
5725A
Instruction Manual
4-30
to approximately 33
Ω
/
°
C by R615. Op amp U603A provides a reference voltage of
about -0.77V. This reference voltage is applied to the circuit containing summing
amplifier U603B, R611, and the linearized thermistor. The output of U603B is signal HV
TEMP M, equal to 10 mV/
°
C.
A voltage proportional to the temperature rise from the heat sink to the junction of the
transistor is added to HV TEMP M through R610. This is done via +400V IM from the
Power Supply assembly. Resistor R610 is selected to properly scale this contribution to
the 10 mV/
°
C output of U603B. Capacitor C610 provides averaging for the ripple on the
current-sensing resistor, and CR604 prevents C610, an electrolytic capacitor from being
reverse charged.
High Voltage Sense Assembly (A6)
4-54.
In addition to ac voltage sensing for which it is named, the High Voltage Sense assembly
provides four major functions for the 5725A. These additional functions are the
following:
•
Analog monitoring of the 5725A status
•
Interface with the 5700A controller
•
Switching input signals from the 5700A
•
AC Line Power switching
Because it performs all the above functions, the High Voltage Sense assembly plays a
primary role in controlling the instrument, attaining ac voltage specifications,
performing 5725A calibration, and maintaining instrument safety.
The High Voltage Sense assembly has the following six sections: sense amplifier, analog
monitor, serial interface/guard crossing, analog input switching, control, and mains
switching. Each section is first briefly described, then described in detail. For reference,
see Figure 4-5, the block diagram for the High Voltage Sense assembly.
•
Sense Amplifier Section
The sense amplifier section consists of a precision ac amplifier configured as an
active attenuator, a buffer amplifier that isolates the 5725A high quality ground from
the 5700A ground reference, and a precision true rms converter circuit for 5725A
calibration. Together, these circuits accurately attenuate the output of the 5725A in
ac voltage function to drive the 5700A Oscillator control circuitry. The sense
amplifier section is essentially a gain-determining feedback element of a loop whose
forward path consists of the 5700A Oscillator and the High Voltage Amplifier
assembly (A3).
•
Analog Monitor Section
The analog monitor section is comprised of a bipolar output dac, a comparator, and a
16-channel multiplexer. The inputs to the multiplexer are scaled voltages
representing critical parameters in the other 5725A assemblies, particularly those
involving high voltage and/or current. Each input can be compared to programmed
limits set by the dac under microprocessor control. The comparator gives simple
go/no go decisions, which are then acted on in a more sophisticated way by the
software. An additional function of the analog monitor section is to provide access to
the B-RCL line used by the 5700A during 5725A calibration.
Summary of Contents for 5725A
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Page 62: ...5725A Instruction Manual 4 4 Figure 4 1 5725A Overall Block Diagram...
Page 78: ...5725A Instruction Manual 4 20 aq20f eps Figure 4 3 Current Amplifier Assembly Block Diagram...
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Page 132: ...5725A Instruction Manual 8 6 aq24f tif Figure 8 1 Final Assembly...
Page 133: ...List of Replaceable Parts 8 8 7 aq25f tif Figure 8 1 Final Assembly cont...
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Page 135: ...List of Replaceable Parts 8 8 9 aq27f tif Figure 8 1 Final Assembly cont...
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Page 137: ...List of Replaceable Parts 8 8 11 aq29f tif Figure 8 1 Final Assembly cont...
Page 138: ...5725A Instruction Manual 8 12 aq30f tif Figure 8 1 Final Assembly cont...
Page 139: ...List of Replaceable Parts 8 8 13 aq31f tif Figure 8 1 Final Assembly cont...
Page 141: ...List of Replaceable Parts 8 8 15 5725A 1611 aq36f eps Figure 8 2 A1 Interconnect PCA...
Page 145: ...List of Replaceable Parts 8 8 19 5725A 1650 aq37f eps Figure 8 3 A2 Current Amplifier PCA...
Page 149: ...List of Replaceable Parts 8 8 23 5725A 1661 aq38f eps Figure 8 4 A3 High Voltage Amplifier PCA...
Page 153: ...List of Replaceable Parts 8 8 27 5725A 1631 aq39f eps Figure 8 5 A4 Power Supply PCA...
Page 155: ...List of Replaceable Parts 8 8 29 5725A 1650 aq40f eps Figure 8 6 A5 Digital PCA...
Page 159: ...List of Replaceable Parts 8 8 33 5725A 1601 aq41f eps Figure 8 7 A6 High Voltage Sense PCA...
Page 161: ...List of Replaceable Parts 8 8 35 aq32f tif Figure 8 8 A12 Transformer Enclosure Assembly...
Page 162: ...5725A Instruction Manual 8 36 aq33f tif Figure 8 8 A12 Transformer Enclosure Assembly cont...
Page 163: ...List of Replaceable Parts 8 8 37 aq34f tif Figure 8 8 A12 Transformer Enclosure Assembly cont...
Page 164: ...5725A Instruction Manual 8 38 aq35f tif Figure 8 8 A12 Transformer Enclosure Assembly cont...
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Page 169: ...Schematic Diagrams 9 3 9 Figure 9 1 A1 Interconnect PCA 5725A 1611 aq48f eps...
Page 170: ...5725A Instruction Manual 9 4 Figure 9 1 A1 Interconnect PCA cont...
Page 171: ...Schematic Diagrams 9 5 9 Figure 9 1 A1 Interconnect PCA cont...
Page 172: ...5725A Instruction Manual 9 6 Figure 9 2 A2 Current Amplifier PCA 5725A 1650 aq52f eps...
Page 173: ...Schematic Diagrams 9 7 9 Figure 9 2 A2 Current Amplifier PCA cont...
Page 174: ...5725A Instruction Manual 9 8 Figure 9 2 A2 Current Amplifier PCA cont...
Page 175: ...Schematic Diagrams 9 9 9 Figure 9 2 A2 Current Amplifier PCA cont...
Page 176: ...5725A Instruction Manual 9 10 Figure 9 3 A3 High Voltage Amplifier PCA 5725A 1661 aq56f eps...
Page 177: ...Schematic Diagrams 9 11 9 Figure 9 3 A3 High Voltage Amplifier PCA cont...
Page 178: ...5725A Instruction Manual 9 12 Figure 9 3 A3 High Voltage Amplifier PCA cont...
Page 179: ...Schematic Diagrams 9 13 9 Figure 9 4 A4 Power Supply PCA 5725A 1631 aq59f eps...
Page 180: ...5725A Instruction Manual 9 14 Figure 9 4 A4 Power Supply PCA cont...
Page 181: ...Schematic Diagrams 9 15 9 Figure 9 4 A4 Power Supply PCA cont...
Page 183: ...Schematic Diagrams 9 17 9 Figure 9 5 A5 Digital PCA cont...
Page 185: ...Schematic Diagrams 9 19 9 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 186: ...5725A Instruction Manual 9 20 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 187: ...Schematic Diagrams 9 21 9 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 188: ...5725A Instruction Manual 9 22 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 189: ...Schematic Diagrams 9 9 23 aq45f eps Figure 9 7 A12 Transformer Enclosure Assembly...
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