On Tue, Apr 12, 2016 at 10:50 AM, Bill Sudbrink via vcf-midatlantic < vcf-midatlantic@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