Video-mod for 7800 (NTSC version only)

[WERY]

I have recently got interested in the 7800 system(only NTSC). Since I started with videogame collecting, I only use "scart"(composite/s-video/RGB) connection on my systems for connecting to AV channels. Now the problem is that the most of Atari systems newer used a better connection than RF, thus an "early" system should be modified for RCA output.

 

I searched the internet for information on how to modify a 7800 system and got a guide in PDF that describes to whole procedure. It also stated that besides of the tools, you need a so called "videomod card" thats gonna supply the s-video, composite and sound but it has to be purchased from somewhere. I checked ebay but there was no such card for sale which make me think they are'nt usually for sale.

 

Does anyone here know how much that videomod card cost and has anybody tried that mod and where can I find it?

 

If I buy a system that has been modified already, how much does that cost(s-video is not a must)?

 

If you know better AV-mods for the 7800, you are welcome to bring this hints up as well. As I said, s-video does'nt has to come along with the mod. If there are good hints on just composite mods, they are welcome as well, I just dont want to use RF.

 

I was unable to attach the file of the guide but you find it here:

 

http://www.google.se/search?hl=sv&client=firefox-a&hs=4a2&rls=org.mozilla%3Asv-SE%3Aofficial&channel=s&q=7800+videomod&meta=&aq=f&aqi=&aql=&oq=&gs_rfai=

 

Look at "Atari 7800 Video Mod Installation Guide". I'ts a PDF file for download

[Shawn]

Read post #97 of this thread. It's the easiest and cheapest video mod for the 7800.

[+Mitch]

Since you are in Europe is there a particular reason you don't want a PAL 7800? There are even SCART PAL 7800 systems available though they can sometimes be a bit hard to find. Nearly all of the 7800 library was released in PAL format as well.

 

Mitch

[WERY]

Since you are in Europe is there a particular reason you don't want a PAL 7800? There are even SCART PAL 7800 systems available though they can sometimes be a bit hard to find. Nearly all of the 7800 library was released in PAL format as well.

 

Mitch

 

Well in this case I have not compared the NTSC and PAL version of the 7800 but I am sure you are talking about french 7800 systems that use SCART for their SECAM colorTVsystems. There aint time and money to hunt these secam-systems down and when they are rare, the competion is higher and so are the prices

 

I usually buy games from America and Japan, when living in Europe and it is easier to find games in America for Atari systems and the prices are way much cheaper in USA.

 

I searched ebay and found lots of complete games to both VCS, 5200, 7800 and Jaguar where many of these are sealed as well. Where I live, you dont see these games so often and they are either loose carts(to a fair price of course) or complete and sold very expensive with high prices from certain sellers like www.spelfyndet.se

 

We sure got the games here but market is not as big as in USA which makes it natural that you dont see the games so often. USA most likely have the widest Atarimarket in the world when it comes to these games. Besides I have the opportunity to buy most of the games when I please and not just when they happen to surface on tradera

 

I am a collector of NES and I certainly got more to choose from when using ebay when as good as all of the games surface everytime

[WERY]

*UPDATE*

7-8-2008; I have updated the instructions to include the POKEY audio fix and a resistor change that will bring down the brightness so light collored objects are not over-driven. Here is the info for the mod:

 

Parts List:

------------------------------------

2.2k 1/4 watt resistor

3.3k 1/4 watt resistor

75 ohm 1/4 watt resistor

47K to 68K 1/4 watt resistor

47K resistor (optional)

2n2222 or 2n3904 transistor

2 RCA jacks

hook up wire

-------------------------------------

 

Procedure:

 

1. Open up the 7800 and remove the metal shield.

2. Locate R3 and R5 and remove them. this is a good time to drill two holes and install the RCA Jacks. I installed mine facing down on the edge of the case.

3. Locate R11 and replace it with a 47K resistor. This is optional but it cuts down the brightness a bit. I didn't have this problem on my magnavox monitor but on my TV some light collored characters were over-driven.

4. Cut the pins that connect the Video modulator to the board. (don't do this if you ever think you will use the RF out in the future)

5. Build the circuit in the schematic. I just soldered the parts together then soldered the transistor's collector to the 5V connection on the expansion bus connector. The connection is the third point from the bottom on the right side. I made my ground connection by soldering the resistors to the edge of the board. I then ran a small wire to the video connection on the expansion bus connector. Finally I ran a yellow wire to the RCA jack. this worked well for me but it may be easier for some to build the circuit on a small piece of PC board such as Almost Rice did.

