This manual may contain references to HP or Hewlett-Packard. Please note that Hewlett-. Packard’s former test and measurement, semiconductor products and. Chapter 2 Getting Acquainted with the HP C How to Get the Most Out of the HP C “General Information” section of the Operating Manual has. This page is devoted to the repair of my HPC Network Analyzer. section or page of the HPC Service Manual PDF file) and got these results.
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You can see from page of the PDF what the different displays hp8753 be in a working unit. Setting Observed frequency Error approx kHz Source adjustments As Manuaal said before, I was afraid of trying any test which would write on the configuration EEPROM, as I had no way to restore the previous configuration if things got worse At least now the power supply was running and I was able to check the voltage and ripple levels on the pre- and post-regulators per the Service Manual and it all looked fine.
But with some determination and efforts even a very complex equipment can be repaired. That was the breakthrough and I realized that the shutdown condition was caused not by a overcurrent but by hp87753c undervoltage.
Knowing that the analyzer seemed to run fine with an external reference was a good thing, as it really pinpointed the A3 SOURCE as the real culprit. Other smaller problem was that the power switch was semi-stuck, wth a gummy touch, making it very hard to power up and down the unit.
So it appeared the problem was not in the display circuitry. The board has LEDs along the top of the board that indicate power status for each post-regulator channel. I connected a scope with a DC input to the pin 2 and But I stopped early, as it suggested to do a recalibration and I was afraid that would only make things worse; I checked the RF OUT in CW mode with an spectrum analyzer and an oscilloscope, at different frequencies.
The right half was the line input and the controller circuit, which became the subject of my further investigation.
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Here you have what I got: Clicking sounds produced by the attenuator h;8753c switch relays could also be heard. I hope you enjoy it! The controller board before the fix. That puzzled me off completely. This time removing one or two boards in no particular order allowed the power supply to start. The controller board after the fix.
In the picture on the right the post-regulator board can be seen in the middle of the frame by the back panel. So I run all the tests which were janual to it.
The following part of the schematic shows the critical elements of the PWM controller. During normal bp8753c all the LEDs are on and start flashing when the shutdown circuitry detects a overcurrent, overvoltage or undervoltage condition. But as I had never used an C before, I was not aware that the Channel 1 should be yellow instead of orange The VNA class of instruments was not wide known to or used by the Ham Radio enthusiasts before recently because of very high cost of that type of equipment.
But I could not find it for a while, until I got the info from another manual of an C, where it was pictured. I cut one of the legs off and connected the ohmmeter across the capacitor – it measured a resistance. I could not believe my eyes. The Service Manual instructs to remove the boards one by one to identify which one may be causing the overload condition, which I did with no success. The VNA Service Manual did not go to the level of details about the power supply that were needed to repair it.
Next step is to add an external storage unit to the VNA. It was complete inside I had no way to know before getting the unit, so that was a very welcomed thing and some parts were obviously working, as power supply, fan, CPU, keyboard, display and so on. The cost of this type of equipment is still high these days and is in the range of several thousand dollars.
I was stunned – a one penny capacitor took down the multi-K dollar device.
Every once in a while the C was able to start and work for a period of time and then all of a sudden restarted as was described above. Cleaning works I have done manuwl some cosmetic work on the unit and have also fixed the gummy power button system.
8753C Network Analyzer, 30 kHz to 3 GHz
That oscillator is a 3. The bad C6 bypass capacitor was replaced with a new mica red one which can be seen hp853c the center of the picture. There was no a specific pattern that would allow to predict as to when this may happen next time. I marked with a permanent pen the actual position, so I had a reference to come back if I goofed the adjustment too much .