HP 54616B User And Service Manual page 128

Service
Troubleshooting the Oscilloscope
Low Voltage Power Supply Voltage Tolerances
Supply Voltage
+5.1 V
–5.25 V
+15.75 V
− 15.75 V
Is the fan running?
9
If yes, go to "To run the internal self-tests," on page 4-41. If not, do the steps
below.
The Low Voltage Power Supply has a thermal cut-out circuit. If the fan is
defective, the Low Voltage Power Supply shuts down when it gets too hot for
safe operation.
a
b
Figure 4-6
Low Voltage Power Supply fan connector location
4–36
Disconnect the fan cable from the power supply.
Measure the fan voltage at the connector on the power supply.
See figure below for location of fan connector. If the fan voltage is
approximately +8 Vdc, replace the fan. If not, replace the power
supply.
fan connector
Tolerance
±153 mV (+4.947 V to +5.253 V)
±158 mV (–5.092 V to –5.408 V)
+1.260 V, –787 mV (+14.963 V to +17.010 V)
±787 mV (−14.963 V to −16.537V)