Troubleshooting
A–6 H
2
S in Natural Gas
No reading on device connected to cur-
rent loop
Make sure that connected device can
accept a 4-20 mA signal. The analyzer
is set to source current.
Make sure the device is connected to
the correct terminals on the green con-
nector (see Figure 2–5 on page 11).
Check the open circuit voltage (35-
40 VDC) across the current loops ter-
minals on the green connector (see
Figure 2–5 on page 11).
Replace the current loop device with a
milliampere meter and look for current
between 4 mA and 20 mA. A voltmeter
connected across a 249-ohm resistor
can be used instead of the milliampere
meter; it should read between 1 and 5
volts.
Current loop is stuck at 4 mA or 20 mA Check display for error message. If
alarm has been triggered, reset the
alarm.
On the current loop board, check the
voltage between the end of resistor R1
closest to the jumper and ground. If
the concentration reading is high, the
voltage should be near 1 VDC. If the
concentration reading is low, the volt-
age should be near 4.7 VDC. If not, the
problem is probably on the ARM9 main
board. Return to factory for service.
Reading seems to always be high by a
fixed amount
Capture diagnostic data and send the
file to SpectraSensors. See “To read
diagnostic data with HyperTermi-
nal:” on page 3-16.
Reading seems to always be high by a
fixed percentage
Capture diagnostic data and send the
file to SpectraSensors. See “To read
diagnostic data with HyperTermi-
nal:” on page 3-16.
Reading displays 0.0 or seems relatively
low
Capture diagnostic data and send the
file to SpectraSensors. See “To read
diagnostic data with HyperTermi-
nal:” on page 3-16.
Table A–1 Potential instrument problems and their solutions.
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