TSP

In this episode Shahriar takes a look at a non-functional R&S FSEK 40GHz spectrum analyzer. The instrument’s LCD screen back light no longer works and the front glass is broken. Furthermore, no testing can be done until these problems are resolved. The CCFL tube is replaced with an LED counterpart and a new front panel glass is also installed.
After power on it becomes clear that the instrument has other defects. The internal PLL is unlocked. It is observed that the OCXO module is cold and potentially not working. Examination of the LO board shows a bad inductor on the DC filter side. After this problem the instrument operates correctly but only for signals below 7GHz. After further testing it is discovered that the YIG tuned filter on the pre-selector path is not tuning at all. Eventually the fault is traced to some operational amplifiers on the YIG driver board. The repaired instrument is verified for correct operation.
The Signal Path
www.TheSignalPath.com
/ thesignalpath
www.Patreon.com/TheSignalPath

[@DaruoshAghajaney]

Q: What's the purpose of a spectrum analyzer? A: Repair other spectrum analyzers. I truly enjoyed watching this repair journey.

[@KX36]

The purpose of a spectrum analyser: Each spectrum analyser has a certain value of nerd points depending on the brand and bandwidth. The purpose is to collect and display as many as you can in your lab and post photos on forums.

[@mountainmanws]

We use spectrum analyzers as part of the system to measure electromagnetic emissions. Then using the information, pinpoint the emission source.

[@DaruoshAghajaney]

@@mountainmanws EMC pre-compliance?

[@SirMo]

Spectrum Analyzers are amazing beasts. I use mine mainly for designing and tuning filters. As well as designing and tuning oscillators. SA's tell me the harmonic content of an oscillator (which lets me see and correct distortion). Characterizing filters with SA's is also very useful if you're building sensor amplifiers or test equipment and tools. SA's can be used for so many other things.

[@vadimbellous8313]

@@KX36 Isn't that the truth, I have three of them which I did fix and they do make my lab look more sophisticated.

[@Thesignalpath]

*Thank you Patreon supporters. You make this all possible! Supporting the channel enables repairs and analysis of otherwise cost-prohibitive instruments.*

[@mincukspuncuks8694]

Hi, how to contact you? Mail at www.TheSignalPath.com is not working.

[@valerondany2371]

help me rohde-schwarz FSP13

[@georgelewisray]

GREAT TEACHING:: Most of the technical details are far above my pay grade but thanks to your patient and through style I can (a) follow/enjoy/learn the diagnostic process, (b) steep myself in the vocabulary and concepts that are just barely familiar, (c) reference/note sources of additional detailed explanations (many are your videos), (d) FEEL GRATEFUL for the many who, like you, share their knowledge and enthusiasm about some corner of the universe.

[@Nikkuuu69]

Seeing this in my sub box as soon as I grabbed my morning coffee, start of a perfect day!

[@vincei4252]

Excellent video and great analysis. Thanks for a great start to the week!

[@PlasmaHH]

Starting at 20Hz is really a cool thing, you can use that one for audiophiles, though I am not sure if it goes up enough

[@tedvanmatje]

Cheers Dennis! That's got me chuckling :D

[@SirMo]

I find it rather odd that this microwave class SA can go all the way down to audio frequencies. But yet many SA on the market today don't let you do it, even the hobby ones like 1.5Ghz Rigols. Most of them start at 9Khz or more.

[@PeterWalkerHP16c]

HAHAHAHAHA!!!!

[@km5405]

@@SirMo probably because dealing with those low frequencies probably quite significantly raises the design complexity (and therefore cost) in a other video of the new low cost VA/SA he goes a little into this exact thing : )

[@SirMo]

@@km5405 I think you're right.

[@rtodsoznbfsw9054]

Really an impressive repare, with multiple issues and no schematic and no block diagram ... Thanks for all the work and the time spent.

[@VivekRoy2991]

I have always found analyzers and oscilloscopes the best place to learn analog/RF. And you do an amazing job!

[@d942yd42]

I see that late in the boot sequence Transputers were mentioned - a parallel architecture designed in the UK that probably did the FFTs.

