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Discussion Starter #1
I have an LT 150 at my mercy. It wll beg.. it will squeal... but relief will be found nowhere. No escape for the wicked. We shall see what happens.


First a few hours of normal viewing. Then, under the knife it goes.
 

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"... it will squeal..."

Check the postings on LT150 hushboxes.


"Then, under the knife it goes."

Watch out for that magnesium case. One hot spark...


apg
 

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I kissed my LT150 goodbye and handed it to Ken. Ken, please be gentle! The experiment continues. Oh yes, I almost forgot. I do have two more. ;)


Good Lord - the sacrificies I make for you guys.


Cheers,


Grant
 

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Quote:
Originally posted by Grant Smyth
I kissed my LT150 goodbye and handed it to Ken. Ken, please be gentle! The experiment continues. Oh yes, I almost forgot. I do have two more. ;)
You're on the RIGHT direction! You'll soon find other good places for the 2 LT150 too...


On the other hand, if Ken does fix the motion artifacts, I'll buy back the LT150 from him at HIGH price!


regards,


Li On
 

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Discussion Starter #5
I changed 20 parts before I even turned it on to look at it for the first time. No patience, I guess.
 

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Quote:
Originally posted by Grant Smyth
I kissed my LT150 goodbye and handed it to Ken. Ken, please be gentle! The experiment continues. Oh yes, I almost forgot. I do have two more. ;)


Good Lord - the sacrificies I make for you guys.


Cheers,


Grant
So what is Ken actually doing to it Grant? From what I can gather from this thread, he's using your projector as an extra in Deliverence!


Petey
 

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For those interested, Ken is going to modify my LT150 in the same manner that Thumper does. In fact, Ken tells me he will take it a step further and make some significant hardware upgrades as well.


I am keeping and open mind and trusting in Ken's expertise (he has modified his own digital DLP in the past) and just about every electronic device known to man. I have seen his modified CRT, listened to his modified solid state amplifier and his (along with partners) speakers. This guy is for real!


For a CRT guy Ken has an open mind and a quest for knowledge. In fact, he's going to help me find a CRT and then modify it and calibrate it for me! Once I have both my digital and CRT systems up and running I am going to invite members in the Toronto, Ottawa, Montreal and Kingston areas to come and have a look - I will have everyone who participates rate each system (the positives and negatives) with comments and then post the results. This may not settle the endless arguments on this forum over CRT vs. digital for you, but it will for me!


Not only am I going to see for myself (which I have to some extent already done), I am going to live with both systems! This is the best I can do, I can't think of another solution. At least I am willing to put my money, my time and my effort where my mouth is!


Cheers,


Grant
 

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Ken,


Is this going to be a service you offer or is it a one time thing? If it is a service you offer any ideas on a price?

When Grant reports you may have a huge bunch of people beating a line to your door... Can I be first in Line :D ... One thing I especially like is that you are in Canada...


Miles
 

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Discussion Starter #9
According to what Grant told me when he dropped the PJ off, the bulb seems to loose the red content a bit after about the first 50 hours or so. When I began to use it on a Standard white screen, I immediately noticed (after centering ALL the controls, which will keep posterization to a minimum, IF they are the electronic centers, not the 'idealized' centers), I noticed the usual lack of reds in the spectrum. This is not necessarily true. The electronics are TRYING to get you to a more correct situation, but the bulb has a greenish-blue PUSH of sorts, as usual with this type of bulb and PJ. The best bet is to correct it with a properly color corrected screen, not in the PJ in any sort of way. So, I will target a specific Screen mix for this PJ type, now that I have one to play with. The spectral content on these types of bulbs doesn't vary by much, so the targeting should not be off by much for most other PJ's of this type,with this kind of bulb. Also, the contrast rang is fairly high (yes I noticed this) and it was not anywhere as bad as my older DLP unit. Rainbow effects came to the forefront for me on STATIC images in the first 30 seconds of use....yes I am that sensitive to it.


