To Check The Low Voltage Power Supply - HP 54645A User's And Service Manual

Testing, Adjusting, and Troubleshooting

To check the Low Voltage Power Supply

To check the Low Voltage Power Supply
Disconnect the power cord, remove the cover and set the
1
oscilloscope on its side.
If you operate the oscilloscope without the cabinet, use an external fan to
C A U T I O N
blow air across the system board. This air flow is necessary to cool the heat
sinks on the system board.
Connect the negative lead of the multimeter to a ground point on the
2
oscilloscope. Connect the power cord and turn on the oscilloscope.
Measure the power supply voltages at E1 through E6 on the system
3
board. See the following figure.
Table 7-21 Power Supply Voltage Tolerances
Supply Voltage
–5.25 V
Figure 7-11
Low Voltage Power Supply Voltage Test Points
7-48
5.1 V
15.75 V
15.75 V
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)