6. I connected a resistor to the bottom of C14. This is the audio out. Any resistor value between 47K and 68K should be fine. The other end of the resistor goes to the RCA connector

7. Run a wire from the top of C10 to the audio jack. This is the POKEY audio. I actually made the connection by running a wire from C10 to where the audio jack connects to the resistor I added for the audio output.

8. I connected the ground wires to the RCA jacks and connected the other end to the ground trace on the edge of the board.

9. Put the 7800 back together and enjoy the clean video and audio!

 

Here are some pics that will help explain:

 

Here is the upgrade. You can also see where I cut the RF modulator pins:

 

Here is a close up of the resistors to be removed:

 

Here is a closeup of where to find R11:

 

Here is the Amplifier Schematic:

 

Here is the amplifier installed in the 7800. The only solder points to the board are the 5V, ground, and the video in signal:

 

Here is the audio connection:

 

Here is where to make the POKEY connections:

 

Here is a close up of the C10 connection:

 

Here is a close up of the connection point to the RCA jack:

 

Here is a closeup of the RCA connectors:

 

Here is another view of the RCA connectors:

 

 

Enjoy!

 

This looks like a good way to modify the unit with ease so I will go for it. Thanks a lot to Puppetmark

[WERY]

Finally, I did it. I followed the scheme that Puppetmark made but I used a card to attach the new video and audio circuit. It is written in swedish cause it has been posted on communities there but the text you will see is just a description on what you se on the pictures. I will certainly do this AV-Mod again. I should buy lots of units and modify them

 

Jag har just moddat min 7800 så den funkar med scart-ingångarn på TVn. Fy satan i helvete vilken underbar känsla

 

Här bygger jag kretskortet där bild och ljud skall gå från konsolen och ut till TVn

Den blåa kabeln går till GND på moderkortet och den röda är till för att jorda RCA jacken. Har även limmat på gummifötter på kretskortet så det kan står på moderkortet utan att kortsluta något.

Här har jag kopplat in ljudet från konsolen till kretskortet jag gjorde. Den svarta kabeln går till POKEY'n på C14 och den röda till ljud-output'en på C10

Kassettdäcket är inte lika stort som på NES men måste avlägsnas för att man ska kunna löda en kabel till POKEY'n. Fördelen är att den är mkt lättare att montera av och på samt den har bara 2 skruvar för detta ändamål

Hela konsolen med det nya kretskortet som just kopplats in. Observera att bilden är tagen före jag bytte den röda kabeln som går till +5V outputen på konsolens baksida. Videoinput är oxå dragen på undersidan av kortet då expansinsporten är ivägen. (jag tror detta är den gamla modellen från 1984 då porten sitter kvar men nån får bekräfta om jag har rätt eller fel där)

Även om det var dumt av Atari att inte göra nån form av Scart från början var dom schyssta nog att göra ett hål i RF skärmen för underlättande av VideoMOD VideoMOD-hål FTW!!!

Så löds dom 3 RCA kablarna fast på respektive ställe. Hade gärna haft RCA jacken på sidan istället för neråt men det visade sig att detta var enklast i praktiken

Här är dom. Nästa gång jag moddar en 7800 kommer jag göra hålet för ljudet mkt trångare så det sitter hårdare. Men svårt som fan att skruva i och det sliter lite på kontakterna

Så blev första spelet att prövas Galaga. Det skiljer sig från Galaga på NES och det är kul för nu ska jag göra diverse comparisons mellan NES och 7800 spel. Ser fram emot det som bara fan 8-)

Fotot blev inte så bra men bilden är bra IRL

Ingen vidare ljussättning i rummet men det får duga för tillfället

Jag hann bara spela i några minuter och har redan hunnit få ett första stora favoritspel på 7800. Det blev Robotron 2984 och detta är ett spel som ser ut som om det vore ett ColecoVision spel, och det är en plattforms version av Asteroids kan man säga. Fast man måste gå runt för o kunna fortsätta skjuta och kan inte stå still på samma ställe

Här är schemat för VideoMOD kortet fast ljudet saknas i det och 75 ohms resistorn skall vara en 82 ohms istället

 

Har även spelat lite Donkey Kong och Ms Pacman. Kontrollen verkar funka rätt bra och det vara inte så jobbigt som man kunnat förställa sig av den lite oergonomiska designen. Hittade snabbt det rätt greppet så detta skall man nog klara men jag får inte ta ut nåt i förskott innan jag spelat några timmar. Men jag vill nu börja skaffa in lite enheter och material och börja modda om dessa till denna sorten så man kan sprida ut användandet av 7800 lite bättre. Kanske 5200 nästa...