The trick is to come up with a screen design that corrects the color problem, and keeps the controls centered (to minimize contrast and color depth electronically derived skewing and posterization problems) at the same time. Under these conditions, it should create a 100" diagonal image that creates contrast range in the perceptive sense, but does as little harm as possible to the measured ratio as well. If Thumper is messing with the actual internal tables, and settings, well he is doing more than I am at this point. But, I AM maximizing what the projector can pull OUT of an input signal, and put on the screen. This is much more vital. This is the fundamental of what brings a believable image, same as CRT. Treat the signal right, without beating on it or loosing any of it..and get it to the screen.
 

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Discussion Starter #10
Quote:
Originally posted by mwan
Ken,


Is this going to be a service you offer or is it a one time thing? If it is a service you offer any ideas on a price?

When Grant reports you may have a huge bunch of people beating a line to your door... Can I be first in Line :D ... One thing I especially like is that you are in Canada...


Miles
This is going to be a service I will offer. Grant came over to see the CRT set up at my place about 2 weeks back. The LT 150 never even made it out of the bag.


I do not in anyway have anything against digital projectors, and have been waiting to get the opportunity to play with them. I simply don't have the coin to buy them. So, Grant has given me the opportunity to play with one of his.


I looked him in the eye and told him flat out, "you KNOW that this is the END of the NEC warranty, don't you?" He accepted this, as he was fully cognizant of the situation.


I am going to do a full hardware mod to the PJ first, before attacking the optical situation. I will get Grant to bring over one of the un-modified units to compare to the modified one. We will analyze the comparative data, and see if it was worth bothering with. I very much suspect it will be very different. Then, on to the optical mods. This will NOT be a 'long time coming' kind of thing, I suspect. I move VERY fast, when given the opportunity. The time it takes me to modify a projector, is about the same time it takes me to figure one out in the first place, and complete the modifications. (I had the color balance and contrast range corrected optically on my first DLP projector within an hour of owning it, and I had never seen one before) I am used to working 'on the fly' in development work; that's the only time I find it fun.
 

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Discussion Starter #11
Too late. I am off to get the parts I need to improve the optics (contrast ratio). It is officially fully dismembered. It should be done by tomorrow, as I have to help someone set up a CRT tonight. Damn.
 

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Discussion Starter #12
I wasn't called to setup the CRT unit this evening, so, I managed to put the DLP back together. Noticeably better contrast range and shadow detail. Noticeably more 3-d on a given scene. Noticeably more color saturation, and fine gradation of color. Fully saturated reds under all conditions. Not one weak red that I could see. Usually, I have found with the few DLP units I have tried, that the reds 'unload' down to orange in a brightly lit scene, where they dominate the image. Then they go orange. I never saw any lightening of the reds at all, under any loading. So, it seems as if they have cured this problem with the different wheels, I guess. Or I have fundamentally affected the contrast range.


Grant can have his baby back. From zero to full mod in less than 24 hours. (well, I am sure I can still get it better, with a few more parts and a bit more thinking) For now though, the majority of the final image quality is in place. What it needs now, is a slight grey screen to tame the black level.
 

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Ken,


"The trick is to come up with a screen design that corrects the color problem, and keeps the controls centered"


It seems to me that whereas with a CRT it's better to do all possible with mechanical and optical adjustments before going off center with any of the controls, no such concern exists for a DLP. The bulb is always 100% on and I don't imagine taht anything gets stressed by using the controls, it's just the mirrors' duty cycle.


Would not the best contrast and lowest black levels be obtained by running all the colors at max (but not clipping) in the projector, and establish the proper color balance with color filters or the right screen paint?


If it's not giving anything away, could you say what mods you did to lower black levels?


Thanks
 

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How fast is fast? Ken, I'll try and pick the LT150 up today. I'll need a little time to run it against one of my unmodified ones to test the differences and then I'll report back.


It would take me 24 hours just to figure out how to open it! This I gotta see!


Cheers,


Grant
 

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Discussion Starter #15
I could have kept if for bit longer, and will hAve to get it back afterwards. i still need to keep it to design the screen paint. You can give me an un-modified one to work with instead. That might be a bit more correct insofar as the design of the paint goes.


The 'halo' situation is not taken care of yet, as I was looking at a strategy for handling that...one that would be permanently workable. This is the most sensitive area in the PJ to work with, and I wnted to be sure I had the right solution before attempting to work on the PJ in that area.
 

