[AudioFileZ]

I've been told that to eliminate the greenish cast to the image of my D-ila I need the static shading adjusted or the 1/4th waveplates adjusted-or both. Help, I have no idea what these parameters are. I was told JVC factory software is the only option for the static shading adjustment I was wondering if anyone has had this done and where they sent their projector to in order to get this adjustment? It was advised by the AVS member who told me the above that the 1/4th waveplates needed to be adjusted first because they would effect the shading. It was insinuated that the waveplate adjustment was possilbe without JVC's software, but not confirmed. Can anyone explain all of this in greater detail and tell me who at JVC does this? How do you get hooked up with the right people at JVC to have it done? Thanks for any info and help!

 

[Mark Hunter]

Hi AudioFilez,


Is is quite bad? The reason I ask is that if it is "livable", you may be able to fix it with the Calibration Wizard or the upcoming (final) Dilard Wizard called the Shading Wizard. As others, it will be a free upgrade.


It does not sound like a quarter-wave plate issue to me.


[This message has been edited by milori (edited 08-19-2001).]

 

[AudioFileZ]

Mark:

Good to hear that you feel it is maybe not too bad so, hopefully, Dilard will be able to fix it. I'm hopeful I can bring this baby around! I told several other members that I feel a bit crazy, I got my projector 3 summers ago and I have all of about 55 hrs. on the original bulb. Many factors played into this besides being "a bit crazy". One was I just could never get excited over the picture to the point I felt like, "man I've got to get this permanently installed". So I still have not done that even though I own the Peerless ceiling mount. I hope all this is about to change and I'm wanting to try Dilard to jump start it. One thing I need to understand is why so many folks prefer a certain input, Comp2 I believe. Right now I'm using a vga from Radeon to vga Comp1 into my D'iLA. My vga is male/female so at the projector end I have to use an adapter. Is this a bad situation to use an adapter? Also, can I d/l a "trial" Dilard and do everything but save the changes? If so then I could see the difference prior to purchasing...Right?

 

[John Nelson]

So what exactly does the quarter wave adjustment do. And what is the adjustment procedure. In the service manuals I have, I see no mention of "quarter-wave".

 

[Morbius]

The quarter-wave plates are part of the polarizer for the light from the lamp. The D-ILA chip works

by altering the polarization of the incident light.


So you have to have polarized incident light to shine at the D-ILA chip - that's where the quarter-wave

plate comes in. A quarter-wave plate will convert circularly polarized light to linearly polarized

light and vise-versa.


The adjustment of the quarter-wave plate requires that you open the box and make an adjustment.


You don't adjust the quarter-wave plate with software.


Adjustment of these plates can have a gross effect on the operation of the projector. So you adjust

the plates before you do fine tuning like shading.


If the quarter-wave plates need adjusting - you should send the unit to one of the D-ILA calibration

gurus like William or Cliff.


Greg

 

[John Nelson]

Morbius,


Thanks for the explanation of the function of the quarter-wave plates. From your description, it sounds like the symptom of mis-adjusted quarter-wave plates would be a loss of light from 1 or more d-ila devices and they shoud be adjusted for max light output? Is this correct? Is this a mechanical adjustment to the optical block? From the schematic, I do not see any adjustment points on the DD PWB Ass'y.


My intent is to learn how to adjust and measure every adjustable parameter for absolute maximum performance. I have already gone through the adjustment procedures as outlined in the Factory Service manual (Common Dc, A-D Converter Aperture, Sub-Bright/Sub-Contrast, P.C. Adj, etc). Taking the covers off of the projector does not scare me. If I scr%w it up, I accept that responsibility. I am NOT learning this to go into the calibration business.


The symptom I'm seeing/trying to correct is I'm seeing contrast ratios of only about 300:1. The limiting factor is the amount of available red. To get 6500K at the top end, I have to crank the green and blue way down with the result being less light output/lower contrast ratio. With GIN off, red is almost 40% less than green/blue. Since I do not have another projector to compare against, I do not know if this is typical. Therefore I would like to measure/confirm/adjust the quarter-wave plates.


If anyone could help me out, it would be appreciated. Please do not try to save me from myself. I have the factory service tool, DMM, Oscilloscope, Dilard, ColorFacts, half a brain (most of the time) and time to learn.


While I appreciate what Cliff and William do, that is not me. With as much time as I spend with my projector, It can not be a black box. One of the main reasons I purchased the G15 was it's adjustability, and the knowledge on this forum. (besides the picture).


So if anyone would like to help, we can discuss it here or offline via e-mail.

 

[John Nelson]

Bump.


Hard to believe no one can (or willing) to provide more information.

 

[b-man]

The 1/4 plate retarders are used for skew ray compensation. This is not easy to explain and relates to the off axis rays in the polarizing beam splitter cubes. The LC itself converts the light to circular where it reflects back with the opposite handedness from the mirrored CMOS.


The retarders are usually adjusted for maximum contrast. I suspect that is the fundamental contrast of your system unless the retarders have moved. I have heard that they are not tightened down in some systems. The alternative is the software. Dilard could help you there.

 

[John Nelson]

Now that I know some of the science behind the wave plates, all I need is some guidance on adjustment procedures. Anyone willing to share?