TV Signal Noise

The source of your noise is most likely a poor connection. When you disturb the connection you are upsetting the entropy that sets in overnight. Make sure that you have good quality connections. Crimp on connectors or soldered connectors are best. The screw on connector requires some experience to do those well.

As to why this happens overnight, I would expect temperature cycles would cause enough expansion and contraction to break your marginal connection.

The electrical current you felt is coming from the cable service provider. Specifically, it was the RF energy that contains your TV signal.

Tom,

I respect your difference of opinion. But from personal experience, I can tell you that my cable service provides enough of a signal to deliver an uncomfortable sensation when in direct contact. It does not feel like a 60Hz shock, it has a different character to it but I wouldn't want anyone to think I doing this sort of thing on purpose.

Remember also that any sensation limits set by UL are frequency dependent. That especially means that higher frequencies penetrates the human body more easily. And RF will burn to the bone, given the chance.

So, if one were to unplug all of the televisions in the case above, and then do your test he would still receive an uncomfortable sensation, but it would only be necessary to do it once to prove that it came from the cable. Or, one could just take our word for it.

BTW-testing this theory at the output of a few splitters will probably result in no sensation. That's because the splitter is a voltage divider.

NotUrOrdinaryJoe Why not use a meter to check for this voltage instead of the sensation of feel? A home I built some years back had an unusual problem that may relate. After receiving a shock from an outside faucet while standing on wet ground I checked the voltage with a meter (from faucet to the earth) I had a voltage that varied from 3 to 16 (checking periodically over several days). The house had copper pipe and it was connected to a PVC water main going to the well so the plumbing was not capable of being a ground. I found the electricians had bonded the water heater to the plumbing so I connected a #8 solid copper wire from their connection to an 8 foot copper ground rod that I installed into moist earth. Surprise, the meter reading didn't change. I called the power company and they found the same thing I did, they added 3 more grounds from the pipe behind the faucet to 3 separate ground rods in an arc right in front of the faucet so when you touched the faucet you were standing over the ground rods. I know it makes no sense but we still had voltage from the faucet to earth. The power company then disconnected the house from the grid, also disconnected the phone line and there was still voltage present. The power company had two theories as to what may be happening, there was another ground 100 feet away where the power entered the structure and the house was acting like a battery between the grounds, There was another power system close by and they said sometimes this caused unusual problems between system grounds. My television signal was through a small dish mounted to the wood structure so no input there. This was never solved and the voltage slowly eat away at the copper pipes and my wife and children would never use the outside faucets. (If only I could have found a way to use this free power) Jerrell

In all probability you were located next to a pipeline system that used impressed current corrosion protection, and the protected system had poor electrical insulation. Everything close to the pipeline would be 'corroded away' if it was' grounded' and also connected to the power line 'neutral.'

We had this identical situation in rural Louisiana on our farm. It would corrode through the water well steel casing in 8-10 years. My younger brother was a Corrosion Engineer for a major interstate pipeline company, and when he attached his instruments to the well, he was astonished to see how high the current flow was. It took a 7 amp (24 v) power pack to balance out the current from the pipeline.

Keith E Bowers I believe you have solved the mysterious source of power. I had a cross country natural gas line very close by & a cross country copper & fiber optic phone line that ran across my property 150 feet from my home. I wish I could have pursued this before selling the place. A GA to you for informing me of this power source, I wish I could of harnessed it and sent them a thank you letter to have seen their response. Jerrell

Or may be cable company is injecting too many HOT channels..

We do not know from which country Guest is. But I am happy that such things can happen in USA also. I was under impression that it happens only in developing countries with our sort of spread newwork

One of these cable will be cable from TV cable company.

GA, my thoughts exactly....

Thank you everybody for your answers. I´m living in Mexico, Queretaro State, and I have a cable company signal.

After I read all your comments and I made some quick test and found a TV with a big problem because a moderate-to-big electrical shock told me that. That TV remains disconnected. Also, I have two new preassembled RG-6 coax and one push-on coax, also new. I replaced this one by a new RG-6 preassembled RG-6 type. I also foud a coax with a less diameter (size) than the others and changed it. This morning, the TV signal was much better and I had a great kiss from my wife ( thanks guys !), but still is not clear. I still must work with the ground system and measure the voltage from the cable company.

Guest,

Thanks for coming back to share your findings. I'm glad we could help you isolate the problem. As I said in my first post, the trouble TV would not be able to induce a voltage on your cable if the cable was properly grounded by way of a grounding block where the cable comes into the residence. If your cable provider will not fix the problem, it's not too difficult to install a grounding block on your own. Good luck!

