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Discussion Starter · #1 ·
I've finally put together a free do-it-yourself kit for improving the gamma tables and color temperature of NEC LT100 DLP projectors (also works with Runco VX1, which is essentially a rebadged LT100). This upgrade may work with LT81 and Plus UP-1100 projectors as well, though I have not verified this yet.


With the following procedure, you can update the gamma tables in your LT100 to achieve a smoother, more natural image for home theater use. This procedure will also adjust the projector's color temperature to achieve a white balance that is close to 6500 K.


After completing this procedure, "Normal" gamma will be left intact, but Natural1 and Natural2 will be updated to curves providing gamma factors of 2.2 and 2.5 (respectively) for accurate reproduction of video sources.

This ZIP file contains the software and instructions. I've also included a considerable amount of technical info, including some notes on the format of the gamma tables and scaler memories.


Enjoy!
 

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Hi Mark,

great news!!!

I wonder if this mod could me made to the Nec LT150, as the Plus unit is a LT150's clone, I believe,

thanks

Jose
 

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Discussion Starter · #3 ·
Jose, this upgrade is not compatible with the LT150. The Plus UP-1100 parallels the LT100, not the LT150 (which came out several years later). The LT150 doesn't need as much gamma help as the older LT100, because its factory default curves are closer to what is needed for video.
 

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Hi Mark,

I guess we'll have to wait then.

Please don't forget to inform the LT150's crow once you accomplish the LT150 gamma mod.

Awesome job.

Congratulation.

Jose
 

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Discussion Starter · #5 ·
Quick update: I have been informed that this update works fine on the Plus UP-1100.
 

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Nice to find this post on my first day back to work. I've got a UP-1100 and am looking forward to trying this when I get home tonight.


Right now, when I use the Component settings (YCbCr) settings the picture is too green, but with better color saturation. Will changing the Gamma tables fix this? I currently have the Red and Blue hue levels elevated in an attempt to correct this.


Also, has anyone been able to get rid of the line (tearing) that appears on many of these projectors (including mine) on HDTV material in wide mode? The line doesn't appear in regular mode (there is still an artifact that I can get rid of by adjusting the vertical position) , but that is not an option with the 3100HD cable box I'm using at the moment which only outputs component 1080i. I could use a ISCO or Panamorph lens, but that is not in the budget for the forseeable future.


Thanks again for posting this software Mark.
 

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Discussion Starter · #7 ·
Hi ATM, I've seen that tearing on HDTV material as well. I didn't notice that it only happens in wide mode. Initially, I thought the tearing was due to the projector losing sync as the result of an unusually bright area in the image. But Joe Linn and I tried attenuating the signal and this did not help.


I would like to find a solution to this problem. Maybe adjusting some of the scaler settings for the 1080i mode will correct this. (Check the README file I distributed for what I've learned so far about the scaler memories.)
 

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Quote:
Originally posted by Mark Fontana
Jose, this upgrade is not compatible with the LT150. The Plus UP-1100 parallels the LT100, not the LT150 (which came out several years later).


I will put together a similar package for LT150 in the near future. But the LT150 doesn't need as much gamma help as the older LT100, because its factory default curves are closer to what is needed for video.
How about the LT84/LT140 series that came out in between the LT100 and the LT85/LT150 ? Are you aware if it might work with this generation ?


Thanks for the help.
 

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Discussion Starter · #9 ·
Sergio, I haven't checked an LT84/LT140 but would not expect it to work without modification. I am pretty certain that there were changes to the architecture for that series. Please email me and I will help you determine whether this modification could be adapted to the LT140. If it looks feasible, I'll post an update in this thread.


Folks, keep in mind that it is dangerous to run service mode tools on projectors for which they were not designed... likewise, assuming the flash memory is mapped the same across projector models is very risky as well. This is an area where casual "it's worth a shot" experimentation is a really bad idea.
 

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Hi Mark,


Thanks for the quick response and the warning. Please PM or email your email address.
 

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Put on the new gamma tables last night. Not sure if I like them or not yet (over Normal). I kind of like the over saturation of Natural setting. The gray scale is much better at high and low level detail, but it looks too green compared to Normal no matter what I did. The settings for the Factory, User1, and User2, that you recommend do not look right at all on my unit (Plus UP-1100), so I set them back to where they were originally (make sure you write them down before making changes). FYI the “White segment†on User2 does work with the UP-1100. I always run with it off.


