Re: Convergence and proper color level adjustment (long)

Hi Jon,

> Convergence correction: You have probably seen magnetic shunts glued
> underneath monitor yokes. I was trying to figure out how the placement of
> these shunts affected the display. Apparently, they are not meant to
> correct problems in the corners. They are only used to correct problems at
> the top, bottom, left and right. They are placed under the yoke to make
> corrections in the initial deflection. The placement is an art, as you
> need to move them around to find the sweet spot.

What I have seen from it, the permalloys used in between the yoke and the tube
do convergende the corners. I have used these myself to convergence the corners
of the WG6100. It had most effect on the red and blue beams. I did not really
see any difference in the sections you described. Where were the permalloys
located at your 6100?
If I remember well, the sides could be convergenced by the magnets at the neck.
Opening and closing the pairs would rotate two colors (i.e. red vs. blue for one
pair and red/blue vs. green on the other pair) in opposite directions of each
other. Setting the size of the deflection at the end was done by tilting the
yoke left/right. By these two adjustments I was capable of convergencing the
up/down left/right properly, and still had to use the permalloys for the corner
convergence.
 
> As far as the corners are concerned, there are some chevron shaped magnets
> that you apply further out on the tube to affect the deflection just before
> hitting the phosphors. Again, there is a sweet spot that you can only find
> by moving the magnet around.

Hmm, I have never seen these on a WG6100. Interesting, where are these located?

> Color level adjustment: I didn't like the way this has been described. You
> are instructed to adjust the bias to set the dimmest white line to pure
> white. Likewise, the gain is adjusted to set the brightest white line to
> pure white. What I have found to be the best way to do this is the following:
>
> 1) Adjust the bias and gain knobs so the colors are the brightest (the
> black and white pots are turned in opposite directions to acheive this).
> 2) Adjust the screen control until the dimmest white line barely has any
> visible color (typically only one or two of the three colors is left visible)
> 3) Adjust the black knob for the visible color(s) until the color just
> disappears. The line should not be visible at all.
> 4) Repeat steps 2 & 3 until all three colors appear and disappear together
> when adjusting the screen control.
> 5) Adjust the screen control until the brightest white line barely has any
> visible color.
> 6) Adjust the white knob for the visible color(s) until the color just
> disappears. The line should not be visible at all.
> 7) Repeat steps 5 & 6 until all three colors appear and disappear together
> when adjusting the screen control.
> 8) Repeat steps 2 through 7 until the colors seem to be in sync for both
> the brightest and dimmest white lines. They are all now pure white.

This is indeed the right way to do this. However, I suppose this is the way to
go if every gain / bias is set wrong, or when the tube has been replaced. If I
adjest the tracking of a monitor that is just 'off', I go to the brightness test
pattern (the one with all colors + white fading from dark to bright) and set the
screen so that the dimmest can *just* be seen. You will find that at that point,
the dimm white line is not white anymore and a bit reddisch, blueisch or
greenisch, or a combination of them, if one is weaker than the other two. This
can be seen at the red, green and blue dimmest lines as well, one of the three
will be invisible before others do when rotating the screen setting. Then I set
the R, G and B lines to equal brighness (the white line becomes white) by the
bias pots. The I repeat the same for the brightest areas, whithout changing the
screen. Then set the screen for the desired overall brighness.

This has worked very well for me. Remember, this only works if the colors a
slightly off. It does not setup the biases and gains properly in relation to the
screen setting, use the description Jon made.

Mendel
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Received on Sun Nov 12 10:56:24 2000