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- Опубликовано: 28 сен 2024
- In this episode Shahriar repairs an Agilent N9912A which flags several error messages after bootup. The instrument reports hardware time-outs and occasionally ADC clock source unlock condition. The second error is much more useful in debugging the unit.
The block diagram of the instrument is presented and several potential failures anticipated.
The teardown of the unit and analysis is also presented. After some troubleshooting, it becomes clear that the primary 30MHz TCXO has a broken internal connection. The unit is disassembled and new pins installed. After putting the TCXO back into the unit, the instrument return to full functionality. A few quick experiments verify that the FieldFox performs both CAT and SA modes correctly.
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Sadly more and more test equipment vendors are taking that route, often justifying it as "too complex to repair" or "IP secret sauce", despite much of service needs are just basic information about power supply topology, interconnects between modules and various basic stuff. I even heard weak excuses like "6 layer PCB is too complicated to repair, so that why we don't give schematics" while many can repair broken connection or burnt trace even without digging into inner layers... Sad days. Best we can do is support Right to Repair and support vendors that do provide service info, and make them know it.
As you guessed, that secret IC is a complete VNA front end, designed and manufactured in the Keysight Santa Rosa GaAs IC facility. I think this might have been one of the first complete system GaAs IC's that we developed for instruments. Now all the RF and microwave products are chock full of custom GaAs Asics but back 15 years ago (well, more like 20 when the design started) it was breakthrough stuff.
@wizardkeys1 I wonder if the same chip isn't used in the 50GHz+ models. Small size would really let you go up in frequency.
I never cease to be amazed at how consistently Shahriar is able to find the service manuals of these devives! I can almost never get at them.
One thing I've noticed about newer Keysight instruments is the lack of service manuals. Check out the E5080B or P5000 series VNAs for example. You don't get anything... not even a basic block diagram.
I recall that even in the Agilent days, they used to provide CLIPs (component level information packets) to larger customers for self maintenance.
Are there any kind of laws such as right to repair that are applicable to T&M and industrial electronics?
It's gotten even worse. Keysight is making parts unobtainable. Not even commodity items like knobs, plastic, display, touch panels or power supplies known to be problematic. All say return for repair.
Right to repair is a mixed bag. I'm not sure how you make things repairable today without fixturing, special test and simulation systems and exhaustive documentation and training.
Great video. I had one of these models and it was an impressive little workhorse, but perhaps not the best of RF specs (noise floor, phase noise). Kudos to you for repairing the module. Some months back, I repaired an Anritsu portable SA as you had also done, by repairing one of three VCOs which was defective (poor solder joints internally). I can't recall the manufacturer, possibly Mercury systems (thru acquisition) but they were the most unfriendly people I've dealt with in 50 years of design. Had I been sitting on a 10 million contract, they would never have seen one dime.
This is nuts! Your knowledge of electronics & RF always just creams my pants!
I'm trying to learn the basics for RFI & EMI for get a shitty IoT product getting approved.
In hobby shops there is small metal plates that you can make/fold/solder into boxes. mfg by - K & S Precision Metals -.
Another great episode of RF electronics' Sherlock!
Finally he takes a fieldfox apart! Fantastic!
Still find it fascinating that you can even find these high precision and/or sensitive instruments in ruggedized form (even more so for the 50GHz of course). In my head they've always been relegated to a lab environment.
As digital and multi layer boards made the scene I sensibly rerouted my electronic interests. Hello world of tube amplifiers and audio technology. Down side was I ended up working for musicians and a whole heck of a lot of them had problems. Wall to wall prima donnas and my paychecks sailing up peoples noses. "Hey man, I ain't got the bread right now. How about a few lines instead?"
But still, easier work than 6 layer circuit boards and no schematics. Nothing quite like staring at 800 volt rails as I sip my AM java.
Nice work!
Excellent! I love this content :)
Those copper colored filters are not SAWs, they are dielectric resonator filters. Couldn’t see clearly enough, but appear to be made by Murata.
Yes, you are right. I misspoke as I was looking at the actual SAW filter elsewhere on the board.
Hi, have n9918b and it has a problem, all over the frequency range it measures input power incorrectly, likely -10db relatively input signal till 26.5GHz. We gave it to repair services, but they failed it so now device absolutely can't measure any power approximately in 9.5-15GHz, in the rest of the frequencies problem is the same as before repair.
Now it has message:
"Multiple Failures ... Consider turning Amptd Alignment OFF"
I've opened the RF board (9938b installed) to measure signals unfortunately, input stage was made mmic's crystals welded to board (looks very interesting). During measurement procedure i killed adrf5040 switch (was trying to measure which frequency range it does not switch) so vgg got on control pin and now switch works only in 2 positions (on of them not used at all :) )
And now device works only till 2.5Ghz))
So, ordered this switch, I'll try to replace it and try to bring it back to its post-repair state
The idea is that some of switches dead, maybe in case when input power was enough high to kill some of switches when preamp was turned on. Usually device tells that it overloaded in this cases. Or just input stage is dead.
Maybe any ideas or suggestions in repairing? Have some photos of rf board.
