snippy
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 posted on 27/12/13 at 01:06 PM |
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Lost Tv signal over Christmas - any Tv engineers?
Somehow overnight into Boxing Day all Tvs in my house have lost signal. Problem only showed itself when trying to tune in a new Tv bought for the
kids. It kept finding 0 channels and displayed 'no signal'. I tried other Existing Tvs and they all show same fault. I have a booster box
in the loft feeding 4 Tvs. The roof aerial feeds into this box which then splits it 4 ways. I have bypassed the box connecting the roof aerial
directly to some of the 4 Tvs and still get no signal. The aerial doesn't appear to have moved during the stormy weather we've had. Has
the connector on the actual aerial failed? Any ideas? Could it still be the booster box as I understand they send a small current back up to the
aerial?
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morcus
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| posted on 27/12/13 at 01:21 PM |
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Does anyone in the street have the same problem? It's unlikely but theres a chance the problem isn't at your end.
I don't know enough about digital signals to be certain buit I'd expect a tv connected directly to an arial that usually feeds four to get
some sort of signal. Is the arial deffinitly attached to the cable coming off of it?
In a White Room, With Black Curtains, By the Station.
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rusty nuts
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| posted on 27/12/13 at 01:29 PM |
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I'm no TV engineer but when I moved into my present house I was unable to get a signal which I eventually traced to a badly corroded coax cable
at the aerial end.
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snippy
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| posted on 27/12/13 at 01:41 PM |
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None of the neighbours have any problems. The coax cable appears to be connected to the aerial but it's far too windy to get up on the roof at
the mo.!
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joneh
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| posted on 27/12/13 at 01:54 PM |
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I'd take a guess at the coax core has snapped at the aerial end, in the high wind.
Have you tried an internal aerial connected to the booster?
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Smoking Frog
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| posted on 27/12/13 at 02:02 PM |
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I have a mast amplifier in the loft which sounds similar to your setup. This will have a small power supply which needs to be plugged into a 240v
socket. If this is switched off there is no TV signal. Maybe check that its working by testing the output voltage usually around 9 to 12v. Although
it could well be related to the high winds. I'm also no TV engineer.
Added
If the amplifier has been bypassed then it must be a fault on the coax or aerial.
[Edited on 27/12/13 by Smoking Frog]
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snippy
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| posted on 27/12/13 at 03:08 PM |
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My Booster/ Amplifier box has a red power light which is on so I know it's got power. It also has a green light marked 'surge' which
is also lit up but I think this has always been lit up. I think I'm gonna have to get on my roof next and check the connection there.
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gremlin1234
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| posted on 27/12/13 at 03:44 PM |
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some boosted aerials have an amplifier actually on the aerial itself, so it could be that, the coax to it, or the coax connection on the aerial.
see https://www.radioandtvhelp.co.uk/interference/rtis_tv/amps_basics
as joneh says, an internal aerial would be a good test
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sky12042
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| posted on 27/12/13 at 10:11 PM |
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You could have a mast head amp or just a split aerial, is there a black box attached to the mast just below the aerial, if there is it's a mast
head amp, if no box then just a plain aerial split at the loft box.
I would check the voltage from the power supply for the mast head amp, if it's supplying power then either water ingress in coax, broken core in
coax from loose flapping cable or aerial moved in wind.
Using your voltage meter you can check continuity with the resistance setting, the one where it beeps when you touch +&- together, disconnect the
aerial at the power supply and put a probe on the outer and one on the core and if you get a beep then you know there is no breaks in the cable, but
it would still beep if there is a short or bad connection.
If it's split in the loft then just connect the aerial input direct to one of the outputs and check if there's a signal at that TV, then
you now it's the splitter.
If the aerial looks like it's pointing in the same direction as the other aerials, I would check the connections on the amp and aerial balum.
Could have got water in and they corrode easily. Just remake making sure no outer braid touches the inner core and shorts across, otherwise it could
be the coax, best to replace with fresh as it could have water in or starting to perish.
I'm no aerial expert BTW. my expertise is in satellite TV.
Be careful if you go up on the roof, windy, slippy and loose tiles can lead to disaster.
Andy.
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