lcd banding

mindstein · Post by **mindstein** » Mon May 17, 2004 2:03 pm

I am getting banding on my lcd. It is a RCA pocket tv with a 3 inch screen.(16-3065) I have a modded 4x4 board following Bens directions. It works great. I have the output conected to rca jacks for testing.
My problem is that on a large tv the pic looks great (slight darkening of colors everyone reported but otherwise great picture) When I hook the 4x4 to my rca pocket tv I get a banding of the colors. Alternating shades of lighter and darker colors instead of the color it should be. I hooked up the lcd to my unmodded 2600, by using rf to the vcr from the 2600 and composit from the vcr to the tv. The video on the pocket tv looks great!! no banding.
So to recap using bens video mod it looks great on big tv but banding on lcd.
Lcd hooked up to unmodded 2600 looks great. Anyone have any clues.
If it was a problem with the mod it should show up on the large tv but dosen't.
I am going to try the 4050 video mod to see if it helps with the problem.
If anyone has had this problem please help. This is the last issue with my portable and then it's case time.
Just to let you know it has 2 controler ports (both paddle complient), both dificulty switches, an on-board paddel, 3 inch screen, video out and in, and my real contribution is 4 socketed on-board games. The games are selected via a modified scsi id selector switch, and with the sockets you can swap out the games. V2 will have a programable eprom with a program port to load new games on. This was to ambitious for this project. and will be included in v2.

JackFrost22 · Post by **JackFrost22** » Sat Sep 25, 2004 3:42 pm

Try messing with the pots

mindstein · Post by **mindstein** » Sat Sep 25, 2004 4:07 pm

hi I have actully blown off bens mod in favor of the 4050 chip mod.
It works mutch better. Colors are great.
The issue I am having is that the LCD is making an intrefering RC (radio) signal.
Causing wavy lines on the screen.
I have since tried different LCD and the problem is with the first LCD, not my video mod. I think it is a shealding issue.

I have since played with the first LCD and isolated some of the interferance.
But I cant get rid of all of the interferance.

Oh well, I will use a different LCD in my next mod.
The interferance is berable now and only is bad on a few games.

JackFrost22 · Post by **JackFrost22** » Sat Sep 25, 2004 4:11 pm

Well you could use shielded wire unless you have already tried that.

Post by **gannon** » Sat Sep 25, 2004 4:40 pm

So are you using a portable tv that has rf input, but then just using composite? With the portable tv I traded to NES Man I had to desolder the video pin to fix the banding problem.

segasonicfan · Post by **segasonicfan** » Sat Sep 25, 2004 7:23 pm

RF input is pretty standard with pocket TVs these days. They are listed as "EXT ANT" in but it is exactly the same thing as an RF input sized into an RCA Jack (with ground and the audio/video line).

As for the LCD interference, I've had such problems myself. I can't stand the interference with those wavy lines, even if it isn't the most extreme problem. In referrence to your color complaints, I have much the same. Ive noticed that when a character is against a dark background (common in space shooters) they colors of that characted/ship lighten up and look really awful. This combined with crappy mono sound, wavy lines, and composite input have led me away from pocket TV portables and now I am strictly sticking to PSOne Screen portables.

As for bens LCD mod, could someone send me a link? I haven't been able to find it and I would love to see how he managed to shrink down those pocket TVs.
-Segasonicfan

mindstein · Post by **mindstein** » Sun Sep 26, 2004 2:26 am

The wavy lines is exactly what I am getting.
I also get a slight striping.
But if someone knows how to get ride of the wavy lines that would be great.

So gannon. What video pin are you talking about desoldering?
I think that is the problem I am having.

Post by **gannon** » Sun Sep 26, 2004 9:32 am

In my old pocket tv there was a chip that converted the rf video into composite video, but there was no standard composite input. I looked up a datasheet for the chip and found out the composite output, then I just desoldered that pin and soldered the composite input onto that area.

segasonicfan · Post by **segasonicfan** » Sun Sep 26, 2004 12:08 pm

Well the wavy lines are a result of poor grounding. To get rid of them, you need to simply ground the unit better. If you used a casio EV-680 or similar TV and separated the pins connecting the 2 PCBs you much add shielding to whatever wire you used to connect them again. The RGB lines as well as other delicate information runs through there. If you don't have that type of TV and are experiencing that problem, I suggest you put a copper sheet around the PCB or wiring and see what happens. It has been my experience that the composite input lines have not caused the grounding problem, it's a problem with the TV itself being grounded.

-Segasonicfan

mindstein · Post by **mindstein** » Sun Sep 26, 2004 2:17 pm

OK here is where I am at.
I know that my tv and remote wireing and grounding of the unit are fine because, When I hook up the out put from my NOAC the wavy lines are gone and the screen looks great. Also If I use the output from my tv the picture on my portable again is great.

I only get interferance and wavy lines when I use the output from the cutdown atari board and the video mod.
So you would think the problem is with the cutdown atari board and the video mod I made.
But if I test the cutdown atari board and the video mod on a regular tv it looks fine.
I'm stumped but atleast I know that it is not the LCD.

I wonder if it could be a scan rate problem.
I remember that in the past when I had 2 computer monitors next to each other and the scan rate on the monitors are very different I would get similar wavy lines. (this was in the old days, monitors have better shielding now )

Post by **gannon** » Sun Sep 26, 2004 3:08 pm

hmm....I doubt it's a scan rate problem.....maybe the screen needs a stronger video signal?

mindstein · Post by **mindstein** » Sun Sep 26, 2004 4:15 pm

Do you have any idea how to boost the signal?

It realy looks great with the NOAC playing through it.
I can't wait to start that project.

Here are some pics so that you can see what is going on,
My camera is not good so the screen actualy looks much better in real life

OK here is a pic with the NOAC playing through it and a close-up of the screen.

and here is an atari with the 4050 video mod playing on the lcd.

and here is the same atari with the same video mod playing on my TV
The slight wavy lines on this pic are not realy there. it is from my camera

HK-47 · Post by **HK-47** » Sun Sep 26, 2004 4:25 pm

Mabye you'll have to rebuild the vcsp using bens video out mod. => http://www.classicgaming.com/vcsp/Question2.htm

mindstein · Post by **mindstein** » Sun Sep 26, 2004 4:55 pm

The I have used Bens mod. It is worse. The problem happens with his mod as well.

Post by **gannon** » Sun Sep 26, 2004 5:04 pm

hmm......it almost seems like it might be a sync problem, but I'm not sure how to adjust that with the mod you're using