Agilent Technologies 83438A User Manual page 70

Servicing
Troubleshooting
3 If the green LED is on, the current source driving the pump laser is operating
correctly. If the yellow LED is on, the pump laser's temperature stabilization
loop is not functioning; the current to the pump laser is automatically turned
off which turns the green LED off.
4 If the yellow LED is off, check ribbon cable W12.
5-16