Solved! in wall coax cable no longer sending good signal.

[amcharn]

For the last few weeks, I'm not getting most of my antenna channels on one tv. I go from an antenna to preamp to splitter to in-wall coax to two tv's. The other tv works fine. When I hook the problem tv directly to the splitter bypassing the in-wall wiring, all channels come in. What can cause in-wall coax to go bad and can anything be done to correct it (since I can't run new in-wall coax)?

 

[kanewolf]

Bad termination on the ends is the most common thing. Take the cover plate off the wall and examine the back side. It should be a standard F fitting connected to a barrel connector. If the center conductor isn't sticking out 1/8 of an inch past the end of the F fitting, then it may not make good connection. Verify that there are no tiny wires from the outer braid that are shorting out the center conductor. Check the end that goes into the splitter also. You may have to re-terminate the coax to fix.

Animal chewing and construction damage are the only other two things I can think of that can impact coax not at the ends.

 

[atljsf]

also check the connectors itself and how long the copper in the core is

inside the wall, someone installing something on the wall could have found the coaxial cable inside the wall and perforated it or break it, or too bent to work

unwanted visitors like rodents like to eat that coaxial, don't know why

you could try to rebuld the terminals in both sides of that coaxial cable to avoid what kanewolf mentions, outer shield touching the core of the cable, if it doesn't work, replace the entire cable, is not impossible for the copper inside it to get rusted and when rusted, you don't see any signal

 

[bigpinkdragon286]

Splitters can be defective, or send uneven signal to one leg. I would certainly check both sides of the splitter (assuming it's a 2-way splitter,) and possibly test the problematic coax run without the splitter involved at all. Did you run the test that made you determine that your in-wall coax was bad from both legs of the splitter, or only one?

When you hooked your problem TV directly to the splitter, did you terminate the other side of it?

Does your preamp have adjustable gain? Is your preamp inside or outside? If you're running an outside antenna, how is the grounding?

 

[amcharn]

Splitters can be defective, or send uneven signal to one leg. I would certainly check both sides of the splitter (assuming it's a 2-way splitter,) and possibly test the problematic coax run without the splitter involved at all. Did you run the test that made you determine that your in-wall coax was bad from both legs of the splitter, or only one?

When you hooked your problem TV directly to the splitter, did you terminate the other side of it?

Does your preamp have adjustable gain? Is your preamp inside or outside? If you're running an outside antenna, how is the grounding?

 

[amcharn]

The only thing I changed on my test was using a new cable (run loosely on the floor) instead of the in-wall cable. The splitter is the same, the preamp (inside) is the same, the antenna and grounding is the same. The good tv is working the same. The problem tv worked fine for the last 6 years until 2 weeks ago, and nothing was changed or moved at that time. We haven't had any problems with animals that I have ever seen. Thanks for your thoughts.

 

[jsmithepa]

Don't get bogged down with "this used to work before." Bottom line is, your problem TV is telling you "I am not getting strong enough signal." Electronics age and after a while, all on their own, they want a stronger signal, like my Grandpa's ears

You already swapped cable and connectors, so at this point, can you just reconfigure things so the problem TV is on its own BOOSTED connection?

What I mean is, looks like from above, the signal goes to an active (booster) splitter, then that output goes to a passive splitter. Anytime you go through a passive splitter, the signal weakens (shared). So get rid of that passive splitter and move that other TV to somewhere else, and have your problem TV, the only TV to ONE output of the active splitter. Have all that signal to itself.

Of course you have swapped connections amongst the outputs of your active splitter, to ascertain whether one of its output is not "boosting enough?" Of course you did. Alright then.

 

[amcharn]

New development. I tried some of the suggestions above without change. Then, with the original hookups and coax in place, I noticed the signal strength would come and go without changing anything. Again, the other tv always got good signal, but this second tv would get all the channels one minute, and 10 minutes later only get half the channels without being touched. Most of the time over the last two days it is getting just a few channels, but sometimes it is getting a few more and sometimes getting almost all or all. What could be causing the variation in signal strength on one tv only randomly during the day? Many thanks.

 

[bigpinkdragon286]

Could even be the TV itself. Really can't say without more information, and you aren't being specific about which of the above suggestions you tried.

Since you never tested that leg of your coax before, you really don't have a baseline for whether it was passing great signal or mediocre, and whether or not the signal it's passing has gone down, or rather if the sensitivity of your TV's tuner has gone down.

