Det-Tronics SW9200x Slickwatch IR Oil Detection System - Manual (Page 11)

4. When the maximum possible voltage has been
obtained and recorded with the transmitter, adjust
the receiver angle until a maximum NUMERATOR
signal strength is obtained. Record the voltage.
5. Repeat Steps 3 and 4 to maximize the NUMERATOR
output.
6. Once optimum alignment has been obtained, care-
fully tighten the mounting nuts with a wrench, being
careful to maintain the proper angle of alignment
obtained in the previous steps.
7. Return the MODE selector switch on the front panel
to the OPERATE position.
OPERATION/PERFORMANCE CHECK
SIGNAL STRENGTH
The NUMERATOR voltage should be measured to deter-
mine if the signal strength reflected from the water sur-
face and received by the instrument is within the proper
range. This voltage will decrease as the water surface
becomes more turbulent and will increase as the water
surface calms. The NUMERATOR voltage should be
observed under the worst-case surface turbulence con-
ditions as well as with the calmest water surface possi-
ble.
1. Observe and record the NUMERATOR voltage
under the worst-case water surface turbulence con-
ditions.
2. If the voltage drops below +0.25 VDC, increase the
preamplifier gain as described in Step 3.
3. To adjust the preamplifier gain, follow the Access to
Internal Components procedure (see MAINTE-
NANCE section) and locate the Preamplifier 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 fins from the
bottom of the heat sink (as viewed when the cover is
open but attached to the housing by its hinges).
Turn the Preamplifier Gain Adjustment potentiometer
clockwise to increase the preamplifier gain.
4. Observe and record the NUMERATOR voltage with
very calm water surface conditions.
5. If the voltage exceeds +0.75 VDC, decrease the
preamplifier gain by turning the Preamplifier Gain
Adjustment potentiometer counterclockwise.
OUTPUT ZERO
The Output Zero (RATIO) is factory set for oil-free water.
The Output Zero (RATIO) should be checked periodical-
ly and the ZERO potentiometer should be adjusted when
necessary.
1. With the instrument viewing oil-free water and both
transmitter and receiver windows in place, record
the RATIO voltage at the junction box (TERMINAL
1). If the RATIO voltage is not 1.0 ±0.5 VDC, the
ZERO potentiometer should be adjusted as
described in the following steps.
2. Remove the receiver window and locate the ZERO
potentiometer on the front panel.
3. If the RATIO voltage recorded in Step 1 was higher
than 1.0 ±0.5 VDC, rotate the ZERO potentiometer
counterclockwise until the RATIO output is within the
desired range.
4. If the RATIO voltage recorded in Step 1 was lower
than 1.0 ±0.5 VDC, rotate the ZERO potentiometer
clockwise until the RATIO output is within the
desired range.
OIL RESPONSE CONFIDENCE TEST
To verify that the instrument is responding to the pres-
ence of an oil film on the water surface:
1. With power applied to the instrument, connect a dig-
ital voltmeter between the RATIO output (brown) and
SIG. GND. (green) on the front panel, or on the
appropriate terminals in the junction box.
2. With the instrument viewing clean water, introduce a
small amount of test oil - either in a test pan or on
the actual water surface being monitored.
3. The RATIO should increase above +2.0 VDC. If the
RATIO output does not increase, consult
Troubleshooting Table.
STATUS ALARM CONFIDENCE TEST
To verify that the instrument status alarm is working
properly:
1. With power applied to the instrument, block the
beam with an opaque object.
2. The Status Alarm should activate within 120 sec-
onds. If Status Alarm does not activate, contact the
factory for assistance.
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