Tom

It must be possible to "Opt-Isolate" the "interference".....

My suggestion would be to get rid of the Cable company and get a Satelite dish installed on your roof. This will solve all your problems, and there will be no current or electrical shocks in your CoAx cable anymore. I am sure even in Mexico, you can find some Satelite service provider. This service does not depend on wires coming from the Cable company to your house and no electriity flows through the wires that come in from the dish.

Not fully accurate......

The signals and the control voltages are present on those cables.

I have aslo had this effect on the signal cables from "cheapo" satelite receivers.....wen I touch the ground on the sat receiver and a "real" ground......

I have not actually bothered to measure the voltage difference with a meter, but guessing, its probably somewhere between 30-50 volts AC unloaded....with next to no current behind it......its just a "tickle".....not very scientific, sorry!!!

The receiver that does that is stored in our caravan at this time, no access....

Your TV with extra shocks. See if you can get an isolation transformer to run it.

For each 100 watts of power ~= 1 Amp at 120 volts AC = estimated size of transformer.

A poor mans isolation transformer is use two identical transformers of sufficient power connected back to back.

So lets say you cannot find a 120V to 120V transformer, but you can find 120 volts to 48 volts at 4 amps (192 watts) veru cheap. Use two back to back. 120 volts in to one makes 48 volts, connect the 48 volts out of 1 into the other transformer connected backwards to regenerate the 120 VAC and get isolation. With correct phasing you can use multiple output transformers in this manner as long as they are identical. Often surplus radio shops have bins of old transformers so you can two the same with the ratings for this use cheaply

I have felt the "tingle" from the coaxial cable supplying my signal. It's much lighter than a 110V obviously, but there is a sensation present. As far as the signal quality, I have no useful input.

Two things I can think of regarding this problem; First is that daytime activity in the ionosphere interferes with the more pure signal you can get at night. Second is the mutual capacitance as a result of multiple systems not being grounded. This translates much in the same way you can get a 'dirty' oscilloscope reading. Bond everything, see what happens.

Your cable is connected to two things: the cable provider's transmitter at one end, and the TV at the other. If there is current leaking from someplace, which of those two possible sources seems most likely?

I would guess that one of your TV's is building up a charge in its cabinet and this charge is getting transferred to the cable. You could test this by leaving the cable disconnected from all your TVs overnight, and in the morning check it to see if there is a charge on it. If not, the charge is coming from one of your TVs. You can figure out which by leaving the cable disconnected from one of them the next night.

If the problem is with a TV, you can start diagnosing the TV. If not, then you can call your cable provider and they should be able to remedy the problem with their own equipment.

The individual sets are connected to the AC line and have a ground pin as one side of the AC line. Some have a three wire connection, line, neutral and true ground. The RF cable is grounded to the chassis.

Most sets also have a small high voltage capacitor from the hot side of the line to the chassis. If they do not have a true ground, you can get a tiny leakage through this small capacitor from line to chassis that gives you the tingle.

I have owned many TVs in my 50+ years. ...RCA, Curtis Mathis, Panasonic, Sonys... and not a single one of them ever had a 3-wire power cord; i.e., NO "ground" pins.

Has ANYBODY ever had such an animal (tv)...????

Yes, I have heard, and I own such an animal right now. Its a cheap knock off Chinese flat panel screen... 27" widescreen. It plugs in using a standard computer power cable, the same cable as nearly every computer monitor on the market.

Sounds like crummy made fittings to me. If it's only one TV that has the noisy pictures remake the fittings at the set and the splitter on that run of cable. If it's all three sets remake the fitting that feeds the first splitter. It's building up an impedence over night that you're breaking when you disconect it.

I've also seen a bad ground cause problems. Here in Oklahoma in the hot dry summer I've had to pour water on the ground rod to reestabish a ground. But why aren't you just calling the cable company for a service call. The tech deals with the same 20 or so problems day in and day out and can probably walk right to it.

I would measure the AC voltage very carefully from the copper tip to the ground of the coax. Notify your cable company of this voltage if any and that you may have a bad ground. Ask about service charge first and then scare them a bit and act dumb saying I keep getting shocked by "your cable connections". And tell them what voltage you measured after the measurement. I bet they will waive any service fees or they could be sued if it is there problem and not your TV(s).

Also this shock sounds like static electricity. Is it windy outside? I get shocked all the time when it is dry and windy. This is real bad when you handle ICs. It is in the KV region since you are a capacitor.

