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Troubleshooting
Interpreting Diagnostic Fault Codes
5
5-35
3808 A8: Zero Amp Hi Offset
The Internal Cal Zero Amplifier circuit on the Switch Matrix assembly is tested for
excessive offset in the high gain configuration. This is done by connecting the circuit
input to RCOM, by turning on Q7, and connecting the output to the RCL line where it is
measured by the adc circuit on the DAC assembly. The adc circuit takes ten readings and
this failure occurs if the average value is over 0.155V. A failure indicates the Switch
Matrix (A8) assembly is probably at fault.
3809 A8: Zero Amp Hi Gain Fault
The gain of the Internal Cal Zero Amplifier circuit in the high gain (130) configuration is
tested. The circuit input is connected to the output of the DAC assembly and the circuit
output is connected to the RCL line. The RCL line is connected to the +input of the adc
circuit and the -input is connected to the 6.5V reference. The gain of the Internal Cal
Zero Amplifier is determined by setting the DAC output to the nominal 0.05V and then
adjusted it until a null is achieved. The gain is tested to be 130 ±6%. A failure indicates
the Switch Matrix (A8) assembly is probably at fault.
3810 A8: 2.2V Amp Noise Fault
3811 A8: Zero Amp Offset
3812 A8: 2.2V Gain Fault
3813 A8: 220mV Offset Fault
3814 A8: 220mV Divider Fault
3815 A8: 22mV Divider Fault
3816 Spare
This fault code is not used.
3817 Spare
This fault code is not used.
3818 A8: Out Lo To Sense Lo Continuity Fault
3819 A8: Relay Fault
A fault occurred while doing relay testing on the Switch Matrix assembly.
3820 Spare
This fault code is not used.
3821 Spare
This fault code is not used.