Was the length of coax you tested with of identical length as the run giving you issues?

One thing I don't recall your having mentioned trying is, taking a TV that appears to be problem free and trying the bad leg of your coax chain with it. Preferably one with a signal meter built in for simple testing of various channels. For all we know, the signal chain has remained relatively the same and the TV tuner section has simply gone daft, becoming more sensitive, as jsmithepa has suggested.

Not having a proper signal meter, I generally use the built in channel strength meter on a ~19" digital TV to trace problems. It's crude, but with enough effort, you can generally track down what your average signal coming in on each station your receive is, and once you have a baseline at the antenna, you can trace your signal path and see where each station is being attenuated past viewable. If you're at the antenna and can't get the signal, unless it's outside and needs boosting, I suggest the antenna is the problem for that station. If you test your signal at each point in your chain, you should eventually pinpoint your problem. I've seen band-stop filter behavior from single legs of a splitter before, killing certain channels after the split, despite "working fine for a long time," so don't rule anything you haven't tested out. Even just the physical screwing and unscrewing of your F connectors could be causing your splitter to behave or misbehave.

Keep in mind, the tuners in every TV are going to have different sensitivities, so just because one set works with your signal level, doesn't mean another will be as happy. Heck, depending on manufacturing tolerances, and the low cost of equipment these days, I wouldn't even be surprised to see unwanted tuner sensitivity variations among the same make and model of sets.

 

[amcharn]

Could even be the TV itself. Really can't say without more information, and you aren't being specific about which of the above suggestions you tried.

Since you never tested that leg of your coax before, you really don't have a baseline for whether it was passing great signal or mediocre, and whether or not the signal it's passing has gone down, or rather if the sensitivity of your TV's tuner has gone down.

Was the length of coax you tested with of identical length as the run giving you issues?

One thing I don't recall your having mentioned trying is, taking a TV that appears to be problem free and trying the bad leg of your coax chain with it. Preferably one with a signal meter built in for simple testing of various channels. For all we know, the signal chain has remained relatively the same and the TV tuner section has simply gone daft, becoming more sensitive, as jsmithepa has suggested.

Not having a proper signal meter, I generally use the built in channel strength meter on a ~19" digital TV to trace problems. It's crude, but with enough effort, you can generally track down what your average signal coming in on each station your receive is, and once you have a baseline at the antenna, you can trace your signal path and see where each station is being attenuated past viewable. If you're at the antenna and can't get the signal, unless it's outside and needs boosting, I suggest the antenna is the problem for that station. If you test your signal at each point in your chain, you should eventually pinpoint your problem. I've seen band-stop filter behavior from single legs of a splitter before, killing certain channels after the split, despite "working fine for a long time," so don't rule anything you haven't tested out. Even just the physical screwing and unscrewing of your F connectors could be causing your splitter to behave or misbehave.

Keep in mind, the tuners in every TV are going to have different sensitivities, so just because one set works with your signal level, doesn't mean another will be as happy. Heck, depending on manufacturing tolerances, and the low cost of equipment these days, I wouldn't even be surprised to see unwanted tuner sensitivity variations among the same make and model of sets.

 

[amcharn]

You are right, I have no baseline readings. I just know the main TV keeps the signal consistently across all channels, and the second TV has problems whenever receiving a signal through the in-wall coax, but not when bypassing that cable. I did change out all other parts including the splitter, but the changed parts did not help the problem. So, everything I CAN do points to the in-wall coax, yet I can't figure out how the signal can change so drastically in that coax cable over time. Thanks for your time in sending answers. If it is for some reason that coax, I can't run a new cable in the wall anyway. I'll have to move !!

 

[atljsf]

the cable can get rusted inside, humidity, rodents, bad quality cable

is it rg6 cable?

replace it and see if it helps

how long is the cable, over 10 meters?

 

[kanewolf]

You are right, I have no baseline readings. I just know the main TV keeps the signal consistently across all channels, and the second TV has problems whenever receiving a signal through the in-wall coax, but not when bypassing that cable. I did change out all other parts including the splitter, but the changed parts did not help the problem. So, everything I CAN do points to the in-wall coax, yet I can't figure out how the signal can change so drastically in that coax cable over time. Thanks for your time in sending answers. If it is for some reason that coax, I can't run a new cable in the wall anyway. I'll have to move !!

Swap the two TVs for a while. You need to separate the TV which may have problems, from the input which may have problems.