[@sudoall]

I would really like to see more detail of how you pull them apart and the steps you take care, also your sources for documentation. Awesome channel. I got hooked , keep it up.

[@kkendall99]

Amazing, always learning new things on this channel.

[@saarike]

Simply great repair of that very complex device!!!

[@guynardin]

Hi Shahriar, I've been watching many of your videos. I really like how you guide the viewer to understand the logic behind your hypothesis about the cause of a malfunction. As with Mr Carlson Lab's videos, I've learned a lot by watching them. Thank you very much for sharing your experiences.

[@drulli1]

Wonderful repair, awesome! One of your best!

[@hinz1]

With that counter, every oscillator looks bad ;-) Discoloration at 18:00 probably is silver sulfide, looks like outgassing from IC packages or electrolytic caps, since it's only at places, where these things are. Nice fix of that inductor, btw :-)

[@fichambawelby2632]

Great video, and great job. Congrats!.

[@seanbosse]

Great video as always. Thank you. Btw, the FSEA service manual that's floating around gives a brief theory of operation for all models, including the FSEM and FSEK. Hopefully that may be of some help.

[@garyimmelman7059]

Brilliant work!

[@youpattube1]

Very interesting. One of your best videos.

[@vincei4252]

Wow, did you notice where it said "Booting Transputers" ! Now isn't that a blast from the past!! I didn't know that Inmos got some design wins during their lifetime.

[@trickyrat483]

I programmed them in Parallel C - not Occam - for a while in the 80's. I wasn't a fan (the toolchain was awful.) They always seemed like a solution looking for a problem. We ditched them after only a year or two for other more established embedded development systems.

[@douro20]

They used Transputers to enhance the real-time performance of the instrument by offloading tasks from the main processor. This is one of several high-end instruments from R&S to use them. I believe the solution was attractive to them as they are very easy to interface.

[@feicodeboer]

I actually paused to see if I was reading it correctly. :)

[@maxhadley3753]

@@trickyrat483 I worked on another Transputer-based design back then, also using Parallel C, and yes, it was a bit rough! However we eventually got it all working. We also used one of the very first, launch series Xilinx FPGA's, and very early Intel flash memory, that you had to program using software loops - that took some time to get the bugs out. It all worked eventually, and seeing as it was avionics, there are probably some of those systems still flying today.

[@xDevscom_EE]

My only wish is to have some "boring" stuff also shown somewhere (TSP-2 channel? :D) so for somebody who might have same instrument but with other issues just seeing how cables/wiring/assemblies are connected (you take stuff apart anyway off-camera, I'd assume) could be great help. Especially for instruments like this R&S , where very limited or none service diagrams/photos available online..

[@amirb715]

i second that. very good point

[@dentakuweb]

I'd like to see that too but I also know how annoying it would be to have to light and record working on big clumsy hardware like this and not be constantly blocking the shot. It's the curse of KZbin video making, the camera is always in the way.

[@TheDefpom]

That’s quite a coincidence, I recently had an open inductor on a 1GHz VCO power supply on a HP8648B RF signal generator.

[@jaa93997]

Excellent as always, but needs more pooch the cat, please.

[@leonardpeters3266]

You have caused me to go on one of the worst video binges of my life. I really appreciate what you do. Good work sir. I have been hunting for a spectrum analyzer that fits in my budget. I don't need microwave as I rebuild old radios, so am looking at Hp 8591 and such. But this channel is wonderfully educational. My Christmas break is shot but I feel allot smarter. Thanks

[@Thesignalpath]

You are very welcome. :)

[@IxIVVI]

Super awesome thank you very much!!! You can put the patreon link also in the description :)

[@Turboy65]

For this series of R&S analyzers, they used mechanical hard drives. It's well worth the effort to replace them with a CF card/IDE drive adapter. Make a drive image and burn it to a CF card and now you have modernized the weakest link in these units. You now have the whole operating system on a CF card. Which won't crash like that mechanical hard drive eventually wil.

