Installation Guide – 7800

Atari 7800 Video Mod Installation Guide

Disclaimer: I am not responsible for any damage done to your Atari. This mod is designed to permanently remove the RF output. The mod will work if performed correctly to a fully functioning Atari. Perform at your own risk.

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Tools You Will Need

• Philips Screwdriver
• Soldering Iron and Solder
• De-soldering Tool (De-soldering Iron, Bubble, Vacuum, Braid)
• Wire Cutters/Strippers
• Needle Nose Pliers
• Drill with 1/4″ and 1/8″ bits

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• Turn the Atari over and remove the 5 screws. Set them aside for later. Remove the main board out of the console. Using the need nose pliers, twist the tabs around the metal case so they are straight. Remove the metal casing (top and bottom) and throw it away.

• You should now have the main board like this ready to modify. On the top left hand side of the board are two resistors (R3, R5) you have to remove. They are marked in the picture. Use the wire cutters to cut both ends and throw them away. Then you need to cut the 4 pins going into the RF modulator circuit board (silver box with circuit board attached to side). Then break off the small circuit board attached to the RF modulator and throw it out.

• The picture should look like below. Remove the 4 pins using your de-soldering tool so that the holes are open. Then remove the solder from the other hole marked on the board. These are where the input wires will connect to the mainboard. The system should look like the picture on the right.

• Now it’s time to assemble the circuit board. Just follow the picture below and solder in the transistor,

  2.2k Resistor (Red-Red-Red), and 3.3k Resistor (Orange-Orange-Red). The components are labeled on the circuit board so it should be pretty easy to see where they go.

• You should have two pieces of 4 conductor wire. First, strip off the white sheathing. You can save about an inch of it to help group the wires together if you like. Next, set aside one of the yellow wires (You can use this later for the pokey audio). Now you should have two groups of wires. A group of 3 output wires (Red, Black, and Blue), and a group of 4 input wires (Red, Black, Blue, and Yellow). With the new wire I use, Blue replaces Green and Yellow replaces White in the pictures. The group of 4 wires are the input wires that go to the main board. Strip about 1/2″ off of both ends of the input wires and attach them to the mod kit. Black is the GND, Red is +5v, Blue is Video, and Yellow is Audio.
• The group of 3 wires are out wires that attach to the RCA jacks. The output wires should be stripped to different lengths as in the picture. About 1/2″ for Blue, 1″ for Red, and 2″ for Black. On the output side of the mod kit, Black is for GND, Red for Audio, and Blue for Video.

• Attach the input wires to the main board like in the picture and solder them in from underneath. Make sure the black wire goes into pin 1 where the RF modulator pins were. The Red goes into pin 2, and the Blue into pin 3. The Yellow wire should be soldered to the lower hole underneath the two IC’s. An alternate location for the white wire is the left side of the capacitor(Green component, 2nd from bottom in row of resistors). After this the main board is done. (Unless you want to do the optional next step for the POKEY Audio.

• There are only a couple games that use the pokey audio so this step isn’t necessary unless you have commando, ball blazer, or some custom made game. If not then just skip to the next step. If you want to install it then you will need to remove the C10 capacitor which is located just below the channel select switch. In the picture I removed the switch since it isn’t needed anymore and is slightly in the way. Use whatever de-solder tool you have to clear out the top hole and solder the yellow wire you set aside earlier in the top of C10. All you need to do is combine the audio singles with the Red output wire. The best thing to do is leave the wire connected to the top of C10 until the very last step. After you have completed the mod and are ready to put the cover on, solder the wire to the center post of either the Red or White RCA jack. That will combine the audio signals so you have the pokey for games that use it. (Note: Some people have had an issue with the balance of volume on the main audio and the pokey, if the pokey is too soft add a 6.8k resistor (or any resistor near that value) in series to the main audio out wire. This should balance out the audio better.)

• Take the bottom half of the case and put a piece of masking tape on the left hand side where you want the RCA jacks to go. Some cases can be very brittle so be careful. Use a ruler and marker and make 3 dots on the tape 1/2″ apart. Then drill 1/8” pilot holes on the dots, and use the 1/4” drill bits on the holes to make them ready for the RCA jacks. The tape and marker are just extra precautions, you could also just drill the holes if you want.

• Attach the RCA jacks by mounting them into the case with the ground ring and nut on the inside. Make sure they are tight. Have the ground ring holes be at or near the top and bend them down to make soldering easier. Take the Black output wire with the longest amount of bare wire and solder it to all three ground rings like in the picture below. Take the Red wire and solder it to the Red and White jacks. Take the Blue wire and solder it to the yellow jack.

• Now you are ready to put the main board into the case. Peel off the bottom of the double sided tape and stick it to the left inside edge of the bottom case. Replace the top case and screws and you are ready to play your Atari with composite video! Leave a comment below and let me know how you made out!