Forums

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?

2014-02-05 02.28.17 2.jpg (765.27 KB)

elevator action

2014-02-05 02.23.07-1-3.jpg (477.26 KB)

flicky

P1120031.jpg (254.38 KB)

alex kidd ok

2014-02-05 04.00.17.jpg (511.8 KB)

alex kidd bad

Impedance mismatch causes that kind of stuff aswell as (excess) low pass filtering.
And I it is called ghosting from what I know.

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.

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.

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.

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.

Author	Message
kamillebidan Joined: 25 Feb 2013 Posts: 384 Location: Osaka	Is this ringing? Posted: Tue Feb 04, 2014 7:08 pm
	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? 2014-02-05 02.28.17 2.jpg (765.27 KB) elevator action 2014-02-05 02.23.07-1-3.jpg (477.26 KB) flicky P1120031.jpg (254.38 KB) alex kidd ok 2014-02-05 04.00.17.jpg (511.8 KB) alex kidd bad

TmEE Joined: 31 Oct 2007 Posts: 853 Location: Estonia, Rapla city	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.

ccovell Joined: 26 Dec 2004 Posts: 374 Location: Japan	Posted: Wed Feb 05, 2014 12:02 am
ccovell Joined: 26 Dec 2004 Posts: 374 Location: Japan	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.

kamillebidan Joined: 25 Feb 2013 Posts: 384 Location: Osaka	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.

kamillebidan Joined: 25 Feb 2013 Posts: 384 Location: Osaka	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.

Capt. 2110 Joined: 27 Apr 2014 Posts: 281 Location: Texas	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.

Forums

View topic - Is this ringing?