[@pa4tim]

I repaired a VNA from this serie, to remove the powersupply I had to remove 84 screws. ( i allways check the PSU first) Very nice done trouble shooting. I also repaired a RF generator and both VNA and generator had to much ripple

[@KX36]

Was the fault that it had too few screws holding it in?

[@inductorbackemf7204]

Thanks as always friend! Alex.

[@douro20]

Around the time this instrument was made Compaq marketed one of the first laptops with an active-matrix colour display- the LTE Lite 4/25C. It was actually possible to upgrade a monochrome LTE Lite 4/25 or 4/33 to a colour display just by swapping out the upper unit. I did this to a few I had at one time.

[@preste3]

I have an even older tektronix 492b where the yig needs to be manually adjusted every 500Mhz or so. It must have a much broader bandpass. Easy to forget to "peak". Ranges up to 21GHz - good enough for hobby use. I have been building external mixers for it and have success up to 61GHz by watching your videos and others too. I use a radar module as mm wave source.

[@PeterWalkerHP16c]

God the world has changed. You chuck GHz around like we used to work MHz. When I was young we thought S band stuff was the bees knees.

[@trickyrat483]

Not a loose cable for once! Seems you are losing your buyers touch. :)

[@dtiydr]

Today they do the mesh with just one layer of ITO for sure, totally transparent. Surprised they didn't do the same then since I saw a marking of 2000 on the back plate of the screen so that would absolutely have been doable since that have been doable even since LCD:s came to life, and that is a very long time ago.

[@timthompson468]

Great video. When I was training as an electronics technician in the USMC, the shotgun approach was frowned upon, but you demonstrated clearly that it has its place. It’s a shame we live in a throw-away society, even when it comes to high-end test gear. I’m not sure how long your entire repair process was, but in a matter of hours, you converted what would be considered junk (beyond economical repair) to a working unit, and rescued it from the landfill, with no service documentation. It seems like there could be a viable business in resurrecting this gear. I suspect whoever junked that unit had to pay a lot more for its replacement that the cost of repairs. Of course, it may be obsolete for a modern lab, but I would think a 40GHz instrument caries some value.

[@shana_dmr]

As much as I hate the high-end test gear throwing away culture, try to find a person that will try to troubleshoot it, won't ask few thousand dollars in advance and has the knowledge and tools to do it. I'm really happy it gets second life on a hobbyist bench, like 99% of spectrum analysers:)

[@bloguetronica]

Learned a lot with your video. Even though the OCXO ftom the signal analyzer ran cold, the deviation it showed was a lot less than typical error of the tiny AOCJYR (AOCJYR-10.000 MHz-M5625LF) from Abracon I've used. Although my frequency counter is TCXO based, and not as precise, I'm still puzzled.

[@vidasvv]

TNX for another great video !

[@DrFrank-xj9bc]

I really enjoyed this repair, very clever fault finding! Thanks a lot! What type of OpAmps have you replaced, could you please indicate their designators? (because usually OpAmps don't blow up so easily)

[@robertwatsonbath]

Thanks for the video Shahriar, nice work! I have a screen filter on one of these to fix, interested in where you obtained part, direct from R&S? Couple of pedantic points: 43:40 the low-band mixer almost certainly up-converts first to a frequency above the low-band low-pass cut off, and then the second LO down-converts this the main IF - almost impossible to get good image rejection otherwise. 45:39 I'm sure this is a slip of the tongue, it's not a prescaler (frequency divider) it's a preselector (filter).

[@Thesignalpath]

Yes, slip of the tongue. Thanks. :)

[@IceArdor]

The FSE was discontinued in 2013, which included spare part availability. You can check with your local R&S service center, but they probably won't have spare parts in stock or a way of ordering new spare parts. You're better off finding a donor instrument or living with compromised EMC. You could also bodge together your own screen filter. If the instrument supports an external display, you could use that if your screen filter obstructs the screen.

[@douro20]

What is the connector on the front panel? Looks like you have it adapted to 2.92mm.

[@arrbam02]

Another great video, thank you! What kind of OP-amps did you replace?

