Forum Discussion

cannesdo's avatar
cannesdo
Explorer
Aug 28, 2014

Dish picture slightly wavy in the front bedroom...

A few weeks ago my living room tv died. It took me a while to find the same model to replace it with and in the meantime I got and old CRT 19" tv from Craigslist. It worked great. When I intalled the replacement tv in the living room I decided to use the smaller tv to troubleshoot the Dish connection in the bedroom as I was going to install a flat-screen on the long thigh-high shelf soon.

Turns out I like the location of the smaller tv up high and thought I'd keep it for a while. I figured out which connection in the cupboard in the bedroom was for the digital antenna and which was connected to the tv in the living room. I have been running the 2nd bedroom tv on antenna all week and the picture is perfect. Once I got the 2nd dish remote programmed I was able to pull up the programming, guide etc...but the picture is -- it's like a tremor, very subtle, the horizontal lines are a bit wavy, like 1/8 to 1/4 inch which is minor but pretty annoying.

I bought a new cables for the connections that aren't in the wall. The good kind of coax -- RG-6? That didn't help. (These run 1.) from the connection to the right of the sat. inputs 1 and 2 behind the receiver to the wall connection (that leads to the bedroom auxiliary connection, i.e. 2nd tv) and 2.)from that bedroom wall connection (coming from the living room) to the 2nd tv.

I pulled the plates off the wall where the undseen coax exits the living room and enters the bedroom and made sure the connections were tight. They were. So...what's next? Replace the connectors? Don't know if I can access these cables from the basement. I sort of doubt it. It's hard to believe they've gone bad down there where nothing gets disturbed. Could the problem be that it's a CRT? Is it harder for the signal to travel on to another tv? Is it like a power cord? Does distance matter? Might it be better with a newer, say...LCD tv?

Thanks much....
  • wa8yxm wrote:


    MSW inverters can cause waver



    I have an inverter, not sure what kind, it's about 10 ft away in the basement, and on the other side of the rig.
  • Wavy lines are typically caused by 60 Hz interference, usually a result of ground loops i.e, ground current flowing through the shield of the RG6 (or any other coaxial cable) and modulating the video carrier. Normally there shouldn’t be any grounds from the shield of the coaxial cable to the frame, or definitely only at one end. However, I suspect that both TV set and the DTV receiver both have ground connections through the A/C plug, effectively creating a ground loop if there is any ground potential difference between the front and rear of the coach. So, now what?
    First try running a coaxial cable through the RV (across the floor) between the DTV receiver and the TV, assuming you mean 19” TV and not a 19” CRT such as a monitor. That probably won’t correct the problem, but if it does, check for grounding of the coaxial cable shield to the coach frame. Assuming this test fails to eliminate the wavy lines, run an extension cord from the front TV to the same receptacle used by the DTV receive in the bedroom. If the wavy lines disappear, you definitely have a ground loop problem, in other words, current flowing through the shield of the coaxial cable. If either the first of second test corrects the problem, you can then move on to the solution, which is the subject of another missive.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    First, Dish DVRs use UHF for the 2nd TV... This can be a problem, I really wish I could flip VHF and UHF.. but alas, can not.

    Now.... Things that can affect the picture

    Low quality coax has more loss at higher frequencies but this would more likely cause SNOW than Waver.

    MSW inverters can cause waver

    Nearby FAN can cause waver (or any electrical motor) Does not matter if A/C or D/C.. Have cleared up more than a few headaches by suggesting a store clerk move her fan away from the monitor.

    Beyond that I can not help much.
  • I have a batwing permanently on the roof. It has a line going through the rig to both the living room and bedroom. The coax from the dish comes out of the carryout and through the window, into the receiver, back out of the receiver, into the wall connector which takes it through the walls of the rig and comes out as a separate coax connection a few inches away from the antenna port in the bedroom.
  • You say you ran it off the antenna and it was fine. Was this a portable antenna directly connected to the TV, or the roof antenna with the signal running over the RV coax to the TV?

    If it was the roof antenna, then you've pretty well eliminated the coax in the RV. If you have a selector switch that you use to switch between the antenna and the dish, that switch could be the issue. Try moving the dish wire to the input that the antenna is currently hooked to.

    If you were using some sort of portable antenna on the TV, then try running a piece of coax from the front of the rig all the way to the back. Just run it down the hallway as a test. If things improve, then the coax in the coach is bad.
  • So....kill the 12v in the rig and see if that helps? I don't believe I have any LED anywhere in the rig, and I haven't been using the ceiling fans at all. hmm....
  • RoyB's avatar
    RoyB
    Explorer II
    The DC operated FAN motors are another known source for RFI signals that interferes with TV SETS. The LEDs lights that have built-in regulator chips on the units are also a well known source for RFI signals...

    Roy Ken
  • If it works good on antenna but not on Dish, the TV is probably Ok.
    Wavy lines could be from RF interference of some kind. Maybe others will chime in.
    Could try another tv for troubleshooting purposes.

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