Any TV experts here?

There isn't really any such thing, these days. You take a flatscreen TV, and you do what you can with it, based on experience. A lot of the time, its a case of going down the manufacturers' preferred route, of board swapping. That said, power supplies and backlight inverters are often repairable. So what's the problem ? Good possibility that someone on here might know the answer, or be able to point you in the right direction. If you never actually ask the question, you'll never actually know ...

Arfa

I got quite good on repairing Philco 16 inch, black,and white, TVs back in 1950s

Bill K7NOM

My thanks to 'Arfa Daily' and 'bill' for comments.

Location: East Devon, England

The TV in question is only 10 months old and apart from the odd occurrence of digital picture break-up, has worked perfectly until last Saturday evening when the digital picture broke up into many pieces on the ITV channels yet remained satisfactory on those from the BBC. My wife retuned in accordance with the instruction, both auto and manually but the fault remained.

Yesterday, I reset the TV to factory conditions. I unplugged it from mains power. I retuned without an aerial input (to clear channel settings, I'd read on-line) then retuned again.

I now get a perfect picture on all BBC 'normal' channels. I get a first-class High Definition (HD) picture on relevant channels for both BBC *and* the commercial TV channels (ITV).

However, I'm still not receiving ITV 'normal' channels at all.

(Another TV we have upstairs *does* work on normal ITV channels!)

There's always a reason for everything. Any idea what might be the cause?

--
Dave - I'll contact our Sony helpline later today and see if they can 
help explain matters. I'll report back what transpires.

** Hardly possible for it to be a fault with the set at all.

Signal strength at the set is low on the ITV channels - hence the breaking up etc.

Suspect an antenna or cabling problem or possibly one at the transmitter.

That another set in the house works OK is not relevant until you swap the locations of the sets.

Please describe you antenna and cabling set up - is there a splitter/booster anywhere ?

... Phil

Hi Phil

Thanks for your response.

The antenna is probably 3ft long - a square section, with 8 X's at equal intervals. At the back end there is a < shape with 3 horizontal bars on each arm. (I got my camera to take a picture and found it's battery flat

- now on charge!). I know it's more than 8 years old cause it was up there on the chimney stack when I bought my house!

The cable from the aerial goes into the loft where it plugs into a booster/splitter with four output cables. I did switch a couple around last evening to no effect. Maybe I'll have another try later today.

I fear I may have to get in a professional if there is no possibility that it's the TV itself. What I don't understand is why we should be getting a perfect HD picture but no 'normal' ITV channels.

Dave

They have probably been upping the TX power levels after DSO and your Sony has picked up some channels from the wrong transmitter - you might find the correct channels stored elsewhere (800+?). Suggest you ask in uk.tech.digital-tv giving town or approx postcode and which transmitter your aerial is pointed at. One way of getting round this is to do a manual scan on the correct frequencies only - or watch the auto-scan and plug/unplug the aerial at the right point.

Hello Geo

FYI

Details of Stockland Hill Tx ^^^^^ but it's mostly gobbledegook to me!

Today it's dry with blue sky and sunshine - and the ITV channels are working again now!!!

Thanks for mentioning uk.tech.digital-tv - I'll go and visit! :-)

Dave

BBC and ITV HD are transmitted at high power, the other ITVs are transmitted at low power. Thus an aerial-cable setup that is inadequate for the other ITVs could perform acceptably for BBC and ITV HD.

Was it storming when ITV was pixelated? Look to see if there are any tree branches in line with the aerial and Stockland Hill. You could try reaiming your aerial, or moving it to a different spot on your roof. As old as it sounds, replacement might be a better solution.

Geo Inscribed thus:

Yes, that happened to me ! Where I am there are three transmitters and it was the unwanted ones that were stronger for a short time. 48 hours later and another re-tune, all was well.

--
Best Regards:
                          Baron.

All of the advice and thoughts given, are good and valid. UK digital TV is in a real state of flux at the moment, with transmitter power levels being upped and downed all the time whilst they sort out all of the multiplex locations and powers, since the final demise of analogue. The multiplexes and their contents have changed about three times recently in my ITV region. The Panasonic TV in the lounge has managed to hang in there ok, but the no-name in the kitchen, has struggled. Same antenna system, trunked distribution, slightly higher signal levels in the lounge.