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Discussion Starter #16
Noah:


The reason I say it is PROBABLY best to keep the controls fully centered is that the stepping characteristic of the control system is DIGITALLY DERIVED, an has a limited number of steps. within that limited number of steps, when you skew the set-up to one side or another, you limit the range of motion, or level of fine gradations possible in that given range, be it contrast, color, brightness, etc. They are basically a bunch of 'equations' working on a given set of 'digital' steps, or 'ladders'.


The more 'skewed' the settings are from their center points, the more they interact with one another, and are then limited in their proper range of fine or linear, or proper scaled behavior. For instance, look at the RADEON 8500 thread on gamma in the HTPC forum. A similar control system is used in these DLP units. I am guessing here, and maybe these controls have enough 'bit depth' to avoid such problems.. but that has never been the case in the past. Basically, too much usage of the controls would cause posterization characteristics to emerge in the image, possibly on many different levels. Cranking the controls would ruin the image fidelity, and cause over-saturation at the very least.. with no fine detail on the color gamut.. and no 3-d look or feel, just a flat technicolor (over-emphasized) effect. it would be most noticeable on brightly lit, or dim images..as the 'gradated' image (digitally derived brightness and color depth) slams up against the DLP's internal bit depth limits.
 

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Ken,


when you looked inside an LT150 did you notice anything that would make it possible to silence th PJ internally? I don't want to build a hush box on my table and I'm already considering replacing the interna fans. However, I have heard that it is the colorwheel that is making the most noise (?) Can you confirm this?


cheers,

Halcyon
 

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Discussion Starter #18
As far as i can tell. the large majority of the noise is coming from the fan assembly onthe PJ, not the wheel. If it produced that much noise, the bearings inthe motor assembly for it would fail in the first month. Absolutely no doubt about that.
 

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Discussion Starter #19
Grant wanted an extra HTPC. I took over that duty for him, and made a decision at that point.


I am now officially building HTPCs to MY spec.


Custom dampening in case

Solid aluminum case

Custom niose control

Custom power supply

Custom motherboard

Custom sound card

Custom VGA card

RGBHV out

Custom Video input card

Custom paint


No HTPC out there will touch it.
 

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Discussion Starter #20
Cross posted from another thread (rainbow crusaders) I contributed to.

~~~~~~~~~~~~~~~~


Intensity of color is mostly a perceptive conditional,and relies heavily on overall realizable contrast range in a given scene. Due to the fact the the most deficient are of output in a UHP bulb is the red spectrum, the slight loss in output in this area, results in an orangish perception of the reds..when the scene being viewed 'unloads' the contrast range a bit..and reduces the output of reds to this condition. Suddenly red becomes orange..and it is PURELY a function of the contrast range in a given scene. I have messed with this EXACT 'contrast range situation with a CRT unit. The MEC tubes in my marquee projector are accused of having the same problem,when the lenses are not color filtered. The high level of color filtering has it's problems, though. Because the PJ has a superior contrast range, I immediately noticed the loss of contrast range provided by the use of a red filter. So what, red saturation increased, but at the cost of contrast ratio..and thus, 3-d effects in a given image. NOT acceptable. So, I messed mightily with the innards of the PJ, increased the PJ's inherent contrast ratio with respects to the electronics...and gained a SLIGHT increase in the perceptive saturation of the reds.


Purely a perceptive-difference equation.


Now, back to the PJ I modified for Grant. The LT 150. The reds are NOTICEABLY more correct, and much less susceptible to washout, or weakening, due to the fact that the overall realizable contrast ratio on a give scene is HIGHER than before. The effects of this are MUCH more noticeable than that of what was noticeable with the CRT modifications.


On the LT150, the other colors, incidentally, are noticeably more correct as well. So, perceptually, the PJ's overall balance is more centered to where it theoretically should be. This, by the way, was done on a CRT 1.5 gain white screen.


So, remember, red saturation in a DLP is one part bulb spectrum, and one part inherent OVERALL correctly considered scene-to-scene specific actual contrast range. So, now, Grant's Reds are not susceptible to washout, loss or shifting. They remain saturated in ALL scenes, because the overall contrast ratio is improved.


As for wHat Grant found, that's for him to say.
 
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