How to fix ground loop interference on my TV?
Rob McCarthy
the same timel. The following seems to explain my problem:
"This sounds like a ground loop causing interference on your TV. Is
your TV attached to any external antenna or cable services? If it is,
detach
the ant/cable connector and see if the waves go away. If so you have a
ground loop, meaning that your ant/cable ground is at a different
potential
than the ground in the circuit powering your computer. This causes a
current
to run through your TV, up the s-video cable and out through the ground
connection of your computer. Not only does this distort video and
audio, it is also potentially damaging to your home theatre equiptment.
Video hum
is usually observed as bars rolling vertically through the videoimage,
video hum may also cause video distortion or even tearing of the picture
in severe cases."
Any ideas of how to get rid ot this problem? Keep in mind I'm no expert
when dealiing with this kind of stuff...
Robert Miller
different jacks? You may have incorrectly wired outlets (which may include a
messed up ground).
A circuit tester is about $10 at Cdn Tire/Radio Shack.
As for fixing everything so that it's a common ground... if you're not
familiar, call in electrician.
Essentially... your entire building should be grounded to the same ground.
Typically that's the plumbing (or at least I think it is... I'm no
electrician).
Rob
Thomas Clancy
"Robert Miller" <rmi...@aim.nf.ca> wrote in message
news:38C184B4...@aim.nf.ca...
> Are the power cords for the different pieces of electronics in attached to
> different jacks? You may have incorrectly wired outlets (which may include
a
> messed up ground).
What he is experiencing is quite common, and never noticed until you try it.
The computer is grounded, your TV isn't. You might also notice a "hum" if
you run the outputs from your sound card to your home stereo. The only way I
know to get rid of it cleanly and easily is to remove the ground plug on your
computer cord. This is a no-no for safety reasons, of course. But it does
work. Your TV and most audio equipment do not have grounds.
Regards,
Thomas
Robert Miller
> plug on your
> computer cord. This is a no-no for safety reasons, of course. But it does
> work. Your TV and most audio equipment do not have grounds.
Remove the plug? You could build up enough electricity in the applicance to kill
yourself.
Most appliances that do not have a dedicated ground plug actually ground through
one of the two other prongs (that's why one is fatter). Older houses don't
support those plugs since they weren't wired to support grounding in that
fashion.
The 'hum' is actually electricity passing from one device to the other. Sometimes
the voltage is enough to damage electronics like sounds cards... etc.
Two solutions:
1. Fix the ground problem
2. Plug every device into the same jack with a power bar.
Rob
Harry Mesh
shield.
Harry
On Sat, 4 Mar 2000 18:41:40 -0330, "Thomas Clancy" <th...@thezone.net>
wrote:
>What he is experiencing is quite common, and never noticed until you try it.
>The computer is grounded, your TV isn't. You might also notice a "hum" if
>you run the outputs from your sound card to your home stereo. The only way I
>know to get rid of it cleanly and easily is to remove the ground plug on your
>computer cord. This is a no-no for safety reasons, of course. But it does
>work. Your TV and most audio equipment do not have grounds.
>
>Regards,
> Thomas
>
>
Thomas Clancy
"Harry Mesh" <hm...@nf.sympatico.ca> wrote in message
news:38c19a2d...@news1.on.sympatico.ca...
> Your TV is grounded whenever you hook up cable TV, through the cable
> shield.
>
> Harry
Yes, when you _have_ cable, and presuming they _have_ grounded it. I had to
call them back to come in and ground mine.
Pat Janes
<rmi...@aim.nf.ca> wrote:
> The 'hum' is actually electricity passing from one device to the other.
The hum can be caused by noisy electrical devices like dimmers and
fluorescent lighting. It is still a 60Hz electrical hum but can
sometimes be attenuated by simply reorienting the cables. High-quality
cables with proper shielding will also help.
>
> Two solutions:
> 1. Fix the ground problem
> 2. Plug every device into the same jack with a power bar.
Just because you have a ground hum doesn't necessarily mean you have an
electrical problem in your house.
Isolation transformers can usually, but not always, get rid of the
problem. Following is a url for a company that makes video isolation
transformers. Following that is another url, a plain-english discussion
of why ground hums happen in the first place.
