This course provides a specialized analysis of the LDO circuit powering system on the Antminer T21 BHB68701 hash board. Learn the two distinct power architectures: domains 1-10 use three LDO chips powered through cross-domain voltage division, while domains 11-12 employ an 8-pin MP2019 configuration powered by the boost circuits differential voltage. Detailed explanations cover U141 1.2V LDO and dual 0.8V LDO chips, their pin functions, and practical measurement techniques showing 3V input and 0.8V/1.2V outputs. The tutorial demonstrates circuit tracing methods and voltage verification procedures essential for diagnosing LDO-related power failures, crucial for effective miner hardware maintenance.