Agilent Technologies 85032B/E 50 Specifiche Pagina 158

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Troubleshooting and Block Diagrams 8712ET/ES and 8714ET/ES
Category 1 Failures: Dead or No Display RF Network Analyzers
4-16 Service Guide
Error Occurs During DSP Initialization or Calculating
Coefficients
Clearing the Nonvolatile SRAM
1. Cycle the analyzer's power.
2. After about 25 seconds, the analyzer will emit a double beep. Immediately after this
double beep, press several times.
3. The analyzer will pause after performing the CPU main self-tests and ask if you want
to zero the SRAM. (Note the caution message!) Answer YES by pressing the
key. Continue troubleshooting if the error persists.
Measuring the 5 MHz Reference Signal
The DSP requires this signal from the fractional-N/reference assembly for proper
operation. This signal is routed on the backplane board. Make sure that the
fractional-N/reference assembly is pushed all the way in and making good contact with the
backplane. Measure the 5 MHz signal at J101-C24 on the backplane board with an
oscilloscope. If the signal is present, refer to “Testing the DSP Circuit” on page 4-21 to
check the DSP, or replace the CPU board (refer to “Removing the CPU Board Assembly” on
page 3-6).
If there is no 5 MHz signal at the backplane
Check the reference circuit on the fractional-N/reference board. If an external reference
signal is used, make sure it's a 10 MHz signal with a power level of at least 5 dBm.
If the internal 10 MHz reference is being used, check the crystal oscillator output at
A3J202, which is located on the front of the fractional-N assembly (A3). If the 10 MHz
signal is not present, replace the fractional-N/reference assembly (A3). (Refer to
“Removing the Fractional-N/Reference Assembly” on page 3-10.)
22 DIN Keyboard
Interface
Errors:
DIN Keyboard test FAILED
Problem with DIN Keyboard Power Supply! Check Fuse.
Tests DIN keyboard control portion of the Super I/O. Replace
CPU board or check Super I/O chip, U607, or its clock, U606.
23 Centronics Interface Errors:
Centronics port test FAILED.
Strobe bit error.
Printer reset bit error.
Printer select bit error.
Replace CPU board or check Super I/O chip, U607, or its
clock, U606.
Test Test Name Applicable Error Messages and Notes
Note: Tests numbered: 8, 11, and 1417 are not run during power-up.
PRESET
BEGIN
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