Thought I could post a guide on how to modify the Odyssey 2 since I have done it myself recently
When you modify an Odyssey 2 you build the AV-card like this:

For a sharp picture, use a 100nF capacitor between +5V and GND
When you modify a Videopac G7000, do like this:

To lower the strong color a 270pF capacitor is connected from Video-In to GND. If you do this on an Odyssey 2, the color will vanish and the picture gets extremely bad so don not mix the schematics with each other
Here is the RF-modulator. I will remove the curcuitboard inside the shield and replace it with the AV-card that I am building

Had to solder for a while to remove the RF-modulator

Now the AV-card is put inside the RF-shield and on the subside of the board there are rubberfeet that will protect the circuit from getting in contact with the metallic case. One cable from the circuit is soldered to the case for GND and another one goes from the case to the GND on the RCA jacks.

Once finished, the case is back on the place it belongs and screwed with the GND cable from the mobo. The trimpot must be on the lowest level to get satisfactory picture

In the beginning it was maxed and the picture got bad but now it is good. I use Crypo-Logic to test the color and sharpness in picture and it works great now

Also tried with the PAL version of Pickaxe Pete and it shows a good picture

I recently saw another mod that could be done, probably only to the G7000 but is was far more complicated with more resistors etc so I highly recomend this one, at least for the Odyssey 2. I don not have a Videopac and have newer used one so my experince stands with the Odyssey 2. But that other guide has information on how to modify the G7000 for RGB
Hope someone knows a similiar AV-mod for the 5200 SuperSystem so I can make it simplelike in this mod