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Discussion Starter · #1 ·
Hello,


I just wanted to let you know that I finally exchanged the Madrigal Imaging MP-8 with a SONY VPH-G90 after not being able to chose between the Madrigal Imaging MP-9 and the Barco Cine 9 (formerly known as CineMax) and EH Marquee 9500LC etc... for those of you who recall the previous thread. There is an enourmous difference in brightness and sharpness, even though I haven't yet set up the G90 correctly. But this difference can be seen immediately and I am confident that I made the right choice.


I am having someone over to do the setup in early June, but just noticed some "streaking" after I just hooked up the G90 quickly. I am using the same equipment as before, so it must be something with the new projector. Any of you familiar with this "streaking" problem and how can I get rid of it?


I mean the G90 is highly acclaimed for being amongst the best (if not THE best) 9" CRT, but no one ever mentioned anything about "streaking". So I am wondering is it only me having this problem or will this go away by itself when the unit will be calibrated and setup up as it should. Otherwise this would be quite disturbing and personally I would not rate a projector with a "streaking" problem among the best of the best.


With "streaking" I refer to some brighter horizontal lines in dark scenes. i.e. if you have a candle light in a dark room, the picture would show a horizontal line from the far left side (border) through the candle light to the far right side of the picture. I can take a picture if you don't understand what I mean. But I think it a known problem with some CRTs, I just didn't expect it to be with the G90.


Does anyone have some experience with this and what can be done against "streaking"? Thanks...


Certified D
 

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Discussion Starter · #2 ·
I have to add that I have seen this "streaking" on another G90 as well... the strange thing is it happens not every time the picture shows a bright object in a dark area... but I've seen it on HiDef as well as DVD (with scaler).


Help... :D


Certified D
 

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I am a fellow G90 owner and I had what sounds like a similar problem develop when I changed a refresh rate once. It appears like a flash, only happens in white areas and looks similar to a quiver or streak of bright light.


If that's what you're seeing, you can relax -- it's simply a matter of changing a setting in your service menu screen called "Clamping". It needs to be on a different setting, changed from "auto" to one of the other settings which escapes me at the moment. This clamps the white level so you don't get that symptom that is similar to white clipping. I'll get that exact setting name soon.
 

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I think that the setting Mike is thinking of is the "H/C" setting under clamping. Try that. When you get your projector properly set up by someone like William Phelps you will not see these types of problems and you will see the full potential of this projector.


Chris
 

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Discussion Starter · #5 ·
@ Mike

I am not sure if I am seeing your problem with my projector. The "streaking" I am experiencing happens only in DARK areas, not bright/white. The brightness/contrast setting is at 45/80, below factory standard. I will try to change refresh/scan rates and see if it makes any difference.


@Chris

I hope you're right... I have "someone like William Phelps" to do the setup... ;)


Thanks so far,

Certified D
 

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Hi Certified,


While I can't certify that it is the same as with the previous Sony 9 incher - on the VPH-1292Q there's a tiny switch on the input board (you have to take it out to flip the switch) which might be the source of the problem?


Cheers,
 

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Curious, what is the largest screen a G-90 could do.


I am looking at DILA but would prefer a CRT.


My screen will be 16:9 118" X 66" (w/ Stewart Electrimask).


The screen is to be perforated, too.


Any help would be appreciated.


Jeff
 

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Jeff,


Considering that 10% of your light will go thgrough that screen, I'd say do the DILA. The largest dynamite G-90 image I've seen is the 111" wide Faroudja show at CEDIA. Looked awsome. That wasn't a perf screen, though.


If I had to guess on the largest perf screen a G-90 should handle, I'd say 96" to 100". My opinion only. Your mileage may vary.


Ted
 

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I am not thrilled to move digitally, but the room is designed for such a largescreen.


The room will be there long after the CRT is dead so I have to make something fit this size. I was still holding out hope a CRT could do it.


Thanks anyways.


Jeff
 

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Hi Brett,


nice to see you in the CRT forum of AVS again :)


Could you elaborate a bit on the switch that you can flip on the input board and the exact name of the board ?


Inquiring 1292 owners want to know :D


Thanks


Oliver
 

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Discussion Starter · #11 ·
Jeff,


I have a 120" wide Stewart StudioTek with microperforation. While the SONY does not throw the recommended 9-12 ft/L on that screen, the preceived image brightness is more than enough (assuming your room is completely black). Compared to the MP-8 I had before I almost started wearing sun-glasses :cool: with the G90 ;)


Go for the CRT, but that's just my $.02...


Certified D
 

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Hi Oliver,


Long time no see!


