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Discussion Starter #1
Hi Guys!


I'm posting this thread in hopes of solving, for me and possibly for other forum members, what has become a serious concern:


How to keep from frying my CRT projector by throwing too much at it? :confused:


While it might not be directly related to running his projector at too high a refresh rate, Paul had a problem with his projector which is described here:
http://www.avsforum.com/avs-vb/showt...threadid=89786


Paul's plight brought to my attention what could be an important issue for anyone who has invested both time and money into a home theater CRT: preserving the lifespan of his/her projector and still getting the best possible performance out of it.


I previously experimented with relatively high scan rates, but the resolutions were "card limited" due to the GeForceII 3Mb MX graphics card I was using, which didn't output at the same time the highest resolutions at the highest refresh rates that my projector's specs would apparently handle. Now it is a different story because with a Radeon 64DDR, Powerstrip will allow me to define without any fuss resolutions and refresh rates both in excess of my projector's capabilities.


To make my question simple, here goes:


- the Sony VPH-1292Q can accept 2000x1600 lines


- it is rated for 135kHz and 150Hz with a 120MHz bandwith



So my foolhardy questions are:


1. Can it run at 2000x1600 at 150Hz? (max of all specs at once)


2. As most likely not, what formula is used to calculate the maximum refresh rate at each given resolution?


3. Does one have to factor in the combined frequencies of vertical and horizontal rates in the calculation, or are they determined independently of one another?



Apologies if my ignorance of the technical aspects of these parameters and their interactions shocks the CRT geniuses present - just trying to become a power user without blowing up the machine in the process. :eek:


Thanks in advance for your helpful advice.


Cheers,
 

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Brett,

your projector was designed to handle very high scan rates, and it will do it very well (sync to). now why you would want to go to that rate is your preference, but the projector WILL HANDLE it.


The 1292 has many built in protection circuits and devices, far more than any other CRT projector that I know of. Just think, how often had you heard of a SONY 1292 failing and having such a problem?


Pauls projector has a problem, and from time to time they all break down. But should you worry about high scan rates- NO!

When a projector fails from high scan rates it is an indication that something is wrong with it, that is the thing that would tell an experienced service tech that something in the circuit is breaking down (inability to handle higher scan rates).

If I had a diagram and could show you how well the engineers designed the deflection, power circuits, you would probably buy another 1292 just because they are built so well. Sony's industrial product engineers are extremist, and they really went for it on the 1292, in a sense, it is too well built (did that projector need that many fans: NO!).


Relax dude, enjoy that SONY. It is TRULY an industrial grade projector, and yes, stuff breaks, even a SONY.


Paul, has taking his failure problem to another level. He wants to take ideas from the G90 and include them into the 1292, he has elected to turn his 1292 into a science project. If your projector fails with a simular problem, have it serviced to the original design only (keep it real simple). The G90 is not a better design, it is a different design, they are both very well made industrial grade products.


The earlier model multi-sync CRT projectors (80s) had a problem with external sync frequencies, on the later models, a processor board checked and confirmed the signal before it went anywhere (deflection processor circuit).


Performing at high scan rates is not an issue for the 1292...
 

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To get an estimation of the Hfreq of an image you have to do (nbLines*vFreq*1.1) in fact it seems that this formula gives a result a little greater than reality.


1600*1200 @ 85 Hz = (1200 * 85 * 1.1) = 112.2 Khz (Estimated)


The real hFreq is 107.1 Khz (as shown by my monitor OSD).


So your projector is limited to 1600 lines, 135 Khz (hFreq) and 150 Hz (vFreq) the max you can do is 2000*[email protected] Hz or 800*[email protected] Hz.


I personaly do not find any interest for HT to go more than 75 Hz in vFreq... the flickering is totaly removed at this frequency and if you go higher your signal is more sensible to perturbations (you need a better cable, etc).


Hope this helps.


G_ROM
 

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G ROM is correct, you will be limited by your max H'scan rate.

