No TV Signal - Ariel/Connection Advice

Hi there.
Looking for some advice for a newbie.
When we moved into our house nine years ago, we had to install a TV Ariel.
This was done and a further white box was added to our main TV which the Ariel went in, and the TV connection came out.
The layout of the house is simple: one TV socket on each floor, over three floors. Main TV socket is on the first floor where the White box is located.

So, over the years the connection for the White box is temperamental, meaning no signal on the tele (it also means no tele on either of the other two floors).
I've put this down to the connector going in to the wall, which with a wiggle, turned te White box light from red to green. All the worked.

Anyway, had a problem again last weekend which resulted in me taking the socket plate (?) off the wall to have a look at the connection which seemed ok.
When puting this back on it wouldn't sit slush to the wall, but still managed to wiggle and get a connection.

So this weekend I have put on a new socket plate and put a new end on the cable.
Turned the White box on and bingo...green light all the time even with moving the wire.
Turned the tele on, no signal. Retuned, nothing. Changed to the old connector, nothing.

Completely lost as this should have worked!

Does anybody had any ideas or suggestions before I make that call?

TIA.

Chris

The white box is most likely to be a power supply for a multi-way distribution box somewhere in the house (loft, normally) or mounted on the aerial mast.

If you were losing the green light then something was probably shorting out before. That means the centre conductor and sheilding braid touching somehow. That stopped the power getting up the aerial cable to the distribution box.

When you replaced the wall plate you might have inadvertently chosen one with a power blocking feature. They're known as isolated wall plates, or similar. As long as you haven't connected the power supply the wrong way around then from your description this is one of the most likely causes of your problem.

You might also want to check the wall plate wiring. The centre core and the screen braid mustn't be touching; not even one little strand of braid. If they are, then that will stop the power too.

Thanks Lucid.

Can I change plates (ie touch the the antenna wire) without turning off the electric?

Yes. It's not connected directly to the 240V mains anyway. That would be very dangerous if it were. The only power running through it should be 12V DC from that white box. If you unplug the box from the power socket (which is a good idea anyway) before commencing work then you should be fine.

For the sake of completeness, there is a remote chance of static electricity from wind action on the aerial. Also, a lot of devices such as recorders, Freeview boxes and TV no longer have individual earth's via the mains plug. They are double insulated so have a floating earth instead. If the circuit in the device is a bit leaky, then the aerial cable can act as a secondary means of earthing to another device. The current involved is very low. You'd feel a tingle but it wouldn't do a normal person any harm.

Lucid is correct in all respects and I agree with his diagnosis. You bought the wrong plate. Here's some helpful reading for you:
http://www.satcure.co.uk/tech/wall_plates.htm

Ok. So apart from the spelling error whilst in a rush writing the original post, I have now replaced the plate with the original an put the original connector on as well.
The White box has now turned red, and very short intermittent Orange whilsy bending the cable to the side.
Back to the same problem, except no green lights.

Any thoughts?
Does this look like the cable connector, or the plates connection?
The original connector has an open end, but my new connectors have a closed end.
Any difference or preference which to use?

The new plate also doesn't mention anything about insulation and looks pretty much the same set up as the original plate?

Thanks again.

Ok. So have put my new connector on and with some jiggling again, the light is green and it all works again...until next time it is accidentally knocked.

Now I could be barking up the wrong tree, but would I be correct in thinking that the issue is that the copper wire is not touching the connector properly and the wiggling is making the wire move?
Is is there a connection issue between the the plate as the connector?
Or both?
Or none of the above?

I also found the new plate connection to be wider/loser than the original, so the connectors come out!

I think you need a systematic approach to trouble-shooting here. You need to find where the short is occuring. You can't do that effectively with the entire system connected. So, as the Romans used to say, "Divide and conquer".

1) Disconnect the cable to the PSU socket marked "in/aerial/antenna/UHF". With the PSU powered up, does the light go green? Now wiggle the "in" socket. Does the light go red? If so, then you have a faulty PSU. Get it replaced. If always green then move to the next step.

2) Take the fly lead that goes from the PSU to the wall socket. Connect the end that normally goes to the PSU. Disconnect the end that normally goes to the wall. Turn on the PSU. Check for a green light. Wiggle the lead and observe if the LED light changes colour. If you're getting a red light now then there's some issue with the fly lead or how it is terminated. A red light usually indicates a short i.e. the braid and centre conductor are touching. Unless the fly lead has been completely bent and/or crushed then this isn't going to be a problem somewhere in the length of the cable. It's going to be a badly fitted plug end. As I mentioned in the earlier replies, all it takes is one fine wisp of braid wire touching the centre conductor to make a short. You might need to use a magnifying glass and torch to properly inspect the cable ends before making up the connections. If all is still good though, move on to step 3

3) Connect the fly lead to the wall plate. Does the LED go red? Wiggle the lead. If so, then there's either some problem with the plate (or both plates, but that's statistically unlikely) or it's an issue once again with how the cables are terminated, but this time at the back of the plate. TBH, I would think it would take a tremendous amount of force to be applied to a wall plate socket to then transmit enough to move the connections on the back of the plate to cause a short.


The fact that your PSU shows a red light indicates to me that there's a short. That means that somewhere in the connections that core (+ve) and braid (-ve) are touching. They mustn't touch. You need to keep them separate. It's really that simple. So if you have loose stands of braid filament because the cables aren't trimmed right or there's cuttings everywhere then of course you're going to have a problem. That's what you have to find and fix first. After that, then you can deal with the question "Does power get through this wall plate?"

Make sure your plugs are fitted correctly. You might find this helpful:
http://www.satcure.co.uk/tech/tvplugs.htm

Frankly, I would simply trash the fly leads and make new ones.

Lucid said:

but in practise very few DIYers would go to the length of soldering the centre pin. In fact, there's a lot of us in the trade who wouldn't either, and we have visited installations that are 10-20-30 years old that have got on quite happily without a soldered centre pin.

Click to expand...

If it is only carrying UHF you can get away with it. However if supplying DC to an amp it is essential that the pin is soldered.