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6. Troubleshooting
Authorized Maintenance
With proper care in installation and use, the pressure gauge will require little or no maintenance. If
maintenance does become necessary, it is best to consult the factory before doing so, since some procedures
may require recalibration. Entry into the gauge or tampering with the printed circuit board will void the
warranty.
NOTICE: Do not perform repairs on these assemblies while the unit is still under warranty. If there is a
problem, check the listing below to rule out some of the straight-forward solutions that may exist.
Troubleshooting
6.2.1. Instrument Lists and Codes
If a problem occurs and obvious solutions are not apparent, the internal instrument values can be accessed
digitally. Using a terminal emulation program, type SFL. This command will return a long list of values. These
values can then be sent to the factory to better determine what the problem may be.
Also, issues that may have occurred are recorded in memory and may be accessed using the commands
STATUS, HISTORY and FAIL CODES. See Commands section above.
6.2.2. Possible Problems and Solutions
Symptom:
Not able to communicate digitally.
Action:
Check settings as found in Serial Communications section above. Make certain baud rate and
232/485 operation are correct. If using RS485 with a long cable run, make certain termination
resistors are enabled on the last instrument on the bus.
Symptom:
Pressure gauge is out of calibration and/or non-linear.
Check all fittings for leaks. Pump system down well below 0.1 Torr and re-zero the gauge.
Action:
Symptom:
The output is non-repeatable at zero or span (unit drifts).
Action:
Make certain the instrument is properly warmed up. Pump system down well below 0.1 Torr
and re-zero the gauge.
Symptom:
Intermittent, "jumpy" or "noisy" output from instrument.
Action:
Determine if something could cause the actual pressure to fluctuate. Ensure that the
instrument is well grounded and that all electrical connections are secure.
Symptom:
LED indication is red.
Action:
Cycle power. If symptom persists, check FAIL CODES and consult the factory.
HVG-2020A Instruction Manual
Page 27 of 29
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