Fluke 5720A service manual Spare, Assembly A14 Not Responding, 3136 A14 8255 Was Reset

Troubleshooting 5

Interpreting Diagnostic Fault Codes

3134 Spare

This fault code is not used.

3135 Assembly A14 Not Responding

At power up the instrument checks to see what assemblies are not installed. This test verifies that the High Voltage Control assembly is not responding. A failure indicates the High Voltage Control assembly is probably at fault.

3136 A14: 8255 Was Reset

The control word for the 8255 on the High Voltage Control assembly is read. A failure indicates the High Voltage Control assembly (A14) is probably at fault.

3137 A14/A15/A16: 2.2A AC Range Mag. Fault

The instrument is configured to the ac 2.2A range and set to 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 input current from the Current assembly is is measured at each setting by measuring the voltage drop across the 22 mA range shunt resistor on the Current assembly. This voltage drop is measured to be within 10% ±20 μV of the nominal. A failure indicates the High Voltage/High Current assembly (A15) is probably at fault.

3138 A14/A15/A16: 2.2A AC Range Compliance

The instrument is configured to the ac 2.2A range and set to 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 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.

3139 A14/A15/A16: 2.2A AC Range Amplitude

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 Magnitude Control circuit of the High Voltage Control assembly. The control signal AMPLITUDE is measured to be

=I * 4.23 + 4.447, ±20%. This voltage is divided creating MUX7 which is connected to the SDL line where it is measured by the adc circuit on the DAC assembly.

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