Pat Janes
Russ Gladden
the trick for eliminating ground loops between TV sets and A/V equipment:
Get two 75-to-300 ohm matching transformers (these are the little
cylindrical can gadgets that let you connect the cable TV coax to the
"rabbit ear" terminals on TVs without a cable inlet). Wire them back to
back, with the 300 ohm wires connected to each other and the cable ends
facing out. That's it, instant isolation transformer. You may need a
male-to-male adapter on one end, depending on what you're plugging into. I
can make a crude ASCII diagram if anyone needs help visualizing this.
Results may vary, as some cheaper matching transformers are actually
autotransformers, and don't provide the isolation required here.
Russ.
"Pat Janes" <pjanes@-removethis-newcomm.net> wrote in message
news:040320002228402976%pjanes@-removethis-newcomm.net...
Rob McCarthy
and this completely elimanted the problem? What's the danger in leaving my
computer on like this?
Robert Miller
certain...
The understanding I have, from reading on the subject, is that the applicane can
store power (similar to a battery) and create a leathal shock just by touching a
grounded part of the device (for example, the case on a computer).
Pat Janes
<rmcc...@roadrunner.nf.net> wrote:
> Well I tried removing the third prong on an old
> computer plug I had lying around and this completely
> elimanted the problem? What's the danger in leaving my
> computer on like this?
Assuming you never have any electrical problems - surges, lightning
strikes, spikes caused by fluorescents and dimmers? Nothing. However,
and this is a BIG however, the third piece on that plug is there for a
reason. Removing it removes a vital, possibly life-saving safeguard
from your equipment.
I've learned a lot about electricity through my past involvement in
live sound production. Isolating and eliminating ground loops can be
frustrating but I have NEVER removed the earth ground from a piece of
equipment. It potentially puts lives at risk. Using an isolation
transformer, which can stop the hum-causing loop while maintaining the
integrity of the earth ground, is the only safe alternative unless you
have the time and money to install a balanced power system in your
home.
Have you ever seen what can happen when an ungrounded or improperly
grounded device acts up? I'm guessing not or you wouldn't have done
what you did. I've seen lots of sparks flying. I've shut down shows
because of unreliable power sources. I've refused to let a band perform
because of pools of water on stage. I've also put up with a little buzz
or hum rather than compromise the safety of performers and crew. Lives
are more important than getting rid of 60Hz noise in a dangerous
manner.
There is a great deal of misunderstanding vis-a-vis earth, or AC
grounding, versus signal grounding. The following links may be slightly
heavy reading if you know nothing about electricity but will hopefully
make you think twice about removing the earth ground from your
equipment. The first link wraps to 2 lines in my newsreader - you may
need to copy and paste it to get it to work.
http://www.circumtech.com/development/technology/balancedpower/liftingth
egroundingenigma
http://www.trinitysoundcompany.com/grounding.html
Patrick Walsh
using the computer.
"Russ Gladden" <russ_g...@hotmail.com> wrote in message
news:jAlw4.20262$e53.7...@news20.bellglobal.com...
Robert McCarthy
prong fixed my problem. It has not. what I am finding is that the
interference shows up only after the TV has been on for 10 minutes or so.
Any ideas of what the cause of the problem is now? And where would I find a
ground loop isolator in this city?
Rob
Jerry Richards
check out the links he was good enough to offer.
You'd be very surprised to find out what a measley 10milliamps of
incorrectly placed AC could do! (providing you survived!)
Don't become a "dead short"
jr
Robert McCarthy <rmcc...@roadrunner.nf.net> wrote in message
news:38C3DF33...@roadrunner.nf.net...
Rob McCarthy
now. I had Cable Atlantic come in and check the cable antenna but there is no
problem there and it is grounded properly...
Jerry Richards
person on the matter.(note: that wouldn't be me:^) Before doing this I would
suggest you try another approach to solving or at least eliminating the
source of the problem. If possible, switch out components one at a time and
replace known good ones. Find someone who would be willing to help by
loaning you a working TV for instance. If possible integrate other
components one at a time while checking for hum etc.Sometimes the hum is the
result of poor power supply filtering in a component. An assortment of
filtering designs are used in preventing hum from entering the
chassis/ground of most A/V appliances, and you'd need specific kinds of
equipment to detect and isolate it. A capacitor that looks good for
instance, may well not be performing up to par, or a critical component may
have suffered a bad solder joint. Bad shielding could be another culprit
even.
