peter Posted April 5, 2003 Share Posted April 5, 2003 Hi I was plugging in my tv coaxial feed tonight and recieved repeated small voltage electrical shocks when touching two bits of the connectors. My understanding was that TV Coaxial cable carried signal, rather than anything noticable voltage wise, so why was I getting a shock? :) Peter Link to comment Share on other sites More sharing options...
robloxley Posted April 5, 2003 Share Posted April 5, 2003 Sounds dodgy - I reckon your signal level should only be in the region of a few of mV max. (unless you're next door to the transmitter with a good aerial!). Assuming you're plugging the aerial straight into the TV, it may be an earthing issue, where the earth potential of the screen connector on the back of the TV and the aerial downlead are different; or you could have some interesting fault with your TV. I'd poke a multimeter between mains earth and your TV and then downlead cable and see what you get! Link to comment Share on other sites More sharing options...
themadhippy Posted April 6, 2003 Share Posted April 6, 2003 anyone know how capacitive coax is ? would it be enough to store a largish static charge?as I once experianced something simalar with unterminated micc (pyro) Link to comment Share on other sites More sharing options...
James Posted April 6, 2003 Share Posted April 6, 2003 I was plugging in my tv coaxial feed tonight and recieved repeated small voltage electrical shocks when touching two bits of the connectors. My understanding was that TV Coaxial cable carried signal, rather than anything noticable voltage wise, so why was I getting a shock? I was never particularly good at electronics but it sounds like one end of your coax was pluged into your TV or VCR or DA or other active device. All those consumer devices are almost certainly double insulated class II devices with a floating earth which is causing your shocks. James Link to comment Share on other sites More sharing options...
peter Posted April 6, 2003 Author Share Posted April 6, 2003 My multimeter is reading 25v difference between the outer of the arial lead coming from my TV(card, in my pc) and the outside of the downlead - that can't be right! I also can't get any TV picture. Not sure where the problem is. Link to comment Share on other sites More sharing options...
owen_mcauley Posted April 7, 2003 Share Posted April 7, 2003 25V ac or dc? Might help us solve the problem for you. Owen Link to comment Share on other sites More sharing options...
peter Posted April 7, 2003 Author Share Posted April 7, 2003 25v DC, 60v AC.... not sure which I should have been measuring, but those were the readings Link to comment Share on other sites More sharing options...
owen_mcauley Posted April 7, 2003 Share Posted April 7, 2003 Is anyone out there more knowledgeable about these things than me?All I can think of is inductance or capacitance with reference to this problem.Can't think where from tho! I'm not much help really! :) PS is this the first time you've plugged it in? Owen Link to comment Share on other sites More sharing options...
peter Posted April 7, 2003 Author Share Posted April 7, 2003 No, I used to have it connected but due to the long lead being needed elsewhere had to stop. I then bought a Y-split type connector, which I took a tee-off to connect to the PCTV card. (y-split from tv in another room). After it didnt work (lines on tv-picture, no signal to PC-TV), I tried connecting directly to the downlead. I got shocks from both connections (with the y-split and again with the downlead, thats when I measured the voltage) Make sense? Not to me! Peter Link to comment Share on other sites More sharing options...
tonymaslen Posted May 7, 2003 Share Posted May 7, 2003 Right a full TV signal is in the Region of 1V well its actually .7V as this is a TV card in a computer as opposed to that coming into a TV is sounds like your TV card is not Grounded propally. if this had been a normall tv it would be possible to get a shock in the region of 30,000 Volts I am not kidding! the Tube inside need a mental amount of power to fire the electrons at the screen! Things to check why you have not got a picture.... you are scanning for the correct source I.e Antenna, cable or VRT.also the correct country and singal uk PAL! anything else would cause nothing to be picked up! other problem are that you dont have the correct software installed, check you are running the right software for your operating system and that it is up to date. most manufactures have update on there web sites. hope this is of some help :D Link to comment Share on other sites More sharing options...
NickLee Posted May 7, 2003 Share Posted May 7, 2003 the Tube inside need a mental amount of power to fire the electrons at the screen!:I hate to be pedantic, but it doesn't.It needs a high voltage which is a different thing entirely.What you're looking at is thermionic emission, so you're taking electrons emitted from a heated filament, and accelerating them across a high potential difference; when they hit the CRT and discharge at the other end at high speed, they cause photons to be released, hence light is emitted.My point? The actual POWER required to generate the magnetic fields and accelerate the electrons is not large, but you do need a high-tension supply. Having said this, 30kV is 30kV is 30kV. (and pedantry is pedantry is pedantry) :D Link to comment Share on other sites More sharing options...
peter Posted May 7, 2003 Author Share Posted May 7, 2003 I'm pretty sure my PC is grounded properly... my surge protector says so! Link to comment Share on other sites More sharing options...
tonymaslen Posted May 7, 2003 Share Posted May 7, 2003 my advice is..... take it back to the shop and get a replacement!! Link to comment Share on other sites More sharing options...
peter Posted May 8, 2003 Author Share Posted May 8, 2003 Its worked for a year and a half fine tho. I think I've located the source of the problem, and its actually power coming through the coaxial feed, which is paired off at source, back from my new FreeView digibox. Dodgy or what?! Link to comment Share on other sites More sharing options...
Freddie Posted December 20, 2004 Share Posted December 20, 2004 Maybe not as dodgy as you think Brian. Sky digiboxes (and I think some freeview ones) can be used with remote-control extenders that work through the co-ax, the digi sends voltage up the cable with the video signal, and the IR reciever sends pulses back down. 25V seems dodgy though Link to comment Share on other sites More sharing options...
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