Converter box use and horizontal "waves" in picture

[anet]

Several weeks ago, I installed my Zenith DTT900 converter box. My system includes a roof antenna, a DVD recorder and a Magnavox TV. During the initial installation, I had to move the converter box to many locations before I finally found a place (away from the TV and DVD recorder) that resulted in a clear picture on every station. Initially, I received much interference when the box was too close to the TV...including horizontal waves running through every station and actual color changes (only saw greens and reds) on the TV.

Once I found the right spot for the converter box, all stations were clear.

Now 3 weeks later, I turn on the TV only to find the horizontal waves reappearing on every station! It was fine for 3 weeks! What happened?

It is my understanding that with digital TV, you either get a picture or you don't (or you get choppy break ups). I assumed that the waves were caused by some kind of electronic interference with the box and TV. But, I haven't moved anything and the waves came back. And, I am not using anything either (like microwave, washing machine, etc.). The only difference I can think of is that we now have snow (the weather kind), and we didn't have any snow at all when I set things up and ran the TV and converter box for 3 weeks. Now, there is about 15" of snow on the ground and some on the roof and antenna. Would that make any difference?

I haven't been able to find much about this type of interference. The waves are very annoying...it is hard to even watch TV with them. Help!

Has anyone else experienced this? Does anyone know how to resolve this issue?

BTW, I live in a major city (Cleveland, OH) and I am close (less than 10 miles) to many TV stations. And, my signal strength "meter" (using a button on the remote) shows most of the digital stations have a 90-95% strength signal.

[usually_quiet]

I experience something like what you are describing for a couple of analog cable channels on a TV hooked up to cable, but not to an antenna. I am within a few miles of analog stations transmitting on channels 2 and 11, and I believe cable channels 2 and 11 show interference from the broadcast channels. If you have your converter box hooked up via the coax cable perhaps you are receiving interference from analog broadcast stations transmitting on either channel 3 or channel 4.

If your TV has an RCA composite inputs, you might try using them instead of the coax connection. If not, set up to use the alternate channel for the coax connection.

[Edit] As an experiment, I just set my converter box to channel 4, which is one of my local broadcast channels, and I'm seeing horizontal wave-like interference in the picture.

[anet]

Thanks for your thoughts!

I have tried coax cables and RCA cables...no difference. I also tried my converter box on channel 4 (I currently use channel 3). All I received on channel 4 was static.

I suppose interference from analog signals could be an issue, but I don't understand why I had a great picture for three weeks and then it went bad. My neighbor (who is having the same wavy picture issue) told me he heard that you can have issues if signals are too strong. Anyone know anything about that?

My other neighbor is using the exact same converter box as me and she has had no issues at all. And her roof antenna is older and has pieces broken off!

[vhelp]

A few snap shots would help narrow down the issue of your problem. But..

Sounds like you have a ground loop problem (aka, harinbone noise as you evidense to us vaguely) and it seems that you might have a more serious problem after all.

If you absolutely did not install anything new in your house or apt, ie: cable installation, then it is unlikely that you are causing it..rather, it more than likely that one of your neighbors is the culprit good luck

What I mean is, one of your neighbor's is interupting your video through the AC line. He prob has a grounding problem (and doesn't know it) (and its tapping into your AC line) and is prob having coensidental issues though unknown to you. Maybe take a poll/inquiry around your area to see if anyone is having problems with a certain unit or device that they may have recently purchased. It could be a recent analog or digital cable installation who's hookup has gone bad for some unknown reason--weather maybe, or something else.. I don't know.

If you live in a complex of apts, thats even more difficult to work out. Lots of people doing lots of no-no's, if you know what I mean. Or maybe not..but that there is always potential for *new* things being connected.