Going back to your antenna, if it really is 8 years old, it may not actually be a wideband type suitable for digital. The fact that it has "X" type directors and a ">" reflector, only tells us that it is an 'anti-ghost' type, and whilst many wideband antennas that are around now are also of this design, there were certainly 'chanel-ised' versions made by Jaybeam, I think, cut for particular groups of channels. Depending on how good your signal is in the first place, sometimes you can get away with the reduced response outside of the section of band that it is cut for, but it may be the case that the multiplex that your ITV is in, has moved to the other end of the band, and the antenna is only *just* adequate to receive enough signal at the current transmitter power, and that if there are any adverse weather conditions or other obstructions, poor reception results.

Remember that digital signals do not die gracefully like analogue ones did, where you would have noticed the 'grain' on the picture increasing as the signal level fell. With digital signals, it is the 'cliff' effect, where the decoding and error correction process hangs in there until a given point, after which, bit errors are so great that the original signal can no longer be recovered, at which point, the decoder gives up, and just blanks the screen. If the problem persists, you will have to get a professional rigger out, who will be able to see immediately if the existing antenna is a wideband type or not. If you go down this route, see if you can find a long-established firm, or if you can find an independent dealer locally, pop in and ask them who they use. There are a lot of cowboys and rip-off merchants around in the TV antenna business at the moment, taking advantage of the state of flux of the digital services, and people's lack of knowledge and understanding in that regard ...

Arfa

In the U.S. there is a one-year warranty on new Sonys and my advice would be to get it to a Sony warranty servicer.

Don't know what sort of warranty they have in your country.

Mark Z.

I now understand! Thanks for that.

Not storming, but damp and drizzly! It's rather like that today too, but ITV *is working now*! Grrr! There's no tree branches nearby, I'd not be surprised if there were some shenanigans going on at the transmitter!!!

We've been digital for around two years now with very few occasions of picture break-up. I think I'll sit things out for a few days and see what happens.

Thanks again for your views!

I really appreciate your comprehensive comments, Arfa. Thank you. :-)

FYI, here's a piccie of the antenna:

My eyes were playing tricks on me - it's a round section bar and 9, not

8, X's!

I did speak to Sony's help line (a girl in Cairo, Egypt!!!). Her view was that it is definitely *not* a TV problem, but one of signal strength.

Many thanks for your warning about cowboys and rip-off merchants. I'll be careful to select wisely if/when I need professional help.

Cheers!

Dave

What I see here, looks like a Yagi-like hybrid... a corner reflector, a bowtie-type driven element, and a bunch of bowtie-type director elements. I'm not sure what the flat non-bowtie element right in front of the driven element is.

The bowtie configuration (for the DE and directors) would give a somewhat broader bandwidth than a single-wire dipole element would.

Nevertheless, this looks as if it's probably intended to be rather narrow-band (single-wire-element Yagi antennas have a bandwidth of only a few perent) and quite directional... having a narrow half-power beamwidth, as a way of increasing the forward gain. I'd interpret it as a "deep fringe" sort of antenna, intended to be used in locations quite some distance from the transmitter(s).

The directionality of this design could either work for you or against you. If it's aimed directly towards the best propagation path to the transmitters, it would maximize your signal strength and probably help keep the multipath reflections down (multipath causes ghosting on analog signals, and degrades digital signals in a way less obvious).

On the other hand, if you've got two or more transmitter sites you want to receive from, in somewhat different directions, then a highly directional antenna could cause you problems... aiming the antenna for best signal on some stations could put the other tranmsitter in a non-favored direction. You could lose signal strength, and have increased sensitivity to multipath.

Although it's a pain in the tail to install and manage, you may find that it'd be beneficial to have a remote-controlled antenna rotator, so that you can re-aim the antenna depending on which station(s) you are trying to receive.