I should warn you. Poking around inside a TV looking for something out of
whack can prove fatal. An innocent looking TV can zap you with well over 30
Kv ( yes, Thirty _Thousand_ Volts) if certain precautions are not employed!
Or how about X-Rays even!
HTH
jr
Rob McCarthy <rmcc...@roadrunner.nf.net> wrote in message
news:38C404E7...@roadrunner.nf.net...
Rob McCarthy
properly I had a friend bring over his standalone dvd player and it worked
flawlessy with no interference on that TV. I also tested his very high quality
s-vhs cable with my computer and it gave the same result of interference. So
that only leaves the computer as the problem. But how the computer is actually
causing this I have yet to figure out.
Rob
Lloyd
removing the third prong (ground<-> green wire) will do no harm to the user or PC
pw. supply. If you trace the circuit for this pin you will find that in all cases it
is simply connected to the chassis of the appliance and, when plugged in, the third
wire goes straight to the house electrical panel chassis ground which should be
connected to a reliable earth ground (often a copper cold water pipe). However,
having said that, it is there for a good reason: to prevent electrical shock in the
event that something goes radically wrong with the device causing an electrical
short to the chassis. If this condition occurs with the ground intact, the result
should be a direct pathway to the electrical ground; and therefore a blown fuse. If
it is removed, imagine the situation above, but with a live (120VAC) current
potential on the chassis just waiting to flow to ground through your body.
In the case of devices with no third pin by design, the grounding is carried on the
same wire as electrical neutral. Older appliances had none of this, but today one or
the other is a requirement by code.
Lloyd
Jerry Richards
computer and the ground set-up. Another cause of video hum might be traced
back to the location of cards you have installed in your computer. If you
have an audio and video card mounted close together, separating them as much
as possible, and maybe even some shielding between them might minimize the
hum. Some video cards can be notorious for poor shielding. Audio cards are
not all innocent either. If you do intend to relocate cards to provide some
isolation, take the time to clean any contacts involved and inspect the
works closely.
Just for the record, have you tried plugging the whole works into "other"
power bars and powering the gear from another isolated outlet(s) via
(grounded) extension cords? Are you using cheap power bars? These too can
suffer from inherent QC defects. Some power bars have circuitry to attenuate
line noise. Could the problem actually be an improperly wired outlet
connected to the one's in use? Many A/V appliances are also designed to
attenuate line noise _from_ an offending outlet. Running the vacuum cleaner
or a hand mixer during the OH's soap opera through an older TV can prove
interesting. ( if not fatal !! ;^)
Have you tried posting to a ng that deals with home entertainment devices
and set-ups?
IMHO Rob, what you really need is some real expertise from an expert in the
field. You might have to pay for it; but often what you get in return will
far outweigh the costs incurred. Who knows but it might even save your life!
Gud-Luk
jr
Rob McCarthy <rmcc...@roadrunner.nf.net> wrote in message
news:38C436AE...@roadrunner.nf.net...
> Hi, with regards to the TV, it's only a month old but just to make sure it
works
>
> properly I had a friend bring over his standalone dvd player and it worked
> flawlessy with no interference on that TV. I also tested his very high
quality
> s-vhs cable with my computer and it gave the same result of interference.
So
> that only leaves the computer as the problem. But how the computer is
actually
> causing this I have yet to figure out.
>
> Rob
>
> Jerry Richards wrote:
>
> > Well Rob, I can only suggest you consider contacting some type of
qualified
> > person on the matter.(note: that wouldn't be me:^)
>snip<
Rob McCarthy
1) Plugging all "gear" into the same power bar, at two different locations
2) Cutting the "ground" prong off the computer power cable
3) Had Cable Atlantic come in and test the cable antenna and check for any
ground poblems (which there none)
4) Had a friend try his standalone Proscan DVD player with my TV, which worked
flawlessly
4) Used the same high quality S-VHS cable that my friend got with his DVD player
to connect my computer to my TV and the problem still existed, which rules out
my cabling as the culprit
5) Purchased a Mini A/B Switch (part# 15-1247B) from radio shack where you can
select the between RF sources going to the tv. When you select a source without
the cable antenna attached there should be nothing going to the TV - but the
interference was still there. Radio Shack said the device was highly insulated,
I would think that it would prevent anything from passing through when that
input selection is not chosen
6) Tried both video inputs on my television, using both s-vhs and composite
cables
7) Used utiltiy called Zone Selector to disable macrovision just in case this
was causing some sort of freakish problem when connected to my TV
8) Tried two different cable antennas that we have running into the house, both
having the same result
9) Ruled out interference by close contact with other cables running from my
computer such as audio cables going to receiver (figured this out by removing
all wiring going to tv and running the s-vhs cable directly to tv, as well as
removing all other "gear" from the area around the tv such as receiver and
speakers)
10) Removed all other devices connected by wires to my computer that weren't
necessary in DVD playback such as ethernet cables, sound cables, etc.