For those who remember, Oliver used to go by another name here - he was most valued member of the AVS forum CRT section in its heyday, paving the way for the rest of us. :cool:


There are 2 boards with switches on them in the Sony VPH-1292Q. If I recall (it has been a while and my projector is not working now so I can't verify) I believe that the culprit of the banding problem (light streaking on either side of a bright object in a dark scene) is due to having the switch placed in the ON position on the CAD board, the one above the board to the left when you look at the back of the projector if floor mounted (if cieling mounted, it is the board to the lower right at the rear of the projector). This switch should be placed in the OFF position, unless you use low bandwidth video inputs ie from an analog coaxial cable or whatever...


There is also a switch on the RGBVH input board (the one with 5 BNC inputs and 2 audio jacks) which is called SWI. This one has to do, if memory serves, with color gain characteristics which do not affect banding.


Hope this helps, and maybe also applies to those who are having problems with their G90s - after all if Sony kept a little bit of the prior technology all it would take is a preset in the wrong switch position to muck things up.


Cheers,



---------------------------

Brett

from the LD (ie Low Def LD) oasis!
 

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Oooops,


So used to stripping this beast down that I forgot to mention:


to access the CAD board, you first have to take of the horizontal plastic strip that stretches across the back above the input boards, and then remove a flat sheetmetal cover which closes in the board.


Enjoy ;)
 

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For those of you who may be interested in the SW1 position (i.e. found on the IFB-11 board) here is some more info:

SW1


Has anybody experimented with it?


Renato
 

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Quote:
Originally posted by Certified D
@ Mike

I am not sure if I am seeing your problem with my projector. The "streaking" I am experiencing happens only in DARK areas, not bright/white. The brightness/contrast setting is at 45/80, below factory standard. I will try to change refresh/scan rates and see if it makes any difference.


@Chris

I hope you're right... I have "someone like William Phelps" to do the setup... ;)


Thanks so far,

Certified D
Just to qualify...I didn't mean to suggest that the streak ONLY occurs in bright, white scenes. On the contrary, it could be a dark scene, but as soon as any degree of light penetrates -- the streaking or flashing occurred. It sounds the same to me so I would investigate the Clamp.


Second - 45/80 on your brightness/contrast respectively seems inordinately high for both. I'm sure Wm or whomever you designate for setup will end up with a below 40 brightness and a contrast around 65 to 70 tops. Driving the contrast at 80 would be especially troublesome to me since this plays a big role in aging the tubes. Of course, these levels also depends on your delivery mechanism too (ie HTPC, Faroudja porcessor etc.)
 

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Discussion Starter · #16 ·
Mike,


I did adjust the clamping and it helped to stabilize the picture. Formerly the picture seemed to collapse every now and then, now it's stable. Maybe that's your flashing... Haven't seen any streaking either since the clamping adjustment, but haven't watched a lot (since the setup is not done yet and geometry and convergence are... well, a mess! ;) )


Brightness/contrast are almost factory settings (50/80) and regarding the screen size of 120" (width), I don't know if we can go *much* lower. Anyway, the guy setting my G90 up will arrive today, will go pick him up at the airport in a few minutes...


I am feeding the G90 with a VIGATEC DUNE processor which is fed by a Proceed PMDT with SDI output. There is a slight signal boost on the VIGATEC's output AFAIK.


Will let all of you know how it turns out when the setup is done, somewhen Monday or Tuesday. I appreciate all your help so far... THanX!


Certified D
 

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I didn't realize that you rscreen was 120". Mine is 100", so the numbers you'll end up are likely to be different as you suggested.
 

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Your problem with G90 may be a clamping problem. I have also experienced similar problems with improper synch from certain sources.


On my G90 that WM setup using a Faroudja DVP 5000, brightness was set at 33 and contrast at 80. Depending upon how you set your gray scale you can probably drop the contrast to as low as 73. Once you go below 73 you begin to impact the gray scale. Your experiences may be different.


Operating the projector for several years at a contrast of 80 has not created any premature wear on my projector or reduction in CRT output that I can detect.
 

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Hi all,


Contrast setting is an interesting topic along with light output mode. I see in the G90 spec sheet that there are two light output settings: boost at 350 ANSI lumens and normal at 280 ANSI lumens. MikeM, Mbartok, please correct me if I am wrong.


If wm or another setup man can chime in, will using the lowest output mode available such as for example economy light output mode (the lowest of three modes available on some pj models) projecting onto a small high gain screen lead to improper grey scale delineation and reduced peak light output, which is normally at 1200-1300 lumens?


Thanks
 
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