However in picking a V'scan rate you may want to think about your viewing habbits, if you watch mostly film based material using a V'scan rate that is a multiple of 24 will eliminate the 3/2 pulldown conversion, this is a good thing...film being 24fps.
 

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I would hedge against Power fluctuations (I don't trust those French Power Engineers, sorry) by investigating a Richard Grey powerhouse or a Balanced power regulator. They do visibly improve your picture when the projector is being taxed.


Regards,
 

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Mike, I agree with your comments about the 1292. I have my setup in the rear projection configuration with a vutec screen and the picture is awsome!
Quote:
Originally posted by mp20748
Brett,

your projector was designed to handle very high scan rates, and it will do it very well (sync to). now why you would want to go to that rate is your preference, but the projector WILL HANDLE it.


The 1292 has many built in protection circuits and devices, far more than any other CRT projector that I know of. Just think, how often had you heard of a SONY 1292 failing and having such a problem?


Pauls projector has a problem, and from time to time they all break down. But should you worry about high scan rates- NO!

When a projector fails from high scan rates it is an indication that something is wrong with it, that is the thing that would tell an experienced service tech that something in the circuit is breaking down (inability to handle higher scan rates).

If I had a diagram and could show you how well the engineers designed the deflection, power circuits, you would probably buy another 1292 just because they are built so well. Sony's industrial product engineers are extremist, and they really went for it on the 1292, in a sense, it is too well built (did that projector need that many fans: NO!).


Relax dude, enjoy that SONY. It is TRULY an industrial grade projector, and yes, stuff breaks, even a SONY.


Paul, has taking his failure problem to another level. He wants to take ideas from the G90 and include them into the 1292, he has elected to turn his 1292 into a science project. If your projector fails with a simular problem, have it serviced to the original design only (keep it real simple). The G90 is not a better design, it is a different design, they are both very well made industrial grade products.


The earlier model multi-sync CRT projectors (80s) had a problem with external sync frequencies, on the later models, a processor board checked and confirmed the signal before it went anywhere (deflection processor circuit).


Performing at high scan rates is not an issue for the 1292...
:)
 

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Your comments about the 1292 is correct. My configuration is the rear projection format with vutec screen and the picture is awsome.


:)
 

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Discussion Starter #9
Hi!


First off, I'd like to thank you guys for your advice!


If I didn't do so earlier, it is for shameless reasons: to wait until this thread needed bumping up to front page.


Actually, what I was hoping for was a magic formula that would enable me forever after to calculate the danger threshold of my display device when dialing in resolution and refresh rates. I might ask Ashley, of Powerstrip fame, in the HTPC forum - unless his own forum captures most of his attention these days?


I recall with my previous GeForceII MX dialing in some darn high resolutions at a refresh rate of 144Hz. The projector just took them in stride, throwing a rock solid picture up on the screen without any fuss. It was about 1280x768 if not higher, at 16bit depth for the "underlay".


Now, my ATI 64DDR Powerstrip custom settings don't allow me to dial in such esoteric above spec figures, defaulting to lower refreshes as soon as I raise the resolution. Is Ashley protecting me from myself due to my base instincts?


I don't want to go hogwild on some zanny quest - it is just that I have fully witnessed the effect of such, and now have to live in the "shadow world" of drab low refreshes unless I abdicate and sacrifice resolution, something you feel sorely if you have a small spot size (yeah, I know yours is probably bigger!). ;)


Sumuv youguys will think I've lost it - granted, it even looks that way to me when I spell check. But at least I realize something has gone amiss, and it can't be the upgrade from nVidia to ATI. So I'll just have to chance it at too high scan rates and resolutions and see what it will do. For this I'll have to fake the 1292Q's specs to 3000x2500 at 200Hz and 180kHz, etc. Then I'll be able to come up with my own formulae - for projector replacement...


I'll let you know just how solid state these old Sonys are! ;)


Cheers,
 
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