MIT RPTV Light Enging adjustment screws - AVS Forum
Rear Projection Units > MIT RPTV Light Enging adjustment screws
jsmiddleton4's Avatar jsmiddleton4 10:55 AM 12-27-2012
What do this screws adjust?

videobruce's Avatar videobruce 02:51 AM 12-29-2012
Good question. I would have to say a specific lens for centering or edge focus depending on if they tilt or move the lens. It appears the light path is a straight line at that point.
Which model? Was that removed from your TV and if so, what is the issue?
jsmiddleton4's Avatar jsmiddleton4 09:16 AM 12-29-2012
Good morning,


Having light engine issues on mine and am replacing the light engine probably next week.

I looked at the service manual, at least the one I could find, and nothing about those screws. However on older models the screws to align the picture on the screen both up and down and side to side, are part of the housing or frame of the housing. The 65738 does not have those same screws. So it looks like, looks like mind you, these are the vertical and horizontal gross, for lack of a better term, adjustment to center the image and then you use the service mode to do the smaller adjustments.

At the same time as you noted not sure what it would adjust unless it rotates for vertical and slides the mirror and lens piece out for horizontal.

I can play with the bad one and see what effect is once I get the thing apart to do light engine swap.
videobruce's Avatar videobruce 09:22 AM 12-29-2012
I assume you are replacing the entire LE? If so, there should be no need for alignment other than what is listed in the SM.
jsmiddleton4's Avatar jsmiddleton4 05:41 PM 12-29-2012
Yes, whole assembly.

Just curious.

The way they are sealed with some kind of green stuff I'm gonna guess iti s adjusted when assembled and then end users use the Service Menu.
videobruce's Avatar videobruce 07:37 PM 12-29-2012
If those screws have been painted, then don't try to adjust them.
jsmiddleton4's Avatar jsmiddleton4 09:32 AM 01-05-2013
New to me light engine installed. Time to play with old one.

There appear to be 2 areas where adjustment screws to align the image live. Guessing here as well as guessing design is to set the image via these adjustments to factory spec and then end users can dial the image position in via service menu.

The first is an allen hex screw under one of the many lenses/mirror combinations. It looks to either just secure one of the lenses in place or move it up and down.

The second and where the two screws I asked about is in the image path and those screws adjust this rectangular lens. Would of course move it up or down and back and forth. I get a little lost in terms of the actual image path with all the mirrors, etc., but I'm pretty sure by this point the image is on its way to the main mirror/lens to be projected on to the screen. Clearly an adjustment whereas the allen screw maybe not.

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