wile e cat
@charter.com | [Cable] voltage on coax
I have a house that is producing any were from 2.1 volts to 65.8 volts when metering the center of coax to ground. This is knocking out the cable, Is there a trap or filter to stop the voltage without interrupting the broadcast? |
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JoesphM
@rr.com
| Yes, a Signal Vision Voltage Blocking Coupler. |
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UncleScooter
I once was SatManWorkin
Premium
join:2002-04-15
Tallahassee, FL | reply to wile e cat
That is a very serious problem and you should have a qualified electrician chech your home at once! |
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manboy
@charter.com | what do you need a electrician for? It sounds to me that a surge might have gone through and smoked the gate diode inside the tv. What would a sparky look for? |
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ArgMeMatey
join:2001-08-09
Milwaukee, WI
 ·AT&T Midwest
| reply to wile e cat
As you can see there are a few different ideas about what to do because your info may not be specific enough. You say the "house" is producing voltage.
Have you disconnected the house from the cable drop and checked the house side, with TVs attached?
Drop disconnected, TVs disconnected?
Drop connected, TVs disconnected?
Is the "cable TV ground" bonded to the power company ground?
Have you checked each TV and other RF-connected device to see if any of them are putting out voltage under different conditions?
In other words, is the voltage coming from the cable company's plant, or from a device or connection in the house?
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tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
 ·Hollis Hosting
·Verizon Online DSL
·Fairpoint Communic..
| reply to wile e cat
Need more details. How have you determined the voltage is causing damage? Are you seeing this voltage on CATV feed with inside wiring disconnected? If so contact your CATV provider and have line checked.
While you are at it make sure incoming feed is bonded to building ground as recommended by ArgMeMatey  . If let your CATV provider know.
With the external feed disconnected is the voltage still there? Assuming you have more then one device connected to the coax disconnect them and measure each one individually.
Do you know if there are any pre-amps or line amps remotely powered via the coax. For example we use an outdoor antenna with a preamp, the power supply is inside.
/tom |
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gar187er
Premium Alcoholic
join:2006-06-24
Dover, DE | reply to wile e cat
find the source, and remove it/fix it.....dont just mask it with a voltage stop.... |
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UncleScooter
I once was SatManWorkin
Premium
join:2002-04-15
Tallahassee, FL
·Embarq
| reply to manboy
said by manboy :
what do you need a electrician for? It sounds to me that a surge might have gone through and smoked the gate diode inside the tv. What would a sparky look for?
So what Voltage and Current is showing up on the coax, where is it coming from, is there a chance someone could come in contact with this current and somehow contact a grounded surface? If so, can you explain to the OP what could happen next? 
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I know you think you understand what you thought I said, but what I'm not sure about is that what you heard isn't exactly what I meant. |
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wile e cat
@charter.com
| reply to wile e cat
Oaky I have found out more, I am getting feed back voltage from the tv's going back onto the cable grid for the house. With the coax unplugged from the cable box, tv plugged into the wall there is voltage from the center wire of the coax to ground and all 4 tv's are on the same circuit.
I have also learned that this part of the house is old knob and tube wiring. The whole house was working fine until the plumbers changed alot of pipes. A new ground wire was pulled to the water meter and two ground rod installed. I also changed the service feed from the weather head to the panel.
thanks for all of your inputs on this... wile e cat |
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ArgMeMatey
join:2001-08-09
Milwaukee, WI
·AT&T Midwest
| Is the cable shield bonded to the power ground? Are all four TVs backfeeding the voltage to the RF connector, or just some, or one?
I remember a thread some time ago about LCD sets doing this. I think the cause was a power supply design problem, but I can't remember the solution. Not even sure it was on this board. |
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