Cannot focus uniformly across the projected screen. This seems to be more than a focus problem in that some areas of the image seem blurry as opposed to out-of-focus. Also, in what may be a related issue, I cannot get the keystone correction to work to straighten image when being upwardly projected.

Focus and screen control box / remove front bottom panel there you will find it / it has 3 controls on top 3 on bottom top are focus for RGB tubes bottom controls adjust screen drives for RGB.

You have a focus and screen control box it has 3 controls on top 3on bottom these are the controls for Red-Green-Blue screen drives and for focus to each tube. IT should have Focus /Screen on it.

need to change both convergence ICs STK392-560. you can get replacements at the following link with free instalation instructions with pictures.
http://servicemanuals.vstore.ca/

The tv has 2 focus adjustments for each tube, mechanical and electrical.

1. Mechanical focus is set by looking at screen from back (through inspection plate on back of most samsungs) and rotating the lens assembly on CRT. loosen wing nut and turn lens assembly to go through focus and back to best position.

Put convergence pattern on screen and manually misadjust bottom red and green lines convergence so they can be seen through inspection hole.

With back cover of TV off you can usually reach your hand up beside the lens assembly to loosen the wing nut then rotate to adjust. Green is in the middle. The focus will be obvious when you rotate and look

When you are finished make sure the foam dust protector is not over any of the lens assemblies and the wing nut is tight.

2. Electrical focus - located at front of unit. the front grille/speaker cover is removed and maybe a cover over the front crt inspection hole.

In the inspection hole there is a black plastic "Focus/screen adjust Assembly" with 2 rows of 3 controls.

One row is focus and the other is screen. The middle controls are for green with R/B on either side. Usually the controls are labelled as "focus" and "screen". You want to adjust the focus controls, one for each color. Look for the focus or screen label imprinted in the plastic. Don't play with the screen settings.

With the same misadjusted convergence pattern you can see a red, blue and green line. Adjust green focus and watch green line for best focus. Do same for other 2.

Screen adjustments are very exact and delicate. The easiest way to deal with them is to turn color off in Customer adjust menu. Put any color tone adjustments in the middle (low, med, high, put at med).

You should have a b/w picture if there are no crt or other color related faults. If it is close to B/W leave screens alone.

If the pix is too green, then the green screen setting must be reduced a small amount. Do not play with these adjustments as most TV repairrers have a difficult time adjusting them.

If focus adjustments don't help then focus control or CRT may be defective. Needs expert to determine.

easyab

http://calgaryconvergencerepair.weebly.com/convergence-ics.html

Yes, Convergence settings should be tried first before any color adjustment or any fluid changes are done. Remember that there are 3 colors to notice. Red, Green, Blue. The Green is the only one that you can not move with an adjustment The Red and Blue is ligned up on green. Some cases it does matter how linear the Green color is across the board, just how close you get the blue and red on top of green is what matters.

adjust the flyback focus of your tv
just look at the flyback and you can see there the focus and the adjusting for the screen.

thats only what i know at least maybe it can help =).

Hello, if you want I can supply you with the service manual, please leave your email. Best regards, Arpi

IF the area of the OSD (on screen display) displays the same vertical blue lines as the rest of the screen, then it is most likely the optical block assembly at fault. It's part number is A1606006A and should cost close to $2,000. I'm assuming the set is out of warranty. I know many people are hooked on Sonys, but as a technican that works on them, I wouldn't want one in my home.