CurtPalme.com Home Theater Forum

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

I picked up (2) Panasonic PT-L6600U projectors from a NOC that was being renovated for free. Both projectors power up and throw a picture. These projectors have 2 bulbs in them and if you run both bulbs it will put out 3500 lumens. They make a mount that you can stack these and sync them to be able to throw a picture at 7000 lumens. On the projector in the picture one of the bulbs was broken and I am pretty sure the other one has over 2000 hours. Does anyone know if the blue line at the bottom is a symptom of an old bulb or is this a sign that the projector is toast. Each bulb runs about $280 and before I drop some money on new bulbs I want to see if it is worth it. This was about a $20,000 projector 7 years ago and I see a few new ones advertised on the internet for around $9,000 still. Excuse the screen shot, I set this up in the kitchen for a quick see.
Thanks
Dan

**Curt Palme** · Posted: Wed Apr 14, 2010 4:01 am Post subject:

You got the budget model, you only bought one with blue and green in it. Hey, you told the seller you wanted a CHEAP COLOR TV... Smile

Looks like the blue LCD shifted. Not sure if you can correct it, but give it a shot, you need to shift the blue LCD panel.

At least I think that's the right diagnosis.

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

The blue 'image' looks trapezoidal to me like the image has been keystoned to the nth and is laying down. I wonder if that would the blue LCD or a prism/mirror.
7000 lumes...dang! I wouldn't try it in the kitchen. Wifey will be really po'd when she see a toasty tube looking burn-in on her wallpaper.

WanMan · Joined: 19 Mar 2006 Posts: 10273

That looks more like a dichroic filter problem.

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

There is a lens shift feature but all this does is move the entire image up and down.

mp20748 · Posted: Wed Apr 14, 2010 12:32 pm Post subject:

Project an external test pattern, like a grid or something that would show the entire surface of the raster.

Do that using analog RGB, where you can disconnect each color at a time showing what each color looks like projected.

It appears to be a panel or mirror in the optical path out of alignment, but there's no way of knowing for sure without seeing each entire color projected one at a time.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Geez Dan. Dont you have a white wall in your house? Laughing

Is the main image normal? I cant tell if its green because of the wall paper or not. But the whites look white and not yellow. Plus I dont see a separate blue image. Also the blue area at the bottom does not look like it has any image.

If all this is correct then I will next assume your projecting a 16X9 signal and the native panel is 4X3. So the blue area should be black or gray depending on the setting. This would then seems to indicate that the blue panel is allowing some light through. Probably not the filter because the filter does not control the passing of light.

Of course this all depends if my first assumptions are correct or not, lol.

ecrabb · Posted: Wed Apr 14, 2010 2:45 pm Post subject:

That's a 3LCD machine, and problem is an all-fuzzy blue... So I'd guess the blue panel, or a lens or filter is out of place in the blue light path.

Wow, high light output, 1280x1024, power focus and zoom, plus lens shift... and best of all free! That bad boy would make an awesome back-yard/outdoor theater projector! I wish I could score a deal like that! I'd love to do some outdoor theater in the neighborhood this summer, but I don't want to spend money on a POS digital that I'll only use for outdoor theater.

SC

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

Well it looks like the blue lcd is shot on both projectors. I did as Mike suggested and connected an rgb source and then disconnected the lead for the different colors. Attached is a pic with only the blue connected. If I move something across the computer screen I can just barely make out the movement on the projector screen. I am assuming these are not worth repairing unless someone knows different.
Thanks
Dan

WanMan · Joined: 19 Mar 2006 Posts: 10273

Hmm, LCDs work by taking a white light source and using dichroic filters to split the wavelengths to come up with the red, green, and blue light that goes into their individual LCD panels. If you fed a blue-only signal to the projector and get the image above then I would have to ask how could Blue be failing? If the Blue LCD panel failed then you should get a green light output. LOL

I say open up one of the units and have a look around.

**Curt Palme** · Posted: Thu Apr 15, 2010 2:37 pm Post subject:

No, I get it. The original pix was misleading. Looked like the blue image was shifted down, but he's got no blue. He's feeding a 16:9 image into a 4:3 panel, right?

the last pix above shows light leakage, whereas it should have bright blue all over the screen. the blue panel dies first as it's the darkest, and absorbs the most light and heat from the bulb. Sucks, but I've seen this fault many times before.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

I know the problem. I think the parts are still available. I would probably need the units to verify and for specific info.. Let me look and see if the general parts is available. Of course I dont want to infringe on Curt here if this falls under projector repair. Smile

**Curt Palme** · Posted: Thu Apr 15, 2010 3:17 pm Post subject:

Nah, have at it! Smile

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

There's a VERY strong chance that the LCD panels are actually fine but the blue dichroic filter has bleached out from long usage.

If that's all it is, then it can be restored to service by simply replacing the blue dichroic filter elements, which may or may not be
separate filters that are easily replaceable and not very expensive.

If the dichroic filter element is bleached out, where it's bleached you don't get that color...just like what you see here.

CJ

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

OK, I had a little bit of time tonight and took one of the pj's apart. I have had 2 people suspect the dichroic filter. The problem is I do not know what one of these looks like. There are a few pieces of glass in the light path. One has a blue tint to it and another has a yellow tint. The piece of glass in the middle of the projector in pic #48 below the brown ribbon cable has the blue tint. Would these be the dichoic filters? I have posted a pic of the inside of the pj if someone can point me in the right direction it would be appreciated.
Thanks
Dan

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

A blue dichroic filter will have a blue color when you look through it and a yellow reflection when you look at it from an angle.

Its color should be uniformly blue from edge to edge. If it is bleached, its color will not be uniform and may be totally gone in the middle section.

There are three dichroic filter elements: Blue, green, and red. The green one will have a magenta reflection and the red one will have a cyan reflection.

Most likely, only the blue one will be bleached.

All the color you see is due to the dichroic filters. As they bleach, colors weaken.

From your photos, I THINK I see a significant bleaching issue on the blue filter that's visible toward the lower left.

Ideally, you'd carefully remove it and look at it against a white background to be sure. Don't scratch it.

Check ALL the optics for clarity. If they need cleaning, use only optical grade microfiber wipes and optically safe cleaning solvents,
available from your local camera/photo specialty shop.

ecrabb · Posted: Thu May 27, 2010 3:44 am Post subject:

CJ, isn't the green one in the middle the one that's badly faded?

SC

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

You guys aren't even close.

Dan, if you still want to send one I'm back now.

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

To the same address as the receiver? I would have thought the filter would have to be after the LCD panel which I assume is part of the assembly with the 3 ribbon cables coming out of it.

ecrabb · Posted: Thu May 27, 2010 4:06 pm Post subject: