From Halopedia, the Halo wiki
Tipping Point is an achievement in Halo: The Master Chief Collection. It is awarded for activating the fourth Halo 3 Terminal on The Covenant. The achievement is worth 5 gamerpoints and can be unlocked on any difficulty. The player must scroll through and access both parts of the terminal to unlock the achievement.
The terminal is inside the first structure with the first shield generator. It is located near the elevator control. Rather than going up the elevator, continue past the controls to a ledge on the opposite side. The terminal is against the wall.