Keysight Technologies E4981A, Service Manual

Page: 49 / 152

Chapter 4 47
Troubleshooting
Troubleshooting Using Service Function
4. T
roub
lesho
o
ting
Troubleshooting Using Service Function
The Keysight E4981A has a service function to diagnose the analog measurement section,
digital section, and internal dc power supply voltages. The Power On Test or Self Test of
the service function makes it possible to isolate a faulty board assembly.
Power On Test
The Power On Test always takes place once the E4981A is turned on. When a failure is
detected, a message "Power on test failed" is displayed in the system message area and the
normal measurement screen does not appear (Service Mode). The Service Mode is a state
that occurs when the power-on test fails. Here, the characters on the display turn yellow
and all of the front panel keys are unavailable.
NOTE
When you want to use the front panel keys in the Service Mode while carrying out any
repairs to the unit, Power Preset keys can be pressed. The characters on the
display turn yellow too, but you can use all keys.
Contents of the power on test results
The Power On Test contains tests as shown in Table 4-3 . If the power on test is failed, an
error code or an error message is also displayed. You can identify a failure section with the
error code or the error message. The error code or error message is related to each test
group as shown in
Table 4-3 . For example, the first item of the error code is for CPU test
group, second item is for System test group, and sixth item is for A34 test group. The value
for each test group is given in hexadecimal.
Example of error code: Power on test failed: 0,0,0,0,3f,1f
NOTE
When the test no.1 or 2 of System test group fails, tests of A31, A34 test groups are not
performed. In case of this failure, the value for the fifth and sixth item is indicated as ffff.
Self Test
The Self Test can perform some test items of the power on test. Pressing the [System] key
followed by the
SELF TEST
softkey opens the SELF TEST page. The SELF TEST page,
intended for maintenance and repair, allows you to check the digital and analog behavior of
E4981A. You can choose one of the available test items with the cursor placed in the
corresponding field (parenthesized field).
• Choosing a Test Item (TEST No. field)
Figure 4-3 shows the fields available on this page along with the softkeys corresponding to
them.