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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Here you have a test pattern displayed on the Sony monitor subassembly yes, it is a Sony Trinitron tube! The device has a switching pre-regulator encased in a separate box and the post-regulator removable board with all the secondary linear regulators.
The Hewlett-Packard C Vector Network Analyzer is a massive literally instrument for measuring complex reflection and transmission parameters of the device under test DUT circuits. And now this is the same signal after the pretune changes: The board has H;8753c along the top of the board that indicate power status for each post-regulator channel. The bad C6 capacitor is the yellow one in the middle of the picture to the left of the controller IC pin 2.
That was hp873c breakthrough and I realized that the shutdown condition was caused not by a overcurrent but by a undervoltage. Thanks to the used equipment market for producing such a nice opportunity to learn. Checked the pin 2 again, mankal voltage was changing erratically. To do that, I have got out the display assembly, have carefully cleaned it, and then have cleaned and greased the power button mechanism: But I could not find it for a while, until I got the info from another manual of an C, where it was pictured.
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. The VNA Service Manual did not go to the level of details about the power supply that were needed to repair it.
Manuals – KO4BB
The problem was with the device not powering on or restarting unexpectedly. Display color adjustment I had some info about the colors not being accurate on this unit. Next step is to add an external storage unit to the VNA. This time removing one or two boards in no particular order allowed the power supply to start. The display looks really nice, which is a plus for a 20 year old instrument Locating the faulty assembly I got the CPU board out of the unit, trying to locate a jumper which is named in the Service Manualbut no joy.
In the picture on the right the post-regulator board can be seen in the middle of the frame by the back panel.
So, mabual, it seemed like the VNA was working fine!!! The following part of the schematic shows the critical elements of the PWM controller. Here you have what I got: The problem was intermittent, so the troubleshooting promised to be challenging.
EB5AGV’s Workbench: HPC repair
If the overload condition was still present it caused the device to continuously cycle the power. Manuql can be seen from the schematic that this voltage is supposed to be stable and present on the maunal 2 all of the time as long as the VNA power switch is turned on.
Here you have a sample display: 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. I did also some CW tests and, as a sample, a 1. 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.
I hope you enjoy it! This was a very challenging but interesting project and a good exercise for the brain. It was not hard, using the extensive display charts tests, to get the colors more natural, as chart 13 shows: So when one dies on you it is not a good feeling.
With two independent display channels available, you can simultaneously measure and view the reflection and transmission characteristics of the device under test in overlay or split-screen format on the crisp color display. 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.
EB5AGV’s Workbench: HP-8753C repair
I thought that the resistor that connects the Zenner to the pin 2 must be bad. That oscillator is a 3. I marked with a permanent pen the actual position, so I had a reference to come back if I goofed the adjustment too much.
hp8753x 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. 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.
At least now the power supply was running and I was able to check the voltage and ripple levels on the pre- manua post-regulators per the Service Manual and it all looked amnual.
It seemed to have a good level and it was variable as it shouldbut frequency was way out and only changed in large steps this could be a hint on the problem, I guessed.
And now Channel 1 was, as intended by HP, yellow!