Agilent Technologies 8753ES Option 011 Service Manual page 218

Digital Control Troubleshooting
CPU Troubleshooting (A9)
Checking A9 CPU Red LED Patterns
The A9 CPU has five red LEDs that can be viewed through a small opening in the rear
panel of the analyzer. (See
be viewed by looking to the left at an angle.
1. Cycle the power while observing five red LEDs
Cycle the power on the analyzer and observe the five red LEDs. After an initial pattern,
the five red LEDs on the A9 CPU board should remain off.
• If the LEDs remained off, then proceed to the assembly that you suspect has a
problem.
• If the LEDs did not remain off, switch off the power and remove the bottom cover for
further troubleshooting.
Figure 6-3 CPU LED Window on Rear Panel
2. Cycle the power while observing all eight red LEDs
With the analyzer positioned bottom up, cycle the power and observe the eight red
LEDs while looking from the front of the instrument.
NOTE If firmware did not load, a red LED on the CPU board will be flashing. Refer
to "Loading Firmware" on page
3. Evaluate results
• If either of the following LED patterns remain, go to
A18, A19, A27)" on page
• If any other LED patterns remain, replace the A9 CPU after verifying the power
supply.
6-6
Figure 6-3.) Four LEDs are easily viewable. The fifth LED must
3-35.
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6-7. ( = LED is on.)
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0
✸ ✸ ✸ ✸
0
(front of instrument ⇓)
"Display Troubleshooting (A2,
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0
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0
Chapter 6