HELP - Electrical Fault - The case on my DVD & VCR are l

[breezer]

i think its the tv, since electrician and supply co gave the green light.

how do you get a voltage from a tv, mine is plastic housing, amd so are most.

one last thing try it at a friends house, if you still get voltage its tv

 

[Bell]

Breezer.

You may need to correct me here if i am taking readings incorrectly.

I put one end of my multimeter on the TV coax socket (on the rear of the TV), but without the coax cable connected and the other end of the multimeter on the screw of the wall socket, although the electrician tried it directly onto the earth pin.

When testing the DVd and VCR I have put the multimeter probe on the screws holding the outer casing in place and again onto the earth of the wall socket.

Hope this makes sense.

 

[breezer]

you are.

which is why no one can find a "fault" but you

 

[ColJack]

check at the plug between live and earth, live and neutral, and earth adn neutral.. post the results..

I'm hazarding a guess that it's something to do with the neutral and earth being at different voltages since it's a reading to earth..

bad neutral, floating earth? leakage from other equipment?

 

[bernardgreen]

The metal cases and earth or signal ground side of input and output connections of double insulated equipment such s DVD and VCR recorders and players are electrically floating. They are not connected to anything.

Hence the metal and signal ground connections assume a voltage that is a capactively coupled low energy voltage which can give a strong tingle when touched by an earthed person but can be disapated via a high impedance connection to earth.

When connected to other equipment there is a common signal ground which will float at some voltage depending on the various bits of equipment. This is not a problem as the voltage is very low energy.

If it becomes un-pleasant then earthing the aerial coax close to the first piece of equipment will remove the voltage. There should be only one earthing point other wise signal earth loops can be formed which can reduce the quality of pictures and/or sound.

Very often the aerial coax is connected to the mast of the TV aerial which mounted to the brick work provides a high impecance route to earth whichis enough to disperse the very low energy.

 

[Bell]

Hello Coljack.

Could you let me know how best to take these readings.

Is it okay to insert my multimeter probes directly into the plug socket, or should I remove the socket fascia and put the probes on the wires inside.

Just want to be sure that it is safe to do so.

Thanks

 

[Bell]

Thanks for your help.

I understand what you have told me and perhaps this is the case. I can certainly try earthing the coax and will let you know the result.

The thing that concerns me is that the voltage reading is variable, I think the highest reading that I have had is 62V ac. I am worried that it may be higher than this at times, but obviously I cannot be sure if it is going higher than this. The electrician told me that anything over 50V ac is potentially dangerous and I should really try and get to the bottom of the problem.

Thanks.

 

[mike++]

Now i'm wondering if these voltages are being induced by the house wiring and you have an open circuit earth somewhere??

 

[Bell]

Hello Mike.

I do suspect the house wiring, especially as I know that the property was rewired recently.

Can you suggest any tests that I can perform that may help to find a fault with the house wiring.

Thanks.

 

[mike++]

Hi Bell,

Sorry, no i cant suggest any tests that you can do. I'm not qualified to advise you. If you had someone look at this fault already and you're not happy, call them back and get THEM to touch the "live" parts.

 

[Bell]

Okay, thanks.

 

[mike++]

Oh, another thought, is this voltage enough to get a glow from a neon screwdriver?

 

[Bell]

I can't answer that one as I don't have one of those screwdrivers.

However, the voltage on the case of the appliances is definitely live and when touched you do get a mild shock.

 

[mike++]

Then i would say that's not normal and i wouldnt accept it in my house. I would call the electrician back, and soon.

Would be interested in hearing the outcome though.

 

[Bell]

Hello Coljack.

Results a follows;

Live to earth - 245V

Live to neutral - 243V

Earth to neutral - Zero volts