Yikes, Holy Focus Guy Kuo - Page 4 - AVS Forum
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post #91 of 163 Old 07-23-2003, 10:51 PM
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Guy Kuo,

You are the man!

Thanks for all that you have done.

Pocatello
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post #92 of 163 Old 07-24-2003, 09:57 AM
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Guy,

I agree with Pocatello,

You are the man!


Miso

I'm no genius, but I do have a million monkeys with typewriters in my head.
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post #93 of 163 Old 08-09-2003, 10:27 AM
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post #94 of 163 Old 10-01-2003, 08:48 AM
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I have an NEC XG-1100 and in adjusting the CPC magnets I notice I get a LOT of raster movement. Since there are no raster centering magnets on this projector, once the astig is set by your procedure, it may take a lot of adjustment of the electronic raster centering controls to get the raster in the middle of the tube.

Is there a better way to do this, do I have to compromise astig setting so the raster stays where it belongs, or is it okay to do whatever is necessary to center the raster with the electronic controls?

Thanks!
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post #95 of 163 Old 11-20-2003, 10:07 AM
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Following the postings on AVS for the past year, at least once, since Guy started this thread, a person reported that the "blue" masking tape left a mark on their screen. Perhaps it was left on too long, perhaps it was not applied "lightly," or perhaps the glue on the tape reacted with their screen coating in some way. No matter what... I know that person was not happy with the result.

I posted my solution to this problem in another thread and it was suggested by several other members that I also add my solution to this thread.

Instead of blue masking tape... use two lengths of sewing thread.
Instead of using blue tape to mark the center of my screen, I stretched a black sewing thread across the horizontal and vertical center lines of my screen attaching the ends of the threads to the back of my screen frame (where any marks left by tape would be far less noticeable )

The two threads formed a cross-hair target that allowed us to easily set the center, skew, and bow when adjusting my projector's geometry. Since most of us have access to a spool of sewing thread, this method of locating the exact center of the screen is pretty easy to duplicate, just make sure the horizontal thread is stretched tight and does not introduce any additional bow.

Since my screen is suspended in front of my screen-wall, I have added four small screws, one in the center of each side, on the back of my frame. It is a simple matter now to stretch two threads, wrapping the ends around the added screws, whenever I want to check my alignment. (The added screws are partially driven into the frame, leaving part of the shank exposed to wrap the threads.)

Hope this saves someone from accidentally leaving a mark on their screen...

Joe L
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post #96 of 163 Old 11-21-2003, 03:18 AM
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http://www.keohi.com/keohihdtv/exper...ykuo_tips.html

I did not see this link posted before. It contains the Holy Focus technique with somewhat more pleasant readability and also further tips on astigmatism etc. Overall a great resource.
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post #97 of 163 Old 12-08-2003, 06:21 PM
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Guy: I have been searching for this information for a year. After reading this, I feel like I've just been in an intense lecture and have only grasped a few pearls. I will reread it until I have enough understanding to ask an intelligent question.

This is like food for the hungry. You are the MAN
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post #98 of 163 Old 12-08-2003, 06:43 PM
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Learned gentlemen:
I've got a Dwin HDP500 with Delta HD 145 tubes I have set up the projector and over 5 attempts it looks pretty darn good. All I did was mechanically aim the guns, do a center and edge focus, and then the geometry and convergence which I have gotten pretty good at. I'll bet that my centering of the raster is not good though, and I know the blue tube's cross screen focus is not as good as the red's. Who knows about my lens flapping capabilities of my beam astigmatism!!

Are there any hints with these tubes? Do the lenses come off? There appear to be two thumb screws on the back of each gun. Which is which? Any link to more detailed info on my specific situation.

Thanks in advance for any help you can provide.

Thanks Mr. Kuo for getting me thinking.

Scott
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post #99 of 163 Old 01-11-2004, 06:37 PM
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Quote:
Speaking of which, the next steps in projector setup would be

Rough geometry and convergence
Grayscale calibration (with possible blue gun defocusing)
Final geometry and convergence

Those next steps are not discussed in this article.

So, who's going to write up the details on those in as good a style, detail and intelligence as Mr. Kuo?
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post #100 of 163 Old 08-07-2004, 09:08 PM
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I have a SONY CRT VPHG70Q.. The shape of the Blue image on the screen is concave at the top (u shaped) and convexed at the bottom edge (upside down U).. The Green and Red are fine.
I have gone in the service mode using the remote. and tried to adjust the top & bottom edge shapes so that they are parallel to the horizontal center line of the screen using the vertical BOW key .. The status numbers change but does not seem to have any effect on the blue image? Any idea as what might be wrong/defective? Thanks.
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post #101 of 163 Old 08-07-2004, 11:29 PM
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Guy,

Thanks muchly for reposting this as I am trying to talk myself into reseting up my 1272 as I've just upgraded from SD cable to Digital, even with the crappy job I did on setting it up going to digital has improved the PQ no end.

I'm unsure what I'm going to suff up in going thru your setup proc.

Whats the worst thing that can happen ????


TIA
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post #102 of 163 Old 12-24-2004, 09:40 PM
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Bump!

