Hello,
I am using a DA-550 Channel Plus 8-Way distribution panel with a 2 channel modulator and I have Antenna feed going directly into the antenna input on the distribution panel and satellite going through the modulator then into the distribution panel. The satellit picture looks very good through out the house but for some reason channels 4 & 5 on regular TV has vertical lines going through them but only when the upstairs TV is turned on it effects the picture on 4 & 5 in the rest of the TV's. Is there something I can do to fix this?

Thanx in advance

What channel is the sat modulated on?

Thon,

I have modulator for Satellite set on Channel 62

Just a couple quick stabs in the dark...

I understand that the trouble only arises when you power up the upstairs tv?

Sounds like your problem is power based, not signal based, but I wouldn't swear to it.

Have you tried one of Monsters, or someone elses, isolation transformers at the upstairs TV? It might help to remove that TV from the ugly, dirty realm of grounded whole house AC power.

Make sure your dish is grounded to the same circuit that the rest of the house is grounded to. Establishing a new ground for the dish can cause all kinds of beeeezar problems.

Beyond that, are you talking about vertical lines (in the horizontal sweep?) or are you talking about horizontal lines (in the vertical?) TV is confusing that way...

I have three TV's on this system the two downstairs have a beautiful picture both Satellite and Antenna, the upstairs TV picture looks good except for channels 4 & 5, these channels have vertical lines always going through the picture and if you unplug the coax to the TV the lines then change from Vertical to Horizontal. Also, once you turn on the upstairs TV it effects the reception on the other two TV's.

I may be barking up the wrong tree, but it still sounds like dirty power to me. Have you tried a decent line conditioner?

Also, have you eliminated the upstairs TV as a possible culprit by throwing a working TV in it's place?

HDTVJunkie,

Yes, I have eliminated the TV as being the problem. But, I also think it is a power issue. As it turns out the upstairs receptical is not a grounded one. Is there any way to correct this without pulling a new electrical cable?

Nothing that's legal that I'm aware of. I guess you could temporarily run a piece of wire through the house, down the stairs to a grounded outlet just to see if it helps, but it's been my experience that earth grounds cause more trouble than they solve. I would only bother with it if you have a component upstairs that requires an earth ground and only after trying a line conditioner. Also, be sure the satellite ground is the same ground that the rest of the house uses. That could be your only trouble. Look at these sites for a bit more info on the subject. There used to be a real good one, including how to build a ground trouble checker, but I can't seem to find it today.

[Link: epanorama.net]

[Link: epanorama.net]

You could try a Coax Ground breaker on that TV Tributaries sells a good one.... As does/Did Mondial (Now owned by Klipsch... The "Magic Box" is now disco I think)

A reletively innexpensive groundgard can be constructed using a 75--->300 Ohm adaptor connected to a 300--->75ohm adaptor,

Check your wiring carefully.

I once had a problem like that where someone had connected a splitter wrong. The input from the cable was connected to an output, and the two TVs were connected to the input and the other output. The upshot of this was that the two TV antenna inputs were connected to each other without the isolation that normally exists from one output of a splitter to the other output. When both TVs were on, weird things happened to one as you changed the channels on the other one, and it worked, or rather malfunctioned, slightly differently but both ways.

You probably have a harmonic interfering with channels 4+5. It is possible to have a modulated channel 40 or 50 channels to produce this effect. The are bandpass filters to take care of this problem. Basicly they are notch filters with -80db notch outside the modulated channel's frequency.

It is also possible that the upstirs TV is backfeeding something nasty into the system. This is not a ground issue as it the ground would be present on all channels not just a few. It is possible that the upstairs TV is producing this ground problem though but I would not bet on it.

Alan

It's possible that anything in the house is backfeeding the ground or the common. If the little nasty is a harmonic of 4/5 you will see wierdness.

I don't think I'd go to the trouble of notching or passing bands unless you can remove your modulator and make the problem disappear.

I'm dumb struck. Would you explain this one to me please? I'm sure others will think it's obvious, but I'm not getting it. Thanks in advance!

Baulins are transformers and transformers do not pass voltage. Ground loops are stray voltage passing down the shild. To remove the ground loop you need to remove the stray voltage. A baulin is a transformer whose primary purspose is to convert one impedance to an other but as it is also a transformer it may remove this stray voltage too - with the very likely possibility of screwing up the wave form too. Why, because these are very cheap transformers and easily over driven. Transformers do not pass voltage but magnetically couple the signal. Voltage is blocked on one side by the air gap but the desired signal is passed magnetically across the air gap.

The big differnece betwwen a baulin and say, a Jensen isolation tranfromer, is the quality of the transformer. As McIntosh has demonstraited for years, if a transformer maintains its linearity it will not adversely affect the signal. Out of linearity it will contribute all sorts of nasties to the signal.

Alan

This message was edited by Audible Solutionns on 04/10/04 15:17.