75 Volts off TV F-connector?

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pjm@see_my_sig_for_address.com wrote:

One with the appliances. Or no problem at all and misinterpretation of the data. WHen i get a chance, i will fluke some pieces i have laying around and see what the results are. If any reads high, i will put a leakage tester on them and recheck. Personally, i doubt that its in the wiring unless it has been tampered with.
Bob

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That is the problem, you are an electrician and not into the electronics. Many devices will have some leakage to them . A digital voltmeter will show high voltages but do not take into account the current. To see if the device is really leaking enough current to be a hazzard to the user you need to use a special meter or load the meter you have with a resistor of a known value.
Some times the capacitors and surge supressors will become damaged due to old age or voltage surges. This can then become a big issue.
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Ok, master electrician. The GFCI compairs the current going into the device on the hot wire and comming out of the device on the nutral. As the mixer probably does not have a ground wire the GFIC will not detect any leakage to ground as there is no ground involved. If it did have a ground wire the gfic would be tripping if there was a leakage of a big enough current. A device can have a small ammount of leakage and not be detected by the GFIC . A very high impedance voltmeter will show some voltage. A good old Simpson 260 will show a much lower voltage than a digital meter if this is the case.

Hate to tell you but the analog voltmeters are actually current meters and are calibrated in voltage. If you take care to look at the Simpson 260 you will see it is a basic 50 microamp meter and resistors are put in series with it to give a voltage reading. There is also a diode to convert the AC to DC for the basic meter movement. As analog meters usually have a much lower impedance they will read a lower voltage than the the digital meters if the voltage source can not supply enough current due to the impedance of the circuit.
I work in a large factory and deal with everything from low miliamp circuits to 480 3 phase circuits at 600 amps. In the last couple of months I have started some training on the 4160 volt and 13 K volt main feeders in the plant.
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Luke wrote:

gets its power from the cable itself. That's on the order of 75 volts send down the large center conductor of the cable. You might need a visit from the Cable Guy to check it out.
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William W. Plummer posted for all of us...

--

Tekkie

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Tekkie wrote:

All the amplifiers in a community cable distribution system get their power from the cable itself. It is 60 Hz whereas the cable signals are 50+ MHz and higher.
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William W. Plummer posted for all of us...

frequency. So let us know what you are asserting here... volt amps frequency pick one then stick with it. --
Tekkie
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Tekkie wrote:

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William W. Plummer posted for all of us...

called on it change the subject. YOU said 75 volts is sent down the center conductor, then you change to frequency. Bozzie read YOUR posting above. I didn't check but are you on webtv? --
Tekkie
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I have seen many "newer" (15 years old or so) where the power internally is derived from inverters right off the AC line. In many cases the, so called chassis voltage (chassis "ground"), ends up being something other than 0 volts. I have seen it to be 1/2 the line voltage. The tuner input (the 75 ohm F connector) is capacitively coupled to this internal chassis non-0 volt-"ground". It is a very small capacitor as it only has to pass high frequency TV signals in the MHz range. However, with a high impedance meter, one will read some of the 60Hz line through that capacitor. As others have stated, with a old meter, i.e. 20000 ohms/volt, you probably won't see the voltage. I would, however, make sure there is not a fault condition.
Bob Urz wrote:

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Sounds like induced voltage. Put a resistor, say 47k up to 470k, across those points and measure again. You can use a night light if you don't have any resistors. If the voltage goes away, it's induced voltage, which is harmless. If it looks gone, take the meter down to a lower scale, say 10Vac, and see if it still reads zero. If the voltage doesn't go away, and especially if it stays at the previous voltages, it's dangerous. Start disconnecting things one at a time until it goes away. I suspect it will go away. Hope you'll post back with the solution; interesting problem.
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they get to around 85-90V. If it's zero with the bulb, then it's just induced voltages. He said they were 2 prong outlets and thus no earth ground is present.
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them in order to post here, and he also has the advice to work that out without bringing in a hi-priced electrician (yet) to tell him it's induced voltages or worse yet a few thousand in repairs, most of which he probably doesn't need. IFF the equipment came as two-wire, he's fine. If he's fiddled with removing ground pins for two prong outlets eg plugged 3-wires into unearthed outlets, he's not likely to call in an electrician, is he? Thimk man, thimk! Yes, I said thimk! Pop
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wrote:

never recommend against it. The only real problem here is the buffoon with his egocentric mouth-hole in gear without a running motor to drive it. Concensus usually wins out with most posters, so one of that ilk only causes a little momentary stress. It's also possible he's right but he's bypassing the simple things that might easily determine that an electrician isn't needed, and that it won't take digging into anything more than a light bulb or resistor to measure across in order to see what kind of current might be there. Besides that, he probably enjoys flames because he gets to show off the vocabulary his father taught him. Pop
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Luke wrote:

