Atari 7800 Composite mod - Wrong colors?

[Amerika]

Hello!

 

So I recently modded my Atari 7800 with composite out and everything seems to have gone well except for the colors. I've adjusted the pot and I just can't seem to dial in anything that looks correct compared to videos I've seen on Youtube or Google images. This is the mod I am using.

 

Here is a video of some capture from my system. I adjust the pot during the demo playthrough to show everything.

 

The video is darker than what my TV shows so don't worry about that. It's just the colors don't seem to match up with most everything I've seen.

 

Does anybody have a good idea what might be causing this? Or is this just what is expected with a composite mod and some 7800's?

 

Thanks!

 

Michael

[+-^CrossBow^-]

First the video isn't bright enough for me to see any colors really. I do see where you turn the color pot and can see the water turn blue to purple..etc. But the rest of it is way too dark. Is that how it actually looks because that isn't normal at all.

 

Even if you get the brightness corrected, it is just a fact of life that current NONE of the 7800 mods actually produce the correct color hues on modern LCD televisions. The 7800 relied a lot on persistence of vision and crt artifacting to produce what would be considered normal. Best mod available for both composite and s-video is really the UAV board.

[Amerika]

First the video isn't bright enough for me to see any colors really. I do see where you turn the color pot and can see the water turn blue to purple..etc. But the rest of it is way too dark. Is that how it actually looks because that isn't normal at all.

 

Even if you get the brightness corrected, it is just a fact of life that current NONE of the 7800 mods actually produce the correct color hues on modern LCD televisions. The 7800 relied a lot on persistence of vision and crt artifacting to produce what would be considered normal. Best mod available for both composite and s-video is really the UAV board.

Oh, weird. On OBS it was dark but not that dark. I never checked what it looked like on YT before posting as I thought it would be similar to what I saw on OBS which is traditionally darker than what the video ends up looking like on YT. But, you're right, it's way too dark to see so my apologies. My TV is much brighter and looks totally fine. It's an CRT (32" WEGA 60hz).

 

I looked up the UAT mod but I don't know where to buy the board/parts outside of contacting Bryan on this site. Which I did but I have not heard back (it was only a week ago). I would gladly rip out my composite mod and install the UAV if I can get my hands on a board.

Edited May 28, 2018 by Amerika

[+-^CrossBow^-]

Just have to be patient. He is basically done with the current Rev D version of the board but was planning to make up a few more. So I would suggest sending him a PM again if you haven't recently and see what he has to say. I'm pretty confident this latest batch he is making up will be his last until he has the new revision done.

[Osgeld]

its a poor transistor bias, typical of passive mod's

 

if you do not want to wait for the next version of the excelent UAV shoot me a pm, I have a halfway point that does great with 4 siwtch 2600's and 7800's

 

transistor mod's do work, and work well but people have to put like math and effort into them ... which you wont get with a grand total of 5 cents of parts sold for 14 bucks on ebay

Edited May 28, 2018 by Osgeld

[Amerika]

So, I found this video when searching Bryan's post so that I could read up on the UAV a bit and to see what is in the new revision. I believe it was a video made by Crossbow (excellent job explaining btw). It would appear that the colors being shown on the finished s-video mod actually match my own almost perfectly. So, I guess that is accurate? It's odd that other screenshots and videos I've seen have vastly different coloring.

 

Even if that is the case, I would still be interested in the UAV as s-video would play much nicer with my capture chain. I could definitely hold out for the new revision since it seems like my setup is mostly fine now. What are the updates to the new revision? I failed to find out any info on it.

 

I did this composite mod almost to the letter: http://vintagegamingandmore.com/installation-guide-7800/ Am I going to have any issues installing the UAV? As in, will I need to replace R3 and R5 that I cut out? Or the c10 cap I removed to pull my pokey audio (with a 6.8k resistor for hopefully proper mixing)? It's not a big deal if I need to but what I did might not be included in any UAV install instructions. Speaking of UAV install instructions, are there any handy I could read? The thread I linked didn't actually have much for instruction despite the name!

 

Sorry for the ignorance and the questions. I've searched to answer my own questions but I keep coming up with either very little or conflicting info. I really appreciate you guys taking the time to assist me here. I've really been enjoying my 7800 (and 2600 games on it too). Way more than I ever thought I would despite growing up with an NES and only playing a 2600 a few times as a kid.

[+-^CrossBow^-]

Both of those videos were done by me. And the link for the instructions I wrote are also linked just below the second video:

 

http://atariage.com/forums/index.php?app=core&module=attach&section=attach&attach_id=510016

 

To answer your question, I've been replacing all removed components from other modded consoles sent to me for UAV installation. Although to be honest, since we are grabbing the video points from the south legs of the resistors, they likely don't need to be there are all. But the point of the UAV is to keep the system modding to a minimum so that you can bring it back to stock condition pretty easily. So you will definitely need to replace R5 back in the system for audio.

 

As for the audio, the cap is likely fine as my instructions will also show, it is best to pull the audio from the north legs of R5 And R6 and use a 10uf cap for filtering. Bryan did create a separate audio board known as the UAC Ultimate Audio Companion, but he is out of them currently and advised he didn't have plans to make any more given how difficult they are to make at such a small size.

 

I don't know all of the plans that Bryan has for the UAV revision. I do know that he plans to increase the quality of the video output when it is used on the 5200, as many 5200 exhibit a noticeable jail bar pattern on the left half the screen. I saw it on a 5200 I modded and others have as well. Additionally some 5200s seem to work with the UAV with their buffer chips removed whereas the one I did ( a 4 port unit) refused to operator without that chip still being in the mix. So I believe Bryan's next revision will incorporate an SMD newer replacement for the 4050 buffer so that it can be removed and the UAV plugged into its place. I believe Bryan also advised that he might add the UAC functions into a future revision as well, but I don't know if that is in the current works.