If you have digital cable for instance, that could be the source of your problem, too. Bad grounding or stronger channel signal, etc. Some say that if a channel is too strong you may need a variable gain control to reduce it so that you get a proper picture. But like I said, even if you don't have cable, you could still suffer from someone else's mistake, (all-the-while they are abilivious to your induced problem while they are clean on their end) and you may never know who it is that is inducing yours.

I have analog cabletv. I've had it for prob somewhere around 10 years. Anyway. Over the years I've had problems with line noise of varying degree--some my fault and some not. What I have found out is that (including my current situation) since I am the last apt in the whole complex, and all the cable that goes through all the buildings/apts, that basically, what I am looking at is a form of "filtering" is going through the wires, from every apt, includes clean-to-bad conditions in every apt. So, in the end, I get the shit end of the deal. So, my analog captures have these line noise that is a product of filtered waist, maybe some 40 or more apts at least. Oh well.

And if its not any of the above, then its prob radio waves from a nearby: landmark; hospital; police; fire; or other entity ( UFO ? ) or something else.

But it sounds more likely the origin of your source problems is AC lines and at least one neighbors and his/her equipment is somehow interfearing or disturbing your AC lines through their device/equipment.

-vhelp 4997

[usually_quiet]

I have tried coax cables and RCA cables...no difference. I also tried my converter box on channel 4 (I currently use channel 3). All I received on channel 4 was static.

I suppose interference from analog signals could be an issue, but I don't understand why I had a great picture for three weeks and then it went bad. My neighbor (who is having the same wavy picture issue) told me he heard that you can have issues if signals are too strong. Anyone know anything about that?

If the RCA cables don't solve the problem, then it isn't likely to be caused by an analog TV broadcast signal interfering with the converter box's output. If your TV is tuned to channel 4 and your converter box is also set up to use channel 4 for coax, then you should not be seeing static.

There can be problems if the signal is too strong, but I haven't seen a description of what that would look like.

As for having a great picture for 3 weeks, all I can say is something changed. We just don't know what at this point. TVs pick up somes trange things at times. I hear a police radio on one analog UHF channel nearly every Saturday morning, but not at any other time.

[edDV]

Several weeks ago, I installed my Zenith DTT900 converter box. My system includes a roof antenna, a DVD recorder and a Magnavox TV. During the initial installation, I had to move the converter box to many locations before I finally found a place (away from the TV and DVD recorder) that resulted in a clear picture on every station. Initially, I received much interference when the box was too close to the TV...including horizontal waves running through every station and actual color changes (only saw greens and reds) on the TV.

Once I found the right spot for the converter box, all stations were clear.

Now 3 weeks later, I turn on the TV only to find the horizontal waves reappearing on every station! It was fine for 3 weeks! What happened?

It is my understanding that with digital TV, you either get a picture or you don't (or you get choppy break ups). I assumed that the waves were caused by some kind of electronic interference with the box and TV. But, I haven't moved anything and the waves came back. And, I am not using anything either (like microwave, washing machine, etc.). The only difference I can think of is that we now have snow (the weather kind), and we didn't have any snow at all when I set things up and ran the TV and converter box for 3 weeks. Now, there is about 15" of snow on the ground and some on the roof and antenna. Would that make any difference?

I haven't been able to find much about this type of interference. The waves are very annoying...it is hard to even watch TV with them. Help!

Has anyone else experienced this? Does anyone know how to resolve this issue?

BTW, I live in a major city (Cleveland, OH) and I am close (less than 10 miles) to many TV stations. And, my signal strength "meter" (using a button on the remote) shows most of the digital stations have a 90-95% strength signal.

I've got a Zenith DTT901 and am in almost the opposite situation to you. I'm >40 miles from the closest Class A low power ATSC translator (Ch28) and >60 miles from the closest medium power ATSC UHF TV station (Ch43). Believe it or not, I can get the translator with the DTT901 using a simple wire dipole antenna (the kind packed with a TV).