11) Tried routing the cable antenna through a vcr first and then into the
televison
As for interference caused by other hardware in my system, I can't see this
being a problem because if it was wouldn't it show up when outputting to the
monitor as well as the tv? When viewing on the monitor there is not
interference..but I shall remove the other hardware and give that a try. This
reasoning could also rule out a defective DVD decoder card since it should show
when ouputing to the monitor as well as the TV. But then again, output to the
monitor is done through the monitor cable and pass thru cable while tv output is
doen through a separate s-vhs port on the decoder card.
The s-video input jack is meant to recieve signals at 75ohms, possible that port
on the decoder card is not outputting at this correct level? Any way of testing
it?
I believe that is a list of everything I have tried, I dont' think I left
anything off it but if I did and I think of it I'll post it up. Just thought I'd
let you know what I have done so far.
Thanks to everyone who has helped.
Rob
Jerry Richards wrote:
> jr
>
> Rob McCarthy <rmcc...@roadrunner.nf.net> wrote in message
> news:38C436AE...@roadrunner.nf.net...
> > Hi, with regards to the TV, it's only a month old but just to make sure it
> works
> >
> > properly I had a friend bring over his standalone dvd player and it worked
> > flawlessy with no interference on that TV. I also tested his very high
> quality
> > s-vhs cable with my computer and it gave the same result of interference.
> So
> > that only leaves the computer as the problem. But how the computer is
> actually
> > causing this I have yet to figure out.
> >
> > Rob
> >
> > Jerry Richards wrote:
> >
> > > Well Rob, I can only suggest you consider contacting some type of
> qualified
> > > person on the matter.(note: that wouldn't be me:^)
> >snip<
Jerry Richards
Investigative minds want to know! Have you grounded all unused A/V and/or
capped all open/unused inputs/output connections? Would there happen to be a
transformer not related to the setup located very close-by(a doorbell
transformer maybe)? Is there a power transformer mounted on a pole very
close to where your set-up is located. Have you considered a minute voltage
leak coming _from_ a incorrectly wired outlet and travelling _to_ your
set-up via the ground plug? Is your main signal cable affixed to a wall
using poorly placed staples that might have punctured the shielding at some
point and is also conducting from the centre conductor to the shielding?
Have you checked the DVD specs for unexpectedly higher hum ratios? Have you
inadvertently pre-amped an already pre-amped signal and over-driven at the
final? Are your speakers too close to the TV, and causing "pulling" of the
video? Do you have an UPS close to your setup? Have you considered bringing
the RF SW back to RS and asking them to confirm it is not defective? Is
there a possibility that one ground inside the setup is loose or making poor
contact thereby causing a difference in ground potential somewhere in the
system? Have you checked the main electrical ground where the waterline
enters the house and ensured it actually is in good order? Have you
carefully read instructions for small print that might indicate a choke
might be needed in some applications, and might be available free upon
request from the manufacturer? Has a bug somehow gotten into some part of
the gear and died across two traces? How about humidity concerns?
Have you become obsessed with the whole thing and begun to think the whole
mess is a complicated one when actually it isn't? have you considered asking
a student at a competent electronics training facility? (Something like this
could make a good term paper or expose a thoroughly crazy student )!! 8^) I
know, some of these questions couldn't apply here but it's nice to be sure
you've rule them out.
Have you taken the time to look in the phone book for a reliable expert on
such matters?
Marconi is not pasta.
jr
Rob McCarthy <rmcc...@roadrunner.nf.net> wrote in message
news:38C58410...@roadrunner.nf.net...
> So far here are all the things I have tried to solve and/or locate the
problem.
>snip<