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Is this ringing?
Posted: Tue Feb 04, 2014 7:08 pm
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I have a problem with my current setup.
I use this monitor, with composite input. I get the artifacts you see in the pictures. Essentially, if I have a clear object it is followed by a dark line and if it is dark it is followed by bright line Is this ringing or does this have another name? I wonder why it happens a lot on green or yellowish background, but I cannot see it on blue or red background. I tried changing the cable but that didn't solve the problem. I tried putting a 220uF capacitor in series but nothing changes. When cleaning the tube, I am worried I may have touched a potentiometer. Do you think that could be a cause? Do you have any suggestion? |
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Posted: Tue Feb 04, 2014 7:14 pm |
Impedance mismatch causes that kind of stuff aswell as (excess) low pass filtering.
And I it is called ghosting from what I know. |
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Posted: Wed Feb 05, 2014 12:02 am |
A lot of professional monitors need a BNC terminator if you're not passing the video through it to another monitor. The terminator is just a BNC dongle with a 75 Ohm resistor inside.
Attaching that to whatever free output is on the back should clear up the ghosting / ringing. |
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Posted: Wed Feb 05, 2014 5:59 am |
Thank you Tmee, yes, impedance mismatch is what I was imagining, even if I wonder why it becomes significantly visible only on green backgrounds. I tried changing console, and the result is pretty much the same.
What could I try? ccovel, thank you. The monitor indeed has a BNC as input, and a BNC output, so I guess it is exactly the case you have in mind of the possibility of passing the video through it. Actually, the RCA to BNC adaptor (simply a "piece of metal") is one of the things I doubt as responsible. It seem also to have a terminator inside. It has a switch, with 2 options, 75ohm or open. When I set it to open the colors become much more bright, as they clearly become not attenuated by the 75 ohm load. Do you have any suggestion on what I could try? Now that you told me about this, I thought that maybe I could try to add a pot at the output bnc, leave the switch as open and see if a value other than 75 is the right one for the cable I am using. |
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Posted: Thu Feb 06, 2014 7:39 am |
I tried to use the potentiometer as a terminator, but in the range 500 ~ 20 ohm it doesn't disappear, just (obviously) the color gets darker as I reduce the resistance. | |
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Posted: Sat Jul 05, 2014 3:42 pm |
This happens a lot on the SGG(Sega Game Gear) when the screen starts failing. I wonder if the brightness is just too high on your TV set. Turn down the brightness, your TV may also just be old. | |