Optoma H77 Dvi>HDMI : Extreme Color banding - AVS Forum
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post #1 of 10 Old 05-25-2012, 03:05 PM - Thread Starter
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Hi gents,

I got my hands on an Optoma H77, and ran it through its paces against a white wall, and I have a sinking feeling I've been had...

I have extreme colorbanding, to the point where I suspect the unit is running in 256 colors mode.

Here is an example:


I tried 3 different HDMI cables and 3 different sources (Mac, DVR, AppleTV2) and always have had the exact same results.

What are the symptoms of this?

The HDMI connector is using an HDMI (F)> DVI (M) converter - I will do another round of testing with a new one, but would really appreciate your advice before I turn back on the seller of this item.

Thanks!
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post #2 of 10 Old 05-26-2012, 03:45 PM
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It does it with component cables also? Usually it's the video board went out.
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post #3 of 10 Old 05-27-2012, 06:36 AM - Thread Starter
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Hi,

Yes this also appears with component but it's intermittent. I got 5 hours of perfect HDMI yesterday night...
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post #4 of 10 Old 05-27-2012, 08:16 PM
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That's hopeful maybe it has to loosen up. I was going to say reseat the board connections, maybe clean the color wheel. Keep using it maybe the problem will go away.
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post #5 of 10 Old 08-25-2012, 11:47 PM
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Hey I hope I can help. I was having very similar issues with my HD20 and found your post while trying to correct my own. My issues began when I replaced a broken color wheel. I wonder if the same did not happen to the previous owner. My solution was simple, however completely undocumented.

Solution:
-Open up your projectors service menu
quick google shows you need to "hit the three buttons at the same time???
-Open up an image or video with extreme color banding
-Find the "Color Wheel Index" option
-Adjust this setting up and down until you find an area in which the banding disappears

I really hope this works for you and anyone else who is google'ing for a solution.
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post #6 of 10 Old 08-27-2012, 05:10 AM - Thread Starter
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Thanks for the tip, I tried doing this already, but to no avail.

I am pretty convinced there is a loose connector / solder in the input circuits as I got the projector to work without fiddling with the settings at some point.

I am trying to open it and see for myself, but apparently removing the screws isn't enough, the plastic casing won't move. Time to look-up these youtube videos!

Also, the problem I am having is tied to the green channel but does not flicker like in this video: http://www.youtube.com/watch?v=Uz3z129CDzk
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post #7 of 10 Old 08-27-2012, 11:45 AM - Thread Starter
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Using a gradient pattern from http://www.colorsimulator.com/color_test_pattern.htm the vertical gradients are fine (red->magenta and green->cyan), but I get bars on horizontal gradients as shown here: http://imgur.com/degnL
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post #8 of 10 Old 08-30-2012, 02:45 AM - Thread Starter
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Thanks to all of you who pitched-in, it's fixed now!

With the encouragements and support of Foranzi I eventually got the PJ open, in order to clean the color wheel and its sensor, but to no avail. I decided to go for broke and disassembled the motherboard / daughterboard setup, clean all components, connectors and make sure everything was grounded:



It seems like the daughterboard got loose in its riser during transport. All works like a charm! Thanks!
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post #9 of 10 Old 10-08-2012, 01:44 PM
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That's excellent. Sorry to bring a thread back from 2 months (I'm sure there's been worse) but I am wondering how the heck you got the thing apart. If you have any tips for getting the top cover off, please let me know.

I'm happy to demo, unless you look like you simply intend to "case the joint", in which case I will introduce you to my all-steel Equipment Defense System...
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post #10 of 10 Old 10-08-2012, 01:52 PM - Thread Starter
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Once you removed all the screws / torx you can see the secret is...

The nuts holding the DVI connector at the back!

Then it peels of like a banana!
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