HIKVISION DS7208HVI-ST Product/Maintenance Manual page 17

⑩.USB Fault
Step one: measurement SESR05 (QA1 or QA2) 2, 3 feet voltage difference
value (normal voltage difference about 3.05 V), as well as the impedance to the
GND, or replacement
Note: SESR05 (QA1 or QA2),front and after USB interface is independent of
each other
SESR05 （ QA2）
SESR05（QA1）