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Need help - no signal from TV antenna in the attic

Discussion in 'Electronic Repair' started by [email protected], Dec 4, 2008.

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  1. Guest

    Hi,
    I just moved in to the new house. There is a 4-way coax splitter in
    the attic, which has one input and four outputs (to different rooms).
    I know that previous owners had a cable (from the cable company). It
    looks like the cable was going into the same splitter in the attic,
    and then routed to rooms downstairs.
    I want to use the TV antenna in the attic.
    I tried connecting the TV antenna to splitter's input – absolutely no
    signal is getting to TVs downstairs. I also connected the antenna to
    each of splitter’s outputs (which go to TVs) – exactly the same
    outcome - not even a change in a static when I plug in the antenna.
    I bought a TV signal inline amplifier from RadioShack – absolutely no
    difference.
    However, if I drop a 100' coax cable directly from the antenna in the
    attic to the TV downstairs (bypassing the splitter and all of the home
    cable wiring), the picture is crisp and perfect.
    Can I run some tests to ensure cable continuation (from the attic to
    rooms downstairs).
    Does anybody know how I can get the signal from the antenna in the
    attic to TVs downstairs?
    Thank you.
     
  2. Bryce

    Bryce Guest

    Have you looked behind the wall plates downstairs? Perhap a band-reject
    filter? Are you certain the cables from the attic don't go somewhere
    else before going to the downstairs TVs?

    To check continuity: first use an ohmmeter to verify that the cable reads
    open-circuit at DC in the attic. Then connect a 1.5v battery across the
    disconnected cable in the attic and check for 1.5v downstairs.

    If all else fails, move the TVs up to the attic.
     
  3. Mikepier

    Mikepier Guest

    You did not mention, is this for HDTV? If the cable is old like RG58
    or 59, it might not be able to handle the UHF bandwidth of HD
    channels. If the 100ft cable you tested was RG6, and it worked, that
    would make sense. But as the other poster said, try testing the cable
    and see if there is continuity.
     
  4. UCLAN

    UCLAN Guest

    Sounds like he already did:

    "However, if I drop a 100' coax cable directly from the antenna in the
    attic to the TV downstairs (bypassing the splitter and all of the home
    cable wiring), the picture is crisp and perfect."

    *If* we take what he wrote above verbatim, I would suspect the cable from
    the antenna to the splitter. I would try his 100' bypass cable again, but
    this time include the antenna feed cable in the path. If it doesn't work,
    it's that lead cable.
     
  5. Guest

    What??? RG-58 is 50 ohm IIRC and while RG-59 isn't the best coax, it
    will pass HDTV RF properly. The best of the RG-59 is Belden 1505 and
    is nearly as good as RG-6. I would look for corroded connections at
    every junction point and replace when found. Any rodents chomping
    through the cables?

     
  6. Ron

    Ron Guest

    Or, just use screw the bypass directly into the splitter.
     
  7. Franc Zabkar

    Franc Zabkar Guest

    IIUC, the inline amp comes with a separate DC or AC power injector.
    With this injector plugged in, test for 9VDC or 9VAC or whatever at
    each of your RF sockets.
    - Franc Zabkar
     
  8. RickMerrill

    RickMerrill Guest

    Every 4-way I have seen has actually been an amplifier - look at it
    from all sides and see if there is a power connection: it would probably
    be DC power from a 'wall-wart' located elsewhere.
     
  9. Ron

    Ron Guest

  10. lurch

    lurch Guest

    Hi,
    I just moved in to the new house. There is a 4-way coax splitter in
    the attic, which has one input and four outputs (to different rooms).
    I know that previous owners had a cable (from the cable company). It
    looks like the cable was going into the same splitter in the attic,
    and then routed to rooms downstairs.
    I want to use the TV antenna in the attic.
    I tried connecting the TV antenna to splitter's input – absolutely no
    signal is getting to TVs downstairs. I also connected the antenna to
    each of splitter’s outputs (which go to TVs) – exactly the same
    outcome - not even a change in a static when I plug in the antenna.
    I bought a TV signal inline amplifier from RadioShack – absolutely no
    difference.
    However, if I drop a 100' coax cable directly from the antenna in the
    attic to the TV downstairs (bypassing the splitter and all of the home
    cable wiring), the picture is crisp and perfect.
    Can I run some tests to ensure cable continuation (from the attic to
    rooms downstairs).
    Does anybody know how I can get the signal from the antenna in the
    attic to TVs downstairs?
    Thank you.


