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MONTAC Enterprises
ATTN: MTB Madness
Pending New...
Azle, TX 76020


Front Panel Removal & Prevention
of "Lenticular Sag"
(This procedure applies specifically to the 65H80 and possibly other models. The principals of the procedure however should apply across many/most models.)

(NOTE: This procedure may appear fairly complicated and involved. This is due solely because the procedure is "evolving" into its final form. Once finalized, the procedure will be re-written and I assure you that it will be much simpler in appearance and implementation. 

Getting rid of the Front Panel from the screen stack is one of the best tweaks available. I absolutely loathe screen glare, and this procedure will end it, period! One problem that almost always rears its ugly little head when removing the Front panel is "Lenticular Sag". 

Lenticular Sag is the tendency for the much thinner Lenticular screen to have (or develop) "wrinkles" or other multi-planar indications. Building upon what some others have done, I think I have found a top notch method for 1) getting rid of the Front Panel, 2) drastically reducing frame flex and screen slip, and 3) virtually eliminating lenticular sag as a concern when removing the Front Panel.

Warning: Monkeying around inside an AC electrically powered device is DANGEROUS!! You could seriously injure or kill yourself if you make the wrong move. Do not attempt this procedure unless you have the requisite skills and knowledge to complete it successfully. This article is provided for information only, and I accept no responsibility for damage or injury resulting from the use of the information contained in this article.



Article Index:
Complete the Basic Front Disassembly Procedure in preparation for beginning this procedure.
(NOTE: You may click on any image to pop up a larger version of the image with arrows indicating action points.)
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Step 1
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Step 2
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Step 3
Always wear clean and dry latex gloves when handling the screen stack elements. This is a close-up of the top of the frame at the center. In this image I am lifting at the center of the frame with about 5 lbs. of force. Notice the extreme amount of frame flex present. There is actually a gap between the frame and the screen stack! That gets fixed in this procedure. This deficiency is what makes it necessary to handle the screen exclusively by the corners. With the Screen Assembly resting vertically, top rail on the floor, remove ONLY the clamping strips. Top and bottom clamps have 5 screws each. Side clamps have 3 screws each. Note how I am arraying the clamps/hardware. This insures that the clamps and each piece of hardware goes back exactly from whence it came. Not a critical point here, but a good habit to develop.
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Step 4
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Step 5
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Step 6
Handling screen elements by the outer 0.5" of the edges, remove entire screen stack from the frame and lay it down flat on a 100% cotton sheet (not brand new; washed several times at least) with the Front Panel on top.

The screen elements have the following thicknesses:

Front Panel = 0.079"
Lenticular = 0.039"
Fresnel = 0.078"

In addition, there is an approximate 0.031" free gap between the stack and the frame with the clamps fully seated.... NOT good.

Separate the Front Panel element from the screen stack, making sure not to slide the faces across one another. Set the Front Panel element aside, or PREFERABLY, package and store it properly NOW.

I have mine stored inside two large garbage bags, sandwiched between two heavy-weight pieces of cardboard, and clamped between the wall and my DVD shelves. Just make sure it stays flat and safe from impact/scratches. 

Here is the empty Front Mask frame resting upside down against the wall. 
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Step 7
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Step 8
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Step 9
Corner of the frame showing the joint between the corner fittings and the sides. Note that there is only ONE screw on each leg of the fitting....  I'm pretty sure the engineer knew what he was doing when he put THREE holes in the fitting's design. I will likely install the remaining 16 screws if I can find an exact match to the stock hardware.

The other point I want you to see is the screen element bearing surfaces. The front surface is right at 9/16" wide. Thus, I chose 1/2" as the width of the gaskets to maximize bearing surface, while insuring that the gaskets will not protrude beyond the edge of the frame.

Knowing the element thicknesses and the gap width, it was possible to calculate the approximate total gasket thickness needed to insure a static frame to screen stack installation with the clamps installed. I know many folks have used basic weather stripping as gasket/spacers, but I chose not to. Weather stripping is intentionally compressible, and is very unstable in the shear direction when compressed. This doesn't make for a very good clamping gasket.

I chose to use a cloth impregnated, hard rubber sheet in 1/16" and 1/8" thicknesses. This sheet material is similar to pump diaphragm material, is almost incompressible, and has very good shear adhesion properties.

 Source for mine was Orchard Supply Hardware (OSH): 1/16" sheet (a12065639 @ 1.96/sq. ft.) and 1/8" sheet (a12065647 @ 3.96/sq. ft.)

Using the square and numerous single edged razor blades, I cut the sheet into 1/2" strips.

Before installing the gaskets, make sure to clean and dry the mating surfaces with something like alcohol prep pads (EXCEPT the screen elements). The frame had a lot of chalk-like substance on it, and the gasket material was dusty. Clean surfaces will "stick" better. Make sure you dry all of the alcohol residue away thoroughly.
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Step 10
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Step 11
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Step 12
Tough to see, but here you can see a section of the outer gasket in place against the frame's screen element bearing surface. On the outer gasket, I chose to completely line the entire perimeter with the 1/16" gasket material. Here you can see the end of the top bracket installed with the 1/8" inner gasket material in place. This combination gave me just enough compression when the clamps were installed to secure the screen stack, but still afforded the option to add another 1/16" in the back at a later time if necessary to compensate for frame flexing over time. 

Difficult to see here, but there is a pronounced gap in both corners of the top rail. As the screen elements have a very true edge, it is obvious that the frame is "warped". It is critical that the screen stack be mounted squarely against the top rail and that it be centered from side to side. Not hard to fix, but necessary....

Center the stack side-to-side in relation to the top rail by insuring that there is equal space between the edges of the stack and the top corners. Tighten the center screw ONLY insuring that the screen stack is fully seated against the center of the top rail. Then tighten the left-center, and right-center screws in order. Gently lift the appropriate corner a bit if necessary to seat the stack at the screw location. Finally, tighten the left and right most screws. If there is a gap, you will have to lift the corners sufficiently to close the gap while you tighten the screws. With the top clamp completely installed, you should be able to turn the screen assembly right side up and the screen stack will be retained (hanging) by the top clamp.
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Step 13
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Step 14
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Step 15
The side and bottom brackets need not be completely lined with the inner gasket. Long strips at each screw location is sufficient. 

I ran out of time in this session, and wasn't able to properly set/tune the screen. I simply tightened the clamps from top to bottom and center to corners to get everything back together.

OK, don't freak out. I can see the "sag" too. Actually, it only amounts to about a 1/16" separation between the elements in the stack 2/3 down from the top.

I purposely used a very high flash level on the camera to accentuate it. It's very hard to see without a super bright light or looking at less than 5 degrees from the parallel. 

I needed this pic to analyze what MY particular frame does to the stack when installed on the chassis. The frame/stack tends to behave differently when installed vs. free-standing or suspended in free-air.

Even with the 1/16" separation, Matrix still looked awesome...  We are talking MAJOR improvement. I watched it in daytime and in low-light. Both conditions showed marked improvement in light level, elimination of front-lighting glare, improved color saturation, and most importantly.... well, it's hard to describe...  

I've seen this movie many, many times, but it was like I was seeing it again for the first time. Every few seconds I picked up on a new image detail I had NEVER SEEN BEFORE! 

Hang with me... In Part II of this procedure, I will work on eliminating virtually all of the screen element separation and consequently the visible lenticular distortion. 



Copyright (C)2003 MONTAC Enterprises.  All Rights Reserved©
Revised: March 03, 2006 .