Industrial Fiber Optics IF-FOM, Руководство оператора

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3. Insert a small NON-METALLIC screwdriver (standard blade type) into the hole
marked “ZERO” on the test set front panel and engage the slot on the internal
potentiometer. Adjust the potentiometer until the display reads as close to zero as
possible.
Note: This potentiometer turns only 3/4 of a revolution; do not adjust
beyond this amount or permanent damage to the test set will result.
4. In certain conditions of ambient light, there may be suffi cient leakage past the
protective cap to cause diffi culty in the “Zeroing” procedure. If this occurs, remove
the protective cap and attach the test cable supplied with the test set to the LED
and “DETECTOR” receptacles. Repeat steps 1 through 3 above.
Note: Do not
press the “LED ACTIVATION” button during this zero check. If this is done
inadvertently, turn the test set off, then back on to reset the LED circuit.
5. Turn off the Fiber Optic Test Set by pressing the “ON/OFF” switch. Remove all
cable ends from the test set receptacles and replace the protective caps.
LED Power Adjustment Procedure
The LED optical source in the Fiber Optic Test Set is factory-adjusted to deliver reasonable
power with good battery life. After this adjustment the transmission of the fi ber optic test
cable is measured using the test set LED and radiometer. This reading is supplied as a
calibration value with the test cable.
As the test set is used, the LED power may drift from the factory setting, or the user may
desire a different power level for a specifi c application. The following procedure will restore
the LED power to the factory setting,
or allow a different power level to be
established.
1. Remove the four screws at the
corners of the Fiber Optic Test
Set front panel.
2. Carefully lift the front panel
from the test set chassis and
place it on a table or bench
with the display side facing up.
3. Attach the fi ber optic test cable
supplied with the test set to
the “LED” and “DETECTOR”
receptacles. Turn the “DISPLAY
SELECTOR SWITCH” to the 2
mW range.
4. Push the “LED
ACTIVATION” button and
Figure 4. Test Set front panel showing the
location of the potentiometer for adjusting
the LED current
1020.eps
Potentiometer for
adjusting LED current
ZERO
FIBER OPTIC TEST SET
DISPLAY
SELECTOR
SWITCH
ON/OFF
SWITCH
20 μ W
200
μ
W 2 mW
20 mW
Industrial Fiber Optics
LED
ACTIVATION
WAVELENGTH
( λ )
650 nm
850 nm
LED TURNS OFF
AFTER 10 MIN.
DETECTOR