The Zenith DTT9xx* is an extremely sensitive tuner and has been voted most sensitive to distant stations at the AVS forum. Since you are within 10 miles of the transmitters and using a roof antenna, my guess is you are dealing with signal overload and/or multi-path interference.

Overload might be reduced by using a smaller antenna and a shorter well insulated cable (quad shielded RG6) or even a signal splitter or attenuator in the input cable.

If it is multipath caused by signal reflections, you need a more focused directional antenna. Directional antennas boost level so you may also need an attenuator to bring the level down. Quad shielded cable is also helpful. If all transmitters are in the same direction, then one directional antenna is enough. If stations are in different directions, a rotator, or a so called "smart" antenna may help. Smart antennas work with the tuner to electronically focus antenna pointing direction and amplification when channels are changed. Unfortunately the DTT900 isn't compatible with "smart" antennas.

"usually_quiet"'s suggestion about RF output is also a possibility. Try using the composite and audio outputs (Yellow-Red-White) to connect to the TV instead.


* The Zenith DTT900/901 and the electronically identical Insignia CECB's sold at Best Buy are actually made by LG.

Also see the AVS "Coupon Eligible Converter Box (CECB)" Forum
http://www.avsforum.com/avs-vb/forumdisplay.php?s=&daysprune=&f=186

[LordXander]

The problem you are experiencing is more common than you think. I am an ex-cable installer and have come across your problem so many times its pathetic and annoying. The good news is: it should be a relatively simple fix. You said that you recently got a lot of snow (weather). What is happening is moisture is getting into your outside coax connections and is either grounding it out or they have loosened up enough to let in radio interference. To fix it: check those connections, look for rust or corrosion of any kind. If you can loosen them with your fingers then that's a problem. They should be pretty tight. If you need to, change out the connectors on the ends of the coax and any ground blocks, splitters, barrel connectors, or amplifiers. Make sure you do have your antenna line grounded, for safety. Following the electrical ground is best, but a rod in the ground is fine. Make sure to use a ground block and don't mount it with the ends pointing up and down, you want it horizontal, otherwise you get water in it anytime it rains. The last thing you can do for those outside connections is use some dielectric compound on the threads, use silicon based as it helps seal the threads and makes a good ground. Also check your cable itself, you don't want any sharp bends or breaks in it, that center wire can be real delicate, especially if its RG59. If you still have interference after all that, check to make sure that you don't have power or electrical cords running along, parallel to, or across any signal bearing cords and cables. Those things give off a lot of interference. And finally, make sure all of your electrical components are grounded as best as possible.

Sorry for the long post, but I felt that you and everybody else could benefit from all that information. I lost count of the number of trouble calls I had, when the problem was really easy to fix. Like tightening a connector! Oh, use a 7/16 wrench on those but don't over-tighten them. I was with the cable company for only a couple months but I still sometimes carry a 7/16 in my back pocket. Used it a lot!

[edDV]

Great info LordXander.

Several weeks ago, I installed my Zenith DTT900 converter box.

...Initially, I received much interference when the box was too close to the TV...including horizontal waves running through every station and actual color changes (only saw greens and reds) on the TV.

Once I found the right spot for the converter box, all stations were clear.

Now 3 weeks later, I turn on the TV only to find the horizontal waves reappearing on every station! It was fine for 3 weeks! What happened?

It is my understanding that with digital TV, you either get a picture or you don't (or you get choppy break ups). I assumed that the waves were caused by some kind of electronic interference with the box and TV.

It would help if you could better describe "the horizontal waves". Power and grounding issues usually result in horizontal bands running vertically up the screen. This is caused by power line 60Hz (the bands) interacting with the 59.94 Hz. video. Horizontal movement usually results from two video sources running at slightly different clock rates. Your local TV stations usually sync off a common clock but free running video equipment in your home may be leaking into the analog TV station feed (output of tuner box). The TV set usually locks to incoming video so I'd suspect a game machine, VCR or DVD player near the TV. Unplug these one at a time to see if the interference goes away.

