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Discussion Starter · #1 ·
Hey Everyone,


I've been a long time "lurker" and this site is full of great information. I'm hoping you guys can point me in the right direction with my problem.


The short story is, I have an NEC VT800 with a color alignment problem (I believe it's convergence?). Is there any way I can adjust this? A secret "service" menu or something?


I called NEC and the rep I spoke with said that the only way to "calibrate" the projector is via their software...which is only available to authorized service centers of course.


Why does the projector have this problem, you ask? I "self serviced" the projector. I'm a computer technician for a school district (I.E. jack of all electronic trades) and this projector developed horrible picture quality. I took it to a repair center and they determined it needed to be cleaned (they were right). My supervisor declined to pay for the cleaning since he deemed it "too expensive". So, since the projector was useless as is, I decided to clean it myself.


Disassembling it and cleaning it was actually pretty easy. The projector has a GREAT picture now...besides the whole color alignment issue



I took it apart a few times and tried to adjust some stuff (I don't know the technical terms for projector parts) and got it a little better, but I can't get it quite right.


Is there anything I can do?
 

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He didn't give you an accurate answer. Yes, NEC has special software for some of their projectors for internal adjustments. But nowhere in the software is a routine for convergence. There are adjustments for flicker and uniformity, but if the images look like you need 3D glasses then the software will be of no use to you.


Did you actually disassemble the optical block? I can't recall the last time I was in a VT series, but I don't believe the panels are removable or adjustable. I could be wrong,a s I said, it's been some time. But if they are permanently fixed, as many LCD units are, there is nothing you can do.


However, if they have have small adjustment screws, and I am talking about the LCD panels. NOT the polarizers, then they can be adjusted but it has to be done "live" so you can see what you're doing and you should use a grid for alignment.
 

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Discussion Starter · #3 ·
Unfortunately, I can't do anything live as I have to remove the main circuit board to get to the internals of the projector.


You'll have to bear with me as projectors are fairly new to me when it comes to assembly and disassembly. I'm not up on the terms of the parts inside a projector.


I believe I did disassemble the optical block. I went as far as to remove and re-install the LCD panels (they had dust directly on them). However, the way they mount seem fixed. The only components besides the blue mirror that seems to be adjustable are these "window" like pieces that sit in front of the round "magnifying glass" looking lenses (with the green LCD having two...one stacked on top of another). They seem to be able to rotate. I believe these are these the polarizers. I removed them to clean them before I realized I could remove the entire assembly. D'oh.


Other than that, I don't believe I did anything that brought anything else out of alignment.


The picture does look like you need 3D glasses. When the projector menu is on screen, you can see the box 3 times each slightly off from one another. I'll bring a camera with me to work tomorrow so I can post a picture.
 

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If the panels are adjustable, the only way to do it is "live', otherwise you'll spend days tweaking, assembling, testing, disassembling, tweaking, assembling, testing, etc.


Yes, the polarizers are adjustable for optimum contrast.


Yep, you definitely "altered" the convergence by taking it apart and it's going to be fun to get it back.
 

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Discussion Starter · #5 ·
Ok. I'll post pictures of the internals and of the picture the projector produces. Maybe you'll be able to tell me where to start.



Is this how an authorized repair center would be doing it...as in tweak, assemble, test, tear down, tweak again? Or, does NEC have a magic tool that makes it easier? lol
 

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Nec has jigs and wiring harnesses that are used to extend boards out so the projector will still function even though it is still partially disassembled. Problem is, there is a different kit for each model or set of models that are similar enough internally. That represents a significant investment for any repair center if they want to work on them.
 

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Discussion Starter · #7 ·
Inside the projector:




Picture samples:




So, to fix this, I need to adjust the LCD panels themselves? There may be a little play in how they're mounted (screwed directly onto the block). Hmm...
 

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Correct. Since I haven't been inside that series in quite awhile, I've sent a query to my NEC rep for guidance. I'll post back here when I have more for you.
 

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Dont remove the LCDs from the block - IIRC they are mounted, then soldered (!) together in convergence on the block. No easy way to do this without the nec jig, may have to live with it. I did this also by mistake on a VT440K.
 

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Discussion Starter · #11 ·
The LCD panels unscrew from the block. There are three phillips head screws that mount each panel to the block. Once I removed the screws, the LCD panels literally "fell" off.


I have a second VT800 that also needs a severe cleaning. I'm going to take this one apart and swap optic blocks (I will clean it the best I can WITHOUT taking it apart) and see if I can build one decent projector.


I'll take pictures of the optic block when I start disassembling so you can see how easily the LCD panels can be unmounted.


Now that I know that's the source of my convergence issue...I won't do it again!! lol
 

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Discussion Starter · #12 ·
Optic block:




Screws on LCD panel:




This is how they originally came off. As soon as I un-did the last screw just a teeny bit:




Do not unmount LCD panels, check. Can I separate the lens from the optic block and clean between the two without risking convergence issues?
 

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Discussion Starter · #14 ·
Woo hoo!! I took apart the 2nd dirty projector and cleaned everything WITHOUT disassembling the optic block (though I separated it from the lens to clean between the two). I used a "data vac" to blow everything out and only physically wiped any components that still looked dirty (which wasn't much).


I put it back together and the picture is GOOD!!!


My supervisor gave me the spare VT800 we had, so the one with the convergence issue is now our "spare". I may just put it back together and have my supervisor pay a service center to fix it if/when we need it...unless more information surfaces.
 

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Hi All

I appreciate that this thread is pushing up the daisies but thought I'd check for an update.

Yup - I've been a muppet and removed one lcd panel from my NEC VT540 which has a very similar set up as the VT800.  And yup, I cleaned the panel and now get a lovely clear picture but the blue lcd panel no longer converges correctly resulting in a yellow shadow.  Arrgghhh!  There seems to be no give in the screwing together of the panel to the lens block.  I took it all apart again and tried slackening screws, pushing the panel and tightening.  This made the yellow shadow worse but at least I know which direction to try to push it next time.  Any word from your NEC rep Sheridan1952 ?

Steven the Muppet
 
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