No Freeview Signal

bob_Campbell · 08-02-2015, 10:41

Moved wall tv back to original location in bedroom and now have no signal. Apart from fitting a new co-axial socket no changes have been made to either the cable or the aerial in the loft I get the Freeview blue signal and the names of the various channels but even after returning to factory settings, the scan finds no channels whatsoever. Help would be appreciated.

chrisjr · 08-02-2015, 11:15

First thing, never ever retune a TV that is not receiving anything until you have eliminated every other possible reason first.

You say the aerial point has been changed so therefore the first suspect has to be the aerial point. There are a number of possible reasons why there is no signal.

Most common is the cable is not terminated correctly, for example there are strands of screen braid touching the inner conductor terminal. I have even seen screws tightened up so hard the conductor has been broken!

So I would check the cable connection to the aerial point and make sure it is sound. And this is why you should not have retuned the telly

Had you not retuned you could plug the TV back in and check you are getting a signal again.

bob_Campbell · 08-02-2015, 21:49

Checked connection and it was fine but still no signal. Then, just in case there was something amiss with the co-axial socket, removed it and attached a co-axial plug to the cable which I then plugged into the RF socket on the tv but still no signal. Should I buy and try a length of top quality co-axial cable and try replacing the old one?

chrisjr · 08-02-2015, 22:30

Do you have any other rooms fed from the same aerial? Do they work OK?

Double check the cable end. Make absolutely sure that no strand of screen braid has wrapped itself round the inner conductor. I've had that happen and it is easy to miss.

If there is enough slack for you to be able to pull the cable out and plug directly into the TV try cutting off a couple of inches of the end and remake the termination. Not impossible that the inner conductor has broken near the end.

bob_Campbell · 09-02-2015, 06:09

Quote:

Originally Posted by chrisjr

Do you have any other rooms fed from the same aerial? ..........No.

If there is enough slack for you to be able to pull the cable out and plug directly into the TV ............already tried that. See my previous post.

try cutting off a couple of inches of the end and remake the termination..........did this too. Cut about 2' of excess cable off.

Had a few friends round yesterday who had a look and are completely baffled. All agreed that the connection at the aerial which hasn't been touched, is sound and intact and that the fitting of the cable into the coax socket is also good. Even downloaded an app to check the orientation of the aerial and no adjustment was required.

Stig · 09-02-2015, 07:06

Although moving the TV again might be hassle, you need to connect it to an aerial socket that you know works, and then retune the TV again.

chrisjr · 09-02-2015, 09:45

Quote:

Originally Posted by bob_Campbell

Had a few friends round yesterday who had a look and are completely baffled. All agreed that the connection at the aerial which hasn't been touched, is sound and intact and that the fitting of the cable into the coax socket is also good. Even downloaded an app to check the orientation of the aerial and no adjustment was required.

Do you have a multimeter, or can borrow one from someone?

If so try measuring the resistance between the screen and inner conductor with the aerial connected. It should measure close to a short circuit (a few ohms at best) which is normal for DC as used by the meter. If however you get a very high reading or open circuit then that implies there is a break in the cable somewhere.

Now disconnect the lead from the aerial and make sure the screen is not touching the inner and measure again. This time you should read open circuit. If it still reads a few ohms then that implies there is a short in the cable somewhere.

Are you sure it is one continuous run of cable from bedroom to aerial? I'm wondering if there could be a join in the cable somewhere and this has pulled apart when you swapped over the socket.

And is the aerial in the loft? That can be an unfriendly place for aerials. Doesn't take much to mess up reception. Just moving stuff around can affect things.

But I suspect you will have to chase the cable run and look for cable damage or something like a plug and socket in line that have been used to either extend the cable or repair a previous break and have come adrift from each other.

oilman · 09-02-2015, 11:44

You need to do a process of elimination. I suggest the following should be tried:-

Perhaps it is the tv socket that is damaged. Try plugging an indoor aerial (with a booster if possible). You should get some stations even if you don't get them all unless you are in a really poor signal area. If this works TV is OK.

