Crawling Horizontal Lines on Projector - Help!

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FlatBlackCoffee

Limp Gawd
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Oct 27, 2008
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I spent the morning at my boss' house troubleshooting an issue with his projector. I read a little about ground loops. Tried different configs. - the results seem counter to what I thought I understood about ground loops.

His Sharp XV-Z0OU projector has scrolling horizontal bands when all of his gear is plugged in on the same circuit.

If we connect the DVD player directly to the projector with component cables, the bands remain - bands disappear if we unplug the audio from the DVD player. If the audio cables are connected to the DVD player, the lines appear even if the receiver is unplugged.

If we leave everything connected as he had it in his old house, but run an extension cord from the projector to a different part of the house (different circuit), the lines on the screen go away - even with DVD audio cables connected.

I've read solutions about grounding every component. One chap in another forum said the Ebtech Hum Exterminator solved his problem.

Is there an easy fix I'm missing that would allow him to have a clean picture for his party tomorrow (Friday)? Appreciate any advice you may have on this problem.
 
Sounds like you already found the problem - the circuit you are using has a bad ground, which is why using the extension cord fixed it. Might just be a loose ground wire behind the socket, but then again you might need an electrician. Do you happen to have any way to test for a ground fault? I know a lot of UPS's have them if you don't have anything else...
 
No doubt it is the old part of the house that is taking its toll on the projector, as what frost has said, you need an electrician to fix the wiring of the room. :/
There's interference because of the old material that is not good at shielding the electric current.

What you can do, is get an adapter and see how it fares as it filters the current, temporarily.
 
We have an electrician down the hall. I'm going to ask him. Thank you much!

I didn't know a loose ground wire would be capable of this. We did try multiple outlets on the same circuit. It is odd that the problem would go away if the only thing we did was unplug the audio from the DVD player. How does the ground wire hypothesis fit into that?

Thanks Again!
 
FlatBlackCoffee said:
We have an electrician down the hall. I'm going to ask him. Thank you much!

I didn't know a loose ground wire would be capable of this. We did try multiple outlets on the same circuit. It is odd that the problem would go away if the only thing we did was unplug the audio from the DVD player. How does the ground wire hypothesis fit into that?

Thanks Again!
Click to expand...


Lol, I'm not an electrician, so I can't give you a technical reply. My best guess would be that the receiver is not a grounded plug (AKA - Only 2 prongs). This normally wouldn't be a problem, except when one or more of the devices connected to it are also not grounded. If the other device(s) require a ground and don't have it, it's got to go somewhere, and the audio cable must be the easiest path. Removing the audio cable sends it down another cable that doesn't cause as noticable interference.....


Hmmmmm, that actually sounds pretty good for pulling it out of my ass...:p

I came to the ground fault conclusion by process of elimination actually. Like I said, since the extension cord fixed it, I would look at electricial issues. I've seen ground faults cause interference like what you describe before, it's not incredibly uncommon. The only weird thing is that the audio cable causes it, because usually from what I've seen, the coax cable is the culprit.
 
xFrostx, that did sound pretty awesome. You could do trade school lectures. I think what you've concluded through pure logic is congruent to what our resident electrician just told me.

First, the receiver isn't grounded. No 3rd prong on the power cord for a ground.

The electrician said that it is best if amidst all of this gear, there is one point that is a ground. A light went off when he said this. I think the cable box is grounding via the coaxial cable.

I suggested to my boss that he disconnect everything from the receiver, plug in the video directly to the projector, and then connect the audio to the receiver with nothing else plugged in, and he should see no lines/bands. Next, start reconnecting components to the receiver, one at a time, and when the lines appear, we know which dastardly gadget is fouling the cinematic experience.

I'll keep you posted on the results.

Thank you so much for your help!
 
FlatBlackCoffee said:
xFrostx, that did sound pretty awesome. You could do trade school lectures. I think what you've concluded through pure logic is congruent to what our resident electrician just told me.

First, the receiver isn't grounded. No 3rd prong on the power cord for a ground.

The electrician said that it is best if amidst all of this gear, there is one point that is a ground. A light went off when he said this. I think the cable box is grounding via the coaxial cable.

I suggested to my boss that he disconnect everything from the receiver, plug in the video directly to the projector, and then connect the audio to the receiver with nothing else plugged in, and he should see no lines/bands. Next, start reconnecting components to the receiver, one at a time, and when the lines appear, we know which dastardly gadget is fouling the cinematic experience.

I'll keep you posted on the results.

Thank you so much for your help!
Click to expand...


You probably don't need to go as far as testing each component. You got the point though which is perfect - [Jeff Goldblum Voice] L̶i̶f̶e̶ Electricity will find a way... [/Jeff Goldblum Voice]. :p

First off, you could probably ignore any device with only a 2 prong plug. They don't need the ground, so they probably aren't the cause, they are just getting stuck with the bill. I now notice that I think I swapped "Receiver" with "DVD player" in your original post. DVD players typically aren't grounded either though, so it's kind of a moot point. The point is that if the ground is bad on your electrical circuit, the config of the devices is irrelevant since they all will be plugged into the same circuit. We have no way of knowing what shape the internal wiring of the house is in right now. A brand new house that just passed inspection would open a whole new can of worms, as in the electrical should be fine because it just passed an inspection. If it's an older home, the ground wire for the electrical circuit could be nothing more than an old speaker wire tied to the bathtub drain.:eek: I suggested a UPS or a ground fault tester (They are cheap at Home Depot I believe, only like $5-$10), becuase it would be a cheap and easy way to confirm the ground fault idea before you dig into a possible electrical issue like this. Like I said, a lot of UPS backup batteries and even some nicer power strips have ground fault lights on them. Plug one into the electrical outlets and see which ones trigger the "Ground" light and you will have your culprit. If none of the electrical outlets show a ground fault, I would look into what Skero said about possible EMI interference from something unsheilded. I would save the testing each component method for later if we get more desperate.
 
Is there a noticeable humm coming from the audio gear as well? I would take an old three prong plug and cut off the two and leave the ground on top and and ground the wire to the chassis of the amp, make sure its plugged into the same power strip or whatever your using. This sounds like a 40 cycle interference.
 
Many thanks, Atticus_gamer, xFrostX, and Skero.

I talked to the boss man and he discovered the coax to be the scoundrel connection. I let him know that I read of a man in a forum who replaced his cable booster and it solved his problem. My boss's booster has 8 'teets' on it and he uses them all.

Perhaps, there is a grounded booster or some kind of filter that can be put on the coax for cable. His coax goes from the cable company, to the booster, from the booster to the cable box, and finally, from the cable box to the receiver.

I wonder if getting a power strip that has the coax connections would help. There is talk in the avs forums about the bestest cable splitter/booster, but it is over my medicated (cold) head.

We're getting there!
 
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