    You have shown the antenna and downstairs TV are good. Something you
    bypassed with the 100' cable is bad. Add parts of the bad system, one at a
    time, into the good system. Suspect ALL connectors and extension cables
    until they work with the good system. The splitter is the main suspect as
    all four down cables shouldn't fail at the same time. The inline amp may be
    needed to overcome the loss of a 4-way splitter but you should see something
    without it.

    I hope the house wiring is RF and not fiber-optic!
     
  11. Franc Zabkar

    Franc Zabkar Guest

    This one is passive:
    http://www.dse.com.au/cgi-bin/dse.storefront/en/product/L4664

    AIUI, a 4-way splitter will have at least 6dB insertion loss, so this
    may account for the difference between a borderline good signal and a
    non-existent one.

    - Franc Zabkar
     
  12. RickMerrill

    RickMerrill Guest

  13. Ron

    Ron Guest

    No doubt. Won't work with cable either, at least not with my cable.
    The former owner of my home was using that POS in the attic to split
    the signal, and the picture on each TV was horrible. The cable company
    installed a 6 way splitter/amp and that resolved the problem.
     
  14. TKM

    TKM Guest

    A similar problem in my home installation recently was traced to a broken
    center pin in an RG-6 connector. When I stripped the cable to install the
    connector, I nicked the copper center wire. When it was pushed into the
    splitter, the pin broke and continuity was lost.

    A continuity check is a good idea.

    TKM
     
  15. UCLAN

    UCLAN Guest

    Sure, but since he already knows his 100' bypass from the antenna to the
    TV works, adding just the lead from the antenna to the splitter would
    quickly identify the culprit.
     
  16. Ron

    Ron Guest

  17. buffalobill

    buffalobill Guest

    multimeter ohmmeter, small pocket or portable tv with rf to coax
    adapters, some barrel connectors, some spare splitters. there's no way
    to say where the open circuit or short might be without disconnecting
    the branches of the octopus and one bad cable end or a terminating
    screw-on resistor cap. if this is cable company wiring it may actually
    belong to them. if the cable service is terminated, maybe it is cut at
    the outside service box with a device, a ground, or a separation.
    these may be on the wiring where you haven't looked yet.
     
  18. Since the antenna is working (when bypassing the splitter), there are a
    couple of things to look at. One possibility is that the splitter is
    defective. Another is that the cable(or the connectors on the ends) from
    the antenna to the splitter is defective. Try connecting the antenna to the
    splitter with a different piece of cable, or with the 100 foot cable that
    you know is good. If this gets the signal to your sets, then the cable was
    the problem. If it still doesn't work, then I would say that the splitter
    needs to be replaced.
    Ken
    Hi,
    I just moved in to the new house. There is a 4-way coax splitter in
    the attic, which has one input and four outputs (to different rooms).
    I know that previous owners had a cable (from the cable company). It
    looks like the cable was going into the same splitter in the attic,
    and then routed to rooms downstairs.
    I want to use the TV antenna in the attic.
    I tried connecting the TV antenna to splitter's input – absolutely no
    signal is getting to TVs downstairs. I also connected the antenna to
    each of splitter’s outputs (which go to TVs) – exactly the same
    outcome - not even a change in a static when I plug in the antenna.
    I bought a TV signal inline amplifier from RadioShack – absolutely no
    difference.
    However, if I drop a 100' coax cable directly from the antenna in the
    attic to the TV downstairs (bypassing the splitter and all of the home
    cable wiring), the picture is crisp and perfect.
    Can I run some tests to ensure cable continuation (from the attic to
    rooms downstairs).
    Does anybody know how I can get the signal from the antenna in the
    attic to TVs downstairs?
    Thank you.
     
  19. TKM

    TKM Guest

    multimeter ohmmeter, small pocket or portable tv with rf to coax
    adapters, some barrel connectors, some spare splitters. there's no way
    to say where the open circuit or short might be without disconnecting
    the branches of the octopus and one bad cable end or a terminating
    screw-on resistor cap. if this is cable company wiring it may actually
    belong to them. if the cable service is terminated, maybe it is cut at
    the outside service box with a device, a ground, or a separation.
    these may be on the wiring where you haven't looked yet.

    Who knows if it's OK to measure the resistance (using a standard multimeter)
    of a coax line connected to an amplified antenna after disconnecting the
    amplifier power supply, but not the antenna. I'm concerned about damaging
    the amplifier inside the antenna, but suspect an open line going from the
    lightning arrestor up the roof to the antenna.

    TKM
     
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