The other antenna/coax problems I mentioned above would occur in digital reception before the tuner. Grounding issues mentioned by LordXander would cause power line interference into all your connected video equipment.

[creakndale]

I used to live south of Cleveland, Ohio and watched their TV programs.

1) You should NOT be setting the Zenith converter box and TV to channel 3 as that is a strong NBC station (WKYC). You should be setting the Zenith and the TV to channel 4.

2) Make sure the outer shield on all coax (RG59 or RG6) cables are making good contact to their "F" connectors.

3) Plug the Zenith converter box and the TV into the same outlet. Sometimes a receptacle's hot and neutral have been accidentally wired backwards from the standard. A tester will show if there's a problem.
http://shop.ebay.com/?_from=R40&_trksid=m38.l1313&_nkw=electrical+outlet+tester&_sacat...All-Categories

An intermittent coax, center conductor or shield connection, can be marginal and just barely making contact. Then, after 3 weeks, the temperature changes, a cable is bumped or any number of things could cause the connection to open, causing your problem.

creakndale

[edDV]

All good points.

[anet]

Many thanks to everyone who took the time to write a reply!
It looks like I have some checking to do.

For those that are curious...
I would describe the horizontal waves as horizontal bands running vertically up the screen slowly with some flickering (kind of like computer screen flickering). I read all of the posts tonight, and did the easiest things...checking connections (indoors) - all were tight. I made sure both the TV and box were in the same outlet (they are). I made sure no electrical wires were running along or near the antenna cable (they weren't). I also reset the TV and box to channel 4. This was the only thing that led to some improvement in picture quality, but not enough to say the problem had been resolved (I am leaving things on channel 4 now).

Tonight, there was a "digital test" for 5 minutes on local stations. I watched the same (wavy) local channel before the test and kept right on watching it during the test. During the test, the station came in CLEAR. I then used the remote to see the other stations and almost all of the channels came in perfectly clear! The only two wavy ones were local weather stations that I never had before and do not care about. During this test, the local stations stopped broadcasting analog signals. So, the analog signals may be part of my problem.

I also talked to a friend tonight who lives very near a TV station and he complained of the same issue. Perhaps too strong a signal or too many signals (analog and digital) are still an issue for me? That would explain why things work best for my neighbor who has the worst antenna. Of course, it doesn't explain why everything worked well for 3 weeks...and worked well on channel 3.

Maybe, I have more than one issue going on.

I think I will do some of the other tests mentioned above this weekend and see how it goes...maybe try connecting the box to rabbit ears instead of the roof antenna. But, there'll be no roof antenna check for now with the snow!

Maybe, when the air "clears" of most analog signals on Feb. 17, my TV will be OK. Maybe, the only thing I need now is patience...

Again, THANK YOU for your responses! You gave me a great deal to think about and look into.

[edDV]

Vertical moving bars indicate power line/grounding issues so revisit LordXander's post. First correct the ground.

You may see some improvement when analog is shut down but many digital stations will change channels and increase power then.

[LordXander]

Just remembered something that, from your description of the wavy lines, might be another cause or factor of your problem. When I was at the local cable company, my boss always made sure that I checked the signal levels. Especially when it was a trouble call. And one of the things that can and will cause your problem is: too much signal. You said your signal meter was reading 90-95% strength. That will cause problem. I've seen it more than a couple dozen times. The best way to fix it, if it is indeed your problem, would be to "pad it down". Basically just add a 4-way splitter, preferably as far away from the TV as possible but anywhere is really fine. Make sure, if you don't add any other connections to that splitter, to put some button terminators on the other legs. You don't want any more interference to leak in, or out. You might find the terminators at Radio Shack, but I'm not sure. You can go to your local cable office, though and ask them for some. They always get a good bulk rate on things like that. Lordy, I could go through a bag of 50 F-connectors in a single day, and that's covering a town with less than 5,000 people, about half of which have satellite.

