Toshiba 36ZP48 colour purity problems?

Has anyone with the new 36ZP48 (PF3) noticed any colour purity problems?

Last year I bought a 36ZP38 (PF2). It displayed a light-blue/turquoise patch in the top left-hand corner. Robertson's arranged for Toshiba to exchange it and the replacement was much worse - great big discolourations down both sides of the screen - so Toshiba took it straight back. The 3rd replacement also showed discolouration - slightly worse than the original set but, this time, I was told it would go away in a week or two.

It didn't and Robertson's arranged for a Toshiba rep to call. He said that colour purity was an inherent problem with all 36" CRTs and would not arrange for a further replacement so the the set was taken back for full credit. Last year, the forum was full of comments re this colour purity problem but, so far, nobody has mentioned it in connection with the new 36ZP48.

In every other respect the PF2 was brilliant but I just couldn't live with bands of colour where they didn't belong. Has this problem gone away with PF3?
TIA
Ian

[DRGL]

In my experience poor purity is due to bad setup at the factory,my current HQ100 displays a slightly pink area when the screen is RED(BBC1 b4 a lot of programs displays a solid red screen) It is only about 2cm square. Previous sets had bad white purity I've got the service manual but setting this up isn't easy!!(HQ100 that is) It is true that a larger CRT is harder to setup-too much £££ on a mass produced set i think......

[Laurel&Hardy]

Two things

Purity cannot be influenced by bad set up at the factory, unless you mean the CRT factory. There is nothing in ANY TV menu, service, design, ect. that affects purity. To adjust it you have to a) adjust the DY position, then b) use special magnets to deflect the beam. These stick to the back of the CRT.

Large CRT's, especially the flat types are more affected by purity and focus than smaller ones. This is because CRT design is beign stretched to it's absolute limit in size and the bigger you make it the more magnetic effects you will see.

[DRGL]

And where do you think these magnets are installed?? THE FACTORY! I've got the service manual sat in front of me-page after page of magnet position etc etc,as this is done at the FACTORY of course bad setup can effect purity! This can not be done at the CRT factory as this is performed when the set is built.

Originally Posted by DRGL

I've got the service manual sat in front of me.

DRLG, if you have the service manual, can you tell me in the service menu, what does the OPT menu do, what are its settings etc..

Also would it be possible for you to mention what settings and menus are available from the service menu's.

Where did you get the manual from?

Cheers

Baz

[DRGL]

As above,i've only got the service manual for my Sony HQ100,my post was intended as a guide as CRT setup is similar on all makes. Do you need the HQ100 manual or the Toshiba?

The Toshiba...

[Laurel&Hardy]

Originally Posted by DRGL

And where do you think these magnets are installed?? THE FACTORY! I've got the service manual sat in front of me-page after page of magnet position etc etc,as this is done at the FACTORY of course bad setup can effect purity! This can not be done at the CRT factory as this is performed when the set is built.

You talk like somebody who thinks they know how this works, when in fact you don't.

I've been to a CRT factory so I know where and how this is done - as part of the visit I adjusted the convergence and purity on a few of their training CRT's!. You can do further adjustment after it leaves the factory for sure, but I would be surprised if anyone bothered because manual purity adjustment takes lots of time. TV factories would never consider it because in this cut throat world time is money is expense.

Also please read my message before you rant - I did ask if you were referring to the CRT or TV factory.

So, does the above mean that the PF3 is as bad as the PF2 in terms of colour purity problems? Like I said, the forum was full of this issue last year re PF2 and I got 3 duff ones on the bounce. It would be a shame if PF3 didn't improve/eradicate this problem.

Do PF2 and PF3 use the same tube?

[DRGL]

"Factory" was used as loose terminology So poor setup at the factory can not = bad purity eh? So this page of the service manual talks rubbish too does it
I suppose all my years of servicing computer monitors means i know nothing too? Don't get me wrong,i'm NO expert but to say poor setup at the factory can not result in poor purity is utter rubbish.I suppose poor setup at the factory can not result in poor convergence and geometry too........

[DRGL]

Originally Posted by Laurel&Hardy

Also please read my message before you rant - I did ask if you were referring to the CRT or TV factory.

CRT/TV factory,who cares! Where did i refer to a certain factory? how pedantic My reply was not a rant,just simply trying to explain to the original poster that there may not actually be anything wrong with his set,just poor setup.........

