[vcf-midatlantic] Final class schedule for this Friday

Matt Patoray mspproductions at gmail.com
Tue Apr 12 11:48:47 EDT 2016


On Tue, Apr 12, 2016 at 10:50 AM, Bill Sudbrink via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

>
>
> I don't know if I'll be there in time for your monitor
> class, but one of the things I've always had trouble
> with is how to tell where the problem lies.  In
> particular, image issues like "ghosting", "wavy"
> images, general fuzziness.  Sometimes it seems like
> the source is the problem, but then you try the same
> source with a different monitor and the problem is
> gone.  So you try the "bad" monitor with a different
> source and there's no problem there either.  What
> the...? you ask yourself.  So you put the original
> monitor and source back together and the problem is
> still there.  Very frustrating.
>
> Bill S.
>
>
> Bill,

First off i am assuming that we are talking about conneciting an NTSC style
source to an older NTSC CRT based monitor. I will not get into the issues
of using ann LCD/Plasma to display NTSC...

I am going to cover the 2 most common causes of "fuzzieness".
1. Convergance, this is where the 3 electron beams from the CRT do not meet
up percicely at the shadow mask/apature grill of the CRT, thus the beams
strike the wrong color of phosphor. this can easily be seen with white text
or lines/boxes, you will see that in the center of the white area
everything is white but then there are little color "fringes" of red, green
or blue.
The procedure is differnt forn diffent styles of monitors/tvs say
Trinintron vs non trinitron, but if the monitor/tv has a menu system see if
you can find a convergance menu (sometiems a service menu) and select the
options for comvergance and alllign everything meet in the center, for
convergance you leave the green alone and move the red and blue to meet
green.
 If there are not menus you will have to get inside the monitor, for non
Trinitrons the convergance adjustments are generally on the neck of the
tube as a set of movable magnetic rings on the neck of the tube, they get
rotated to change the allignment. Real old sets have a "Convergance Panel"
inside the set with the adjustments as a large field of pots and coils.
For Trinitron based monitors, they have the magnets on the neck of the CRT
as wll as a "H-Stat" atjustment on the flyback, you adjust that to get
things as close as you can horozontally then go to the rings on the neck.

For most older monitors convergance is a compermise, it will always be best
in the center and drift out twards the edges of the tube, you just get it
as good as you can.

2. Focus, this is general fuzziness even when the convergance is good, as
such the convergance needs to be close before focuse can be properly
adjusted. This is an internal adjustment, sometimes as on Trinitron
monitors the focus control is on the flyback, but on most monitors it will
be genrerally in the same HV area as the flyback, you just adjust for the
best results.

Hope this helps.

-- 
Matt Patoray
Owner, MSP Productions
KD8AMG Amateur Radio Call Sign



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