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 TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
12-18. Other instrument and meter consider-
any torques produced by a stray field are equal and
ations.
opposite.
Most troubles have simple causes and may be easily
--
12-17. Calibration of instruments and fields.
corrected.
a. Indicating instruments. Table 12-1 indicates
The frequency of calibrating instruments and
causes and remedial actions for common troubles
meters depends on the use and accuracy desired. If
that might occur with respect to indicating instru-
calibration standards and equipment are not avail-
ments.
able, instruments and meters of nearly the same
b. Recording instruments and meters. Table 12-2
rating can be checked against one another. When
indicates causes and remedial actions for common
wide discrepancies are noted, the instrument or
meter that is obviously incorrect should be
troubles that might occur with respect to recording
meters and instruments.
recalibrated and any needed repairs made.
Table 12-1. Troubleshooting chart for indicating instruments
Trouble
Cause
Remedial action
No indication,
Instrument disconnected
Check external connections.
Internal open circuit
Check for circuit continuity.
Moving element jammed
Check alignment of movement.
Internal short circuit.
Check internal connections.
Sluggishness or incorrect indication
Tight bearings.
Clean or replace bearings.
Adjust bearing bushing.
Dirty . . . . . . . . . . . . . . . . . . . . . . . . . . .
General cleaning.
Rubbing.
Check alignment and movement.
Look for bent pointer.
Corrosion.
Replace bearings if corrosion shows. Clean and
give acid bath to part involved or replace.
Increased friction
Pointer riding on scale due to warped scale.
Spring touching. Magnetic dust in air gap.
Table 12-2. Troubleshooting chart for recording instruments and meters
Trouble
Cause
Remedia action
Chart stopped
No driving power
Check power source.
Broken drive train.
Repair or replace drive train.
Chart jammed
Check paper alignment.
Noinkrecord...............
Ink well empty
Fill well and clean pen.
Broken ink tube
Replace tube.
Broken pen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replace pen.
Adjust pen holder.
No pen contact.
Clean pen.
Plugged pen . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No registration
Open gear train.
Check gear and pinion alignment.
Broken gears
Replace gears.
Replace registor.
Jammed registor.
Check external electrical connection.
Meter disconnected
Internal open circuit
Check for circuit continuity.
Inaccurate readings.
Needs adjustment.
Check with standard and adjust.
12-6
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