Det-Tronics PW9200x Pathwatch IR Gas Detection System - Manual (Page 18)

Section 3
Maintenance
GENERAL PRECAUTIONS
As with all precision electro-optical equipment, care
must be taken to avoid sharp blows to the instrument.
Do not drop it or allow heavy objects to strike it. Do
not touch the windows, lenses, lamps, filters or other
optical surfaces with bare hands. Customary precau-
tions for the use of explosion-proof instrumentation in
hazardous environments should be observed. Ensure
that no hazardous vapor conditions exist in proce-
dures where either the cover, window assembly or
junction box are to be opened when circuits are alive.
WARNING
Live line voltage is exposed at several points
within the PW9200. This is potentially danger-
ous and contact by maintenance personnel must
be avoided.
The threads of the housing cover and window assem-
bly are lubricated to eliminate the possibility of seiz-
ing. The threads should be checked periodically and
lubrication should be added when necessary. When
adding lubrication to the threads, care must be taken
to ensure that the lubrication does not touch the win-
dow surface.
GENERAL INFORMATION
The receiver electronics are comprised of six printed
circuit boards and electrical wiring and components
located on the receiver baseplate and the motorbox.
Two of the printed circuit boards are permanently
mounted and the other four are easily removed and
replaced as indicated below:
P.C. BOARD PERMANENT/REMOVABLE
Preamplifier permanent
AGC/TE cooler removable
Synchronous demodulator removable
Rear panel removable
Options removable
Connector/Relay permanent
The receiver functions described in Section 1 and
Figure 1 of this manual are located on a printed circuit
board or assembly as shown below:
RECEIVER FUNCTION LOCATION
Infrared Photodetector D e t e c t o r / P r e a m p
assembly
Sync Circuitry Rear panel p.c. board
and sync demod p.c.
board
Amplifier Preamp p.c. board
and sync demod p.c.
board
Signal Processing Electronics AGC/TE cooler and
sync demod p.c.
board
Ratiometer Rear panel p.c. board
Threshold Detector Rear panel p.c. board
OR Gate Function Connector/relay p.c.
board
Obstruction/Status Alarm Relay Connector/Relay p.c.
board
Adjustable Threshold Detector Rear panel p.c. board
HC Alarm Set Rear panel p.c. board
(accessed from front
panel)
HC Vapor Alarm Relay Connector/Relay p.c.
board
4 to 20 mA Converter 4 to 20 ma output p.c.
board
Assemblies and printed circuit boards are available
as spare parts. To facilitate troubleshooting and cor-
rective maintenance of the PW9200, users are
advised to stock LEVEL ONE and LEVEL TWO from
the “Recommended Spare Parts List.”
ACCESS TO INTERNAL
COMPONENTS
All internal components of the transmitter and receiver
are mounted to the cover of the housing (see Figure
3). Access to these components is obtained either by
swinging open the cover on its hinges or by removing
the cover and associated components from the hous-
ing.
1. Disconnect all power to the instrument.
2. Remove the 20 bolts that hold the cover to the
housing.
3. Swing open the cover to permit access to the
connector(s). DO NOT OPEN the receiver cover
more than three inches to prevent undue stress
on the connector(s). The transmitter cover will
open more than three inches.
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