Run Display Test 55; Inspect Ribbon Cable Repeat Display Test 55; Perform Walking One Pattern - Agilent Technologies 8719ET Service Manual

Digital Control Troubleshooting
Troubleshooting the GSP (A19) and the Display (A18)

Run Display Test 55

1. Press the following:
PRESET: FACTORY
Preset
SERVICE MENU
System
EXECUTE TEST
• If the analyzer passes the test, it will display 55 DISP/CPU COM PASS. Press
PRESET: FACTORY
• If the analyzer fails the test, the display will appear blank and the front panel LEDs
will stay on. Continue with the next check.

Inspect Ribbon Cable Repeat Display Test 55

Inspect the ribbon cable (W20) that connects the CPU board (A7) to the GSP (A19) for a
loose connection. Repeat
pattern will be continuously transferred from the CPU, through the cable, to the GSP.
Immediately go to the next check.

Perform Walking One Pattern

Use an oscilloscope and a probe to verify that a walking one pattern is transferring from
the CPU board (A7). The walking one pattern similar to the one shown in
found on pins 3 through 10, and 13 through 20. (See
• If the signal is present at the A7 connector of the ribbon cable, verify that it is present
at the other end of the cable.
• If the signal is not present, replace the cable.
6-10
Preset
TESTS DISPLAY TESTS
CONTINUE
and go to
Preset
"Run Display Test 55."
"Run Display Tests 59-61" on page
If the analyzer fails the test, a walking one
Figure 6-5.)
8719ET/20ET/22ET
8719ES/20ES/22ES
RF Network Analyzers
Preset
6-12.
Figure 6-6 and is
Service Guide