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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Plasma TV Adjustments

 
 


Jerry8A
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Oct 20, 2005, 3:56 AM

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Plasma TV Adjustments Can't Post
Plasma TV Adjustments –



I am familiar with analog TVs using CRTs and their internal (technician) adjustments. However, plasma TVs are new to me.



My question is do Plasma TVs have internal adjustments for Focus? Or, is focus set by video and screen technology?



Thanks,

Jerry



rrobor
Veteran

Oct 20, 2005, 11:06 AM

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Focus is used to align light or electrons going through a lens at a distance from the receptor or transmitter of energy, as this is not the case in plasma, focus is not an issue. Its like saying how do you focus a photograph, you cant, its as it was taken. So if its out of focus, regardles of what you do it will remain so.


Jerry8A
New User

Oct 20, 2005, 9:10 PM

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rrobor-



Thanks for the reply. I suspected focus was not applicable to plasma TVs. Perhaps you can answer the following for me.



In an analog TV using a CRT, there are technician types of controls such as focus, high voltage, CRT brightness, etc. that a TV technician can adjust on the chassis. These are not customer controls.



In a plasma TV, are there similar types of internal controls or adjustments that a technician can adjust to change the picture performance? (I'm not referring to the customer controls.)



Jerry


mikemaiertv
Enthusiast


Oct 20, 2005, 11:43 PM

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The anwer is yes, however like almost all newer TV's these are in the service menu, and for many of these high end sets these service menus could and most often do control hundreds of values. (A Sony DLP for instance has over 23000 diferant varibles in 124 differant sub menu and then differant menus for every mode the set can run in ) And if by chance someone gives you the service code to enter the adjustment mode, in all most all cases this void your warentee. And in other cases makes the problem far worse than before and/or compleatle destroy the set. Best and only advise is if you have a problem take this to a qualified service center
Mike Owens Owner Competition TV Spokane WA.


Jerry8A
New User

Oct 21, 2005, 2:36 AM

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Re: [mikemaiertv] Plasma TV Adjustments [In reply to] Can't Post
Mike –

Thanks for your answer. It was really appreciated. However, your explanation brings up a hypothetical question. As you probably know, SAMS publishes TV schematics. And, aside from a qualified service center, there are competent people who have the knowledge to utilize that information. Do you think when SAMS gets around to publish schematics for plasma TVs, they will publish the service menus and explain how to access them? Perhaps you may know this answer from other high end TV sets.

Do you agree with rrobor's answer, that focus is not adjustable, even from a service menu?



Jerry

(This post was edited by Jerry8A on Oct 21, 2005, 2:42 AM)


mikemaiertv
Enthusiast


Oct 21, 2005, 3:04 PM

Post #6 of 14 (2635 views)
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It's possible to adjust things like Gamma and the default color to give the impression it's better focused but the question is it's out of focus at what distance? Seem some people get these plasmas or LCD's hook them up to a computer and use them as a montor and they are sitting within three feet of the set. At that range almost all but the extream high end sets will look out of focus.


And if you get the service manual and it tell you where all the controls are located in the service menu It's still a experienced tech that knows what they do. Just because you now know that third item down in the fith menu is VPARB The manul wont tell ya what VPARB does bthen most of these settings interact with others, and thats not covered in the service manual as well
Mike Owens Owner Competition TV Spokane WA.

(This post was edited by mikemaiertv on Oct 21, 2005, 3:09 PM)


Jerry8A
New User

Oct 22, 2005, 5:23 AM

Post #7 of 14 (2629 views)
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Re: [mikemaiertv] Plasma TV Adjustments [In reply to] Can't Post
Hello Mike –

Thanks again for your explanation. Rest assured, I am not using my set as a monitor.

My focus problem, although minor, is for real. I’m inclined to think the picture focus quality I see is designed in my set. Since you have been so nice to detail your answers to me, perhaps you may be interested in why I have come to this conclusion.

In the design of Projection TV one of the early video problems was video highlight saturation. It was also evident on some TVs. This often manifested itself to what is called “blooming.” To negate this problem, designers would shape the preshoot of the video signals to minimize the leading edge of the video, hence soften the peaks of a video signal. They would also limit CRT beam current at peak video signals. And, they would sometimes clip the peaks of the white video signal.

Now, in plasma TVs, one of the drawbacks often mentioned is burning in an image on the screen. And, of course, peak video would make this problem worse. I intend to think that some TV manufacturers could, by design, soften their video highlights to minimize this burn in problem. And, when they do, often highlights can look out of focus if the video is improperly shaped. Now, in my case, the out of focus condition is noticed in the whites of a person’s eyes and in the details surrounding the eyes. Although minor, you can also see it in some white lettering. You can tell the video preshoot of the lettering has been softened. Of course, this won’t be noticed by your average viewer. Usually, a person familiar with video processing will see the result.

So, after all is said and done, since the rest of my picture looks fine, I believe my focus problem is probably designed in by choice.

