Atari 7800 s-video mod (with pics)

[Jamisonia]

Just finished modding my Atari 7800 for s-video. I ended up using these instructions: http://saundby.com/atari7800mod/7800_vi ... ction.html

I do not suggest using the often quoted Atari resistor ladder quoted here: http://atari7800.org/7800mod/7800_mod.htm as it created a very dim image for 2 7800s I tried it on. The other author of the Saundby site had the same issue.



RF Output Xevious


S-video Output Xevious


Look first at the lettering and numbering and see how much more clear the s-video is. Then look at the dark green bushes. You can see blue pixels in the s-video picture that you cannot see in the RF picture. The bushes tell the tail of the improvment s-video can provide more than the lettering.

Obviously pictures do not do the mod justice. It looks excellent. But more than that it sounds excellent. The RF sounds tinny, restrained, and muffled. Seperating the audio signal opens up the soundstage. You can hear much more tonality, more dynamic range, and clearer sound.

Please click on my link for more pictures, and bigger pictures of the ones I posted here. Tell me what you think, and if you need help doing this to your 7800 please ask.

http://s1182.photobucket.com/albums/x447/jamisonia1/

[BRIK]

That's some awesome improvement!

[Dakinggamer87]

Nice improvement!!

[fvgazi]

Looks great!!! I was wondering why you even wanted to do this, but it really made a huge difference.

I hope that keystone coupler didn't give you too much trouble.

[Jamisonia]

I had to make it much shorter though. I used some nips from harbor freight I purchased a few years ago. Too bad I didn't line up the RCA jack better though. That looks pretty bad.

[Hobie-wan]

Much better. Like the 2600 mod, makes a huge difference on the older machines that never had great RF to begin with.

[CFFJR]

Definitely impressive.

How long did it take you?

[Hatta]

I noticed the ship is beige in the RF and white in the YC. I wonder which one is "right".

[RyaNtheSlayA]

I noticed the ship is beige in the RF and white in the YC. I wonder which one is "right".

Well, I think the RF would be "right" as thats all the 7800 used, thus graphics would be designed around that?

[Jamisonia]

Definitely impressive.

How long did it take you?

This mod took me a week, mainly because I kept following the Reqsoft version, that uses Atari's resistor ladder, and they kept producing a dim picture. When I finally changed to the Saundby version, which uses a small potentiometer to adjust the brightness, it all worked very well. From talking to the guy who wrote the Saundby mod about using Atari's resistor ladder he said

The folks who use the same
resistor values as the original ladder aren't accounting for the
difference in loading between the RF modulator and a direct video input

I highly suggest using the saundby mod. Using the Reqsoft version will result in a decent picture for 7800 games. They will look okay, albeit a bit dark. Atari 2600 games will be unplayable. The trees in Pitfall were black, while the background was in very dark green.

This isn't mod isn't the easiest in the world, compared to say the Genesis or SNES Mini s-video mod, which only uses a few components, but its not really that hard as long as you pay attention when placing the components into the board. I have not been able to test any Pokey audio, as I do not have a game that uses the Pokey audio chip.

Had I used the saundby mod initially I believe I would have finished in two evenings. One to do the mod and test it, and one to install the jacks and get it all closed up.