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Troubleshooting
Interpreting Diagnostic Fault Codes
5
5-25
within ± 100 mV. A failure indicates the Oscillator Control assembly (A12) is probably
at fault.
3414 A12/A13: Nonlinear Control Loop 2vrng
The instrument is set for 1V 1 kHz operation. Signal ERROR INT. OUT on the
Oscillator Control assembly is measured via the SDL line to be 0V ±5.0V. A failure
indicates the Oscillator Control assembly (A12) is probably at fault.
3415 A12/A13: Nonlinear Control Loop 20vrng
The instrument is set for 10V 1 kHz operation. Signal ERROR INT. OUT on the
Oscillator Control assembly is measured via the SDL line to be 0V ±5.0V. A failure
indicates the Oscillator Control assembly (A12) is probably at fault.
3416 A12/A13: DAC 15th Bit Fault
The instrument is set for 1V 1 kHz operation. Bit 14 of the 15 BIT DAC is checked. A
failure indicates the Oscillator Control assembly (A12) is probably at fault. Check FET
Q19.
3417 A12: DC Sensor Buffer Fault
The instrument is set for 1V 1 kHz operation. The output of the DC Sense Buffer, on the
Oscillator Control assembly, is measured via the RCL line. This measurement is done by
comparing it to the DAC assembly output voltage. The difference is measured to be 0V
±500 µV. A failure indicates the Oscillator Control assembly (A12) is probably at fault.
3418 A12: Sensor Loop/SQ. Root Amp Fault
The instrument is set for 2.19V 1 kHz operation. The output of the DC Sense Buffer is
connected to the main ac/dc sensor on the Oscillator Control assembly. The output of the
main sensor is measured via the RCL line by comparing it to the DAC assembly output
voltage. The difference is measured to be 0V ±100 mV. A failure indicates the Oscillator
Control assembly (A12) is probably at fault.
3419 A12: AC Sensor Buff (2V Range)
The instrument is set for 2.19V 1 kHz operation. The output of the AC Sense Buffer is
connected to the main ac/dc sensor on the Oscillator Control assembly. The output of the
main sensor is measured via the RCL line by comparing it to the DAC assembly output
voltage. The difference is measured to be 0V ±160 mV. A failure indicates the Oscillator
Control assembly (A12) is probably at fault.
3420 A12: AC Sensor Buff (20V Range)
The instrument is set for 21.9V 1 kHz operation. The output of the AC Sense Buffer is
connected to the main ac/dc sensor on the Oscillator Control assembly. The output of the
main sensor is measured via the RCL line by comparing it to the DAC assembly output
voltage. The difference is measured to be 0V ±160 mV. A failure indicates the Oscillator
Control assembly (A12) is probably at fault.
3421 A12: AC Cal Sensor (2V Range)
The instrument is set for 2.19V 1 kHz and configured as in the 2V range ac/ac
calibration. The output of the ac/ac sensor on the Oscillator Control assembly is