Vaisala HMT370EX - Troubleshooting; Problems and Their Possible Solutions

12. Troubleshooting
12.1 Problems and their possible solutions
If you have a problem with using HMT370EX, check the following tables before contacting
Vaisala. If the problem you have is not listed in the tables, or if the proposed solution does not
fix the problem, contact Vaisala technical support.
Problem: Analog output level appears incorrect
Possible cause: Solution:
Insucient supply voltage Ensure that the transmitter is powered correctly.
12 V DC is the minimum voltage in all conditions,
measured at the transmitter screw terminals.
If the supply voltage is less than 12 V DC, the
analog output current can be erroneous.
For information on testing and adjusting analog
output level, see Analog output level test
(page 111) and Analog output adjustment
overview (page 122)
Problem: Transmitter does not power on when power supply is switched on
Possible cause: Solution:
Analog output channel 1 (CH1) not wired Analog output channel 1 (CH1) must always be
wired. The transmitter receives power through
the Channel 1 screw terminals, and does not
power on if only Channel 2 (CH2) is wired.
For wiring instructions, see Wiring (page 86).
Incorrect supply voltage Ensure that the transmitter is powered correctly
using a supply voltage range of 12 – 28 V DC.
12 V DC is the minimum voltage in all conditions,
measured at the transmitter screw terminals.
Incorrect polarity Check that the screw terminal connections have
been made correctly.
For wiring instructions, see Wiring (page 86).
HMT370EX User Guide M212305EN-B
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