By the way, in service they tried to swap ic's and switches, but it didn't lead to anything good.
Some years before we had the same problem with the same device ( it worked good but measured power -10db to input in all frequency range), but all the repairs came down to replacing rf board, and i don't know where was the problem there, but dead rf board naw acts like donor or reference in my rf projects.
Nice!
❤ Ihave to find some of this Signalfoxes with exavt this error 😂👍😎
I am curious to know if the thermal characteristics of the DYI shielding is similar to the case you replaced, assuming it is indeed a TCXO. 🙂
DIY and yes thats a good point, The characteristics can't be the same without a massive stoke of luck but I wonder if the system can track and stay on temp or even if it matters that much ?
@@andymouse Well, if anything, it is useful confirmation that the problem was isolated to the TCXO. One can always hope to find a replacement part down the road.
*Abstract*
This video documents the repair process of an Agilent FieldFox N9912A RF analyzer experiencing hardware timeouts and ADC clock unlock errors. Through analysis of block diagrams and hands-on troubleshooting, the issue is traced back to a faulty Vectron TCXO master clock module. By repairing the faulty module and implementing proper shielding, the instrument is successfully restored to working order.
*Summary*
*Initial Problem (**0:07**)*
* The Agilent FieldFox N9912A RF analyzer is malfunctioning, displaying "Hardware timeout" and "ADC clock unlocked" errors.
* The instrument is slow and unresponsive, particularly when switching modes.
*Analyzing Block Diagrams (**1:28**)*
* The block diagrams reveal the instrument's architecture, highlighting the RF board, system board, and ADC.
* The ADC clock originates from the time base on the system board, which also provides a 30 MHz reference signal to the RF board.
* The external reference clock is also connected to the time base, ensuring synchronization.
*Investigating the Time Base (**4:05**)*
* The time base is identified as the potential source of the problem, as it generates the ADC clock and other reference signals.
* The 30 MHz signal is absent at the output of the system board, indicating a malfunction in the master clock generation.
*Examining the System Board (**9:58**)*
* The Vectron TCXO module on the system board is suspected to be faulty and is removed for testing.
* A missing pin is discovered on the TCXO module, potentially caused by rough handling or a manufacturing defect.
*Testing with External Clock (**11:44**)*
* An external 30 MHz signal is applied to the instrument in place of the faulty TCXO module.
* The instrument functions correctly with the external clock, confirming the issue lies within the TCXO module.
*Repairing the TCXO Module (**14:56**)*
* The TCXO module is carefully repaired by soldering wires to replace the missing pin and adding insulation.
* The repaired module is tested and found to generate a clean 30 MHz signal.
*Reassembling and Testing (**15:58**)*
* The instrument is reassembled with the repaired TCXO module and proper shielding is implemented.
* The instrument functions normally, with no errors and proper performance in both network analyzer and spectrum analyzer modes.
*Conclusion (**16:57**)*
* The repair is successful, highlighting the importance of careful troubleshooting and analysis in identifying the root cause of the problem.
* The video concludes by thanking viewers and Patreon supporters.
Disclaimer: i used gemini 1.5 pro to summarize the transcript
Basically if China, India respected copyright and IP you would have service manuals, but they do not
This is nothing new, 'copyright and IP' is just a convenient excuse to keep all the repair, service and new equipment sales in house, it's been going on with T&M manufacturers for a couple of decades now, hell even the Field Fox in this video is 15 years old FGS.
I guess at least you're keeping fit jumping to those dog whistles though.
@@M0UAW_IO83 the world did exist before the iPhone....
You see in the video how easy the problem could be located, wouldn't have been much faster with a service manual. Block diagram is more than enough.
Look at all that via stitching of the grounds on the RF board! The PCB fab house must really go through the drill bits.. Amazing construction and functionality for such a compact instrument. Always nice to see a Pooch guest appearance!
Thanks for the look inside a FieldFox. I was a tech support engineer for HP/Agilent, and made several enhancements to the features of FieldFox models. It is one of my favorite products we ever created. Good Job!!!
Give pooch a little pet for me. My Russian Blue cat that I had for 12 years went missing about 6 months ago and I haven't been same since
Sorry to hear that :(
OH hell no! That is awful!
Pooch @ 10:24 ❤
The series of equipment repairs attracted me to this channel years ago and I must admit, I missed it :)
Why not just replace the TCXO with an equivalent one? Saves the trouble of worrying about the damaged TCXO breaking again.
Less fun 😆
I tried to find a replacement. It is surprisingly rare!
@@Thesignalpath huh, well that’s unfortunate
@@ThesignalpathThanks, I had wondered that as well.
Why the noise floor changing so strangely as the swipe goes on? At the very end of the video.
See the previous review of the Sanko GH60 ruclips.net/video/qyi6UkvJy7I/видео.html It explains how that's the expected behavior of the noise floor based on the (somewhat uncommon) layout of the filtering and attenuation stages.
I've always been amazed by your magician
thanks for showing the RF board :D
I really miss an N9951 fox at my first job. It was a good time.
X-ray!