While there you could also ask for a noise filter, too. That will block out most signals below 28-30 Mhz. Which is most FM radio, that can cause a lot interference as well. Just remember, none of this will do you a whole lot of good if the entire system is not grounded properly. That braided jacket on the coax is the second most important part of relaying good TV signal. When you put on an F-connector, make sure that the braided jacket is peeled back all the way around the cable. Don't strip off too much insulator, either. Don't need little braids sticking out, or an extra long stinger (center conductor). Oh, and check for little bits of the braid wrapped around the stinger too. That will ground the signal completely and really ruin your day. Take the time to check so you don't have to do it again.

If you need anymore help, let me know. I'll walk you through it all, step by step, if need be.

[usually_quiet]

The signal meter on CECBs is probably not as accurate or meaningful as the instruments used by cable installers. One of my boxes typically shows a 100% signal strength for the closest stations, according to its signal meter. The other shows a signal strength above 90 for those stations. I get great reception for those channels.

If a temporary analog broadcast shutdown improved the picture, and switching to channel 4 for the coax connection improved the picture, it is surprising that connecting the TV to the converter box with RCA jacks and disconnecting the coax cable did not help at all.

As for rabbit ears, if someone is close enough to transmitters they can work very well. Although I find I do need to change the location and adjust the orientation fairly often to get good reception for the stations that are furthest from my home.

If the wavy lines disappear using rabbit ears, I would say that the likelyhood that the wavy lines are caused by one of the suggested outdoor antenna problems is pretty good.

[edDV]

The signal strength meter on the Zenith DTT901 is optimized for finding weak signals when pointing an antenna. It shows weak signals that must reach ~50% on the meter before the signal is decoded into a picture. The signal must get into the "good" end of the scale to avoid occasional picture breakups. There is no advantage to peak the meter. The picture quality is the same from ~50% up.

[LordXander]

I will say both edDV and usually_quiet are both correct in their replies. However, I could still be right with my second guess. I did come across situations where the all digital channels had too much amplitude behind them and caused them to either not appear, ghost, or even display analog distortions like described. Going over it like we are is really not the best way to diagnose the problem. If I was up there I would be more than happy to spend a day tracking down the problem. But alas, I'm not. I'm a little too far south to be much help in the physical sense.

Thinking, and reading the replies again I am more inclined to back up my original suggestions even more. Especially since switching to the RCA jacks didn't help. Now there is a very good indicator of the problem. Most RCA cables are un-shielded. Though most are short enough to not pick up a whole lot of interference, they still can. Anet can try using some expensive shielded RCA cables, but I'm pretty she he does not want to spend a lot of money tracking down a simple interference problem. From everything we've been told, and everything I've learned installing cable, it's got to be a bad F-connector, ground, leak or anything real simple to fix.

You've also got to remember that, while the local TV stations are broadcasting simultaneously, they can either be using most of the same equipment as the analog, or their antennas and amplifiers are close to each other. The interference could be mostly their fault, like during the "digital test", most everything came in clear. But it definitely sounds like the problem can be taken care of on anet's end.

He could also build himself a custom noise filter. They're pretty simple devices. They easy one are just a couple of specific capacitors wired into a special coax connector, and the capacitors filter out the the most common frequencies. That would actually be a pretty good test/indicator. He could go out and pick up a few small size capacitors and stick one end into the input connector while touching the stinger of the coax. Do it between the digital box and the TV. If some of the interference goes away, or changes at all from the described pattern then it most likely would be something that he could fix easily. All that may be impractical, but I do know it works, because as a teenager without cable or satellite, I was obsessed with getting in certain OTA stations. I spent a lot of time fiddling and studying radio, TV, video, audio-you name it I probably know a little about it. I'm still like that, thanks to this website, I love every minute I spend learning something new here.

Anyway, keep us apprised of the situation. I'm eager to help.