Here in the U.S., one tends to see log-periodic designs rather than Yagi-type - broader bandwidth, but less gain and a poorer front-to-back ratio. This may be less true in the future, I suppose, as fewer and fewer stations are operating in the old VHF spectrum - most of the digital stations are now in the UHF range, and less antenna bandwidth is required.

[The lower antenna looks like a folded-dipole driven element, with a single parasitic - probably a reflector? It isn't wired to the same feed-line, is it?]

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

No! That one is for radio reception - not currently connected!

Thanks for your comments, Dave.

Looking at the OP's "Freeview" link, the transmitters cover a narrow range of UK channels, from Channel 22 to 29, or roughly US channels 15 to 25.

His local transmitters are all on the same tower on Stockland Hill in Devon, so once he peaks the signal, that should do it, right?

Looking at the picture, I think that you can be 90% sure that what you have is a narrow bandwidth antenna from the analogue days. It may or may not ultimately prove satisfactory for digital. If you remember back to the early days of the 'digital TV revolution' with the TV ads featuring Johnny Vegas and Monkey, the basic message was that you could just glue your shiny new digital TV or STB to your existing antenna, and immediately enjoy all of the benefits of the digital system. Well, yes and no. As far as I know, it was always the intention that when everything was finally settled, the multiplexes for each TV region, would largely match the blocks of band originally used for analogue TV in those areas - hence an existing antenna should work ok. However, it never really worked out that way in the interim. To avoid interference problems to and from existing analogue services, whilst these were phased out over whatever time period it was - around three years I think it's been - multiplexes belonging to a geographical area, were shoved all over the whole UHF band, which is about 400 MHz wide. So you could easily finish up with one multiplex at the bottom of the band, and another for your area, right at the top. That's the way it was where I am. Also, whilst best efforts were made to co-locate digital transmitters on the same sites as the existing analogue ones, that didn't always work out either, so you could finish up with the analogue service, and the digital service broadly in the same direction, but possibly several degrees apart. If you have a highly directional existing analogue antenna, that could make it quite a bit 'off-beam' for the digital service. On top of all of this, they have had to adjust transmitter powers up and down as well, because of mutual interference problems, and multiplex contents have also been shuffled around. It is only in the last few months, as the analogue transmitters have gasped their last, that there has finally been some efforts to stabilize the whole situation, with finalised transmitter powers and multiplex locations within the band. There has also been some shenanigans regarding what parts of the UHF band are left available for TV use, after revised chunks are sold off to the cell-phone operators. This has caused some problems with space that the broadcasters thought was already allocated to allow broadcast of HD within the Freeview terrestrial service, and has resulted in a rethink as to how this is now being accomplished.

All in all, if you can live with the current situation for a little while longer, you might find that it all settles down enough to give you perfectly acceptable results, using that antenna. Of course, the exact reverse might also turn out to be true ...

It would probably ultimately be worth getting the antenna replaced with an up-to-date one, as you would then be guaranteed good reception under all weather conditions, but as I said before, choose your rigger with care. Have a look at the size and type of antennas that have appeared newly on your street. If they are not massive and very complicated looking, then you should be able to get a new one rigged on your house, again assuming that it's not a 'difficult' installation, complete with new cable, which will be very much better performing than the current cable you have, for less than

100 quid. A reputable rigger will not try to sell you anything different than anyone else in the street has, and will not try to persuade you to have a 'booster'. There have been a number of cases of disreputable riggers cashing in on this whole affair, and the public's lack of understanding of it, and plus 70 quid for a five quid un-needed Chinese amplifier, is one of the rip-off methods that has been used by them.

Arfa

Thank you for sharing your knowledge with me, Arfa - I am certainly a much wiser man now. It's obviously a very complicated business but you seem to know your stuff!

Hahaha! Indeed it might well be the reverse! I'm not a great fan of TV nowadays, but when I DO want to sit down and watch something, I do want it to work! I'll let things run as they are for a short while longer.

All your comments are most helpful, Thank you so much for taking the time and trouble to advise me.

Have a great day! :-)

Thanks again, 'Arfa' (great nym!)

On this note, this site made me crease up with laughter. scroll down to see some hilarous aerial bodges!

regards, B.