5-30
Servicing
Replacing Instrument Assemblies
To replace the A5 Laser Driver Board Assembly
Three resistors on the A5 Laser Driver Board Assembly limit the maximum
current to the A2A3 Pump Laser. These resistors are matched to the particu-
lar pump laser installed in your instrument. New A5 assemblies are shipped
with these three resistors unloaded. You must load new resistors, which match
the values loaded in the original A5 assembly, into the new A5 assembly. A bag
of resistors is supplied with the new assembly. Refer to “Major Assemblies” on
page5-37 for the part number of the A5 replacement assembly.
WARNING Failure to load the proper resistor values as described in this
procedure could destroy the laser or result in increased laser output
power from the front-panel OPTICAL OUT connector. Increased laser
output power may change the laser classification of the product.
1Remove the A5 Laser Driver Board Assembly from the instrument.
2Locate resistors R2, R8, and R9 as shown on the following diagram.
3Read the values of each of these three resistors, and write them down. The
values should be printed on the sides of each resistor.
The possible values of each of resistors is 82Ω, 100Ω, 125Ω, or 150Ω. In the cir-
cuit, they are wired in parallel.
4Locate the bag of resistors that was shipped with the new A5 Laser Driver
Board Assembly. Find three resistors with identical values to those identified
in the previous step.
5Solder these resistors into the new A5 Laser Driver Board Assembly.
6Installed the new assembly into the instrument.
7Use an optical power meter to confirm that the total output power emitted fr om
the front-panel OPTICAL OUT connector does not exceed the following limits:
Maximum: +8.1 dBm (6.5 mW)
Minimum: +5.5 dBm (3.5 mW)
Maximum: +5.1 dBm (3.2 mW) (Option 009)
Minimum: +2.5 dBm (1.8 mW) (Option 009)