[Laurel&Hardy]

You need to be specific because the two are not done in the same place. Service manuals cover ALL operations/processes, not just the ones in the final assembly factory. If additional purity adjustment is needed then this is often done 'in the field' or by the supplier of the CRT before it goes into a TV set, not at the final assembly plant. If you think about the pages and pages of information you have in front of you about magnet placement, then think also about the myriad of possible purity, convergence and geometry errors that can be corrected by magnets, and the different types of magnets used to do this then you realise why this is not something that can be done quickly as a manual operation. Most modern CRT factories have calibrated gears that evaluate the white field display and tell the operator where to place the magnets. But this is massive investment, and it won't be done twice simply because it would cost so much it would add to the end cost of the product. And as I have said several times, nobody wants to pay decent money for decent CRT anymore.

Forgive me for being a little 'up front' at first, but it does matter who does what - final assembly plants normally only assess CRT's, they will not usually adjust them unless they have the CRT factory right next door, which is very unusual. In Sony's case they may well have a small team at each site to adjust the bad CRT's since they don't tend to use other people's CRT's in their own sets. Philips may be another example of this but it does depend on the manufacturer and how they supply their CRT's to their customers (the final assembly plants).

Also, don't forget that poor handling of the product by transport can also screw purity as well - the shadow mask/aperture grille is a delicate item and it doesn't take much of a sudden impact to wreck it.

[Laurel&Hardy]

Originally Posted by IanR

So, does the above mean that the PF3 is as bad as the PF2 in terms of colour purity problems? Like I said, the forum was full of this issue last year re PF2 and I got 3 duff ones on the bounce. It would be a shame if PF3 didn't improve/eradicate this problem.

Do PF2 and PF3 use the same tube?

Simple answer to both questions is don't know because I've not seen a PF3 up close and personal. I've seen two PF2's, one in a shop (looked terrible thanks to utterly crap signal and bad picture setup) and my mates which was amazing once you got out of reset 1 and set the picture controls properly! Never saw any purity error of note in his, maybe he was lucky. A part of me wonders if some of this is caused during transport because these things are massively heavy and it only takes a sharp impact in the corner thanks to it being dropped to muck up the purity permanently. Where was the purity bad on your 3 duff ones? The same place or different every time?

[DRGL]

How hard a knock would it have to take to knock the purity out? Surely the only part that could move would be the DY? I've had three HQ100's now,two of them had bad white purity,the one i've got now has slight pink sploge in the bottom left corner when the screen is 100% red(Like on BBC between programs) I've decided to live with it as eash set i've had has had some sort of purity issse. I know of other people who have had this too, at the moment i'm more inclined to think that this is just down to the setup at the factory (CRT or otherwise ) either that or all of these are getting damaged in transit I'm even more inclined to think this as every HQ100 i've had/seen seems to suffer from red colour bleed/bad red convergence.You comments would be appreciated Like you say made to a price

[Laurel&Hardy]

I've seen as little as 6 inches do permanent damage on a tube as heavy as a 36". What happens is when it is dropped from a sufficient height the shadow mask deforms and therefore screws the purity. This cannot be corrected. However, since the Sony is an aperture grille I am not so certain how these are affected by 'unofficial drop tests', if at all.

The DY shouldn't be able to move at all. At the CRT plant I visited it's screwed down after purity adjustment and wedged when adjusting the geometry. The wedges are then glued to the DY and taped to the CRT for extra security. So if this moves it normally means the neck is broken! Either that or it was never fastened - I'd expect such a failure to be found at the final assembly plant because of pcture rotation and other issues. I think this process is pretty universal - it certainly looks like how a lot of CRT manufacturers do it from the CRT's I've seen over the years.

If you've had 3 with different purity issues it does sound more like a CRT based problem than clumsy courier staff. See the other thread we have going about my comments on convergence. Patchy purity is curable only by magnets, and since you have the service manual for it I guess you have the task of correcting what Sony apparently can't control! Happy hunting - I think you'll be there a while chasing it and the geometry!

To be fair though it is a hellish task to get good purity on flat CRT's expecially ones as big as 36" - I mean let's face it, when CRT technology was developed and shown to the world I think the forecast size limit then was about 19" and that was in the goldish bowl days. I think Baird would be speechless if he could see his technology today, still going strong working way beyond what was initially thought possible.