Agilent Technologies 54845B Manual page 91

Replace any shorted assembly.
C
You can locate the shorted assembly by disconnecting assemblies from the power supply, one at
a time. Use the power supply distribution chart in table 5-4 as a guide to locating the shorted
assembly.
Reconnect Assemblies and Cables
Reconnect all assemblies after testing. The oscilloscope must have all cables connected for correct power
up.
If you want to test the power supply without any assemblies connected, the +5 V supply must be loaded
to 2 A. Use two 5Ω, 10W resistors between the +5 V output and ground.
Table 5-3 Power Supply Distribution
Assembly
Acquisition
Motherboard
Probe Power &
Control
Front-Panel
Keyboard
Scope Interface
Board
Display Board
Backlight
Inverter
Flat Panel
Display
Floppy Disk Drive
Hard Disk Drive
Override the Remote Inhibit signal.
D
Power up the unit by connecting a resistor between pin 3 and pin 11 of power supply control
cable W2. Use a resistor in the range of 196-220Ω, 1/8 W, such as Agilent Technologies
P/N 0698-3440 or 0757-0407.
See figure 5-4.
Figure 5-6
Power-up Sense Resistor Connection
+5.1 V -5.2 V Ground
X X X
X X X
X X
X X
X X
X X
X
X X
X X
X X
Power Supply Trouble Isolation
+12.2 V -12.2 V 3.3 V (generated on Motherboard)
X X
X X X
X X
X
X X X
X
X
Chapter 5: Troubleshooting
5–13