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Lost BBC1 and 2 and some Freeview

Discussion in 'Audio Visual' started by delboy51, 29 May 2017.

  1. delboy51

    delboy51

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    Hi All
    Current setup is a roof aerial about 17 yrs old fitted at time of first DTV. Splitter at aerial - one side goes to Optima box indoors and in to newish TV. Other cable goes to a 4 way powered amp which supplies the bedrooms and kitchen. Suddenly we have lost BBC1 and 2 and a handful of other channels.

    We suspected the old way 4 camp as the light flashed and so replaced it -Up until now there has never been any issues with any channels. ITV is reporting 60-70% signal but no BBC channels.

    I have checked cables and the ends seem good. We are in NN12

    Any thoughts.....Some neighbours seem to have different looking aerials but point the same way as ours.
     
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  3. Lucid

    Lucid

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    Have you tried a manual channel scan just for the affected channels? The method can vary depending on the TV, but in general put the TV on one of the missing channels, then go in to the tuning menu and choose 'Manual Scan' or whatever the equivalent phrase is for your TV. This is a very selective way you can refresh or update the channels that are received on one particular frequency. [Please note: This is NOT the Automatic Channel Scan and it is NOT the First Time Install option.]

    Depending on your exact postcode you could be receiving from Sandy Heath, Sutton Coldfield, Waltham or Oxford transmitters. You can check which one by putting your postcode in to this page: http://www.digitaluk.co.uk/coveragechecker/main/index/dummy/NA/yes Knowing which your local transmitter is helps with trouble-shooting. It allows you to check which mux is affected (think of a mux as a package of channels ) and enables you to find out on which channel it broadcasts. For example, if you were receiving from Sandy Heath, and given what you said about this affecting only a handful of BBC channels, then it would be a good bet that you're having problems receiving the BBCA mux on channel C27 at 522.0MHz.

    There are a few reasons why you might lose a very specific group of channels (a mux) and they range from a bit of coax being bent or crushed in such a way that it causes a frequency notch, or it could be simply that the channel was moved as part of the Freeview reshuffles, or it could be an early warning sign of something failing. These aren't the only reasons, but given that there's not much info in your post then they're the most likely scenarios based on the limited information. The fact that you still have the other channels means you have a little time to diagnose what's happening. Come back to us and let us know the results of the manual retune(s).

    [Did we help? Then use the THANKS button. It's free and it marks good advice for other readers]
     
    Last edited: 29 May 2017
  4. Tigercubrider

    Tigercubrider

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    Tried a retune?
     
  5. delboy51

    delboy51

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    Thanks Guys

    Tried the Manual Retune without success. Aerial points to Sandy Heath yet we get Meridian info (SOUTH) on Itv. Towcester is renowned for poor signal though we are at a fairly high point. Am I over amplifying ? splitter/masthead amp to newish DTV and on the other cable a 4 way amp ??

    Will check for crushed cables.

    Thanks anyway.
     
  6. Lucid

    Lucid

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    Over amplifying is a possibility but the main ITV and the BBC/ITV mixed HD mux both transmit at the same power (180,000W) so I'd expect to see the problems on those as well.

    Have you lost BBC on all the house TVs or is it just the new one that's affected? Also, have you checked the fitting of any cables and plug ends that might have been disturbed during the swapover to the new TV?

    [Did we help? Then use the THANKS button. It's free and it marks good advice for other readers]
     
    Last edited: 29 May 2017
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  7. delboy51

    delboy51

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    Thanks Lucid

    No strangely the newest TV (HDTV) which is on one of the cables from the aerial has all the channels and HDTV. On the other cable which distributes via the 4 way Slx ? amp the only two TV's are not HDTV (about 6 yrs old ) and it is on these that there is no signal on BBC channels.

    Ironically, we haven't touched anything BUT when I changed the 4 way I noticed on one of the outlets I detected a discernible "current" - that could mean that in the weatherproof box up on the aerial the current going up is coming back down the other wire ?? Is that possible ?

    Derek
     
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  8. Lucid

    Lucid

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    It's possible; many of the powered masthead amps/splitters have power-in on all the legs. If your Optima has DC pass-through for Sky Eyes then there's a path. I'd doubt you'd feel the 12V 50-100mA from the masthead power supply though. There's not enough voltage to get the current in to your skin.

    Current is determined by resistance and voltage. The resistance of a human body is about 100,000 Ohms in dry conditions. If my maths is correct (V=IxR) then you'd need 10,000V to get 100mA of current, so the 12V from the power supply just isn't enough to be a serious danger. A more likely source is the 120V floating earth that's common with double insulated electronics. But again the current that can be drawn is negligible otherwise we wouldn't have this kind of earthing arrangement in TVs, recorders, Sky boxes, DVD players, audio systems etc etc.

    If possible, you could try a temporary test by moving a TV to the location of the 4-way amp, then disconnect the cable feeding the amp's input and connect that direct to the TV. Check if you get the missing channels back. If so, double check the wiring of the plugs (it's a good thing to do anyway), then reconnect the 4-way amp and re-test.
     
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  9. delboy51

    delboy51

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    Brilliant idea- one of the TV's is a small flat one so easy to put in the loft and connect -

    Thanks Lucid
     
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  11. ericmark

    ericmark

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  12. delboy51

    delboy51

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    Thanks guys
    Returned from a weekend away to find absolutely zilch on any channel so checked and the input into the masthead splitter had come out in the wind- Sorted and now seems all ok. Thanks for all the tips.

    However, I am only getting about 35-38% on 2 of the TV's on most channels - so I have two options

    1.- try a re-orientate the aerial
    2- run new digital cable to the TV's with poor signal (they were run 15 yrs ago and with brown cable)

    1 is not too difficult, 2- is a pain but do-able

    What cable would you guys buy ? I may as well do itt properly as will be here for a while unless err indoors kicks me out....

    del boy
     
  13. Lucid

    Lucid

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    Webro WF100 / Triax TX100 / Labgear PF100. They're all a very similar paper spec but Webro WF100 just feels better made.
     
  14. winston1

    winston1

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    2 is impossible as there is NO SUCH THING as digital cable.

    However the cables Lucid suggested are good.
     
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  15. delboy51

    delboy51

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    Thanks Guys-good advice
     
  16. foxhole

    foxhole

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    Compass apps for mobile phones make getting the direction of aerial simple, used together with suggested site the compass will give the exact direction of nearest source.[See Lucid post above].
     
  17. JohnD

    JohnD

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    now that's a good idea.

    I went to the trouble of getting a prismatic compass.

    And I suppose a long spirit level would help as well.
     
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