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682XXB/683XXB MM 5-37
A10 ALC
Error 121 Unleveled Indicator Failed
Error 122 Level Reference Failed
Error 123 Detector Log Amp Failed
Error 127 Detector Input Circuit Failed
Description: Error 121 indicates a failure of the circuit that alerts
the CPU whenever the RF output power becomes unleveled. Each of
the other error messages indicates a problem in the circuitry on the
A10 ALC PCB that provides control of the RF output power level.
Step 1. Replace the A10 PCB, and run self-test.
If no error message is displayed, the problem is cleared.
If any of the error messages, listed above, is displayed,
contact your local ANRITSU service center for assistance.
Error 142 Sample and Hold Circuit Failed
Description: Error 142 indicates a failure of the sample and hold cir-
cuitry on the A10 PCB.
Step 1. Set up the 682XXB/683XXB as follows:
a.
Press SYSTEM , then Reset .
b.
Press MODULATION , then Pulse to go to the Internal
Pulse Modulation Status display.
c. Press On/Off to turn on pulse modulation.
Step 2. Disconnect the cable, W122, from A6J6.
Step 3. Using an oscilloscope, verify the presence of a pulse train at
A6J6 (sample and hold signal to the A10 ALC PCB) with an
output level of 0 volts to +1 volt, a pulse period of 1 ms, and
a pulse width of 200 ms.
If the signal is present and correct, reconnect cable W122
to A6J6 and go to step 4.
If the signal is not present or is incorrect, replace the A6
PCB.
Step 4. Disconnect the cable, W122, from A10J1.
Step 5. Using the oscilloscope, verify the presence of the sample and
hold signal (pulse train described in step 3) at the end of the
cable, W122.
Table 5-17. Error Messages 121, 122, 123, 127, 142, and 143 (1 of 2)
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