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LG 19LS4D - UHF Channel 52 Problems

Discussion in 'Freeview' started by CJL, Dec 31, 2007.

  1. CJL

    CJL Member

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    Just a question i'm now struggling with, and hope that there is someone out there that can help.

    We currently have a digital ariel in our loft. The ariel supplies the the signal to the three points in the house (One of the ground floor (Study), one on the first floor (Lounge) and one on the second floor (Bedroom)).
    We have always had a Flat Screen TV (7 years old, and not an LCD/Plasma), has the signal going through a booster/amplifier and then a seperate freeview box). On this setup, we recieve all channels without any problems.

    Anyhow, we decided to change our TV in the bedroom, and after trying a number of different sets, we ended up keeping (I had 4 TVs with technical faults) getting the LG 19LS4D, with integrated Freeview.
    When we set up the TV, everything looked ok. All the channels had loaded up. However, when we started looking through the channels, we started to notice something. None of the Channels submitted on UHF 52 (Sky News, Sky Sports News, Dave etc) had a good signal, with the picture and sound looking/sounding like it had interference.
    We tried the automatic search a few times, but the same still happened.
    However, what we did notice, was that when the LG TV was on in the Bedroom (It didnt matter which channel), the UHF 52 Channels on the Lounge TV also had interference. Once the LG was put on standby, the Lounge TV returned to normal.

    I have also tried the LG TV in the lounge socket and through the booster, but still we get poor signals on the LG.
    Also tried was a separate amplifier/booster in the bedroom, but still the same.
    I have checked with coverage, and the channels available/will be available do not match that on the Freeview website check. As I mentioned, it is only the UHF 52 Channels that are missing on LG (these should be recieved according to the check), but are picked up by the stand alone freeview box in the lounge.
    The retailer thinks it is to do with the reception of the channels on UHF 52, or to do with the ariel (But not the TV).
    In terms of transmission, UHF 52 Channels are broadcast at maximum from the Sutton Coldfield Transmittor.

    Does anybody have any ideas what could be the problem, and what could be done to help? :lease:
  2. mrfreeview

    mrfreeview Guest

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    Intresting!

    Have you tried powering up the LG Flat screen but disconnecting its aerial connection. What impact does that have on the other Freeview decorders? If the LG flat is radiating something then this will provide if it is via the aerial cable.

    Also have you tried to tune in on analogue at channel 52 with another receiver with the LG flat powered up...just to see if you can see anything.

    If the LG flat is radiating noise at channel 52 then it could verywell be defective.

    The CE marking on the equipment is there to demonstrate that the design meets the EMC requirements for domestic: immissions and suseptability. Of course this assumes that all is functioning correctly.

    I hope my post has been of use :)
  3. CJL

    CJL Member

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    Thanks Mrfreeview.
    I'm now in two minds. Is it a defective TV (which would be just my luck), or do I need a better ariel? The amplifier used with the LG (Socket to Amplifier to TV) didnt make any difference.
    I might try with the ariel disconnected on the LG, and then try the Freeview downstairs.
    I'm just wondering whether it is within my rights to exchange for a new set, as it would at least eliminate that possability?
  4. CJL

    CJL Member

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    Have now sorted it (Hopefully). Tried the LG on Digital Mode (Still problems), Analogue Mode (Still Problems), but then...I kept the TV on, and took at the ariel. The interference was still there on the lounge TV. Put the LG on standby, and the interference stopped.
    Took it back to the retailers, took home the display model (which worked 100%), and now have a new set. Just about to set it up, so fingers crossed.
  5. mrfreeview

    mrfreeview Guest

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    Excellent. Sounds like the LG had a fault causing a radiated immission problem or a direct coupled problem via the mains.

    Really your retailer should now be returning the item to the manufacturer for investigation as an immission issue means that if your item had actually been EMC tested it would have failed for domestic and could not, legally, have been CE marked or indeed sold, at least not in the EEC!
  6. CJL

    CJL Member

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    After spending most of New Years Day driving back and forward to Currys, I just got a refund (Was gutted, as the TV was at £219 and a bargain for what it should do). Also, with 2 new sets doing the same thing (and with the Display model working), I can only guess it could be a batch fault with one of the parts.

