50Hz /60Hz Mod (Atari Jaguar)

the atari jaguar can switch between 50/60hz by simply removing a resistor r140 on the b4 signal line, letting it float to 5v (via the resistor pack rp1) then adding a switch to pull it to ground or float back to 5v when grounded its pal 50hz , when floating to 5v its ntsc 60hz remove r140 to allow it to float this resistor pulls u25 pin 11 to ground, so not it is removed we can control that pin to use a switch simply wire a switch with one point to u25 pin 11 (the 50/60hz b4 pin) and the other point that is joined when the switch is on to ground this way when the switch joins the two pins it is pal 50hz , and when it is open (in the other position) its as if there is no resistor and runs at ntsc 60hz for ground i chose the pad c48 which has continuity to ground and is close to my switch the location is not ideal as it is hard to remove and install the pcb in this position note you have to power cycle the system between switching frequencies it will not change on the fly also, the audio and speed of the games doesn't change it is just the output frequency so you probably won't notice anything obvious change unless you are using an ossc that displays the frequencies for example i noticed as with many consoles, the retrotink range of products struggles to work with even stock jaguars in 50hz every other device from cheap converters to ossc and real crts have no issues video encoder composite color the jaguar also uses the mc13077 video encoder to handle the 50hz or 60hz output color on the chroma of composite if using rgb this is not a problem as it doesn't use composite color the board comes with a resistor pad to install a 0r resistor to ground for ntsc (60hz) or left floating for pal 50hz the resistor is located at the top left of the pcb for pal, have it removed, for ntsc have it bridged you will have to also swap the crystal around if toggling between modes and using composite, otherwise your color will be wrong if you wanted a working composite 50/60hz switch, you would need to use a logic inverter so that when the b4 pin (u25 pin 11) is ground, it sends this pin high, and vice versa, along with a dual frequency oscillator that changes up the composite crystal y1 between 14 32mhz for ntsc or 17 72mhz for pal