Page 1 of Picutre blocking on my Toshiba 32ZD26

Hi there

This problem has been ongoing for a long long time now. The query is a bit long, but the problem has got me stumped.

I have a 32ZD26 TV (bought 09/03) which a had a great picture. I moved home back in April 04 and have been suffering from picture problems ever since.

I have been suffering from a blocking effect with the pictures. This is more noticeable with large areas of colour, say a background wall, someone in a suit or peoples faces during close ups. It also occurs when images change rapidly on the screen and with effects such as rain, fire or crowds clapping. Football matches can cause particular problems with the pitch blocking and a fuzzy halo surrounding the players.

Initially the problem appeared to be related to my Sky set top box, as terrestrial signals were not suffering. Having had it reinstalled in the new house, I found that the picture suffered from periodic blocking. This does not seem to occur all the time and is better or worse depending on the Sky channel chosen, though again there does not appear to be any pattern to which channels or when it occurs. This is the really frustrating thing
because it doesn`t happen all the time and I cannot find a pattern to it.

I contacted Sky and they came and changed the box. They have changed the box and / or the dish many times now and the problem remains.

To check this, I bought a free view box and have tried this. Although to a lesser degree, this too suffers from blocking, so I am now led to believe it is the TV. I have also noticed that in some cases I suffer the blocking using DVD also. This seems to be restricted however to areas such as the `coming soon` sections at the start of the DVD`s rather than the main features, which I`m guessing are formatted in a better quality. I hadn`t picked up on this before as I generally have the contrast right down (30/100) when watching DVD`s.

This brings me to when the blocking is most visible. If the contrast of the TV is set above 40/100 then the blocking becomes very clear. That`s not to say I doesn`t happen below this level, it`s just not so noticeable below this. The thing is sometimes you have to have the contrast above 40 to see the picture well.

I am beginning to wonder if the problem relates to the scart /component parts of the TV as the terrestrial signal is not affected at all (whatever the contrast level).

Before I moved we did not suffer from this problem at all. When I moved the TV was packaged properly (in ALL the original packaging) and moved with great care. Either something has happened in the move or maybe it is the signal in our area, I just can`t tell and have run out of ideas myself.

Last night I connected my portable TV and didn`t appear to get the same problem. Managed to set up both TV`s at same time to compare. Now it is fair to say that the contrast feature on my Toshiba does seems to go a lot higher than the portable, so did see `blocks` more clearly with contrast right up, but the portable seemed spot on whilst my Toshiba seems `uncrisp`.

It it confusing me entirely now. Why would terrestrial signals be fine, but the digital signals (is the clue there?!) from Sky and Freeview, plus some DVD component signals be off? Is there a possible reason as to why this fault might occur in my TV?

I would say you have a combination of 2 causes.

1) The digital channels use variable bit-rates (Google "Statistical multiplexing" if you want to know more) and when the bit-rate is low there will be some artifacts generated and these will be far more noticeable on a larger screen - and incidentally even more so on an LCD or Plasma screen. This is an adjunct of the GIGO (garbage in, garbage out) rule.
With a slightly weaker (digital) signal, the lower BER (Bit Error Rate) will make things yet more noticeable ; this could explain why you didn`t notice this at a previous location.

2) Digital processing in the TV itself can make any imperfections worse. Turn off all enhancement modes (e.g. pixel plus, DRM or whatever it`s called for your TV) and see if that helps.

Chris Muriel, Manchester.

Happens with my Panasonic TV when using my NTL box. It`s down to the compression of the digital signal (bit like jpegs I think). I`d put money on it that it`s the same problem.

Doesn`t happen when playing DVDs or any of my consoles.

Cheers

Si



Our Collection (including the ones that belong to the kids!)

`I have something to say. It`s better to burn out than to fade away.`

Thanks for the replies. Looking likely it is as you say to do with the compression of the signal :/ . I guess where we`ve moved to has a slightly weaker signal too, so this isn`t helping. Probably not suprising given that most of the time we cant use our mobiles in the area.

Shame there isn`t a way of boosting the signal - is there? :(

Cheers

Andy

Best way to check is to whack a DVD through the TV and look for blocking. I`ve got the same TV as you and there`s much noticeable artefacting when watching Telewest`s digital service, but that`s because Telewest`s digital service is s***e. The TV is spot on with DVDs, unless of course they`re poorly encoded.

The 32ZD26 doesn`t really have any mode like Pixel Plus etc, just a pseudo prog scan mode. I guess there is the option of having it in 100Hz, Natural or Active, but that`s not as major as the stuff on Phillips TVs. I tend to leave mine in Natural for the best image.