This thread has been way at the bottom for almost five months.......Time to get back to the top!

John
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post #103 of 163 Old 12-26-2004, 04:40 PM
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It says that it was updated. What were they?

Call AVS For the Best Deals!!!


My new favorite game is Stop the Bots
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post #104 of 163 Old 12-26-2004, 05:47 PM
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Nothing substantive. Just cleaned up and got the attributions at the start up to date.

Guy Kuo
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post #105 of 163 Old 03-24-2005, 03:57 PM
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Thanks guy for the post and the time you put into it...

some screen pictures of this process while doing it would have made thing seasier to understadn i think...
just a suggestion

thanks
Martin
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post #106 of 163 Old 03-24-2005, 04:35 PM
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hi fellows...

ok now i have been asking myself more wustions than before,,,
i just bought a barco 8xx projector for a fellow avs member near my house...
i brought it home and switched the celing/table top switches..
i have connected it to a svideo source and the pciture seems focused and nice but when i look at the screen (as oppose to the tubes..) i see three colors one picture...
i mhave read guy's post and got more of an understadning of what i need to do...
but here is what ia m wondering...

since this thing was set up prtty nicely at this guys house, by simply moving it i dont this that the g2 and other settings that are not meant for th edn user have not changed...hense i just need to center the tubes and do a convergence...
now am i right to assume that this pj just need a convergence and a aligfment oif the focus...or do i need to do everything described in that post...stuff like astig and other terms...

also since thsi is a barco and is not em focused..there is one manual forcus correct??

tahnsk for any info/help in advance..

Martin
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post #107 of 163 Old 03-24-2005, 04:48 PM
 
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If the beam setup was good at his place, it's worth checking, but likely will still be ok. You will mainly need to do the gun aim for your throw distance, and optical focus, and convergence. It is always a good idea to check the full setup though, and tweak if necessary. If you've not done this before, I would always tend to recommend that if beam setup is decent, to leave that to the future, and get a good solid picture with basic focus, gun aim, and convergence. Then delve deeper into the beam setup and such and get that spot on as you gain understanding about the set, etc.
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post #108 of 163 Old 03-25-2005, 03:21 PM
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thanks chriswiggles..

As i said it seemed to be in order when i saw it runinng..i also feel the same..i just want to get it converged and focused properly and when i feel more at ease try the beam settings and hwat not...
I have read guys post and understood most of it..with the exception of some of the more intricate settings..like blue being defocused or something to get good grayscale...i would think that this one would need a light meter of some type.,..
but otherwise understood the main steps and what to look for to achive a good picture quality..

He also talked aboiut of a point where the flying debrit looking stuff diapear when you get to that certain treshhold while looking into the binoculers,,but again i m noit sure if he meant looking to the screen through them or into the tube..i m sure its the screen but tehn i am alittle confused..so i figure you guys/gals shoudl know...

Thanks
MArtin
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post #109 of 163 Old 03-25-2005, 03:35 PM
 
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I'll have to admit it's been a while since I've read through his entire Guide, but I don't recall him talking about "flying debris" unless you break something....

If you could point me to that, maybe I could clarify what he means?

Second, about blue beam defocus, you will come to understand this better as you actually attempt to focus the blue beam. This is something I just typed on a different forum, that may shed some light on blue defocusing/focus:

"First, please don't confuse beam focus and optical focus, as these are two completely different systems, that add together to form the final image at the screen. A "focus problem" can be the result of either system being out of focus. This is related solely to blue BEAM focus, not optical focus!

Blue is difficult also for your eyes to focus on, so even if blue is quite sharp, it's difficult for your eyes to see it quite as sharp as the other tubes. This can make judging the focus of blue quite difficult, because it can be very difficult to get anything but a ballpark guess when doing beam focus and setup adjustments just looking at "sharpness." It is also almost impossible to see scanlines in the blue, even if they are there. A great strategy is to adjust focus, and in the range where focus seems good, there is usually a point where blue gets really well focused, and will dim ever so slightly. Move the focus setting in either direction and you probably won't observe any changes to line thickness, etc, but you may see blue brighten up a tad. Where it is dimmest, is your tightest focus. If you are trying to achieve more light output, then you can defocus the blue slightly to achieve that slightly boosted output. "

So you can help this attribute to help you focus the blue beam tightly, and also to get slightly higher top-end blue output capabilities if you need/want it.

Hope that helps!
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post #110 of 163 Old 03-25-2005, 04:09 PM
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that sounded more in debt that what he mentioned...
Regarding the flying debri..i was talking about the is called the gibbs effect..i believe...you get that "junk/artifacts" in the bckground of the picture in the colors that are more abundant...like black and while...specially white..
this was the reason that i went out and bought a barco crt and a video processor..over my infocus...and it is exactly this effect and other color mishaps that i wanna correct the most..
I have 20/20 vision with good attention to details,,,hense the smallest problem...that is present in almost most configuartions drive me nutts and stop me from enjoying the pciture...but i ahav ecome to reduce that effect on my x1 by fiddeling with all of the settings for a really long time...(almost from day one...six months ago!!!)

