5-17
Servicing
Troubleshooting
To check the A2A2 Laser Modulation Board Assembly
1Check the +5V supply by probing the center pin of J11. The modulation input
cable from the rear panel connects to this jack.
2Check the –15V supply by probing any of the three resistors that are located
next to J2. These resistors are loaded in a straight line and have the label “1471”
printed on them.
3Locate the large 3W black resistor on the assembly that is closest to the pump
laser.
4Measure the voltage on the end of the resistor that is furthest from the pump
laser. The voltage should measure approximately –1V to –2V.
5The pump laser is being driven by the current source and should be turned on.
6Press the front-panel ACTIVE key so that the front-panel ACTIVE light is turned
off. The voltage measured at the 3W resistor should now be approximately
+0.7V.
The pump laser is turned off.
7If the voltage measured across the resistor is incorrect, return the instrument
to Agilent Technologies for servicing.