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5725A
Instruction Manual
4-10
Inside the 5725A, B-SENSE LO is buffered by the 5725A, with the equivalent
voltage called MCOM.
• B-FEEDBACK
During ac voltage operation, B-FEEDBACK is the output of the High Voltage Sense
assembly; this signal represents B-SENSE HI divided by -100, and drives the 5700A
ac/dc thermal sensor. During low-frequency ac voltage calibration, this is the sense
path for the -260V dc from the 5700A Power Amplifier.
During ac current operation, B-FEEDBACK is the output of the current calibration
amplifier. It represents the output current divided by -5 and drives the 5700A
Oscillator feedback.
During dc current operation, voltage from the 5700A 2V dc range is fed to the
5725A on B-FEEDBACK.
If B-FEEDBACK is out of tolerance during 5725A ac voltage or current operation
but no other faults are reported, the 5700A sends a message to the 5725A asking for
a sequenced shutdown into standby, and displays a fault message on its Control
Display. The 5725A FAULT indicator lights. A faulty 5700A/5725A interface
connection could cause this problem.
4-13. Functional Summaries by Assembly
For an overview of all the assemblies in the 5725A and the functions contained on each,
refer to Figure 4-1, the overall block diagram, and the following list:
• Interconnect Assembly (A1):
• Connectors and traces to link other assemblies and fan
• High voltage transformer secondary switching circuitry
• Power Supply Assembly (A4):
• Rectifiers for high voltage supplies
• Filters for high voltage supplies
• High voltage current-limit circuitry
• High voltage supply-monitoring circuitry
• Rectifiers for system supplies
• Filters for system supplies
• Regulators for system supplies
• Rectifiers for fan supply
• Filter for fan supply
• Digital Assembly (A5)
• LED front panel status annunciators
• CPU, RAM, ROM, EEROM, watchdog timer, logic
• Current Amplifier Assembly (A2):
• Transconductance amplifier
• Current shunt
• Heat sink and current power devices
• 5700A current routing circuits
• Filters for high current supply
• Rectifier bridge for high current supply
• Regulators for low current supply
• Current heat sink temperature monitor