[@grilledpoin1566]

Hi, Thank you indeed for your great content. Recently I got a FSEB 9kHz ... 7GHz spectrum analyzer for my home lab, it powers on but screen remains black and apparently cannot boot. Any advice what should I do to make it work?

[@KX36]

I wonder if you could take a spectrum analyser or some other RF equipment and bypass certain components such as filters just so we could see what symptoms that causes.

[@funkyironman69]

Great video.

[@OneBiOzZ]

I have never seen a metal mesh screen protector, i have used an LCD screen protector for a microwave detector that used a thin coating of metal on the surface, so thin it's practically transparent i think it was silver, maybe platinum but i think silver

[@thekaduu]

Fantastic!

[@zyspan]

Would the firmware support replacing the 3 1/2 " floppy with an SD floppy emulator?

[@niceguy60]

Hello I have a S Analyzer that throw back this error "RF path post wide band noise power expect minimum -32db" Any ideal where the problem could be on the front end

[@willernst8376]

What was the video that you experimented with yig filters and oscillators? I can not find it on the channel but it sounds really interesting. Yig filters are black magic to me, so you explaining it would really help me grasp the way they work.

[@kcmichaelm]

Yes! New Signal Path :D

[@gglovato]

Fascinating, did you try to find updated firmware or software for the unit?

[@udhayakumara4033]

Can you give the link to purchase the display shield mesh, because I'm in need for one.

[@nicwilson89]

What's the video called of which you mentioned with the HP 40GHz source that you used to test the unit?

[@icesoft1]

Would Indium Tin Oxide coated glass be a possible substitute for the mesh laminated glass? Just curious, as it may offer a few more replacement options for broken glass in other devices...

[@bartomiej368]

There is a mesh on the screen to protect against rf noise, but what about that dc / dc converter that you installed? These are pretty good rf noise generators.

[@kirkpennock2997]

They are terrible, but cheap.

[@jonka1]

They are but nothing was showing on the screen so I suppose it is not a problem.Maybe the screen protection is total overkill.

[@Miguelocod]

Please, can someone give link to the YIG video mentioned at 34:51? I can't find it.

[@tamaseduard5145]

Thank you 🙏🙏🙏

[@W8ASA]

Very interesting and informative. Thank you. Ken W8ASA

[@oriole8789]

Excellent video. Be careful of the (typically massive) noise from the DC-DC converter in the LED driver. One thing that many people who are unfamiliar with this type of work may not appreciate, is the delicate touch that it takes to work with these units. You can't afford to make a single mistake in your entire process, so you're always double and triple checking everything meticulously. Killing these units or creating new problems is very easy. I reverse-engineer many "unique" items (if I kill something, there are no replacements), and that kind of paranoia is very familiar to me as well haha.

[@kieranj67]

Thank you

[@sonicmanic1972]

Does anyone know where I can get an image for this model. I have one which I believe has a failed hard drive. See drive on power up but then just shows booting. Can an image be downloaded? Thanks for your help and what a great KZbin channel.

[@bernardbernardin5187]

Brilliant!

[@stargazer7644]

Mad skills.

[@samuellourenco1050]

Unheated OCXOs jump around a lot in terms of frequency. The crystal is just not at its optimal, more stable point at ambient temperature. These crystals are cut so that they are very stable at a constant 70°C (mileage may vary). My guess is that the heater has gone kaput. Anyway, I want to congratulate you for another excelent video.

[@stargazer7644]

You probably should watch the rest of the video :)

[@samuellourenco1050]

@@stargazer7644 I did, eventually. It was an inductor.

[@ChavacanoYo]

Could you provide Rohde & Schwarz FSP-30 and keysight E4446A spectrum analyzer performance comparison.

[@user-wh3ok7gt8w]

Hello engineer. I have a FSIQ26 signal analyzer that I have been using.Recently, there is no measurement data when using high frequency measurement. After testing, I found that the A80 YIG UNIT is damaged, so I bought a second-hand normal I use YIG, but after installation, the frequency response of the filter is abnormal.The voltage provided by the filter is lower than the standard value of 0.05V at all frequencies, and the center frequency response is different by 200MHz. After checking, I found that the FSP series equipment is in the same situation will occur after replacing the A80 YIG. The data manual says that the FSP-FRQ.EXE file is needed for frequency response calibration. I think you can provide me with FSIQ26 related software to provide me with calibration.

