Troubleshooting; No Signal; Existing Signal But Nothing On Lcd Display; Steady Signal, No Change When Level Varies - GE Masoneilan 12420 Instruction Manual & Safety Manual

10. Troubleshooting

10.1. NO SIGNAL

♦
Check connection wires to 12400 Series instrument.
♦ Check polarities of the connection wires.

10.2. EXISTING SIGNAL BUT NOTHING ON LCD DISPLAY

♦
The electronic module might be damaged and must be replaced at factory.

10.3. STEADY SIGNAL, NO CHANGE WHEN LEVEL VARIES

♦ In case of external mounting (see Section 4.2.1), check that displacer lock up in the displacer chamber, made for
transportation purpose, has been removed.
♦ Check the instrument is not in FAILSAFE mode.
♦
Check the device is in NORMAL operating mode (alternating display of signal and level variable).
♦ Check correct coupling between transmission rod and mechanism sub-assembly by moving flexure (59), which allows
simulating a level change.
♦ Check that the correct supply voltage is applied to terminal blocks of main analog output connections (AO_1).

10.4. OUTPUT SIGNAL DIFFERS FROM VALUE DISPLAYED ON LCD

FULL COMPLIANCE WITH STANDARDS REQUIREMENTS RELATED TO INTRUMENTS INSTALLED
♦ Check the load resistance is compliant with Section 5.4.5 and the power supply applied to main analog output signal is
greater than 10 VDC.
♦ Insert a reference milliamp meter in series with the 4-20 mA signal loop.
♦ To recalibrate the internal milliamp meter, enter the [VAR SET] sub-menu via the ADVANCED SETUP menu (see
Appendix C).
Enter into [MA LOW:mA]. Decrease or increase value (ranges from 2900 to 3500 by increment one) until the
o
reference milliamp meter indicates 4.000mA (see Appendix C).
Enter into [MA HI:mA]. Decrease or increase value (ranges from 2900 to 3500 by increment one) until the reference
o
milliamp meter indicates 20.000mA (see Appendix C).
Enter into [SIG GENE] via the ADVANCED SETUP menu to generate various output signals and check the current
o
signal versus the reference milliamp meter (see Appendix E).
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WARNING:
IN HAZARDOUS AREAS MUST BE ENSURED.
Masoneilan 12400 Series Transmitter/Controller Instruction Manual | 53