Obviously, try a different fly-lead as well from socket to TV. If no difference, cable is probably not the cause.

Do you have a another TV you could connect to wall socket. If that works, then you may have a TV issue. If it doesn't work, cable to socket is probably the problem.

Winston_1 · 09-02-2015, 19:18

Quote:

Originally Posted by chrisjr

If so try measuring the resistance between the screen and inner conductor with the aerial connected. It should measure close to a short circuit (a few ohms at best) which is normal for DC as used by the meter.

Sorry that is not reliable. Not all aerials are short circuit at DC, some are open circuit. Also if there is a splitter in the line the reading could be almost anything.

grahamlthompson · 09-02-2015, 20:06

Quote:

Originally Posted by chrisjr

Do you have a multimeter, or can borrow one from someone?

If so try measuring the resistance between the screen and inner conductor with the aerial connected. It should measure close to a short circuit (a few ohms at best) which is normal for DC as used by the meter. If however you get a very high reading or open circuit then that implies there is a break in the cable somewhere.

Now disconnect the lead from the aerial and make sure the screen is not touching the inner and measure again. This time you should read open circuit. If it still reads a few ohms then that implies there is a short in the cable somewhere.

Are you sure it is one continuous run of cable from bedroom to aerial? I'm wondering if there could be a join in the cable somewhere and this has pulled apart when you swapped over the socket.

And is the aerial in the loft? That can be an unfriendly place for aerials. Doesn't take much to mess up reception. Just moving stuff around can affect things.

But I suspect you will have to chase the cable run and look for cable damage or something like a plug and socket in line that have been used to either extend the cable or repair a previous break and have come adrift from each other.

A folded dipole (a half wave loop) will appears as a short circuit, a straight dipole as open circuit when measuring DC resistance.

http://www.radio-electronics.com/inf...ded_dipole.php

Only way to tell is disconnect the antenna.

bob_Campbell · 09-02-2015, 21:49

Don't have, or have access to a multimeter.

However, took the tv through to another bedroom where the tv there is working well on another aerial in a separate loft. Result? No signal. It would appear therefore, that it is the RF socket or something else in the tv that is faulty and not the newly resited aerial socket . I can test this further tomorrow by taking the tv that is working, through to the new aerial point in the other bedroom and see what happens there.

Is there anything else I can do?

EDIT: Got it wrong! There is nothing wrong with the tv because after retuning in the other bedroom, got the full range of channels.

bob_Campbell · 10-02-2015, 09:49

After retuning the tv in the other bedroom last night, took it back to the original bedroom this morning and tried retuning again. Now have all channels back. Breaking up a bit but there must be a way round that too. Thanks for the input guys!

Chris Frost · 10-02-2015, 10:16

If the signal is there but breaking up then it points to an issue with the cabling to the bedroom. You've established that the aerial and the distribution amp is working by successfully tuning the TV when connected at another aerial point.

If the signal is there but weak in the bedroom then I would start by rechecking your connections. I know that seems like a faff because you've already done it, but you're losing signal quality somehow and the main cause for that in situations like this is poor connections followed then by cable quality issues. All it takes is just one single solitary strand of that gossamer-thin braiding to touch some part of the centre core and you'll slash the signal quality instantly. Get a torch and magnifying glass, or just remake the connections and pay particular attention to keeping braid wire away from any parts connected to the centre core.

I wouldn't rule out a break in the centre core of the cable either. It defies logic that the cable can be broken but still work, but strange things happen at the frequencies involved with TV signals. There's a phenomenon known where the signal will 'jump' across a small connection gap. The power of the signal is greatly reduced, but nonetheless the cable still appears to work. If the wiring to the socket has been disturbed then that could have been enough force to fracture the centre conductor. A continuity test using a multimeter will show if there's a conductor issue because the signal used won't be able to jump the gap.

Winston_1 · 10-02-2015, 18:15

Quote:

Originally Posted by bob_Campbell

After retuning the tv in the other bedroom last night, took it back to the original bedroom this morning and tried retuning again.

