On Tue, 06 May 2008 19:03:42 -0500 Jer <gdunn@[EMAIL PROTECTED]
> wrote:
| Ed Powers wrote:
|> Hi Phil & group,
|>
|> Thank you for the responses. As I tried to explain, sometimes
the
|> bars were more dispursed and didn't affect the picture -- that's how it
was
|> when the cable guy left - but they drew them selves down to about 2"
and
|> were much more pronounced (affecting picture)that afternoon. Today I
tried
|> something - probably the first thing I should have thought of - I
simply
|> disconnected the coax input to the cable box - problem went completely
|> away - nice clean gray screen with absolutely no bars! When I hook the
|> input from the cable company back to the cable company tuner - bam, the
|> problem is back (with the tuner turned off ) - green and magenta bars
|> traveling up the screen! Even thought the cable dude brought a
computer
|> and said that the signal was OK - I'm quite certain the interferance is
|> coming down the line. I suspect when I show them this the next time,
|> they'll realize that it IS coming down the line -- the cable dude saw
the
|> lines (dispursed) on both cable boxes but didn't know what the problem
was.
|>
|>
|>
Thanks
|> again / any thoughts? Ed
|
|
| Two words... ground loop.
|
| There are two different ground circuits being fed to your equipment -
| one to the cable box, the other to the TV - and one of them isn't really
| a ground. When the cable guy fed the signal to his PC, he wasn't
| connected to the same ground your TV is, assuming his PC had any ground
| (which I highly doubt), and the problem didn't present itself to the PC.
|
| Fix the broken ground and the problem will clear up.
Exactly.
To Ed:
If you have a voltmeter, measure the voltage between the cable wire and
the
box. If you get anything, be sure the cable guy sees it.
Check where _everything_ coming into your house is grounded. The correct
way
is to have it all coming in at the same place (within a few feet) and
grounded
in common. That includes the phone lines, too. Even the water and gas if
they are metallic pipes (you don't want to see voltage between the gas
line
and power ground wire, do you?).
If the cable wire is coming in to a different place where it cannot be
grounded
properly, they need to move it.
--
|WARNING: Due to extreme spam, I no longer see any articles originating
from |
| Google Groups. If you want your postings to be seen by more
readers |
| you will need to find a different place to post on Usenet.
|
| Phil Howard KA9WGN (email for humans: first name in lower case at
ipal.net) |
|
