Unique fix for DLP overscan? - AVS Forum
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post #1 of 8 Old 08-14-2008, 04:34 PM - Thread Starter
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I recently purchased a new Mitsubishi 73735 to replace my 62525, and one of the primary reasons I made this upgrade was for the hope that this new TV would act as a better computer monitor.

With this new set, when monitor resolutions aren't down-scaled, the picture is perfect, but overscan is pretty bad. I tried some different solutions to correct the overscan, such as playing with the service menu's geometry, but nothing really worked....then I got curious about the easy access panels on the side of the TV which allowed me to peer in....

To my surprise, the overscan associated with this TV didn't come from the DLP chip, but rather the fact that the TV's case didnt match the output from the DLP chip! The entire image was being projected, but the mirror, screen, lens, and dlp chip dont match up well enough to allow the whole image to be seen! Here: you can see from the inside of the TV part of the image getting cut off by the bottom of the screen, not to be seen on the other side.....

To make matters worse, this happens with all 1080p signals.

So, my question here is has anyone tried to re-align anything to make the picture fit? Perhaps there are screws that can be adjusted?

I understand that with some sources, I may have a black box around the image, but for the 90% of the time that I use it on 1080p sources, Id be getting the whole image projected.....

So any ideas?
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post #2 of 8 Old 08-15-2008, 12:11 AM
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I like the rare Rear Pros that give you inspection holes either side to see what goes on inside. Actually it looks VERY similar inside to my LG LCoS rear pro.
Whatever you do don't touch the glass and if you do it might still look clean UNTIL YOU TURN THE TV ON!!!!
Overscan on rear pros are a pain in the butt because if you have shinny brackets holding your screen or speakers the reflection on them will cause artifacts off the mirror and onto the screen.
This is where I like my LG on all inputs I can adjust the overscan from the hand control from around 5% to just about nothing using a DVE essentials blu-ray disc or you just have a play until you see or remove the black line.

When using it as a monitor the Component and HDMI inputs can be adjusted in seconds but also can be set to your preference in the service menu first..
PS if you ever pull the front off paint anything that shines with flat black paint.
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post #3 of 8 Old 08-15-2008, 12:16 AM
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I have set both my LG's I have (same model) around 2% overscan and no more, If you do less you will see that ugly line now and then and you don't want that.
Have fun with it, stick more pictures up when you have it in pieces.

Look at the lens and you can see a upper and lower eye lid. I bet fresh filtered air runs across the lens (keeps dust off) and gets sucked back inside via a air port. Maybe they copied or LG copied them

See the shiny bracket that holds the screen, its a NO,NO (reflections)
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post #4 of 8 Old 08-15-2008, 06:48 AM
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I just wanted to say: awesome and enlightening photos! They sort of make me want to convert an RPTV into a front-projector...
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post #5 of 8 Old 08-15-2008, 07:03 AM
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Great pics!

I'm on my second WD-73735, this second one is actually worse in some ways. I don't really have a beef with the 2% overscan, but I am very annoyed with tilted and distorted projection... two horizontal parallel lines run away from each other by a few degrees, putting them about a quarter inch further apart on left side compared to the right side.

This looks like a simple adjustment of the projector angle relative to the mirror and screen. (Unless, of course the mirror is out of alignment.)
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post #6 of 8 Old 08-15-2008, 12:22 PM
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Here's another unique RPTV overscan fix: maybe if you removed the brackets that secure the screen you could replace the screen with a slightly larger (and... lower-gain!) screen?
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post #7 of 8 Old 08-18-2008, 03:17 PM - Thread Starter
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Just thought I would give an update on this....

I spent some time on the phone with the Mitsubishi Customer Care line...curious to see if there was a hand control like Blackman had mentioned. After making my case for a long time, and having to go through the typical trouble shooting (yes, I'm familiar with the "format" button), I eventually was connected with a local service man who confirmed that there was no "technical" way to correct it, and that the overscan was within manufacturing specs and wasn't covered by any warranty.

So, back to finding a solution that isn't "technical", I liked the idea of replacing the screen with a larger one..... but I'm a bit scared of trying to modify the original case that much. Would the new image be out of focus in that case?

For acting like a computer monitor, I did find this fix:

http
://drivers.softpedia.com/get/GRAPHICS-BOARD/NVIDIA/NVIDIA-Overscan-Compensation-Fix.shtml

(sorry thats not a proper link, AVSForum said I didnt have enough posts to post links yet, and I might be a spammer!)

While this works as a good solution most of the time, it tends to get messed up whenever another program highjacks the resolution to something else. Guess I'll go with that until I see anything else better come along... thanks for your responses!
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post #8 of 8 Old 09-01-2008, 09:18 PM
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Quote:
Originally Posted by strangesmell View Post

...I eventually was connected with a local service man who confirmed that there was no "technical" way to correct it, and that the overscan was within manufacturing specs and wasn't covered by any warranty.

Every type of HD tv suffers from some annoying thing that prevents it from being the perfect tv. For rear projection tv's, that annoying thing is overscanning. In the infancy of HDTV, I splurged for a 64" Pioneer Elite PRO 720HD to the tune of $6999, not including the cables or 5-yr warranty. I spent months... MONTHS trying to figure out why my picture was exploding off the screen and why I couldn't see the sports tickers at the top and bottom of the screen. All I could get was finger-pointing. Pioneer said it Dish's & Sony's (DVD player) problem. Sony & Dish said it was Pioneer's problem. Audio King said it was my cables (I love that) but couldn't reproduce the problem in their store because they only showed movies or Discovery channel flowers and waterfalls. FINALLY, I used my warranty and had a tech come out to my house. I showed him the problem, he said, "yeah, that is lame" but told me exactly what you said- "...within manufacturing specs..." Feeling sorry for me, he spent THE ENTIRE DAY trying to get my overscan reduced so I could at least see the lousy tickers. It was ridiculous. It took him about an hour to calibrate 1 input at a certain resolution (1080i, 720p, etc.) in a certain mode (FULL, ZOOM, CROP, etc.). It would have taken him a week to calibrate everything so he only did the inputs I needed at the res & mode I was running them at.

Moral of the story: don't buy a rear projection tv until you see what ESPN looks like. ESPN uses every available space on the screen above and below to put scores, breaking news, etc. so you'll be able to see any effects of overscanning.
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