IQB64W10W Astigmatism Adjustments
<< Back to Zenith Tips
Tip from Lenny Zimmermann: "After finishing up a move and putting together a dedicated home theater
room in the new house I finally ahd time to sit down and takre a good hard look at the
service manual and decided to try and figure out a couple of things that were in there
that my current Service Manual Operations article here doesn't cover very well, because I
hadn't done them. These are just some observations I have that directly refer to my
Servicing Methods and Tweaks at http://www.keohi.com/keohihdtv/brandspecif...b64_tweaks.html
for doing this stuff. With that in mind...
The biggest thing I really wanted to do was to better work out
the alignment of my guns. Unfortunately I still have no idea where the "yoke clamping
screw" is to realign the yoke tilt to line things up a little better. Oh well.
What I did find, though was for one of the next few steps out
of the service manual dealing with Raster and Astigmator Alignment.
If you look on the CRT assembly from underneath you'll notice
all of these plates with prongs sticking out with glue gobbed onto them to hold them in
place. There are 3 sets of two of these on the lower part of the tube assembly and there
is one pair near the top.
I primarily first did the "2-Pole Magnet Adjustment
(Raster Positioning)" with the pair at the top. One of the prongs, when moved, will
move that CRT color left and right, while the other will move it up and down. So using
these two prongs you can center the entire convergence grid properly, as per the
directions in the above listed link.
A couple of steps later in the document I cover
"Astigmator Alignment". In this case we're talking about using the 3 bottom
pairs of prongs to make these adjustments. First off, though, below all of these prongs
there is a grey plastic ring,or wheel, with four round plastic arms. I guess if you could
get it off it the tube it might look a bit like the steering wheel from a ship. At any
rate this thing needs to be turned to the left and loosened up a little before moving the
prongs. It seems that Zenith used two methods to hold all of these settings in place by
having this ring tighten up on on the magnets to make them hard to move, as well as
holding them in place with caulk. You may not want to loosen it all the way, though, since
having a little bit of friction on the prongs prevents them from moving too freely and
being too subjective to moving from where you were trying to set them. Just try it an
you'll see what I mean.
At any rate the bottom two prongs are for the "2-pole
magnet" adjustment. The next one up is for 4-pole and the top two are for the 6-pole
part of the adjustment. Double reference the other Astigmator links I have for tips on
doing those steps, though. The important thing to know is that you have two prongs to
control each of the adjustments and that by moving those prongs farther apart or closer
together is how you make the changes to perform the adjustment you are looking to do.
Pretty simple in concept, but it's sometimes a bit tough to watch what affect moving these
things around is having while also trying not to disturb one of the other pairs of prongs.
So just be patient and persistent when working with these.
At any rate, I hope that clears up at least those two steps a
little bit. I'll get that document rewritten and submitted to the site later to
incorporate what I've found out. Maybe someday I'll also get around to taking some
pictures and/or making some line drawings to help explain things better as well.
Oh, and if anyone comes up with where the heck that darned
"yoke clamping screw" is, please let me know!