HP 6038A, Руководство по обслуживанию

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To troubleshoot the power supply the A4 power FET board and A2 control board can be raised out of the unit using
extender boards and cables provided in service kit P/N 5060-2865.
Main Troubleshooting Setup
Figure 3-5 shows the troubleshooting setup for troubleshooting all of the unit except the front panel and initial no-output
failures (see Page 49). The external power supply provides the unit’s internal bus voltage. The ac mains connects directly to
the unit’s A1T3 bias transformer via the isolation transformer, thereby energizing the bias supplies, but it does not connect
to the input rectifier and filter to create the bus voltage. With the external supply the unit operates as a dc-to-dc converter.
The supply biases A4Q3, and A4Q4 PFETs with a low voltage rather than the 320Vdc bus voltage. This protects the PFETs
from failure from excess power dissipation if the power-limit comparator or the off-pulse circuitry are defective. It also
reduces the possibility of electrical shock to the troubleshooter.
Figure 3 5. Main Troubleshooting Setup