Service Information Sheet
Calibration Adjustments for Serial Numbers
<
79130000
3
Calibration Adjustments for Serial
Numbers < 79130000
(for later serial numbers, see page 6)
To ensure that the laser source performs to
specifications, calibrate it annually using the
procedure that follows.
Always perform the complete calibration
adjustment procedure.
Step 1: Preparing for Calibration
Before you start the calibration procedures
described in this sheet, do the following (refer to
Figure 1 for locations of components on the circuit
board):
1-1.
Turn off the laser source.
1-2.
Remove the battery door and the 9 V battery.
1-3.
Remove the four Phillips screws from the back
of the source. Remove the top case.
1-4.
Unscrew the external retaining nuts from the
source’s power switch and
CW/MOD
switch.
1-5.
Carefully remove the laser source circuit board
from the bottom case. Take care to not strain
the fiber that connects the circuit board to the
ST connector mounted in the bottom case.
1-6.
Before applying power to the source, do the
following:
a.
Remove the jumpers from J2 and J4.
b.
Adjust the internal potentiometers R4 and
R14 to their full counterclockwise
positions. You will hear a faint click at the
full counterclockwise position.
c.
Adjust the external
OUTPUT ADJUST
potentiometers (R24 and R35) to their full
clockwise positions. You will hear a faint
click at the full clockwise position.
1-7.
Adjust the dc power supply to 10 V ±0.25 V
with the output current limited to 250 mA.
Connect the power supply's positive lead to
BT1 on the source; connect the negative lead
to BT2.
1-8.
Set the laser source's
CW/MOD
switch to the
CW
position.
1-9.
Set the laser source's power switch to either
the 1310 nm or 1550 nm position. Verify that
the laser source
LOW BATTERY
LED is off
and the
SOURCE ACTIVE
LED is on.
Step 2: Checking the Laser Drive
Voltage
Use the following procedure to check the drive
voltage for the laser diodes and to verify that the
laser source's low battery detection circuit is
operating properly.
2-1.
Set up the DMM to measure dc voltage.
Connect the DMM to the laser drive voltage
between J2-6 and J2-4 (Gnd). Verify that the
voltage is between 3.2 V dc and 3.5 V dc.
Record this measurement for use in the next
step.
Note
To avoid overshooting the target voltage in the
next step, slow the adjustment rate on the
power supply as the voltage approaches 7 V.
2-2.
Decrease the power supply voltage just until
the laser source's
LOW BATTERY
LED lights.
Verify the following:
a.
The power supply voltage is between
5.4 V dc and 6.2 V dc.
b.
The DMM reading has changed less than
0.3 V dc from the reading you recorded in
step 1.
2-3.
Connect the DMM's positive lead to U3-5.
Verify the reading to be < 500 mV dc.
2-4.
Turn off the laser source and the power
supply. Remove the power supply leads from
the laser source's battery terminals.
2-5.
Reassemble the bottom case, as follows:
a.
Verify that the star washers are in place at
the bases of the laser source switches; then
carefully reinstall the PCA into the bottom
case. Ensure that the fiber connecting the
circuit board to the ST connector is not
pinched between the board and the case.
b.
Reinstall the external retaining nuts on the
laser source's power switch and
CW/MOD
switch.