One question for you Mark, could you post the original factory settings on your LT-100 for reference. I’d like to see how they compare with my projector’s settings from the factory. This is a really cool utility, thanks again for providing it for free Mark.


A couple more observations. The first thing I did is to back up the flash memory in case I did something stupid. Also, putting the numbers in directly did not work. I had to adjust it through the bar meter under each setting. Finally, you can run souce material on the projector while making these changes to see what they are doing. Nice if you have a DVD with test signals.
 

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Discussion Starter · #12 ·
ATM, once the tables are installed, you need to calibrate specifically for Natural1. If you calibrate for Normal, Natural1 will look wrong and vice versa. This is because the Normal setting has some strange nonlinear color correction built into the table itself, and I removed that for the new Natural1 and Natural2 tables for better greyscale tracking.


You can type the numbers in directly if you place the cursor at the end of the field and use backspace to delete the current value first. Did that not work?


The problem of having an image that is too green is unrelated to the gamma tables but should be something you can correct with the User2 or Factory settings. (You mentioned you were having this problem before the update as well.) What are you using as a source, by the way? If you have more than one component source, are they all too green?
 

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I have 2 component sources, a Scientific Atlanta 3100HD cable box and an Iscan version 1 that can do either RGB or Component. Both look too green on component. I always preferred RGB to Component, but because of the limitations of the cable box output I am now using the YCbCr input. (I had recently bought a DTC100, but have decided to stay with cable because of convenience.


I have the User2 YCbCr settings for Sub brightness at 40 for both Red and Blue up from the default 32. Setting them to 37, 24 is way off on any of the Gamma settings.


Using your settings make the picture look:


1) Way washed out with Contrast between 37 and 45 on User1 with Brightness down at 12. I currently run both in the mid thirties for RGB and Component.


2) Very muddy red throughout the picture with the R,G,B sub contrast and sub brightness set where you recommend.


3) Your numbers call for Factory Contrast settings to be 72 for RGB and 161 for YCbCr. My factory defaults were 53 and 112. They look much better, the higher numbers wash out the picture even more.


I was looking at previous posts and ran across this German site http://www.cinehome.de/reviews/plus880rev.html that has a supposed firmware upgrade for Plus UP-880 and UP-1100 modes that correct tearing in PAL. I never bothered using it since I don't use PAL material, but I wondered if you had any experience with it for solving the tearing problem with HDTV? Also, do you know how this software works? Where doe's it write to?
 

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Discussion Starter · #14 ·
Hmm, sounds like there could be some differences between the LT100 and UP-1100. When I plugged the same numbers into a friend's LT100, the results were identical to mine. My unit was calibrated with a spectroradiometer and looks very good, with perfect skin tones and not washed out at all.


Since you have two component sources, what are you using to switch between them? The switcher could potentially be at fault, especially if it is a powered KVM switch that actually boosts the signal (to offset attenuation in longer cable runs).


I'd recommend leaving the new gamma tables in place, using component video for all sources, and tweaking the Factory settings to eliminate the green picture (make the adjustments while displaying a grey ramp from AVIA).
 

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Since I just started using the 3100HD I'm manually swapping the inputs. I wonder if anyone out there can give me their calibrated settings for their UP-1100? Any ideas Mark on what the "firmware upgrade" I mentioned does, or if I should try it?
 

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Discussion Starter · #16 ·
I have a copy of that Plus firmware update, but I haven't tried it on the LT100 yet since I don't know if it's compatible. NEC insists that there were never any firmware updates for the LT100.
 

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Is there anybody out there that can post what the settings are for their gamma corrected UP-1100 projector (without Thumper mods)?


I'm a bit surprised that this thread hasn't grown larger given the number of UP-1100, LT100, and DX1 owners there are (or were). It was one of the first projectors that became popular on the forum back in 1999.
 

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Discussion Starter · #19 ·
The LT150 package is a no-go. But my understanding is that one or more closed-loop calibration systems may be available for this projector shortly.
 

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FYI, I loaded the Plus firmware update this evening. Worked perfectly on my UP-1100, the tearing with 1080i material in wide mode is totally gone. Not sure if someone can attest that it will also work on the lt100.
 
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