Originally Posted by Mike Garrett
I am confused with his posts. First he said JVC said a keystone image meant the projector was defective. Then I posted the procedure to align the projector with the screen and he said that is the procedure he was told to follow. Two conflicting posts. Anyway, he has the procedure and I think he understands how and why. So he should be good to go, to set up the replacement.
It looks to be more a case where inexperience led to a misunderstanding of exactly what was being related and why.
Mike, you said that the PJ casing would have to be tilted forward or back (slightly) to get the Lens level if the two aspects were not exactly in line. That would seem to be what the poster said JVC related....although 30 degrees is incredibly excessive, and does point to misinformation....by someone.
It certainly is no help that these PJs weigh in at close to 50 lbs. That makes making minute adjustments problematical in the least. Then there is the Mount being used that can come into question. More likely there is a combination of things at play going on.
I've encountered variances...times when I have taken pains to get a PJ precisely level on both axis and the Lens "supposedly" plumb to the wall, yet still have a "slight" trapezoidal image. But usually it was only one corner that was out/in. A incorrect Lens mount seemed to be the only answer...but tweaking the mount (...Chief mounts are unusually adept at that...) usually resolved the problem, and/or Border Masking took care of any remaining small amount.
More common was the Wall / Screen was actually out at one side or the top or bottom. No one wants to consider that their wall is pitching in or out or their room is out of square, but it's actually quite common.
Unless there is actually a 30 degree pitch prevalent at the Lens Face when the PJ itself is leveled on all corners. That would have to be a Mfg issue.
You did an excellent job explaining the basic procedure....perhaps having another go at it will bring a revelation to the poster.