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5700A/5720A Series II Calibrator
Service Manual
5-16
3140 A14/A15/A16: 2.2A AC Range Abs. Value
The instrument is configured to the ac 2.2A range and set for an output current of 0.22A
at 1 kHz, 0.6A at 1 kHz, 1.1A at 1 kHz, 0.6A at 40 Hz, and 1.1A at 50 Hz. The output
current from the High Voltage/High Current assembly is routed to the Current assembly
where it is connected to the 1.2Ω load resistor. The Current control signal G OUT from
the High Voltage/High Current assembly is routed to the Absolute Value Circuit on the
High Voltage Control. The output from the Absolute Value circuit is a positive voltage
which should be = 3.07 * I, ±10%, where "I" is the output current. This voltage is
divided creating MUX6 which is connected to the SDL line where it is measured by the
adc circuit on the DAC assembly.
3141 A14/A15/A16: 2.2A DC Range Dummy Load
The instrument is configured to the dc 2.2A range. The output current from the High
Voltage/High Current assembly is routed to the Current assembly where it is connected
to the 1.2Ω load resistor. The resulting voltage across this load resistor is measured by
connected DUMMY LOAD on the Current assembly to the SDL line where it is
measured by the adc circuit on the DAC assembly. This fault occurs if the determined
current is over 10% ±5 mA of the nominal. A failure indicates the High Voltage/High
Current assembly (A15) is probably at fault.
3142 A14/A15/A16: 2.2A DC Range Compliance
The instrument is configured to the dc 2.2A range. The output current from the High
Voltage/High Current assembly is routed to the Current assembly where it is connected
to the 1.2Ω load resistor. The compliance voltage is determined by measuring the output
side of the 22 mA range shunt resistor on the Current assembly. This is done via the
Current Compliance Monitor circuit on the Current assembly and is checked to be less
than 10V. A failure indicates the High Voltage/High Current assembly is probably at
fault.
3143 A14/A15/A16: 2.2A DC Range Magnitude
The instrument is configured to the dc 2.2A range. The output current from the High
Voltage/High Current assembly is routed to the Current assembly where it is connected
to the 1.2Ω load resistor. The output current is calculated by measuring the voltage drop
across the 22 mA range shunt resistor on the Current assembly. This fault occurs if the
determined current is over 10% of the nominal. A failure indicates the High
Voltage/High Current assembly (A15) is probably at fault.
3300 A9: 8255 Control Word
The diagnostics software reads the control word of the 8255 IC on the Ohms Cal
assembly (A9). A failure indicates the Ohms Cal assembly (A9) is probably at fault.
3301 A9: 8255 Port a Fault
The diagnostics software writes and reads data to port A of the 8255 IC on the Ohms Cal
assembly (A9). A failure indicates the Ohms Cal assembly (A9) is probably at fault.
3302 A9: 8255 Port B Fault
The diagnostics software reads port B of the 8255 IC on the Ohms Cal assembly (A9)
during the instruments dormant state. A failure indicates the Ohms Cal assembly (A9) is
probably at fault.