Det-Tronics PW9200x Pathwatch IR Gas Detection System - Manual (Page 25)

Appendix
This APPENDIX contains:
Optical Alignment Procedure for Installations Using a
Mirror
Receiver Interconnections
Voltage to Current Transfer Curve
Calibration Graphs of a Typical Instrument.
OPTICAL ALIGNMENT PROCEDURE
FOR INSTALLATIONS USING A MIRROR
After the Initial Setup procedures have been followed
and the instrument has been operating continuously
for at least one hour, alignment of the transmitter,
receiver, and mirror is best accomplished by two peo-
ple using the following procedure:
1. Attach the mirror pan-tilt mount with U-bolts to the
user supplied 4.5 inch O.D. mounting pipe at the
desired height. Roughly set the mirror for the
appropriate angle, and securely tighten the U-
bolt.
NOTE
The cross hairs of the alignment scopes have
been factory set for alignment of the transmitter
and receiver WITHOUT MIRRORS at the operat-
ing distance indicated in the Test Record. If this
separation distance is not the same as the actual
installation because mirrors are used, the cross
hairs of the alignment scopes will need to be
reset after the instrument is properly aligned.
IMPORTANT
Optimum alignment must be maintained to
ensure reliable operation of the instrument.
2. With the transmitter roughly facing the mirror, view
the mirror through the alignment scope attached
to the transmitter mount. Adjust the pan and tilt of
the transmitter housing until the cross hairs of the
transmitter alignment scope are centered on the
mirror.
3. Adjust the pan and tilt of the receiver housing until
the cross hairs of the receiver alignment scope
are centered on the mirror.
4. One person should remain at the mirror to adjust
the pan and tilt. The second person should stand
about six feet from the mirror and find the reflec-
tion of the transmitter lamp in the mirror. The first
person should adjust the pan and tilt of the mirror
so that the second person is moved into the direct
line between the mirror and the receiver, keeping
the reflection of the transmitter lamp in sight.
Once on the direct line, the second person should
back away from the mirror toward the receiver,
keeping the reflection sighted. The first person
should adjust the pan and tilt of the mirror so that
the second person keeps the reflection in sight as
he gradually backs up to the center of the receiv-
er.
5. Remove the receiver window assembly by rotat-
ing it counterclockwise. Avoid touching the win-
dow with bare hands. Move the window assem-
bly to a safe place, being careful not to scratch
the window.
6. Set the MODE selector switch on the front panel
to the “align” position.
7. Using the test jacks on the front panel, connect a
digital voltmeter (with a resolution of at least 1 mil-
livolt dc) between the NUMERATOR and Signal
Ground (SIG GND) and note the signal strength.
8. Make small adjustments in the receiver pan and
tilt to maximize the amplitude of the voltage at the
receiver.
9. Make small adjustments in the transmitter pan
and tilt to maximize the amplitude of the voltage
at the receiver.
10. Make small adjustments in the mirror pan and tilt
to maximize the voltage at the receiver.
11. Replace the receiver window assembly and read
the output at the junction box. The output
obtained should be between 0.3 and 0.5 vdc.
NOTE
For any given path length, the signal strength will
decrease as the angle formed by the transmit-
ter/mirror/receiver configuration increases. If the
output obtained is not within the specified limits
after following all steps of the “Optical
Alignment/Signal Strength” procedure. The
preamplifier gain must be adjusted as described
in Step 12. If the output is correct, proceed to
Step 13.
12. To adjust the preamplifier gain, follow the
“Accessing Internal Components” procedure (see
“Maintenance” Section) and locate the preamplifi-
er p.c. board within the heat sink fins. The
preamplifier gain adjustment potentiometer is
located on the preamplifier p.c. board and can be
reached by inserting a screwdriver between the
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