Film-Tech Forum ARCHIVE: DLP projector image going dim

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Posted by Frank Angel (Member # 248) on 12-30-2007, 03:49 AM:

My nephew called and said the image on his InFocus DLP home theatre projector has dimmed considerably to where it is obviously much darker than when it was new. He wanted to know if he should replace the bulb (at abuot $400 a pop). I am a little skeptical that the bulb is the culpret. Although I have not dealt with toy (er...consumer) DLP projectors, I am skeptical that it is only the bulb. Wouldn't the bulb just burn out? It's not a xenon where you might find a lot of darkening of the envelope before it actually won't light. I believe the unit is about 4 years old. Don't these bulbs just go out when their time is due? There shouldn't be that kind of serious dimming of it, should there?

I would hate to tell him to buy a new bulb ($400 a pop) only to find that is not the issue. Another consideration is the fact that the price of the bulb is 1/3rd the price of the projector when it was new. He might be better off buying a new unit if indeed it is something other than a dying bulb.

Any suggestions would be appreciated.

Posted by Stephen Furley (Member # 1277) on 12-30-2007, 04:38 AM:

Just about any type of lamp will show some fall off in light output during its life. This lamp is almost certain to be either a metal halide or UHP mercury type; UHP are more common on newer projectors. Is the illumination uniform across the screen? If not suspect either entire lamp has shifted, or arc tube has gone put of alignment in the reflector, possibly due to overheating. Has projector been knocked or dropped? Did light output fall off gradually, or suddenly? Has the light gone an odd colour? Metal halide lamps often show a colour shift towards the end of their life.

It's difficult to say what the lamp should look like, unless you've got another one to compare it with. The arc tube of a UHP lamp tends to look cear, though is sometimes difficult to see. Metal halide lamps often have 'muck' deposited on the inside of the arc tube when cold; the colour and position of this can vary with the lamp type and its position when cooling. Here are a couple of pictures of metal halide lamps; they are not projection lamps, the first would typically be used in display lighting, and the second in streetlighting, but the arc tubes look quite similar to those in projection lamps, and they are easier to photograph, because there is no reflector.

The photographs aren't very good, but in both cases you should be able to see the 'muck', mainly towards the left-hand end of the arc tubes. This is quite normal in metal halide lamps, though some show it more than others. It's simply where the halides have condensed as the lamp cooled.

I don't have a UHP lamp to hand, and they are difficult to photograph, but there is one here:

web page

You may just be able to see that the arc tube looks clear. It's very small, and cylindrical. You can't generally see any mercury in them.

It's generally not easy to measure the lamp current on these projectors, even if you what the correct lamp current was. About the only way to be sure is to replace the lamp with a known good one, or to try his lamp in a known good projector. Unfortunately, because there are so many different lamp types, finding a different projector which takes the same lamp type would not be easy. I don't suppose he knows anybody else who has the same model of projector?

What does the lamp reflector look like; is the surface in good condition? Is it very dirty?

How many hours does the lamp have on it? Just about every projector has a lamp hours display somewhere in its menus. Of course, it's possible for a lamp to fail before its time.

Does the fall-off in brightness affect images generated internally within the projector, e.g. menus?

How sensitive is your Nephew to changes in screen brightness? Some people notice this more than others.

Are your nephew and his family heavy smokers? I'm not joking, you should see one projection lens and screen surface that I once saw!

Posted by Mark Gulbrandsen (Member # 72) on 12-30-2007, 09:12 AM:

Tell him to look for a good deal on a new projector... When I was at COstco the other day they had small DLP projectors for about $699.00! In Focus is the "Mr Haney" of projector manufacturerts!! Not only are In Focus projectors notorious for very high lamp cost but they are famous for eating lamps as well... They have actually discontinued several models whose lamps used to regularly explode....

If he pops for the new lamp he should ONLY order it from In Focus and for an extra 90 bucks get the Extended Lamp Warranty. Although this warranty is only 1 year these lamps rarely reach their rated hours before failing and if he uses it alot then it can save him from having to purchase another 400 buck lamp in that time period. This warranty is great for movie theaters that use In Focus equipment for pre-show projectors... they can literally get a years supply of lamps in that years time for the extra 90 bucks.

Mark

Dell makes a small home projectors whose lamp cost is about $200.00. I've seen many a theater steer away from Panasonics and In Focus projectors they had been using and go to the small Dell... Its brighter to boot!

Posted by Frank Angel (Member # 248) on 12-30-2007, 02:12 PM:

Thank you very much guys....very good info. I will relay to him, especially the warrantee info.

Posted by Steve Guttag (Member # 268) on 12-30-2007, 05:12 PM:

Typical small projectors that use lamp modules have 1000-hour lamps. It is VERY common for them to darken over time and they are really a "pig in a poke" as to ones that go for a long time versus the ones that fade quickly.

The fact he has 4-years on his projector means he probably has gotten a good life out of it. With cutting edge technology, Mark is right, he should compare a new machine to his current one...he might find that for little money more, he could have a substantially improved projector that will come with a new warranty.

Also note, projector manufacturers only have a 90-day warranty (From time of sale, not installation) on lamps. Most projectors have a way to read the number of hours that are on the lamp...it might be a good idea to check that.

Steve

Posted by Scott Jentsch (Member # 1681) on 01-02-2008, 03:03 PM:

When my UHP lamp started to go, I noticed a subtle color shift at first, and then it got dark, and then it got really dark. [Smile]

Then one day, pop! No more bulb. I was just happy to open up the projector and see that everything was still in one piece. I've heard stories of shattered glass and I really didn't want to deal with that.

If I recall correctly, I had just over 430 hours on it over the course of 2 3/4 years.

Given the current jumps in performance at the same price point I paid (3 years ago this week!), I wouldn't pay another $300 to replace the bulb again. I'm hoping to trade up for a 1080p model before I get to that point.

Buy.com has the Sharp XV-Z12000 MkII DLP projector for just over $1300. It's still a 720p projector, but it's a highly regarded projector at a really good price.

Posted by Ron Funderburg (Member # 4561) on 01-02-2008, 08:06 PM:

I have two DLP2 light projectors for home theaters that I used in a video store I had and in a theater lobby. They are great projectors don't remember the make off the top of my head, but they use 2500 lumen's bulbs and they are pretty expensive bulbs but they do dim down with time. I have one that is like it was new still and the other that is about half as bright as when we started. I assume the dim one is the one that ran the most!

Posted by Tim Reed (Member # 137) on 01-20-2008, 02:28 AM:

quote: Steve Guttag
Typical small projectors that use lamp modules have 1000-hour lamps.

Why couldn't they have come up with this kind of longevity on 8mm and 16mm projectors?! I hated relamping my Super 8 projector when I was a kid, knowing how long I'd saved my allowance to buy the bulb and that it was only going to last 15 hours - or less, given how many changeovers I used to make with them (50ft. reels)!!! I remember one I didn't even get an hour out of! [Frown]