And what does the first sentence in post no 2 say?

niall campbell · 10-02-2015, 19:59

I would go for the co-ax socket being the problem

I use MK ones from B&Q

bob_Campbell · 10-02-2015, 20:52

Quote:

Originally Posted by niall campbell

I would go for the co-ax socket being the problem

I use MK ones from B&Q

Although the box is still in place, the coaxial socket is not. Instead I have attached a coax plug to the end of the cable and plugged straight into the tv. No improvement.

bob_Campbell · 10-02-2015, 20:59

Quote:

Originally Posted by Winston_1

And what does the first sentence in post no 2 say?

Since I got my channels back, I will forgive myself for retuning again this time.

bob_Campbell · 11-02-2015, 15:47

Quote:

Originally Posted by chrisjr

Double check the cable end. Make absolutely sure that no strand of screen braid has wrapped itself round the inner conductor. I've had that happen and it is easy to miss.

Cheers Chrisjr and cheers too to the other Chris for his magnifying suggestion. Using the latter, found a single wire touching the copper core, fixed it and retuned yet again. TV reception is perfect now with all channels and no breaking up!!!

Chris Frost · 11-02-2015, 16:23

Quote:

Originally Posted by Chris Frost

All it takes is just one single solitary strand of that gossamer-thin braiding to touch some part of the centre core and you'll slash the signal quality instantly. Get a torch and magnifying glass, or just remake the connections and pay particular attention to keeping braid wire away from any parts connected to the centre core.

"Yup. Exakally wot I sed in ma furst powst"

Glad you got the cause found and the situation sorted.

08-02-2015, 10:41	#1
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	No Freeview Signal Moved wall tv back to original location in bedroom and now have no signal. Apart from fitting a new co-axial socket no changes have been made to either the cable or the aerial in the loft I get the Freeview blue signal and the names of the various channels but even after returning to factory settings, the scan finds no channels whatsoever. Help would be appreciated.

08-02-2015, 11:15	#2
chrisjr Forum Member Join Date: May 2004 Location: Reading Posts: 27,916	First thing, never ever retune a TV that is not receiving anything until you have eliminated every other possible reason first. You say the aerial point has been changed so therefore the first suspect has to be the aerial point. There are a number of possible reasons why there is no signal. Most common is the cable is not terminated correctly, for example there are strands of screen braid touching the inner conductor terminal. I have even seen screws tightened up so hard the conductor has been broken! So I would check the cable connection to the aerial point and make sure it is sound. And this is why you should not have retuned the telly Had you not retuned you could plug the TV back in and check you are getting a signal again.

08-02-2015, 21:49	#3
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	Checked connection and it was fine but still no signal. Then, just in case there was something amiss with the co-axial socket, removed it and attached a co-axial plug to the cable which I then plugged into the RF socket on the tv but still no signal. Should I buy and try a length of top quality co-axial cable and try replacing the old one?

08-02-2015, 22:30	#4
chrisjr Forum Member Join Date: May 2004 Location: Reading Posts: 27,916	Do you have any other rooms fed from the same aerial? Do they work OK? Double check the cable end. Make absolutely sure that no strand of screen braid has wrapped itself round the inner conductor. I've had that happen and it is easy to miss. If there is enough slack for you to be able to pull the cable out and plug directly into the TV try cutting off a couple of inches of the end and remake the termination. Not impossible that the inner conductor has broken near the end.

09-02-2015, 06:09	#5
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	Quote: Originally Posted by chrisjr Do you have any other rooms fed from the same aerial? ..........No. If there is enough slack for you to be able to pull the cable out and plug directly into the TV ............already tried that. See my previous post. try cutting off a couple of inches of the end and remake the termination..........did this too. Cut about 2' of excess cable off. Had a few friends round yesterday who had a look and are completely baffled. All agreed that the connection at the aerial which hasn't been touched, is sound and intact and that the fitting of the cable into the coax socket is also good. Even downloaded an app to check the orientation of the aerial and no adjustment was required.