Let the repair guy try to solve the problem with no service charge just tell the operator that I think this will "electrocute me" and see how fast they come to your house. LOL

Do you connect to a digital TV box? I use the Sky TV box & they warn you that the co-ax from the box to the dish carries a voltage.

Check the integrity of the ground and ground rod of your residence. If this ground has a problem, your cable will carry a portion of the ground current instead. The result will be inline with the symptoms that you described.

Check the integrity of the ground and ground rod of your residence. If this ground has a problem, your cable will carry a portion of the ground current instead. The result will be inline with the symptoms that you described.

Hello all,

Tropicalspeed is correct. I am a "X" twenty year TV Technician and have dealt with this more than once.

If the TV had a leaky ground you would see a 60hz "humbar" in the screen all the time and when you touched it you would FEEL it for sure! about 80-90 volts AC at 60Hz will feel like a mule kicked you.

Go out to were your Cable comes into your house. Some place before it actually enters your home will be a grounding block. Its usually hooked to a water pipe, Electrical Box, or sometimes they do it right and actually install a ground rod.

Cut and clean ALL the electrical ground connections on the ground block and however and to whatever they connected the other end to (waterpipe, electrical box, ground rod).

Also, you should check all the connectors in the system. Just disconnect them from what ever they are hooked to and give them a gentle tug. If they come off the ground connection was bad. Replace with ONLY crimp on screw type connections. NEVER use push on connectors or the type that screw onto the coax.

If all else fails call the cable company. But make sure you tell them you have the same problem on ALL your TV's or they will feed you some crap about it being a TV problem.

Good luck

Bill12780

There really isn't enough information here to give a definitive answer. The OP didn't even specify if this TV cable signal is from a cable company provider, satellite dish network or a simple aerial antenna. However, from the fact that he can discharge this voltage and temporarily improve signal quality leads me to conclude he has at least two problems.

1. Somewhere in the network; either the provider, a distribution amplifier, or one of the TVs, the RF electronics has a parasitic leakage current that expects a DC return path. However, no DC return path exists.
2. The TV front end electronics being all AC coupled, the capacitors of the front end are breaking down with too high of a DC component applied.

Fortunately, if this is your problem I can suggest a simple solution for you. Obtain a cheap 3 dB transformer based signal splitter that has a case ground connection. Verify that the center conductor to case (shield, return) is a low impedance path with an ohm meter. Place this at a convenient point where your RF enters your home and a ground lead is available. Splice or connector this splitter into your signal path with your TVs getting one of the 3 db reduced signal and a 75 ohm termination on the other. Attach the case ground to your splitter.

As the other posts have pointed out, it maybe nothing more than a loose/bad connection.

If I'm not mistaken, there should be a grounding block where the cable comes out of the ground to your residence. The purpose of the block is to properly ground the shield of the cable. This block also contains a solid copper wire that is attached to an individual ground rod. I believe that this is required by code. There may be a problem here or it may not have been installed.

This is a curious problem. Please let us know what the solution is to your problem.

The connectors on typical cable company coaxial terminations are also notoriously glitchy, have you considered that the problem may actually be caused by connecting and removing the screw on connectors twice a day? It may be that you are introducing a bad connection by not tightening the screw enough some days, then doing a satisfactory job the next. Also, the correction that you saw by grounding the wire may not have had a thing to do with the signal improvement, it could just be that after getting a small zap you screwed it in more carefully.

It might be best to permanently attach the connector and use a splitter for the other TV's, then trouble shoot if the problem returns, or is still observed.

Go to Radio Shack and buy a thing called a "DC Blocker" this prevents a backflow of voltage to your coax. The voltage originates from line powered equipment that is connected to the cable. Is your coax RG 6 ? It should be. Get the Quad shielded variety. The Big Guy

I have experienced this as well. I put it down to TVs, Receivers and the like that have no frame/safety ground........it happens often....I just pull the mains plugd while working on such equipment, the problem goes.....

Thank you everybody for your answers. I´m living in Mexico, Queretaro State, and I have a cable company signal.

After I read all your comments, I made some quick test and found a TV with a big problem because a moderate-to-big electrical shock told me that. That TV remains disconnected. Also, I have two new preassembled RG-6 coax and one push-on coax, also new. I replaced this one by a new RG-6 preassembled RG-6 type. I also foud a coax with a less diameter (size) than the others and changed it. This morning, the TV signal was much better and I had a great kiss from my wife ( thanks guys !), but still is not clear. I still must work with the ground system and measure the voltage from the cable company.