I do suggest rechecking it with an older analog meter or add a 120V lamp across the circuit before testing. See what you get.
I agree with those who pointed out a number of issues like floating neutral that might be involved. You don't want to mess with this kind of problem, you want to fix it and now.

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Joseph Meehan

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Luke :
Sorry to say that we are having a little problem with one or more local trolls. It should be easy for you to ID them and ignore them.
Turtle somehow get tied up in this. He has been long known for great advice and his gentleman manor. I suggest you ignore his responses to the troll(s) but do listen to his advice.
Note to Turtle.
The less attention given to those who have social problems, the better. Don't let them get you down.
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Joseph Meehan

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Luke wrote:

If your antenna/cable is ungrounded, perhaps the shock was static from dry wind on the antenna and not related to your reading.

they can show the voltage metal picks up from radiated electromagnetic energy. I'd get a resistor of 20,000 ohms or so and clip it between my test leads to see if the reading dropped a lot. I'd be concerned if it didn't drop much. If it dropped a lot I'd measure current.
Either way, I'd see if I got readings with all the circuit breakers turned off. Then I'd check the effect of turning on each breaker.
Choreboy
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wrote:

It can't be induced voltage because you don't get a shock off induced voltage. It can't be a floating neutral because you would be having other serious effects (lights way too bright, lights way too dim) from a floating neutral. And it can't be from your cable system because you don't have a cable system. And that exhausts this group's suggestions.
Obviously you have test more systematically to isolate the problem, but you already know that. Good luck.
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Luke,

AC or DC voltage?
Doesn't sound like a problem with the TV antenna. To check, disconnect the antenna cable and measure for voltage between the center conductor and the screw-on F-connector. You shouldn't see any voltage, or maybe a volt or two at most (induction, meter inaccuracies, etc.).
If you are getting DC voltage from the coax coming from your TV antenna (not connected to anything), see if you have an antenna rotator or remote amplifier. These often get power from DC voltage sent over the coax TV cable. If that's the case, there should be an indoor transformer connected to the coax somewhere. Follow the cable back to the antenna to track it down.

That would lead me to believe the coax cable is grounded too, since the ground and coax connector are at the same voltage potential.

I wouldn't be too concerned about small voltages coming off the F- connectors, but you should not be getting any significant voltages off of the cases of your DVD player or stand mixer.
My first guess would be a faulty electrical ground.
Set your meter to AC voltage and go to a grounded electrical outlet in your house. Measure between the ground hole and each of the two "prong" holes. You should get about 100-130 volts between ground and the small "hot" slot, and you should get 0 volts between ground and the larger "neutral" slot. You should also read the same 110-120 volts between the hot and neutral slots. (You can buy inexpensive plug-in "electrical testers" at any home center to verify the wiring is connected properly).
The ground and neutral should be at the same voltage potential, as they connect to the same bus bar back at the main breaker panel. If you measure more than a few volts between the ground and neutral, you could have wiring problems, either in the house somewhere, or at the breaker panel itself. Time to call an electrician.
Even if the wiring is all connected properly, some old houses used metal water piping as their electrical grounds. It's possible that someone replaced plumbing at some point with plastic (non-conductive) piping. This could potentially leave you without a grounded electrical system. That's why it's not allowed by code anymore. You should have dedicated ground rods for your electrical system. Even if you have the ground rods, it's possible the wires running to them are broken somewhere.
If you are getting voltages outside of the numbers mentioned above, you may have a bad meter. Install a fresh battery and/or try a different meter. If you still get wild voltages, call the power company to come check the voltage to your house.
Also, be sure you are not touching the tips of the meter probes with your fingers. You can induce some wild voltage readings on sensitive meters just with your body...
Anthony
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