TSP #89 - Teardown, Repair and Experiments with a Tektronix RSA 6114A Real-Time Spectrum Analyzer

In this episode Shahriar attempts a difficult repair of a Tektronix RSA real-time spectrum analyzer. This well-equipped instrument reports several error messages during startup POST including LO Unlock as well as Signal Path failures. The service manual of the instrument does not provide any detailed block diagram and no schematics. Most failures require the instrument to be serviced by the Tektronix factory. The equipment has various advanced options including 110MHz analysis bandwidth, digital modulation analysis, wide-band IF output and deep memory.
The teardown of the instrument reveals a multi-board, multi-module design. The top of the instrument contains all digital blocks and boards while the bottom of the instrument houses the RF deck assembly. The RF deck is broken into various stages such as attenuator, RF switches, first converter, second converter, IF block, reference synthesizer and LO generator. For the purposes of addressing the YIG problems the LO board is examined. The problem is traced to two components, both dividers in the complex PLL system of the LO subsystem. The LO board is fully analyzed and described and the defective components re replaced.
The repaired instrument is tested for various functionality including DPX, de-modulation and measurement beyond 8GHz CW tones. The instrument passes all self-tests, alignments and detailed diagnostics.
The Signal Path
www.TheSignalPath.com
/ thesignalpath
www.Patreon.com/TheSignalPath

[@AureliusR]

Shahriar -- KEEP THE MISTAKES! Keep EVERY little detail of the repair -- often you do things that you don't even realize are learning moments for us. PLEASE keep the repair videos long and rambly -- that's how I like them!!!

[@sivalley]

Aurelius R to wit; It is the tiny flaws that truly make a masterpiece. And let us laugh at cat jokes.

[@peterkjellstrom3100]

Regarding the style difference between repair and review. Keep the explain-and-as-you-go style. it's one of the things that make your repairs so good.

[@DextersTechLab]

Excellent video as always! Keep the repair videos detailed, it's great to see how you work through a problem.

[@smgvbest]

Totally agree, love the detail and seeing you go through your thought processes. keep it up please

[@sivalley]

pahom he speculated it was likely due to thermal stresses through the board from the power supply sections on the opposite side. Considering how tight the module envelope is with likely poor airflow (essentially a closed smooth bright aluminum block) I would agree that over time those GaAs devices would fail. Failing that, power supply noise spikes.

[@JJayzX]

The way he flows through repairs is comfortable to watch too, they don't feel long. Some people will have videos a fraction of the size but feel like they drag for eternity.

[@educatedmanholecoverbyrich8890]

@@sivalley noise spikes? No, the power rails will be super smoothed.

[@sivalley]

@@educatedmanholecoverbyrich8890 I was referring to incoming line voltage noise that would make it across the suppression capacitor across the transformer. Those capacitors are designed to couple secondary side switching noise but can also allow noise to feed back to the ground side of the secondary. Those spikes would raise the ground potential and possibly invert the voltage (ground side momentarily higher potential than V+) causing damage to voltage sensitive components without polarity protection.

[@AureliusR]

"I can in fact do FM modulation if I'm fast enough" I was laughing so hard I was almost in tears... that's just awesome!

[@BruceNitroxpro]

Aurelius R , Yes! Truly awesome moment! Well taken!

[@w2aew]

Shahriar - great job with the reverse engineering and repair. As you said, always a bit of a risk, especially when the fault could have been in a custom (unobtainable) device. The "A" series used a 32 bit PC running XP. Unfortunately, the firmware development/enhancement for this series is now frozen. The B models run 64 bit win7, and firmware is still current, so all the latest software options are available. Of course you could always export a TIQ and analyze with newer options on SignalVu-PC. Congratulations again on a successful resurrection of a fine instrument.

[@braylenzeke4269]

you all prolly dont give a shit but does anybody know a way to log back into an Instagram account..? I somehow forgot my password. I would love any tips you can offer me!

[@jasperarian1789]

@Braylen Zeke Instablaster :)

[@braylenzeke4269]

@Jasper Arian thanks so much for your reply. I found the site thru google and im trying it out atm. Takes a while so I will get back to you later with my results.

[@braylenzeke4269]

@Jasper Arian It worked and I now got access to my account again. Im so happy:D Thank you so much you saved my account!

[@jasperarian1789]

@Braylen Zeke No problem xD

[@dufflepod]

I definately prefer these longer repair videos to the teardown ones.