    Still with my luck, 6 tvs later, and 4 brands later, I was running out of options.
    Popped into the other store next door, and they had some good deals on primary producers. Sony Bravia 19"or 20" for £299 from £499. Samsung 19" down to £253 and the Toshiba 19W330DB for £229. All were sold out (In fact, the Samsung was completely sold out everywhere, and I couldnt find another retailer displaying the Sony to price match).
    ended up going to another retail park and different shop, found the Toshiba at £279.99, and they price matched and beat the other store, and sold it at £224.99. All works well with it. In fact, its the best sound and picture out of all those that I tried. Should have done it in the first place, as i;ve never had a problem with my 6.5 year old Toshiba in the Lounge.
  7. CJL

    CJL Member

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    Hhmmmmm....Toshiba now doing it, but on a different UHF Channel.
    I wonder if taking the LG back was not the sets fault?
  8. mrfreeview

    mrfreeview Guest

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    When you say Toshiba now doing it...do you mean that with the Tosh powered up AND with the aerial connection to the TOSH disconnected that you are getting degrade of DVB-T on other receivers.

    If so then I suggest that you need to take a complete look at your installation.

    Ask yourself where is the amplifier located? Is it screened?

    Is the amplifer power fed locally or is it remote power fed.

    Is is actually an amplifer or just a back of the set booster. - what is the gain of the amp/booster?

    What is the quality of the coaxial cable that you are using are there any joins in the cable.

    How is the signal split for distribution to each outlet around the house.

    What is the quality of the signal like without amplification, that is with the aerial connected directly to one receiver and in that mode does just powering up the Tosh cause the same?

    Just so you are aware you should look for everything and anything as a possible cause of problem; I once found 120v AC with respect to mains earth on the sheath of the coaxial cable connected to my aerial! The sheath was continous from the BALUN in the dipole through the diplexer, the mast head amplifer, the amplifer power feed unit and the 4 way passive splitter. Only a maximum of 0.8mA of current would flow between the sheath and the mains earth! Touching the coaxial sheath and the mains earth at the same time was "quite safe"....but perhaps not recommended!

    I located this 120v AC to "standing" on the coaxial sheath connection of a couple of my DVB-T decoders, no doubt some switched mode power supply was the cause!

    What this standing voltage appeared to do was cause very very intermittent impulsive noise on my DVB-T signal. In the end I earthed the sheath of the coaxial cable to the mains earth and this appears to have solved the impulsive noise problem.
  9. JayCee

    JayCee Active Member

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    Just a slight correction here...it's a "Balun" :D
    I'm only pointing this out because members using the search facility using "balun" as the keyword wouldn't find your post.
  10. CJL

    CJL Member

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    Actually. Apologies, its not exactly the same.
    The Tosh is giving me a reception, albeit varied at times, on the said channels. However, there is still interference on the downstairs tv, although now sporadic (The LG had constant interference on the downstairs TV, and you couldnt watch the channels on it upstairs either (On UHF 52).

    Can I suggest what I think could be happening.
    When the Tosh was using the previous UHF (I cant remember what it was now - Lets call it X) for the BBC Channels, the interference on the downstairs TV was much worse than it is now on UHF 41.
    UHF was Waltham, and UHF 41 is Sutton Coldfield. Now that the Tosh is using UHF 41, although there is still interference, it is not all the time, and much better than when the Tosh was using UHF X. UHF 41 is also a stronger signal than UHF X.
    Is perhaps the Tosh using too much of the signal? It just sounds like the signal is being split? Is there a cheap way to rectify it? A booster/amplifier (The downstairs one is already on a booster/amplifier)/?
  11. mrfreeview

    mrfreeview Guest

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    Sorry I am now confused.

    I think you need to read my post #8
  12. CJL

    CJL Member

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    Sorry MrF. I suppose I was trying to self rectify the situation.
    I've read your post, but not sure how to check things (I understand TV's as much as I do about Quantum Physics ;)).
    Its just a hunch I have, that with two TV's using my ariel, that perhaps it is draining the signal between the two sets?
  13. mrfreeview

    mrfreeview Guest

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    This is why I suggested that you look at your whole installation. Provided that you are using the correct type of signal splitter and not just a bundle of cables with the ends twisted together (this is not like splitting the mains supply you know!!!) then splitting shouldn't be a problem. (provided you have sufficient signal strength.)

    Follow this rule and you should not have a problem with splitting a signal. Infact if your splitter is of a passive type or is an amplified type where the multipule outputs from the amplifer are via a passive splitter (be it internal to the amplifier) then you would be expected to connect onto each output from the splitter/amplifer a load (in this case a TV or STB receiver) so as to ensure a correct impedance match.

    There have been cases reported on various forums of people asking why when they disconnect one STB from a splitter the signal quality on another STB via the same splitter goes DOWN! The answer is simple: reflected signal caused by impedance mismatch!

    If I am reading your thread correctly if would appear that you are saying that if you power up a TV in one room with the aerial either connected or disconnected from the receiver it is upsetting reception on a receiver in another room.

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