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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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. The pre-regulator box is made of two halves bolted together via a EMI strip gasket that seals the gap in the assembly to reduce emissions.
Setting Observed frequency Error approx kHz 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. And now Channel 1 was, as intended by HP, yellow!
EB5AGV’s Workbench: HPC repair
More to come soon As you can see, I was right about the offset being an anomaly. The difference between the two was amplified and steered the PWM to regulate the output voltage of the pre-regulator. Hp875c3 connected a scope with a DC input to the pin 2 and So, yes, it seemed like the VNA was working fine!!!
The problem was intermittent, so the troubleshooting promised to be challenging. 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.
This was what I experienced one day when my VNA became erratic. The easy-to-use softkey selection of measurement functions allows you to measure the magnitude, phase, or group delay characteristics of your device under test.
Manuals – KO4BB
The construction of the switching power supply is interesting and deserves a larger photo. The VNA Service Manual did not go to the level of details about the power supply that were needed to repair it.
So I removed the switching pre-regulator box and opened it in a hope to find the answer there. 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: I got a gut feeling that the problem may maunal with the power supply itself.
Here you have the pots: It can be seen in the above picture along the edge of the right half of the box.
It then became apparent that the problem may be with the PWM controller which for some reason restarted intermittently. Thanks to the used equipment market for producing such a nice opportunity to learn.
EB5AGV’s Workbench: HP-8753C repair
It was not hard, using the extensive display charts tests, to get the colors more natural, as chart 13 shows: 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. This time removing one or two boards in no particular order allowed the power supply to start. So I proceeded with some hesitation and hoping for the best The problem was solved.
The device has a switching pre-regulator encased in a separate box and the post-regulator removable board with all the secondary linear regulators.
So when one dies on you it is not a good feeling. I put the assembly over the hp87533c, in vertical position so the control cable could be plugged while adjusting it by means of a long plastic trimming tool: I did also some CW tests and, as a sample, a 1.
Here you have a sample display: During normal operations all the LEDs are on and start flashing when the shutdown circuitry detects jp8753c overcurrent, overvoltage or undervoltage condition. When the power switch was activated, the VNA appeared to be starting up but as soon as the CRT display was about to come up it produced a hissing sound and the device shut down and immediately restarted in a continuous loop.
That oscillator is hp753c 3.
Here you have the apparently good check of the YO coil drive: So I run all the tests manuxl were related to it. But before doing them, I thought that a good way to know if the rest of the system was OK, was to check the unit with an external reference.
8753C Network Analyzer, 30 kHz to 3 GHz
After spending time with a pen, paper and a continuity meter to understand the schematics, and search on the Internet for the datasheets of the parts used in the pre-regulator, I got what I wanted which was understanding the power supply PWM controller circuit. 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.
Also, it was unusual that this type of component, a small axial bypass capacitor, would develop resistance and caused that much of a problem, rendering the whole system unusable. 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