This focused repair guide addresses Antminer T21 BHB68701 hash boards showing "0 ASIC" detection caused by RI signal level shifter U2 failures. Learn to diagnose U2 chip abnormalities through specific voltage measurements: pins 1-2 (1.2V) and pins 4-5 (3.3V). The course covers comprehensive testing procedures including resistance measurement of connected components, diode mode testing for short circuits to ground, and proper chip replacement techniques. Special attention is given to distinguishing between U2 chip failures versus peripheral component issues, and methods for verifying repairs through post-replacement voltage checks. This targeted knowledge enables technicians to efficiently restore RI signal communication on BHB68701 boards and recover miners from complete communication breakdowns.{{ item.name }}
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