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| HP 8595E spectrum analyzer repair |
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| kada:
I bought a nonworking 8595E analyzer. The analyzer did not turn on. I was able to repair the power supply. When I inserted the repaired PSU to analyzer the -15V LED turns off and -15V disappear. The problem was in the burned shorted tantalum capacitor located on the Narrow Band IF Board which was replaced: After it I can power on the analyzer but other problems were revealed: 1. Very slow reaction to controls and display refresh - need to wait 10-15 seconds after each key presses. And spectrum refreshes once every ~30 seconds. Empirically I found out that if disconnect the A25 Counter Lock board the problem is resolved. The board is defective? 2. No response of analyzer to 300 MHz calibration signal. The calibration signal level and frequency was checked using frequency meter and millivoltmeter. It corresponds to 300 MHz -20 dBm. If I try to do FREQ CAL the error will appear: CAL SOURCE NOT FOUND. I measured the signal with millivoltmeter at the point A (after Attenuator -> YTF -> LPF) in the band 0 and it seems good. So I guess the problem may be in the Dual mixer or Second converter. But I have not instrument to check the high frequency signal after mixer. How I can to localize the defective part? I have not RF generator or other analyzer. I have only 15 MHz generator and 100 MHz DSO. Analyzer screen after power on (A25 Counter Lock board connected): After 10 seconds: Thank you all who responded. |
| tec5c:
Does the oven manage to stabilise after the unit has been powered on for a significant amount of time, i.e., does the 'OVEN COLD' message disappear? |
| kada:
--- Quote from: tec5c on September 07, 2015, 04:59:27 am ---Does the oven manage to stabilise after the unit has been powered on for a significant amount of time, i.e., does the 'OVEN COLD' message disappear? --- End quote --- 'OVEN COLD' message disappears after 5 minutes. And I got the same error after FREQ CAL attempt: "CAL SIGNAL NOT FOUND" *LOCK OFF SRQ 110 I also tried to do FREQ CAL with "-37Hz" passcode. The process starts in this case and I got the following message at the end of process: "CAL: SPAN SENS FAIL" The same test with A25 Counter Lock board inserted I got the "CAL: ZERO FAIL" error: |
| kada:
Hope this will help. Options: With A25 Counter Lock board inserted: Without A25 Counter Lock board: CAL DATA: |
| KJDS:
Your best bet is to plow through the service manual flowchart to see where that takes you. The only thing of note from your pictures is that it is showing cal date for 10Hz up to 5MHz, and I would have expected it to have started from 1kHz, but check the service manual to see what it should be giving. |
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