09-02-2015, 07:06	#6
Stig Forum Member Join Date: Sep 2003 Location: Sandy Heath, Beds. UK Posts: 10,383	Although moving the TV again might be hassle, you need to connect it to an aerial socket that you know works, and then retune the TV again.

09-02-2015, 09:45	#7
chrisjr Forum Member Join Date: May 2004 Location: Reading Posts: 27,916	Quote: Originally Posted by bob_Campbell Had a few friends round yesterday who had a look and are completely baffled. All agreed that the connection at the aerial which hasn't been touched, is sound and intact and that the fitting of the cable into the coax socket is also good. Even downloaded an app to check the orientation of the aerial and no adjustment was required. Do you have a multimeter, or can borrow one from someone? If so try measuring the resistance between the screen and inner conductor with the aerial connected. It should measure close to a short circuit (a few ohms at best) which is normal for DC as used by the meter. If however you get a very high reading or open circuit then that implies there is a break in the cable somewhere. Now disconnect the lead from the aerial and make sure the screen is not touching the inner and measure again. This time you should read open circuit. If it still reads a few ohms then that implies there is a short in the cable somewhere. Are you sure it is one continuous run of cable from bedroom to aerial? I'm wondering if there could be a join in the cable somewhere and this has pulled apart when you swapped over the socket. And is the aerial in the loft? That can be an unfriendly place for aerials. Doesn't take much to mess up reception. Just moving stuff around can affect things. But I suspect you will have to chase the cable run and look for cable damage or something like a plug and socket in line that have been used to either extend the cable or repair a previous break and have come adrift from each other.

09-02-2015, 11:44	#8
oilman Forum Member Join Date: Dec 2002 Posts: 3,854	You need to do a process of elimination. I suggest the following should be tried:- Perhaps it is the tv socket that is damaged. Try plugging an indoor aerial (with a booster if possible). You should get some stations even if you don't get them all unless you are in a really poor signal area. If this works TV is OK. Obviously, try a different fly-lead as well from socket to TV. If no difference, cable is probably not the cause. Do you have a another TV you could connect to wall socket. If that works, then you may have a TV issue. If it doesn't work, cable to socket is probably the problem.

09-02-2015, 19:18	#9
Winston_1 Forum Member Join Date: Oct 2007 Posts: 5,008	Quote: Originally Posted by chrisjr If so try measuring the resistance between the screen and inner conductor with the aerial connected. It should measure close to a short circuit (a few ohms at best) which is normal for DC as used by the meter. Sorry that is not reliable. Not all aerials are short circuit at DC, some are open circuit. Also if there is a splitter in the line the reading could be almost anything.

09-02-2015, 20:06	#10
grahamlthompson Forum Member Join Date: May 2005 Location: Redditch Worcs Posts: 17,293	Quote: Originally Posted by chrisjr Do you have a multimeter, or can borrow one from someone? If so try measuring the resistance between the screen and inner conductor with the aerial connected. It should measure close to a short circuit (a few ohms at best) which is normal for DC as used by the meter. If however you get a very high reading or open circuit then that implies there is a break in the cable somewhere. Now disconnect the lead from the aerial and make sure the screen is not touching the inner and measure again. This time you should read open circuit. If it still reads a few ohms then that implies there is a short in the cable somewhere. Are you sure it is one continuous run of cable from bedroom to aerial? I'm wondering if there could be a join in the cable somewhere and this has pulled apart when you swapped over the socket. And is the aerial in the loft? That can be an unfriendly place for aerials. Doesn't take much to mess up reception. Just moving stuff around can affect things. But I suspect you will have to chase the cable run and look for cable damage or something like a plug and socket in line that have been used to either extend the cable or repair a previous break and have come adrift from each other. A folded dipole (a half wave loop) will appears as a short circuit, a straight dipole as open circuit when measuring DC resistance. http://www.radio-electronics.com/inf...ded_dipole.php Only way to tell is disconnect the antenna.

