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Inspection and Cleaning Section 7-4
Inspection Method In normal environments, inspect the NT631/NT631C at intervals of between 6
months and a year. In environments that are extremely hot and humid, or very
dusty environments, shorten the inspection interval.
Items Required for The Inspection
Prepare the following items before starting the inspection.
• Screwdrivers (Phillips, flat head)
• Tester (or digital voltmeter)
• Industrial alcohol
• 100% cotton cloth
• Hygrometer (required in some cases)
• Thermometer (required in some cases)
• Synchroscope (required in some cases)
• Pen-writing oscilloscope (required in some cases)
Points Inspected
Inspect the following points to determine if there is any divergence from the
stated criteria. If there is, either improve the surrounding environment so that
the values fall within the stated range, or adjust the NT631/NT631C, for exam-
ple by re-tightening screws.
Note 1. Do not disassemble for repairs or modification.
Point
Inspected
Inspection Details Criterion Inspection
Instrument
Power supply
voltage
Fluctuation in power supply terminal
voltage
Permissible voltage fluctuation range
20.4 to 26.4 VDC (24 VDC –15% to
+10%)
Tester
Ambient envi-
ronmental con-
ditions
Ambient temperature (temperature in
the operation panel)
0 to 50°C Thermometer
Ambient humidity (humidity in the
operation panel)
35% to 85% RH Hygrometer
Presence/absence of dust Dust must not be settled Visual inspection
Mounting condi-
tions
Looseness of mounting brackets, etc. To be no looseness Phillips screwdriver
Connector connections of connecting
cable
To be fully inserted and locked, with no
looseness
Phillips screwdriver
Looseness of screws in external wir-
ing
To be no looseness Phillips screwdriver
Conditions of external connecting
cables
Faults such as incipient disconnection Visual inspection
Components
with limited lives
Brightness of the backlight
(NT631C only)
Must be sufficiently bright.
Backlight life:
(Under the normal range of ambient tem-
perature and humidity)
NT631C-ST141@-EV2: Approx.
25,000 hours or longer
NT631C-ST151@-EV2: Approx.
30,000 hours or longer
NT631C-ST152@-EV2/ST153@-EV3:
Approx. 50,000 hours or longer
(Brightness setting is not available for
the NT631C-ST151/152@-EV2/
ST153@-EV3 and the backlight can-
not be replaced.)
Visual inspection