Fluke 5725A, Instruction Manual, Page: 68 / 196

5725A
Instruction Manual
4-10
Inside the 5725A, B-SENSE LO is buffered by the 5725A, with the equivalent
voltage called MCOM.
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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.
Functional Summaries by Assembly 4-13.
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:
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Interconnect Assembly (A1):
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Connectors and traces to link other assemblies and fan
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High voltage transformer secondary switching circuitry
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Power Supply Assembly (A4):
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Rectifiers for high voltage supplies
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Filters for high voltage supplies
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High voltage current-limit circuitry
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High voltage supply-monitoring circuitry
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Rectifiers for system supplies
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Filters for system supplies
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Regulators for system supplies
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Rectifiers for fan supply
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Filter for fan supply
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Digital Assembly (A5)
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LED front panel status annunciators
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CPU, RAM, ROM, EEROM, watchdog timer, logic
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Current Amplifier Assembly (A2):
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Transconductance amplifier
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Current shunt
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Heat sink and current power devices
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5700A current routing circuits
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Filters for high current supply
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Rectifier bridge for high current supply
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Regulators for low current supply
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Current heat sink temperature monitor