Instruction Manual
760000-C
November 2002
Rosemount Analytical Inc. A Division of Emerson Process Management
Maintenance and Service 4-1
Model NGA2000 CLD
SECTION 4
MAINTENANCE AND SERVICE
WARNING
.
ELECTRICAL SHOCK HAZARD
Disconnect power to the module(s) prior to replac-
ing components.
This equipment should not be adjusted or repaired
by anyone except properly qualified service per-
sonnel.
4-1 OVERVIEW
The CLD Analyzer Module requires very little
maintenance during normal operation.
Occasionally, the intake fan screen may require
cleaning, refer to Section 4-3, page 4-1.
Also, the detector's reaction chamber and sap-
phire window may require cleaning, refer to Sec-
tion 4-7, page 4-3.
White crystal deposits on the windows of the reac-
tion chamber and plugging of capillaries and vent
are usually due to sample contaminates such as
ammonia reacting with the high ozone levels and
NO components. To eliminate the contaminates,
the sampling system should be reworked or a pre-
ventive maintenance program developed (if drop-
out is not excessive). Another source of crystalline
formation is contaminated air.
Several components may require replacement.
These are discussed in the following sections.
4-2 FUSES
The main power fuse may require replacement.
NOTE
Before replacing the fuse, remove power to
the Analyzer Module.
See Figure 1-3, page 1-3 for the location of the
Power Supply Board main power fuse, which
protects 24 VDC input to the module.
4-3 FANS
Refer to Figure 4-1, page 4-2. To replace ei-
ther rear panel fan, remove the cover of the
Analyzer Module and then the rear panel.
Disconnect connectors and remove screws.
Assemble in reverse order.
4-4 CONVERTER
Refer to Figure 4-1, page 4-2 and Figure 4-2,
page 4-3. To replace the converter or sensor,
disconnect the two pneumatic tubes and two
electrical connections. Unlace the heater
blanket, and remove the converter. Reassem-
ble in reverse order, ensuring that the con-
verter is oriented with the glass cloth at the
bottom and the sensor is oriented correctly in-
side the heater jacket.
4-5 OZONATOR
Refer to Figure 4-1, page 4-2.To replace the
ozonator, remove the two large straps and all
tie-wraps, and disconnect the one electrical
connection. Reassemble in reverse order.
4-6 PRINTED CIRCUIT BOARDS
All four printed circuit boards can be replaced,
if necessary. Refer to Figure 4-1, page 4-2 for
location of the Driver, Power Supply, Signal
and Computer Boards.
To remove any PCB (
except
the Computer
Board), disassemble the enclosure side first.
Ribbon and other cables are long enough to
allow the entire side to be folded out from the
remainder of the components. This makes
PCB removal much simpler.
Tag each connector and its location before
disconnecting any wiring. This helps in reas-
sembly.
