For NTSC Color Video Output

Step 3- Remove the crystal currently installed and replace it with the new crystal in series with the small green trimming capacitor. This capacitor is 2.5 to 25 pF. The circuit should be as in figure 2 below. The assembly should be held down with some RTV adhesive, but be careful not to get the RTV into the trimmer capacitor, or to allow the metal case of the crystal to contact any of the components on the board. If you will not ever wish to use any of the color features of Apple the new crystal may be installed without the trimmer capacitor.


fig2.GIF @12k

Step 4- Remove the small coil (L2) in the oscillator circuit in the lower right corner of the board and replace it with a 47 Ohm 1/4 Watt resistor.