[@daveblane6442]

WOW. GREAT job! NO schematics, minimal block diagram -- and you fixed it! SOOO impressive!

[@jipihorn]

"It also fails the signal path, which I take offense to". I bet you do !

[@richsmith46]

I really appreciate your style of presentation, please keep it the same - I always learn something new in watching you work. You're very courageous fixing such complex instruments that's for sure.

[@jasonmilldrum]

Thanks Shahriar for this blast from my past. I used to work as a technician on the RSA line when the 6k series was introduced, so it was fun to see an old familiar bit of gear again. I distinctly recall LO1 being a real trouble module. :)

[@nated1971]

I've learned more about RF circuit design and tradeoffs with components from you video than I did from my ECE department....and I'm an RF concentration EE major!

[@rkstr9965]

Always glad to see a new t-shooting video. One part threw me for a loop... While probing the suspect HMC363S8 (@ 44:17) it looked like it was in backwards! As it turns out the datasheet used (@ 39:57) has the wrong pin configuration pin 1/3 IN and 7/5 OUT. Luckly you use a different datasheet (@ 46:40) which shows the correct pin out.

[@k1mgy]

Absolutely brilliant repair. As you walk us through your thinking and experience, analyzing and repairing these magnificent instruments, we are learning. There is tremendous value in the journey to a solution! So please, please don't change anything in your overall presentation.

[@ikocheratcr]

Great repair, congrats you get it done. As for the style, I love to see all of the mistakes. The analysis you made to determine the second chip, that is a video on its own. Keep up the excellent work you do here.

[@garybevis8691]

Shahriar, I very much like this type of teardown and repair video in which you explain and guess at what you are seeing and come to the logical steps of progression thru the trouble shooting and diagnosis. You are a very bright young man and I watch these videos because of this style of yours. I am a recent subscriber to your channel and I am working my way through the entire catalogue and have noticed your improvement over the years. Keep up the good work and you have a way of making sense of circuits and "signal paths".

[@964tractorboy]

Re style: thumbs-up from me on keeping it like it is. The ad-hoc style is "user-friendly" and makes the videos more accessible, so to speak. Love them as-is. Thanks for every one!

[@MoraFermi]

Frankly, I find your repairs -- and this one in particular -- much more interesting than the reviews. Keep them up, please!

[@rcleveacp]

I love the detail in the repair videos. The detail really helps the rest of us. Thank you again for all your hard work.

[@JackZimmermann]

I really like this format of following along. Don't change a thing.

[@sebastianmaderner8727]

Thank you for the great video! Leave the repair videos as they are. I learn a lot from your videos!

[@michaelkarr7558]

I like the mistakes and extra detail. Following along with your thought process is the most interesting part.

[@keithhearns3783]

I like the repair videos as you have been recording them. Your reasoning process is instructive. The repair techniques you use please continue to hint at those as well.

[@Golem386]

I absolutely love the style of your repair videos, because it's much more interesting to watch someone make mistakes and figure it out later. Keep doing the good work ;-)

[@Electrolab28Ag]

Wow! what a gamble. You really done a great job.... Hope the Cat scan work. I really enjoy your explanation and how things work and what should be expected to happen. It really show you skills and knowledge in this field. Keep them coming, we enjoy them. Thanks for taking the time to share.

[@ZEROSTATIC72]

Great video, keep the whole style. One heck of a complex LO generation path. Thanks. :)

[@RodrigoForrequi]

Wonderfull instrument but most impressive it's your goal! No schematics, basic block diagram and you fixed it! Great!

[@pa4tim]

Please keep the repairs as you do now, very educational and it makes me feel better because now I know I'm not the only one :-)

[@babybearkill1]

people cannot learn by quick overviews effectively, only the long and quite internment connection with the signal path proper will suffice. block then detailed circuit analysis is quite refreshing and in my opinion should never be overlooked. keep up the great work and we will keep watching

[@hyperplastic]

Great video! Keep the repair videos as they are - important to see the process!

[@PelDaddy]

Thanks for another great video. I like the mistakes... I like to hear your thought process as you go through things.

[@DoRC]

please keep it the way it is. the reviews are nice but these repair videos are why I subscribed to your channel!

[@ruhnet]

Unbelievable fix, WITHOUT a proper schematic or even decent block diagram! 👍

[@zuccasnow]

Normally I don't bother commenting stuff on KZbin, but it this case... You are deserving this.. thinking to support you on Patreon now... God bless you! Amazing

[@tllong2]

Love your videos & seeing your troubleshooting process. Thanks!

