Installation guide

Troubleshooting
Troubleshooting Analog Bus ADC Calibration Failures
1-88
Troubleshooting Analog Bus ADC Calibration Failures
The Analog Bus ADC Calibration adjusts the ADC reference voltage to match the A12 CPU +10 Vdc
reference.
There are three main reasons that this calibration could fail:
• problems with the +10 Vdc reference
•A12 CPU problems
• an analog multiplexer on another assembly is starting to fail
Depending on the option of your signal generator, perform one of the following:
• Procedure for Signal Generators with Option 501, 502, 503, 504 on page 1-88
• Procedure for Signal Generators with Option UNJ on page 1-89
• Procedure for Signal Generators with Option 506 on page 1-90
Procedure for Signal Generators with Option 501, 502, 503, 504
• Run Self-Test 1100.
— If Self-Test 1100 passes:
a. Turn the power off to the signal generator and remove the A17 Synthesizer
(Option 501, 502, 503, 504)
and A18 Reference.
b. Using service software, run the Analog Bus ADC Calibration.
— If the calibration passes:
a. Turn the power off to the signal generator.
b. Re-install the A17 Synthesizer (Option 501, 502, 503, 504).
c. Re-run the Analog Bus ADC Calibration.
— If the calibration passes, replace the A18 Reference.
— If the calibration fails, replace the A17 Synthesizer (Option 501, 502, 503, 504).
— If the calibration fails:
a. Turn the power off to the signal generator.
b. Re-install both the A17 Synthesizer (Option 501, 502, 503, 504) and A18 Reference.
c. Remove the A13 Output.
d. Re-run the Analog Bus ADC Calibration.
— If the calibration passes, replace the A13 Output.
— If the calibration fails, replace the A12 CPU.
— If Self-Test 1100 fails, refer to “Self-Tests 11xx for the A12 CPU” on page 1-52.