Also . am i correct to assume that i will probably not have to mess with the bean focus for right now...at least not untill i get better at this whole crt pj thing??

Anyhow thanks again

Martin
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post #111 of 163 Old 04-24-2005, 06:46 PM
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Could someone help me understand this paragraph? At first it sounds like he's saying the left most part of the phosphur is the best part, then he says it's the part with the most problems, then he summarizes by saying alot of techs will intentially use this part of the phosphur.

If someone could explain that, I would appreciate it. ALSO, it has been my understanding that the raster is best *centered* on the phosphur face to prevent convergence drift. So... I don't get it.

Quote:


Originally posted by Guy Kuo
When viewed on screen, the leftmost portion of the raster is drawn first after the electron beam completes horizontal retrace. Looking into the projection lens the orientation is backwards. During the first portion of the horizontal movement the beam has not settled completely and one may see some waviness in the image if the extreme left edge of the raster is used. Some installers will intentionally displace the raster slightly leftward so the active image is displayed on the later, more stable portion of the raster.

Thanks!

"The boom is dead, long live the bass"
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post #112 of 163 Old 04-25-2005, 12:46 AM
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He means that after the retrace there is still some ringing on the deflection voltage and so you get small distortions in the picture. This is the reason why there are the backporches after the sync signal. So the first few pixels after the retrace are not used.
Roland

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post #113 of 163 Old 04-25-2005, 02:10 AM
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that sounded simple enough to understand...at least for me!!!
the other "paragraph" had way too much info and scientific sounding wording for my tast...although i woudl think that with a little reasearch i woudl have gotten it,....
but when robro explained it my light bulb had a bright light so to speak!!!hehe
anyhow!!

Martin
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post #114 of 163 Old 04-25-2005, 09:04 AM
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No, I'm confused about his left and right. He doesn't clarify left or right on the screen is what the installers use. He makes it sound like it's the left side of the screen and not the left side of the phosphur face.

"The boom is dead, long live the bass"
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post #115 of 163 Old 04-25-2005, 10:15 AM
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The left side is ringing as the yoke voltage and so the current ramp has to stabilize from the retrace pulse.
The right side is distorted because when the HOT is switched of, it still conducts some time (storage time of the horizontal output transistor) but due to the increased conduction resistance in the storage mode of the HOT the ramp is distortet.
That are the reasons of the back- and front-porches.

Roland
P.S.:
I am talking about left/right on the screen

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post #116 of 163 Old 04-25-2005, 10:14 PM
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CZ Eddie commented:
> it has been my understanding that the raster is best *centered* on the phosphur face to prevent convergence drift. <<br />
That is generally true, although there are exceptions, which is what Guy refers to. I think the part that might be confusing you from Guy's explanation is this...

> Some installers will intentionally displace the raster slightly leftward so the active image is displayed on the later, more stable portion of the raster. <<br />
Think of it this way... if the raster is centered, and the image within the raster certainly is, then that active image area will be relatively close to the leading (left-hand) edge. By shifting the raster off from center, to the left a bit, when you then re-center the active image area, it will be to the right of (outside of) that initial region where there may be beam settling deviations.

- Tim

- Tim
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post #117 of 163 Old 04-26-2005, 12:32 AM
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Tim! That's it... that's what was confusing me!!!!!

DOH!

Yes, okay then... it makes perfect sense now. lol
What my eyes weren't passing onto my brain, was the "active image" vs raster issue.
I was reading them both as raster but in fact, centering a raster on the phosphur is NOT the same as centering the "active image" on the phosphur. Those are two totally different things and I don't know why I didn't think of that when reading the paragraph. sigh.

Thank you. :embarrased:

RoBro & Prehjan, thanks for trying to help.

"The boom is dead, long live the bass"
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post #118 of 163 Old 04-26-2005, 11:50 PM
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so you are talking about a whole range??? (left to right...)

i hope that didnt sound too stupid!!!

anyhow
thansk folks

Martin
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post #119 of 163 Old 04-27-2005, 12:55 AM
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Quote:


Originally posted by Prehjan
so you are talking about a whole range??? (left to right...)

i hope that didnt sound too stupid!!!

anyhow
thansk folks

Martin

Martin, RoBro's explanation helps explain why the raster is "messed up".

Now here is me explaining (hopefully the right way) what I was confused about. I'll need two posts to explain it.

Basically, the standard practice is to center a raster on the phosphur face and then center the picture within the raster.

Like in this attached pic:
LL

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post #120 of 163 Old 04-27-2005, 12:57 AM
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But what Guy Kuo is suggesting is that some installers will not center the raster on the phosphur face. Instead, they shift the raster slightly to the left to avoid letting the active picture area into the unstable portion of the raster.

And then the picture itself is not centered in the raster, but rather it's shifted slightly to the right (within the raster).

So the active picture area is still centered overall within the phosphur.

The attached pic [below] is oriented as if you were standing in front of the projector, looking into the lens. Hopefully, someone will correct me if the orientation is the other way around, but I think I've got it right now. Um, "correct" now.
LL

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