Fluke 5720A S Com Ground Fault, 3700 A21 8255 Control Word, 3701 A21 8255 Port A Fault, Spare

Models: 5720A

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3615 S Com Ground Fault

Troubleshooting 5

Interpreting Diagnostic Fault Codes

3615 S Com Ground Fault

The Current/Hi Res assembly (A7) connects SCOM to the SDL line where it is measured by the adc circuit on the DAC assembly for 0V ±50 mV relative to RCOM.

3700 A21: 8255 Control Word

The diagnostics software reads the control word of the 8255 IC on the Rear Panel assembly. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3701 A21: 8255 Port A Fault

The diagnostics software writes and reads data to port A of the 8255 IC on the Rear Panel assembly. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3702 A21: 8255 Port B Fault

The diagnostics software reads port B of the 8255 IC on the Rear Panel assembly. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3703 A21: 8255 Port C Fault

The diagnostics software read port C of the 8255 IC on the Rear Panel assembly. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3704 Assembly A21 Not Responding

At power up the instrument checks to see what assemblies are not installed. This test verifies that the Rear Panel is not responding. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3705 A21: Rear Panel Data Bus Fault

The diagnostics software writes and reads from a register in the DUART on the Rear Panel assembly. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3706 Spare

This fault code is not used.

3707 Spare

This fault code is not used.

3708 A21: 8255 Was Reset

The control word of the 8255 on the Rear Panel assembly is read. A failure indicates the Rear Panel assembly (A21) is probably at fault.

3800 A8: 8255 Control Word

The diagnostics software reads the control word of the 8255 IC on the Switch Matrix assembly. A failure indicates the Switch Matrix assembly (A8) is probably at fault.

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Page 325
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Fluke 5720A S Com Ground Fault, 3700 A21 8255 Control Word, 3701 A21 8255 Port A Fault, 3702 A21 8255 Port B Fault, Spare