When a failure mode or the symptoms don’t point to an obvious problem or solution, then this order of trouble shooting should be followed. The sequence is progressive and once the problem has been fixed then there typically is not a need to continue with the remaining steps.
Each step may have variations based on what has been observed and consulting with the Fluke Calibration Technical Support Team can be helpful if these steps do not yield the anticipated answers.
1. Is the leak rate less than 0.001% Rdg/second? If not, then fix the leak.
2. [Menu | Setup | Limits:] Review the control and Supply Correction settings. The typical selections are like these:
3. [Menu | Display:] Look at the system sensors to see if the Reference and Control sensors have relatively good agreement. Also check that the other sensor values are reasonable.
4. [Menu | Calibrate | Zero: Mechanical Zero] Is the Mechanical Zero indicating it needs to be adjusted? A good zero will have the yellow bar centered over the green bar. Here is an example of perfect:
Here is an example of a bad one:
5. [Menu | Test | Control:] If the Mechanical Zero is good, then run a “Full” AutoTune.
6. If the poor control response continues then an evaluation for a broken QBT sensor is required. This is accomplished by performing a Tilt Test. A broken hinge on a QBT sensor does not always show as an unstable output when the controller is in measure mode. /en-US/hc/en-us/articles/205626204-7250-7252-7050-7052-Pressure-Controller-Monitor-Tilt-Test