CurtPalme.com Home Theater Forum

voodoo7869 · Joined: 19 Oct 2007 Posts: 193 Location: Chicago, IL USA

I have been reading up on this for a while I will be doing a magnetics alignment on a 9500lc from scratch. (new tube install) The question is how to find the very center of the tube with out removing the c elements I would like to get it as accurate as possible. Any help is really appreciated.

Thank you to all in advance

John

CRT_Ben · Joined: 28 Aug 2006 Posts: 1684 Location: Northern Virginia

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

I center mine based upon distance from the edge of the tube. If your geometry is correct such the both sides are parallel, then equal distance from the edge of the tube means it is centered.

Ile · Posted: Tue Jan 22, 2008 3:42 pm Post subject:

voodoo7869 · Joined: 19 Oct 2007 Posts: 193 Location: Chicago, IL USA

ok then an educated guess it is then Thank you to all well if there is no real procedure then we need to make one.
Thanks All

Mark_A_W · Posted: Tue Jan 22, 2008 8:36 pm Post subject:

Raise the brightness till the raster just shows.

Expand the raster till it's just cut off at the lower corners, and centre the corners to your screen edges. Balance the area each side.

stefuel · Posted: Tue Jan 22, 2008 9:36 pm Post subject:

voodoo7869 · Joined: 19 Oct 2007 Posts: 193 Location: Chicago, IL USA

I know its not rocket science but if a procedure exsists to find perfect center than that is what i would like to do any one can estimate the center. we all have eyeballs Shocked

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

voodoo7869 · Joined: 19 Oct 2007 Posts: 193 Location: Chicago, IL USA

the better the center on the tube face the better the optical alignment the lens has in relation to the raster. and the more predictable the electrical focus can be made.

I.E. as the image moves closer to the sides of the tube the lens needs to compensate more for the longer distances. Have you ever had to do corner focus on a lens and could not figure out why you could not get all the corners equally focused even with lens flapping. the lenses by design are curved to help with the distance change. so if it is uneven in any way one side will be under focused because the further away you move from the lens the more the distortion. try it you will seereally easy to test on ac projectors. move the raster to one side after focus and lens flapping and try to get it to focus in all 4 corners equally you wont one side will soften up. to confirn it is not electrical put a dot on the tube face in all 4 corners of the raster once moved and show a white screen you will see that the dots will not be equally focused based on position away from the lens

Mark_A_W · Posted: Wed Jan 23, 2008 12:08 am Post subject:

If you use the raster edges (the image is irrelevant here) to do toe-in, you have go the tube pointing at the centre of the screen.

This was TSE's tip originally, and if it's good enough for him, it's good enough for me - it does work.

ecrabb · Posted: Wed Jan 23, 2008 12:53 am Post subject:

Yeah, I don't see the quandary here. Set it up so the raster edges are equally spaced on both sides and on all three tubes, adjust toe-in until your cross is pointing at the center of the screen. Done. Problem solved.

SC

AFryia · Posted: Wed Jan 23, 2008 2:40 am Post subject:

Tom.W · Joined: 09 Mar 2006 Posts: 6635

Heres some good graphics ...Thanks to Moe's Realm and Guy Kuo

http://www.moesrealm.com/hometheater/crt-focus-guide.html Wink

voodoo7869 · Joined: 19 Oct 2007 Posts: 193 Location: Chicago, IL USA

great thank you the site helped out alot

Gino · Posted: Sat Jan 26, 2008 5:33 am Post subject:

hehe, I think you are trying to make raster centering overly complex. eye balling is good enough to get you within 1-2mm of perfect centre if you ask me. I doubt that will have too much influence over your end result.