[@demesisx]

WOW. This is the first of your videos I have seen. Thank you for doing this. Amazing content.

[@konradmuller5312]

Thank's for this great video. I really like most of your content, I can't think of any other youtuber doing so detailed videos about testgear and repairing it.

[@m4dizzle]

Definitely keep the "mistakes" and learning process, it's very helpful :)

[@michaelhawthorne8696]

Nice result and a nice instrument too. I prefer this video style where you work on the fly and this reveals your thought processes more, 'warts an all' to quote a phrase. I like all your videos and I'm pleased you're back doing them. What a lab you have there too. I wonder if the cat of knowledge has any input sometimes. She's watched you enough times. lol

[@EcProjects]

Thanks for the video! :) I would say keep doing it the way you do! Works very well in my opinion!

[@frederikfrank5226]

Hi, I also really appreciate your repair videos. I think there's no problem of keeping different styles for different types of video. For a repair, I prefer to hear all the thoughts going into it. The procedure and so on. I can also learn from all mistakes maybe done. So for my point of view, keep it as it is. I love your channel and like the reviews as much as the repairs.

[@stevedavies3985]

Awesome video. Really enjoyed the investigatory approach, including the dead ends. You made one comment about replacing the parts. It sure would have been interesting to see the part replacement mechanics including the who, the how and the equipment involved.

[@docpedersen7582]

Good repair... and your lab is absolutely awesome!

[@netman69]

I love your repair videos, more so than the reviews admittedly. By all means keep things as they are :).

[@Mrjm5411]

Awesome Shahriar, thank you. Like the detail. Please, no need for less. Length of presentation not an issue. Once again thank you!

[@paulrautenbach]

I like both your repair and more structured videos.

[@vincei4252]

A fantastic and informative hour. I can't fault anything here. Keep doing what you do so well. Two takeaways: 1) In advanced repairs just skip everything and replace all the Hitite dividers (programmable or not) :-) 2) I just discovered after your Mantis segway that Vision Engineering is just over the hill from me in New Milford, CT. I think I'll take a wander over there one day during the week and see what's going on. I'd seen the Mantis in several of Dave's videos and really want one! FWIW, regarding Hitite, I seem to recall you replacing a hitite divider in another advanced repair. Cheers, Vince

[@mikedillon729]

No. Don't change anything, this is Great info, and really neat to watch!

[@youpattube1]

More like this. I like hearing you reason your way thru the problem.

[@rysend]

Love the style. Excellent video as always. Thanks!

[@PeregrineBF]

I'd love to see a list of all the equipment you have in your lab. And do keep the full explanations going for the repair videos, watching someone step through the process is far more educational than just getting a final result.

[@drulli1]

This was an adequate repair challenge for you! Serveral hours you needed to spend, aha, and you even had to read some datasheets! :D It is very fascinating to follow your thoughts. And man, sometimes I found myself dreaming that I understood most of the lecture. But only for a view friendly seconds ...

[@jensmarkwart5316]

Keep it as is ;) I like the detail in the videos.

[@waverleyrocker]

Fantastic video. Thanks very much. Good job on the fix!

[@DaruoshAghajaney]

excellent troubleshooting and repair. thanks a lot dude.

[@drdiesel1]

Exceptional video, very well done Sir.

[@tedvanmatje]

if I was to travel back in time and tried to explain Ohm's and Kirchhoff's laws to a caveman, the expression reflected on said caveman's face would most definitely be what mine looks like now. watching this has brought me right back down to earth - if I was to don an animal skin loin cloth, swing my club around a bit and utter gutteral one syllable words right now, i can honestly say that I'd be totally impressed if someone was to throw me a banana for me to gnaw into. what I'm trying to say is Shah (and the above is the long-winded way of doing so), is that you are a veritable genius, man! your video is almost as long as a feature film, yet it's far more entertaining and 'prods' those cerebral areas which rarely get reached by 'traditional' ways and means. with humble respect, I'd like to thank you for dragging my prehistoric self into enlightenment! ....now, if only I can work out how to operate this complicated looking light switch, all will be gravy ;)

[@alankellerhouse1249]

I like your repair videos You explain very well. I also like The detail information on your repairs

[@g1fsh]

i prefer the longer videos where u share everything including mistakes. making.mistakes is one of the best ways to learn. thanks for a great video as always

[@dentakuweb]

It's not equipment I'm ever going to use but to see your process of how you trace down the problem is useful for anyone interested in electronics.

