Outguard Power Supplies Troubleshooting; Inguard Power Supplies Troubleshooting - Agilent Technologies 3458A Repair Manual

Outguard Power
Supplies
Troubleshooting
Inguard Power
Supplies
Troubleshooting
84 Chapter 4 Assembly Level Troubleshooting
h. Turn the instrument on.
i. If the fuse blows again, use the Assemblies Removal/Installation
Procedures in Chapter 3 of this manual to replace the Inguard
Power Supply (A4) assembly.
j. If the fuse is good, use the Assemblies Removal/Installation
Procedures in Chapter 3 of this manual to replace the Outguard
Power Supply (A6) assembly.
Do the following:
1. Use the Covers Removal/Installation Procedures in Chapter 3 of this
manual to remove the instrument's bottom cover, if not previously
removed.
2. Refer to Figure 29. With the test digital multimeter, check for
+5 V (±0.25 V) at the test points shown in the figure.
3. If the voltages are good, the Outguard Power Supply assembly is
good.
4. If a voltage is high, the Outguard Power Supply (A6) assembly is
defective. Go to the Assemblies Removal/Installation Procedures in
Chapter 3 of this manual to replace the assembly.
5. If any voltage is low, the Outguard Controller (A5) assembly may be
loading down the power supply. Continue with the next step.
6. Refer to Figure 29. Unplug the grey 20 pin cable connected to the
Outguard Controller (A5)assembly.
7. If the power supply voltages are now good, the Outguard Controller
(A5) assembly is defective. Go to the Assemblies
Removal/Installation Procedures in Chapter 3 of this manual to
replace the assembly.
8. If the voltage is still low, the Outguard Power Supply (A6) assembly is
defective. Go to the Assemblies Removal/Installation Procedures in
Chapter 3 of this manual to replace the assembly.
Do the following:
1. Use the Covers Removal/Installation Procedures in Chapter 3 of this
manual to remove the instrument's bottom cover and bottom shield, if
not previously removed.
2. Refer to Figure 30. With the test digital multimeter, check for
+5 V (±0.13 V), +18 V (±1.8 V), and - 18 V (±1.8 V) at the test points
shown in the figure.