09-02-2015, 21:49	#11
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	Don't have, or have access to a multimeter. However, took the tv through to another bedroom where the tv there is working well on another aerial in a separate loft. Result? No signal. It would appear therefore, that it is the RF socket or something else in the tv that is faulty and not the newly resited aerial socket . I can test this further tomorrow by taking the tv that is working, through to the new aerial point in the other bedroom and see what happens there. Is there anything else I can do? EDIT: Got it wrong! There is nothing wrong with the tv because after retuning in the other bedroom, got the full range of channels.

10-02-2015, 09:49	#12
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	After retuning the tv in the other bedroom last night, took it back to the original bedroom this morning and tried retuning again. Now have all channels back. Breaking up a bit but there must be a way round that too. Thanks for the input guys!

10-02-2015, 10:16	#13
Chris Frost Forum Member Join Date: Jun 2003 Location: Cheshire Posts: 6,462	If the signal is there but breaking up then it points to an issue with the cabling to the bedroom. You've established that the aerial and the distribution amp is working by successfully tuning the TV when connected at another aerial point. If the signal is there but weak in the bedroom then I would start by rechecking your connections. I know that seems like a faff because you've already done it, but you're losing signal quality somehow and the main cause for that in situations like this is poor connections followed then by cable quality issues. All it takes is just one single solitary strand of that gossamer-thin braiding to touch some part of the centre core and you'll slash the signal quality instantly. Get a torch and magnifying glass, or just remake the connections and pay particular attention to keeping braid wire away from any parts connected to the centre core. I wouldn't rule out a break in the centre core of the cable either. It defies logic that the cable can be broken but still work, but strange things happen at the frequencies involved with TV signals. There's a phenomenon known where the signal will 'jump' across a small connection gap. The power of the signal is greatly reduced, but nonetheless the cable still appears to work. If the wiring to the socket has been disturbed then that could have been enough force to fracture the centre conductor. A continuity test using a multimeter will show if there's a conductor issue because the signal used won't be able to jump the gap.

10-02-2015, 18:15	#14
Winston_1 Forum Member Join Date: Oct 2007 Posts: 5,008	Quote: Originally Posted by bob_Campbell After retuning the tv in the other bedroom last night, took it back to the original bedroom this morning and tried retuning again. And what does the first sentence in post no 2 say?

10-02-2015, 19:59	#15
niall campbell Forum Member Join Date: May 2006 Location: Aberfeldy Posts: 7,035	I would go for the co-ax socket being the problem I use MK ones from B&Q

10-02-2015, 20:52	#16
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	Quote: Originally Posted by niall campbell I would go for the co-ax socket being the problem I use MK ones from B&Q Although the box is still in place, the coaxial socket is not. Instead I have attached a coax plug to the end of the cable and plugged straight into the tv. No improvement.

10-02-2015, 20:59	#17
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	Quote: Originally Posted by Winston_1 And what does the first sentence in post no 2 say? Since I got my channels back, I will forgive myself for retuning again this time.

11-02-2015, 15:47	#18
bob_Campbell Forum Member Join Date: Jun 2014 Posts: 8	Quote: Originally Posted by chrisjr Double check the cable end. Make absolutely sure that no strand of screen braid has wrapped itself round the inner conductor. I've had that happen and it is easy to miss. Cheers Chrisjr and cheers too to the other Chris for his magnifying suggestion. Using the latter, found a single wire touching the copper core, fixed it and retuned yet again. TV reception is perfect now with all channels and no breaking up!!!

11-02-2015, 16:23	#19
Chris Frost Forum Member Join Date: Jun 2003 Location: Cheshire Posts: 6,462	Quote: Originally Posted by Chris Frost All it takes is just one single solitary strand of that gossamer-thin braiding to touch some part of the centre core and you'll slash the signal quality instantly. Get a torch and magnifying glass, or just remake the connections and pay particular attention to keeping braid wire away from any parts connected to the centre core. "Yup. Exakally wot I sed in ma furst powst" Glad you got the cause found and the situation sorted.

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