[@techtalkmike4968]

Regarding your question about teardown & repair video format. I think you should absolutely not change your current format. Watching you go through the troubleshooting process, mistakes and all, is by far the most educational and propitious. I'm new to RF and your videos are invaluable resources -- so much so Shahriar, that I've signed up to your patreon. Keep'em coming!

[@DrekRose]

Great format, more detailed = better. Keep up the good work!

[@philippoMC]

I like the style how it is. Great video!

[@Newsparklabs]

Another great video, thanks Shahriar!

[@prabhnoorkainth1520]

Dang uploading videos at 3AM. Keep up the good work! Should I watch this now or tomorrow? So tempting.

[@tariqgorsi7505]

Brilliant work, thanks for sharing.

[@MeiklesAndDimes]

Definitely like this style of repair videos

[@benrd9111]

Very nice repair wich seemed impossible without schematics ! Congratulations 👍👍👍💪💪💪 You have one more nice instrument in your lab now.

[@rogeronslow1498]

Jackpot. It works! Well done.

[@gbowne1]

"Signal Path" - "FAIL" lol.. that one was hunting for you Shahriar.

[@raccoonnyc]

Definitely an Oscar winning repair!

[@robbowman8770]

I enjoy your 'train of thought' style videos ... takes me back to my days (and nights!) in the lab :) My favourites though, are the lower level ones, like when you made a DAC. Would be great to see some in depth stuff on PLLs as they're so important in the areas you work in? Anyway, thanks for the great vids.

[@AF6LJSue]

I like your repair videos the way they are.. good Stuff

[@SirMo]

"and it also fails the Signal Path.. which I take the offence to" hahaha that one had me laughing out loud! Nice video again Shahriar!

[@MochaboyRC]

amazing job! watched the whole video! Format is fine...don't change a thing

[@glenwoofit]

I like this style of video. Great Video!

[@RobertGallop]

Awesome repair!

[@phuang3]

The Signal Path fixed the signal path failure. Very interesting.

[@Urbanstrangler]

Really cool video. Keep it up, thanks!

[@MauroSedrani]

Excellent video!

[@donreid358]

Yes, keep the detailed debugging. I was a bit disappointed that we didn't see more of it, but of course that would have been many hours of video.

[@grantfullen9559]

I like your repair vids just the way they are :)

[@hpux735]

These videos are great! Please don't change the format :)

[@ernestuz]

A superb video!

[@nikmilosevic1696]

I really enjoyed that video, thanks.

[@widecast]

I know someone else has made a similar comment about the cat but at the time the cat nearly walked on the board I thought that cat should be fitted with an anti static strap as well. As cat lovers will know. The fur on the cat can get very highly charged with static. 😊

[@hannonm]

oh wow...thats a lovely unit.

[@fthorup]

I really enjoyed that!

[@andreykorenev1433]

Hi! Thanks again for your videos! And congratulations with a successful repair! Can you tell us something about probing microwave signals next time? I mean, which types of probes exist, tips and trick of using them. The video about the Agilent power probes was really useful.

[@TheAlfieobanz]

From 47:35 - 53:36 my nose started bleeding. Awesome vid.

[@littleboot_]

You are very smart, thx for this video I learned a lot.

[@positivebits]

Great job!

[@photon6731]

Enjoyed your video

[@PapasDino]

I really like the free flowing narrative as "how" you go about working thru a troubleshooting exercise is very instructive and one to emulate although everyone does it a little differently. Is it possible to donate without going thru the Patreon route?

[@dalmolima8862]

Great job! Congratulations!!! It is fine the way you do. I wonder how many peolpe in the world could do what you just did...

[@Brian-mp6bg]

Great video, and even though this is an enchant video I do like the format

[@OnTheRocks71]

I feel like I'm getting spoiled with all these new videos.

[@gacherumburu9958]

Impressive 👍👍

[@h0ll0wm9n]

Super video! Your repair vids are among the best in the electronic vlogs -- I would not touch your existing presentation format (wrt length, style, editing, Pooch!!) Only suggestion for all your vids: please provide date of manuf . when possible. A close-up of the rear- or bottom-panel "boiler plate" would help. Thx!

[@martijn4740]

cool an other repair video keep up the great work need to find me a decent scope

[@barroweer]

Excellent!