Im troubleshooting a HP 6033A power supply. I am troubleshooting HP-IB board A8. I understand the information about inputs, outputs and nodes but I do not understand how to measure them though. For example measure the input of A8 U8/10 I should get UUUU. How do I read UUUU and with what equipment? I am using the Operating and Service Manual for Instruments with Serial Numbers 02749A-03132 and Above.