HP 54645A, User'S And Service Manual

Page: 237 / 301

To check the Low Voltage Power Supply
1
Disconnect the power cord, remove the cover and set the
oscilloscope on its side.
C A U T I O N
If you operate the oscilloscope without the cabinet, use an external fan to
blow air across the system board. This air flow is necessary to cool the heat
sinks on the system board.
2
Connect the negative lead of the multimeter to a ground point on the
oscilloscope. Connect the power cord and turn on the oscilloscope.
3
Measure the power supply voltages at E1 through E6 on the system
board. See the following figure.
Table 7-21 Power Supply Voltage Tolerances
Supply Voltage Tolerance
+
5.1 V
±
153 mV (
+
4.947 V to
+
5.253 V)
–5.25 V
±
158 mV (–5.092 V to –5.408 V)
+
15.75 V +1.260 V, –787 mV (
+
14.963 V to
+
17.010 V)
−
15.75 V
±
787 mV (
−
14.963 V to
−
16.537V)
Low Voltage Power Supply Voltage Test Points
Figure 7-11
Testing, Adjusting, and Troubleshooting
To check the Low Voltage Power Supply
7-48