Regards,

Jerry

(This post was edited by Jerry8A on Oct 22, 2005, 5:32 AM)


rrobor
Veteran

Oct 24, 2005, 2:47 PM

Post #8 of 14 (2616 views)
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Think about it, A plasma screen lights up one spot on the screen if instructed to do so, there can be no focus of a spot, its like having a page of type out of focus. Yes it could be possible to transmit the effect on an unfocused picture. But understand as there is no lens used there is no focus


Jerry8A
New User

Oct 24, 2005, 9:50 PM

Post #9 of 14 (2610 views)
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Hello rrobor –

Nice to hear from you again. Yes, your response and others who have responded have cleared up the issue of focus. However, when I first posted this query, I should have included the lack of some detail, particularly in a person’s face, was noticed. Often, poor focus or detail can be perceived as the same on the screen. And perhaps, this may be truer on flat panel displays. Nevertheless, I think you would agree that detail or sharpness is a performance parameter that can be modified (or adjusted) in a set design.

As you stated, one spot on the screen is addressed as instructed. However, the way it is addressed can influence the outcome, i.e. focus, details, color, etc. I say this because the algorithm used to light up these pixels will influence their perceived performance as viewed by the home user.

Jerry







(This post was edited by Jerry8A on Oct 24, 2005, 9:53 PM)


rrobor
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Oct 26, 2005, 12:36 PM

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I would suggest you should read up on how the plasma cells work, their advantages and their drawbacks as it's too complex to detail here. I would also suggest that manufacturers have to make choices as to cost effectiveness. I somehow feel you want too much bling for your buck.


Jerry8A
New User

Oct 26, 2005, 8:53 PM

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rrobor

Thanks for your return. Cost is certainly an issue with all manufacturers. However, let me share with you the reasons for my query on focus and details. When I purchased my Samsung plasma TV, the published specs exceeded most others that I was interested in (even the more expensive units, although my set was not much cheaper). And with its 12 bit system (others have less), I expected comparable or better performance.

Now, as you stated, perhaps I was expecting too much. However, that question can only be answered by the end user. You are probably aware of organizations that publish reviews of TV sets. After I purchased my set, I found the following review (bold type was in their review):

“The Samsung SP-R4232 has EDTV resolution but its picture quality would suggest it has even less. Watching a DVD signal over component inputs we were unable to obtain a precise picture. The SR-R4232's 852x480 image didn't come close to matching the clarity we've seen on Panasonic's line of EDTV Plasma Displays. While watching The Fast and the Furious, skin detail was noticeably absent, giving characters a mannequin-like uniform complexion. Since The Fast and the Furious was not the cinematographic accomplishment of the decade, we checked the movie on a Panasonic TH-42PD50U and found that the DVD really did contain skin detail and the Samsung was truly lacking. During the many fast-action scenes the Samsung SP-R4232 couldn't keep pace. Artifacts distracted from the movie.

Color, at the default dynamic setting was artificially red. The standard setting was slightly less vivid and the movie setting delivered a fairly realistic picture. Starting from the movie setting and turning down the color setting resulted with much truer picture. Users can individually tweak the red, green, blue, yellow, pink, and white levels in addition to selecting from the standard picture settings. “

So, it seems logical, that plasma TVs do have the capability of performing at a high level, and it is up to the manufacturers as to how creative their design is. Often TV designers, operating within the same budget constraints will have far different outcomes on their efforts. I don’t discount cost as a factor, but as I stated at the beginning, Samsung’s specs would have one think their performance should be superior.

Now, when I was shopping for my TV, I did look at the Panasonic and I could see the difference in picture detail and clarity. So, why did I not purchase it? Three reasons: Knowing Samsung had exceptional specs, I was hoping when I got the set home I could adjust it for better performance, hence my forum query. And second, retail stores have their sets adjusted for showroom performance (as you stated). And third, the stand on the Panasonic was too large for where I was going to place the set.

Jerry



(This post was edited by Jerry8A on Oct 26, 2005, 8:56 PM)


rrobor
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Oct 27, 2005, 9:34 AM

Post #12 of 14 (2585 views)
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May I repeat my answer, What is acceptable and what is not is subjective, regardless of if you have some wanker who does a column in TV tomorrow, or Joe Soap who watches the thing. Get real, a manufacturer doesnt tell you this thing is crap, he tells you this is dandy, The wanker who writes in TV tomorrow will have his mortguage paid off, and you are the idiot who bought the bloody thing. Cripes where have you been.


Jerry8A
New User

Oct 28, 2005, 2:10 AM

Post #13 of 14 (2578 views)
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rrobor –


Calling someone an idiot has no place in a public forum. Proper Forum word etiquette and respecting opposing viewpoints are always recommended. Doing less only serves to undermine the credibility of one who makes such statements.

I’m sorry you could not accept this conversation as an exchange of professional opinions, that differ. I’m sure there are folks who, with an open mind, can see valid points for each side of this discussion.

But, hey, no hard feelings. These forums serve a very useful purpose and I appreciate the time you spent in answering my questions.

Regards,

Jerry



rrobor
Veteran

Oct 28, 2005, 11:38 AM

Post #14 of 14 (2572 views)
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I suggest you read and understand the gist of what I wrote, Perjhaps i could have phrased it slightly better but the Gist was if one believes the blurbs given out by a manufacturer and the glitter by a salesman, one is an idiot. It was an observation, not an attack on you. The unit you have is not top shelf, its middle of the road, as such my other observation was perhaps you expect to much. As a professional of many years standing, on occasion I gave come across a customer who expects more than is possible, your writing suggests to me that this is what you are doing. Also as the thing is new its under warranty so have the manufacturer check it out if you are unsatisfied.

 
 
 


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