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Instruction Manual
245364-V
May 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Service and Maintenance 6-1
Model 755A
SECTION 6
SERVICE AND MAINTENANCE
WARNING
POSSIBLE EXPLOSION HAZARD
If gases are introduced into this analyzer,
the sample containment system must be
carefully leak-checked prior to initial start-
up, during routine maintenance and any
time the integrity of the sample
containment system is broken, to ensure
the system is in leak-proof condition.
Leak-check instructions are provided in
Section 2.3.8.
WARNING
ELECTRICAL SHOCK HAZARD
Do not operate without doors and covers
secure. Servicing requires access to live
parts which can cause death or serious
injury. Refer servicing to qualified
personnel.
CAUTION
PARTS INTEGRITY
Tampering or unauthorized substitution of
components may adversely affect safety of
this product. Use only factory
documented components for repair.
The information provided in this section will
aid in isolation of a malfunction to a particular
assembly or circuit. No detailed procedures
for component service and maintenance are
provided, as they are beyond the scope of this
manual. A few detailed checks are included,
but only for location of the defective assembly.
It is recommended that those familiar with
circuit analysis refer to the circuit theory in
Section 5 of this manual.
6-1 INITIAL CHECKOUT WITH STANDARD
GASES
If instrument readings do not meet
specifications, the first step in troubleshooting
is to isolate the analyzer from the sample
stream and the sample-handling system.
Admit downscale and upscale standard gases
to the analyzer. Observe readout on digital
display and on recorder (if used).
Digital display reads correctly with
standard gases but not with sample gas,
the sample and sample-handling systems are
suspect. Check these areas.
Digital display reads correctly with
standard gases, but the alarm or output
devices do not, these devices must be
checked individually.
Digital display reads overrange or erratic
with standard gases as well as with
sample gas, the problem is probably in the
detector or the electronic circuitry.
•
Overrange - Turn power to analyzer OFF.
Tap detector compartment with fingers.
Wait 30 seconds, reapply power. If the
suspension within the detector assembly
is hung up, this procedure may correct the
condition. If not, proceed with tests of the
detector and electronics.
•
Erratic - Problem probably in the detector
or the temperature control circuits.
Proceed with tests of the detector and
electronics. Verification that all circuits
are operating properly should be
performed before replacing detector.