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Discussion Starter · #1 ·
No, its not the cathode in CRT, but rather what NEC defines as the measurement from the front of the projector to the screen's surface. But ...

Background:


I have a GE Imager 601 (NEC 6PG) that I am trying to mate with a room to create a TV room. The room's ceiling limitations are such that the tail-end of the projector comes into contact with a tapered ceiling (45?, rise=run). I am shooting for an 80" wide, 4:3 screen setup using a Draper M1300.


The following is the chart I am using, trying to interpret, but a little confused by:
http://home.speedfactory.net/wanman/...ance_Chart.jpg


According to this chart, for a 4:3 screen that is 80" wide I need to have a screen-to-front-of-projector value of 116.16". I assume this is with the raster at factory default, right?


So, looking in the menu (not me, someone else) we find a dial-location of 50 and with the projector being positioned to fit the 80" wide screen, we then measured the 'C' to be 109", and not 116.16".


I was originally looking for the distance between the screen's surface and the from of the ceiling bracket of the projector mount, but my mount is 7.75" deep while the NEC installation guide is for a mount that is 5.12" deep. Weird.


Since the actual measurement is off from that of the chart I am now wondering if I am interpreting 'C' correctly. Anyone?
 

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Based on that diagram, C appears to be a point about 3mm in front of the lenses. I guess this is to prevent you from scratching them with your tape measure?


"Here Bob, hold this metal tape measure up to the green lens so I can measure the C point and make sure this monster is in the right spot!" :D


I'd say you are pretty close, why not use the table method to find your exact throw distance from a point you chose (e.g. your mounting bracket).
 

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Discussion Starter · #3 ·
Actually, when the unit is mounted flush with the ceiling/floor, there is a nice leading edge that protrudes from the lens assembly (about 1/4") and it is that point that sticks out the farthest.


BTW, to use a table method for accuracy to get a measurement to the mounting bracket would probably require me to place the mount back on, and then balance it precariously.


Hey, I just discovered this unit has an NTSC card in it.
 
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