Agilent Technologies PSG Series Service Manual page 34

Amber Standby LED not working
With the power turned off, and the signal generator plugged in, the front panel amber standby LED and the
+15 Vdc standby LED on the motherboard should be on. The amber Standby LED is controlled by a +15 Vdc
standby line supplied by the power supply, which is routed through the motherboard to the front panel.
To troubleshoot the +15 Vdc Standby line, turn the signal generator off and refer to the Power Supply vs.
Assembly Matrix (Table 1-13 on page
Green Line Power LED not working
When the power switch is turned on, the amber LED will go out and the green LED will come on. The fan will
start rotating and the front panel display will become illuminated.
To troubleshoot, refer to the Power Supplies vs. Assembly Matrix
supply voltages at P11 of the A31 Motherboard. If the supply voltages are correct, replace the A3 Power
Switch.
Fan not working
The fan is connected to the rear panel assembly and is audible when the signal generator is powered on. The
fan voltage is temperature dependent. At room temperature, the fan will race at power up and then stabilize
after a few seconds to a fan voltage of approximately +8.6 volts. At higher temperatures, the fan voltage will
increase along with the rotation of the fan.
To troubleshoot, disconnect the fan from the rear panel assembly at P6 and check the fan voltage at P6-2 on
the rear panel assembly. If the fan voltage is correct, replace the B1 Fan.
Signal Generator does not power-up and the power supply LEDs not working
Each of the power supplies has an LED located on the bottom of the A31 Motherboard. If the power supply is
functioning, the green LED will be on. Use a voltmeter to measure the supplies on the A31 Motherboard to
ensure the voltages meet the power supply specification in Table1-16.
Table 1-16
With the exception of the +15 Vdc Standby supply, each supply should have a maximum of 10 mV
The +15 Vdc Standby supply has a maximum ripple specification of 20 mV
using an oscilloscope.
If any of the supplies LEDs are not on or the measured voltage is less than the acceptable value, one the
1-18) to follow the signal path.
Power Supply
+32 Vdc
+15 Vdc
+15 Vdc Standby
+10 Vdc
+5.2 Vdc
+5.2 Digital high
+3.4 Digital low
-7.0 Vdc
-15 Vdc
(Table 1-13 on page
Acceptable Voltage
32 1 Vdc
15 .5 Vdc
15 .75 Vdc
10.2 .2 Vdc
5.2 0.15 Vdc
5.2 0.15 Vdc
3.4 1 Vdc
-7 0.1 Vdc
-15 0.5 Vdc
Troubleshooting Assembly Level Problems
1-18) to verify the power
. The ripple may be measured
p-p
Troubleshooting
ripple.
p-p
1-21