[rorox64]

I'm trying to help a friend of mine with the problem involving those barely visible lines, running up and down on some ECP pjs.


I've found out that the first reason is given by the electrolytic capacitors on the LV power supply line.


Changing all the output voltage lines capacitors almost 90% of the lines disappear. The first reason is the age of the capacitors that lowers their filtering capability, but it's reccomended to

replace some output caps with bugger ones (in MFD).


Another kind of barely visible noise is given by the presence of the ACON board (incredible!) whenever I tried to put it, on some pjs, I experienced some image noises...


I tried to better filter the power supply in input to that board, but that doesn't change anything (and it's almost obvious).


I guess that the problem is related to the generation of the impulse voltage for the step-motors (the NE555 oscillator and so on...). For somewhat reason, a feedback impulse voltage, re-enters the general power supply line.


does anyone have any further info on that? any hint?


thanks in advance


Romano

 

[taylor]

Romano:

I wonder if this sort of problem is the cause of my video noise and interference I have on my Gp-3000. To refresh your mind, what's happening is I have blurring/smearking/echoing in my projected image. If I hit Picture Mute I can see the noise by itself on the CRT faces. If I crank Brightness and Contrast with the test pattern up I see the source noise moving around on the screen. I've tried several different sources and the two possible inputs, RGBHV and SVideo. Also when using my Echostar 6000 HDTV receiver and displaying HD content I can see, periodically a wavy disturbance which is really easy to see if I bring up the test pattern grid. My biggest problem is this echoing, it's really become quite annoying, I've went from cheap VGA-RGBHV, to Homemade, to BetterCables and then to an Extron 109Plus. All had the same problem. (Obviously this isn't the issue since it does the same thing with an SVideo connection). Some have suggested termination, but I point back to SVideo showing the same problem.


Any thoughts on a parallel to your problem/solution and mine?

 

[rorox64]

I don't think that there is any kind of relationship, between that problem and the problem that I solved.


You surely have a problem on the pj. I'd swap the input board, and then probably some other boards, if I were you.


First of all try to localize the problem, looking directly into the htree colors (at low contrast).


If the problem appears just on a specific color (like the green), just try to swap the green carthode amplifier, for first. After that try with the input board and then with the waveform module.


your problem seems to be related to some ground connection (loop or missed...)


Romano

 

[taylor]

ookie, sorry to interrupt your thread. (BTW, it's on all 3 colors, and board swapping plans are in progress)