Agilent Technologies 6012B Service Manual page 34

An isolation transformer provides ac voltage that is not referenced to earth ground, thereby reducing the
possibility of accidentally touching two points having high ac potential between them. Failure to use an
isolation transformer as shown in Figure 3-1 will cause the ac mains voltage to be connected directly to
many components and circuits within the power supply, including the FET heatsinks, as well as to the
terminals of the external dc power supply. Failure to use an isolation transformer is a definite
personal-injury hazard.
The troubleshooting setup of Figure 3-1 connects high ac voltage to relay K1, fan B1, fuseholder A1F1, and
other components and circuits along the front of the A 1 main board.
As a convenience in implementing the troubleshooting setup, prepare cord sets as shown in Figure 3-2. This facilitates
connecting the unit's input power rail to the external supply and connecting the bias transformer to the isolation
transformer.
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Figure 3-1. Main Troubleshooting Setup