1. Home
  2. Electronics Down Under
  3. Why would there be voltage beng fed back to the aerial??

Why would there be voltage beng fed back to the aerial??

Hi all,

A computer fitted with a TV card has been progressively failing by not wanting to go through the boot sequence, It was going past the password screen, then began locking up at the password screen. Some drivers appear to have become corrupted.

The owner started to remove cabling from the rear of the computer and got a light zap when removing the aerial cable from the TV card. Now the computer will not boot up at all.

I got involved and, upon measuring the potential from the aerieal lead plug where it would plug into the computer TV card to a three pin earth in a wall socket, measured around 90 volt using the AC measurement range on a meter.

The aerial has no amplifier, however, it does attach to an LG video and then on to a TV.

Measuring potential on the antenna connection out of the TV gives basically nothing, measuring the potential on the LG video player aerial connection gives the high voltage reading.

Can anyone shed some light on this issue. Both the TV and Video player are double insulated.

I would appreciate comment from PA on this.

Thanks

As an aside, after getting the zap when removing the aerial lead from the TV card the owner now finds the computer will not respond to the power switch. The power supply is working and delivers the correct voltages, it appears the motherboard has failed.

Reply to
APR
Loading thread data ...

On Jun 24, 9:01 am, "APR"

Reply to
David L. Jones

On Sun, 24 Jun 2007 09:01:42 +1000, "APR"

Reply to
Franc Zabkar

"APR"

** Didn't you read this when I gave the link a while ago ?

formatting link

particularly this section...

formatting link

BTW

External ( outdoor /rooftop) TV antennas are required to be earthed.

How come this one is NOT ???

....... Phil

Reply to
Phil Allison

I thought about that myself, and am guessing that the VCR was not connected to an external aerial whilst being connected to / disconnected from the PC. In haste its quite possible that the RF lead to the external antenna (could have been using rabbit ears too?) was disconnected before the PC tuner was.

I actually have a user manual somewhere here for TV or STB that states that a small tingle may be felt when disconnecting / connecting cables and that this is normal. I'm guessing the manufacturer added this to the manual to prevent false warranty returns on the basis of the unit being unsafe. All manuals for equipment I've actually bothered reading tend to make a note regarding connection or disconnection whilst the equipment is switched off.

James

Reply to
James

FFS!!! I wasn't aware that Govco was working toward this insidious little piece of work. Friggin ridiculous what they are doing in the name of "greenhouse effect" and "climate change". Next thing you know they'll have us all huddled together in a cave eating raw beef, since we won't be allowed to start a fire to cook it. Thanks Phil, will work toward drafting a few letters to get to MP's and to the media.

Reply to
Doug Jewell

"Doug Jewell" "Phil Allison"

** Go for it, need any help - just ask here.

Insidious is exactly what it is.

....... Phil

Reply to
Phil Allison

Hi Phil, thanks for the reply and for the links, it explains a lot. The house is rented, a tile roof with the aerial nounted off a timber barge board and the lead going down the side and under the house to enter through the floor. I can imagine this being done by the owner of the building, with him knowing nothing of earthing requirements or any other installation requirements. (makes you wonder if he may have done any 240v wiring in the house) The renter is a bloke I know well, I will steer him in the direction of this newsgroup to have a read and let him determine where he goes from here. I think a good start may be earthing that aerial, though.

Reply to
APR

"APR" "Phil Allison"

** An unearthed, roof top antenna can easily acquire a static charge of 10 kV, or more, on a dry, windy day.

Ouuuccchhh !! !

SMD size semis are likely to use even stronger language ....

...... Phil

Reply to
Phil Allison

Also,

Antennas can pick up quite a big static charge from a dry wind. And a dipole antenna in rain picks up a charge from the rain drops. During a heavy shower I had a disconnected cable for a dipole for the 80 metre band which had a continuous arc from the center pin to the outer part of the connector.

Reply to
Friday

On Sun, 24 Jun 2007 18:20:57 +1000, "Doug Jewell" put finger to keyboard and composed:

I propose that to offset the planet killing impact of these dastardly devices, each of us spend an additional 15 minutes of each day in the prone position. In this way we will lower our metabolisms, reduce our individual CO2 contributions, and entitle ourselves to carbon credits.

- Franc Zabkar

--
Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.