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I own a used 400q that now has about 1500 hours on the lamp. It is still bright. I have used only about 400 of those 1500 hours, so I do not really know how bright a new lamp would be. How much drop in output would it be at 2000 hours?, 2500 hours?, 3000 hours?


When getting a new lamp, does contrast improve, or is the contrast the same, just everything brighter (blacks and whites)?


James
 

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1. I am not sure about exact Lumens at different intervals during the bulbs use. But I do know the loss of Lumens is not linear with age.


2. Not sure.


CAUTION: Remember to reset the Lamp Timer circuit after changing a bulb. The lamp circuitry somehow will lock up the unit if you don't reset it.
 

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James,

Here's a link to check out at the 400Q forum. Read the whole thread, and you'll get a good understanding of the 400q's light output with a new bulb and one with 1000 hours on it.

http://www.thebigpicturedvd.com/cgi-...um=DCForumID24



Here is just part of what Bill Cushman, a 400q expert had to say:


"400 ANSI lumens is achievable on a 100% white field using HBM (not modified) with Contrast and Brightness set to Maximum, and a brand new bulb.

ANSI lumens is an average of many different screen areas. In my measurements I have used center lumens only. ANSI lumens would be about 5% to 10% less.


The difference between 240 lumens and 400 lumens is that the 240 reading is with correct color temperature at D6500, and with Black Level set correctly and Contrast set to 80 (higher will cause the picture to start to turn green). 240 lumens is the maximum realistic output from the VPL-W400Q, measured using the finest professional test equipment when the bulb is brand new.


Home Theater magazine measured 241 lumens output from the VPL-W400Q in their test published in the October 1997 issue. They used the Photo Research PR650. I used a Philips PM5639/00."


Here's a little more from Bill's great thread:


"Typical performance of the W-400Q with a 1.1 gain and a 2.8 gain screen at an image size of 92" x 52" are as follows:


Screen gain 2.8

Light output, new bulb 240 lumens

Full white brightness 20.2 foot-Lamberts

Full black brightness .1 foot-Lambert

Contrast ratio (full black/full white) 200:1


Screen gain 1.1

Light output, new bulb 240 lumens

Full white brightness 7.9 foot-Lamberts

Full black brightness .04 foot-Lambert

Contrast ratio (full black/full white) 200:1


By 1000 hours of typical use, with one bulb start and 3.3 hours use per day, the light output will fall to 120 lumens so the brightness values will be 1/2 of those listed, but the contrast ratio will remain the same."




Bottom line...with 1500 hours on your bulb, you should replace it. You'll see a significant increase in brightness.
 

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Make sure you also apply the Louis service menu tweaks, if you haven't already. Do a search at Bigpicture for gain.
 
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