At present 32 states have petitions in Congress asking for a Convention to address a balanced budget amendment. Should 2 more states send petitions to Congress for a Convention to address a balanced budget amendment, Congress would be required to set a time and place for a Convention to address a balanced budget amendment only. Phyllis Schlafly, Bob Unruh, and other writers who have been trying to whip up hysteria about a possible Runaway Convention have not studied the issue.
If you want a Convention open to address all possible subjects, you need to get 34 states to petition for one. (There are 2 petitions for a General Convention that have been out there since the 1790's, but their "freshness" is subject to debate in Congress and the courts.)