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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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. 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 device has a switching pre-regulator encased in a separate box and the post-regulator removable board with all the secondary linear regulators. There was no a specific pattern that would allow to predict as to when this may happen next time. 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. I had no choice other than to download the Service Manual and deal with the problem.

Manuals – KO4BB

The two halves of the box have connections with each other via disconnectable wire cables. If the overload condition was still present it caused the device to continuously cycle the power.

This time removing one or two boards in no particular order allowed the power supply to start. The board has LEDs along the top of the board that indicate power status for each post-regulator channel.

So that was a good starting point! The bad C6 capacitor is the yellow one in the middle of the picture to the left of the controller IC pin 2. This was what I manuxl one day when my VNA became erratic.


EB5AGV’s Workbench: HP-8753C repair

The problem was solved. 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 manuzl so on. And now this is the same signal after the pretune changes: The right half was the line input and the controller circuit, which became the subject of my further investigation. Doing some extra checkings This kind of microprocessor controlled systems, even being 20 years old inhave usually a large quantity of self checks which save a lot of time measuring here and there.

8753C Network Analyzer, 30 kHz to 3 GHz

Here you have what I got: It was a small yellow axial 0. The Test Set basically has a frequency doubler to multiply the source signal frequency by 2, RF couplers on the two test ports and RF switches to swap the ports.

So I run all the tests which were related to it.

The following part of the schematic shows the critical elements of the PWM controller. When combined with a test set, it provides a complete solution for characterizing linear behaviour of either active or passive networks, devices, or components from kHz to 6 GHz.

Here you have the previous apparently good check of the YO coil drive, which showed some offset: Unit as received I got the unit knowing it had several faults, so there was not surprise when I got the first display from it: Checked the pin 2 mannual, the voltage was changing erratically. That oscillator is a 3. Thanks to the used equipment market for producing such a nice opportunity to learn.

EB5AGV’s Workbench: HPC repair

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. I soldered a new resistor in parallel to it but that did not help. It can be seen from the schematic that this voltage is supposed to be stable and present on the pin 2 all of the time as long as the VNA power switch is turned on. Here you hp8753x a sample display: More to come soon 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 connected a scope with a DC input to the pin 2 and The Service Manual suggested replacing the switching pre-regulator, which was not an option for me because I did not have a replacement. That puzzled me off completely. Source adjustments As I 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 It then became apparent that the problem may be with the PWM controller which for some reason restarted intermittently.

So I removed the switching amnual box and opened it in a hope to find the answer there.

Here you have a test pattern displayed on the Sony monitor subassembly yes, manusl is a Sony Trinitron tube! The Hewlett-Packard C Vector Network Analyzer is a massive literally instrument for measuring complex reflection and transmission hp7853c of the device under test DUT circuits. It was not hard, using the extensive display charts tests, to get the colors more natural, as chart 13 shows: Cleaning works I have done also some cosmetic work on the unit and have also fixed the gummy power button system.

The construction of the switching power supply is interesting and deserves a larger photo.

This was a very challenging but interesting project and a good exercise for the brain. Then all of a sudden the VNA began cycling the power again even with the display power disconnected.

In the picture on the right the post-regulator board can mankal seen in the middle of the frame by the back panel.