Inspect Ribbon Cable Repeat Display %St 55 - Agilent Technologies HP 8719D Service Manual

display:
55 Disp/cpu com -ND-
If the analyzer passes the test, the message TEST RESULT DISPLAYED ON
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LEDS IF FAILED will be displayed. Press Cfl#TXHUR and the analyzer will
display 55 DISP/CPU COM PASS. Press [PRESET_) ~PIH$S~~ FACTlM and go to
"Run Display Tests 59-76 n.
If the analyzer fails the test, the display will appear blank and the front
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panel LEDs wilI stay on. Continue with the next check.
Inspect Ribbon Cable Repeat Display 'I&t 55
Inspect the W20 (A7-A19) ribbon cable for a loose connection. Repeat "Run
Display Test 55." If the analyzer fails the test, a walking one pattern wiIl
be continuously transferred from the CPU, through the cable, to the GSF.
Immediately go to the next check.
Use an oscilloscope probe to verify that a walking one pattern is transferring
from the A7 CPU. The walking one pattern similar to the one shown in
Figure 6-11 and is 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
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is present at the other end of the cable.
If the signal is still not present, replace the cable.
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Digital Control Troubleshooting