diagonal lines on TV reception

Discussion in 'Freeview & YouView' started by Mr Pleasant, Aug 27, 2006.

  1. Mr Pleasant

    Mr Pleasant
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    Watching Freeview in our new property, I'm finding the picture quite badly affected by diagonal lines, usually blue, which are particularly noticeable on the black screen you get momentarily when changing channel. Solid blocks of colour (especially red) also display 'movement', i.e. they don't look solid at all. My leads are all decent quality and I don't recall this being an issue with the same kit in my last property. I can only assume it's one of two things: either it's noise in the electricity supply or the TV signal is too strong, which I've read can give a herringbone effect. Maybe what I'm calling diagonal is what a TV engineer would call herringbone.

    Has anyone else suffered this and if so did you find a solution? I'm loathe to spend a grand on an LCD TV until I've got this one sorted.
     
  2. Andy3

    Andy3
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    This is odd, as it sounds more like RF patterning that you get only on analogue RF TV. How is your Freeview box connected to your TV? RGB, Composite or RF?
     
  3. JayCee

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    Some Freeview boxes radiate interference when placed too close to the TV or VCR...in your new setup has the physical placement of your gear changed compared to your last house?
     
  4. Mr Pleasant

    Mr Pleasant
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    The Freeview box is attached to the TV via the RF loopthru cable supplied by Sony, and the 'VCR' scart output goes to an HD/DVD recorder. I'm not using the scart output labelled TV because my ageing telly has only 1 RGB scart and that is connected to the DVD player. Basically, I watch the Freeview box via the HD/DVD recorder which itself loops through the DVD player. Yes, it's a nightmare, but as a system it worked fine with a cable box (NTL) before I moved and got into a decent Freeview area. Damn, this is complicated! I'm giving you the shortened version, but yes I have used the Freeview box in a simpler configuration without problems while living nearbye for a short time. On the BBC website I tracked down the reception issues page which shows three images suffering problems. The final one is the closest to what I'm getting (not as seriously as in the picture), which is attributed to radio interference. Funnily enough, they don't mention the issue of too strong a signal which I feel may well be the cause since I can practically reach out and touch the transmitter. This is an old property with distinctly dodgy electrics so I can't rule out the old chestnut of horribly noisy AC, even though the effect on screen doesn't match the example on the website. Shame noise reducing filters are so pricey or it would be worth trying one out. Might try JayCee's suggestion of moving the box further from the HD/DVD recorder actually. They are right next to one another. Thanks for the thoughts so far.
     
  5. 12 promises

    12 promises
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    sounds to me like youhave an overdriven signal which may be helped if you insert a vaiable attenuator :)
     
  6. Analogue

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    So if I get this right your feed from freeview is via the RF modulated RF connection to the TV? In which case the output RF channel is not suitable for your new location as it corresponds to a channel from a local (possibly fill in) Tx. Therefore experiment wit a new output channel from your Freeview Box. Alternatively re-think your connection strategy to put Freeview directly connected via the RGB scart and connect other device(s) as input to RGB on the Freeview box or S-Video.
     
  7. JayCee

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    No he's watching his Freeview via scart connected to his DVDR.
    I agree mind you that the modulator in his Sony Freeview box may be sitting on an unsuitable output channel and causing cross-channel interference.
     
  8. Mr Pleasant

    Mr Pleasant
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    Well this is weird - but I think it's good news: last night I took a close look at the one or two recordings made on the HDD/DVDR since we moved in. These were recorded via scart from the F/V box. They are perfect. This seems to rule out incoming signal issues or electrical circuit faults. Furthermore - and this is where the weird bit comes in - if I watch even a few seconds of a recording, then stop it and go back to the current broadcast, the picture then is also perfect. If I put the HDD/DVDR into standby the problem returns; if I switch the HDD/DVDR back on, the problem remains. Only if I watch a recording then stop it does the problem disappear. Presumably watching a recording determines the signal path in some way. I'm going to overheat my brain cells on this one today.
     
  9. Mr Pleasant

    Mr Pleasant
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    PS I tried JayCee's suggestion of moving the F/V box. Didn't move it far as it would have involved pulling the whole rack out, but I didn't see any reduction in the interference. Last night's discovery seems to point the finger at issues with the signal path anyway.
     
  10. jameslindsey

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    May be that the TV is not correctly tuned into the RF channel that the Freeview box is on? See if in the menu of the Fv box you can alter the RF channel it operates on and then re tune your TV to this new freq.
     
  11. Mr Pleasant

    Mr Pleasant
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    I'll check the manual, but I have no idea what that means! After all the head scratching, I am wondering if I'm simply asking too much of the daisy chain and the problem will go away if I take the plunge with LCD and the F/V box has its own direct scart connection and the HDD/DVDR goes in via component. Now I know the trick for getting a good picture, it's pretty darn good most of the time. (There's nothing anyone can do when the basic broadcast quality is pixellated rubbish.)
     
  12. SamRadford

    SamRadford
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    When you watch a recording, the equipment puts 12 volts DC onto scart pin 8 which the TV recognises as a "look at this input" signal. When you put the equipment to standby, the voltage drops to zero (in theory). However, the TV apparently continues to look at that input, either because nothing has told it to do otherwise or because something else is putting a voltage on pin 8 (Freeview box).

    Chances are, when the symptom is seen, there's no voltage or a low voltage on pin 8, which is causing the TV to switch the input to a partially on state which is susceptible to interference. Or something like that.

    Unfortunately the Scart system was never properly designed to handle more than one piece of equipment so odd things can and do happen!

    You could try connecting a 100uF/16v capacitor between pin 8 and video ground. The effect it has might tell us something. Heck, it might even cure it. You could also try connecting a 9 volt battery there.
     
  13. Mr Pleasant

    Mr Pleasant
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    I can't claim to understand all of that(!), but the pin voltage issue and the shortcomings of the scart interface sound very likely. Thanks to everyone for the insights and advice. I'll probably live with the workaround for the next few weeks or months until I finally ditch the TV and buy an LCD with far better connection options.
     

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