The Fans Are Not Working - Keysight N5171B EXG Service Manual

Troubleshooting

The Fans are Not Working

The Fans are Not Working
The four fans are connected directly to the A1 Power Supply. The fan motors
are AC motors, with a DC to AC inverter built into the motor hub. The control,
voltage, and filtering for the fans are integrated into the A1 Power Supply. The
fan control voltage is a nominal 12 Vdc. The control range can vary from a
minimum of 8 volts up to a maximum of 13.8 volts. Using internal sensors, the
control circuit sets the fan voltage to adjust the fan speed to protect the A1
Power Supply and the signal generator. The A1 Power Supply will function at
full output load, up to 25
Power Supply may begin to raise the fan voltage at 25
maximum voltage at no lower than 45
— If a single fan is inoperative, the most likely cause is a faulty fan.
— If two or more fans are inoperative, the most likely assembly at fault is the
72
°
1. Unplug the inoperative fan and one working fan.
2. Plug the inoperative fan into the working fan's connector on the A1
Power Supply.
— If the inoperative fan works, the connector on the A1
Power Supply is faulty. Replace the A1 Power Supply.
— If the inoperative fan does not work, plug the good fan into
the inoperative fan's connector on the A1 Power Supply. If
the good fan works, the inoperative fan is faulty. Replace
the fan.
A1 Power Supply. The four fans are connected in parallel, so if the A1 Power
Supply voltage is faulty for one fan, then by design, the voltage will be
faulty for all four fans. Replace the A1 Power Supply.
C, without raising the minimum fan voltage. The A1
C ambient.
°
Keysight X-Series Signal Generators Service Guide
C and will reach
°