Specifications

To check the Low Voltage Power Supply
1
Disconnect the power cord, then set the oscilloscope on its side.
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 L1, L2, and L3 on the system
board.
Table 4-19 Power Supply Voltage Tolerances
Supply Voltage Tolerance
+5.1 V ±150 mV (+4.95 V to + 5.25 V)
+15.75 V ±787 mV (+14.96 V to +16.54 V)
−15.75 V ±787 mV (−14.96 V to −16.54 V)
Low Voltage Power Supply voltage test points
If the
+
5.1 V measurement is out of the test limits, adjust the
+
5.1 V
adjustment on the power supply. The
±
15 V supplies are not adjustable and
are dependent upon the
+
5.1 V supply.
Blown fuse
If the fuse is blown in the power supply, the power supply is defective. Replace
the power supply.
Figure 4–7
Service
Troubleshooting the Oscilloscope
4–45