a large frequency range so the higher channels should be unaffected and the internet too.
What do you guys think of this inline surge protector? Should I get it?

[Doramius]

I got another idea of what may be causing the lines I see. Could it be a ground loop issue? Like I said before it's just on this line but I found http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-1110 which I'm not sure will be a good thing to install on any of the coaxial lines. Would this help eliminate the white lines because when I ran the coaxial cable through my home theater surge protector the lines faded away somewhat however some of my channels were all messed up so I don't think the frequency range was high enough. But this little surge protector has a large frequency range so the higher channels should be unaffected and the internet too.
What do you guys think of this inline surge protector? Should I get it?

I know there are some power antennas that use the gound line as the antenna, but I don't know about a cable signal. That shouldn't affect it unless there is some sort of filter built in. You'd want to make sure your amplifier is attached between it and the reciever. The are ground loop filters, that may help but I don't know who carries it.

Have you tried just connecting the TV to the line with nothing between it and then connect the item's in between? What are the differences in the lines when you do that? This may give another small idea as to how to approach this. Also, are your splitters for the cable line grounded? Anywhere there is a splitter, try grounding them if they are not. There should be a little screw that loosens and tightens to allow a copper wire to slide through. Just run that to a wall outlet or other grounding source. This should also help if you connect your surge protector while grounding the splitters. If you get a surge supressor, you might as well get one with multiple outlets and has the coaxial ports on it. It'll ground the line and everything else which may help too.

[pyrate83]

Thanks I'll try some of your ideas and see if they help.

[Doramius]

Make sure you post wether they work or not.

[pyrate83]

Interesting development in my problem I thought I'd clue you in on. I hooked the DC block right to the wall plate and then ran the coaxial cable from it to my TV. The white lines were way worse. Then I put the DC block onto the back of my tv and fed the cable from the wall plate into the block before it enters my tv. The lines were then tremendously reduced.

What does this mean?? Does it mean there is interference on only the line coming from the wall to the tv and what would that be from. I've tried turning off devices in my room and nothing seems to change it.

[Megahurts]

pyrate83

You say there are white lines floating through the pix. Are there 2 white lines scrolling up the screen at a slow rate? If not, describe the lines and forget the rest of this message.

Since you're from the Buckeye State, you're in NTSC land. 2 lines scrolling up the screen means a 120 Hz ripple in the video signal caused by bad filtering in the power supply. Are you using a cable box? If so, connect the cable direct to the TV.

Also dimmer switches can cause the same problem.

Regards,

Chas

[pyrate83]

pyrate83

You say there are white lines floating through the pix. Are there 2 white lines scrolling up the screen at a slow rate? If not, describe the lines and forget the rest of this message.

Since you're from the Buckeye State, you're in NTSC land. 2 lines scrolling up the screen means a 120 Hz ripple in the video signal caused by bad filtering in the power supply. Are you using a cable box? If so, connect the cable direct to the TV.

Also dimmer switches can cause the same problem.

Regards,

Chas

Well the lines do scroll up the screen at a slow rate. Mostly it does seem to be just two lines but on some of the channels i'll find there are a few lines some fainter than others and much less noticeable. My cable goes directly into the tv, no cable box or anything. The lines appear on all of the 70+ channels but worse on certain ones. It's not poor signal quality since I have tried amplifying the line directly and the picture improved even more but the lines were still there. I can't find anything in the house that's causing it however as I've stated b4 non of the TV's on the first floor are in any way affected by the scrolling lines. I'm beginning to think that the problem resides only in this room but I can't figure out what's causing it so I can correct it. I'm thinking about using another DC block on the wall plate to block DC current coming out of the wall and then keep the other DC block hooked into the back of the tv. Thy're $1.50 so it's no big deal.

[Doramius]

What I'm seeing is as long as you didn't put the DC blocker in backwards (unless this one is a unidirectional blocker, which is rare) there should not have been a difference wether the blocker was right in the middle of your cable line. This makes me believe, again, that there may be three possible factors affecting it on your second level, or maybe a minute combination off all. 1) standard distortion of frequency higher in altitude (highly doubtful this would really create any problems for you) 2) The distance the cable is travelling from the original input to the home to where the receiver is (amplifier should help fix this and try hooking the amplifier before the signal is separated to all the different rooms). 3) There may be some hidden damage in a cable line, or something that's not grounded properly.

There is a device, but it's not really cheap, that can tell you the signal strength of, or at certain distances from, an input source. It also lets you know if there is a short or an open in a cable line or the shielding. If you did this type of work for a living or were doing something major in rewiring a home, I would suggest trying to find the device, but like I said, it's probably not worth it if you're just trying to clear up one receiver.

[flaninacupboard]

well if one DC blocker didn't fix it, another won't help. sounds to me like a problem with the shield between your wall socket and tv - perhaps the cable has been coiled or kinked at somes stage. is it possible to trya a replacement cable?

[Doramius]

well if one DC blocker didn't fix it, another won't help. sounds to me like a problem with the shield between your wall socket and tv - perhaps the cable has been coiled or kinked at somes stage. is it possible to trya a replacement cable?

That's what I keep thinking it is. The next biggest thought I had was the distance, but the amplifier should have cleared his signal up.

[pyrate83]

Well I'm going to try something different then. I am going to try a piece of new shielded cable from the wall to my tv and see if that fixes it. I am also going to plug another tv into the cable outlet my cable modem is connected to on the other side of the room. That will help me isolate the problem.