[@clementhathaway6778]

How did you clone the hard drive? I just got a used FSEA 30 (20-3.5Ghz) and a concern of mine is the aging hard disk. I'm not super comfortable with all of this yet, so if you were to have any tips I'd be super appreciative!

[@Thesignalpath]

I used just a basic disk cloning software. Nothing special was needed.

[@amirb715]

did you check the low frequency down to 20Hz? because the instrument was showing FSEK20 in the menus.

[@BruceNitroxpro]

Amir B , I think you are showing many users' bias FOR low frequency work! LOL I am one who asked myself the same question. I would love to know if the low frequency performance was equivalent to that of a good low frequency analyzer. BTW, good catch of the FSEK20 message!

[@amirb715]

@@BruceNitroxpro No :-) actually I am not interested in low frequency stuff at all, quite the opposite. However, the reason I was asking was that the instrument is FSEK30 and must go down to 20Hz but in the options menu it shows up as FSEK20 which goes to 9KHz. To me it's not a big deal but I was curious why it showed FSEK20. There is no separate module for low frequency option in these units As to the low frequency performance, since I have both FSEB30 and HP 8560E with option 006 (down to 30Hz) I can say the R&S is way better at low frequencies and specially much faster because of option B5 which is standard on 30 models because it sweeps much faster at those very low frequencies (using FFT resolution filters instead of analog filters)

[@BruceNitroxpro]

@@amirb715 , You are very observant! You also own a lot more LF equipment than the ordinary person. I agree, though, you are better off with a faster FT machine. Good luck! Bruce

[@dtiydr]

If you would have removed the floppy, and looked another way at boot, the thing would actually look quite modern after all.

[@gacherumburu9958]

👍👍

[@YouTubeYouTube-qg6vl]

White paper is amazing

[@btouw8558]

I really really wish i have even 10% of your skills, i have a loge study way to go, these vedeo are geat soucre of information, thank you, thats all i can do, and throw a few bucks you way,

[@egbertgroot2737]

How did you backup the harddrive? I have the FSEA 30 ( 20hz-3.5Ghz)

[@Thesignalpath]

Macrium Reflect is the software I used.

[@egbertgroot2737]

@@Thesignalpath Thanks for you reply, I will search on that product.

[@tommihommi1]

have you tried just asking R&S for a block diagram? I'd expect that quite a few people who work there know this channel.

[@rollinhand4750]

at the end without schematic you have to become a parts changer, anyway fantastic !!!

[@jonka1]

Is that strictly true? I though he'd already suspected them from testing in that area.

[@nxt-1]

Is the signal path website down for anyone else?

[@Thesignalpath]

Yes, there is an issue with the domain. I'll fix it.

[@heinrichhein2605]

this is probably not the original screen cable i have the same unit and i have a nice custom cable in there an the display also looks different, those Ferrites are for common mode interference.

[@joopterwijn]

Heinrich, do you have any documentation with your unit, if so could you share them?

[@heinrichhein2605]

i have some but im bound by contract to not share this with third parties, but it is not much helpful information

[@sparty837]

Where do you get the test equipment that you show on your channel?

[@shifter65]

Buys "not working" from Ebay and repairs.

[@kanetw_]

Rohde & Schwarz has the FSEK service and operating manual on GLORIS. I'm not sure if I'm allowed to send a copy but I have access to it after registering there and putting in my RTB2004.

[@Thesignalpath]

But does it have the block and circuit diagram? Because the service manual you can find online doesn't have that information.

[@kanetw_]

@@Thesignalpath Lemme check, some others definitely did but I didn't look at the FSEK.

[@kanetw_]

@@Thesignalpath You're right, it's missing. Might be worth messaging R&S since there's space for it (final page, Documents: Circuit Diagram) and other instruments definitely have it. I've been looking at a SMBV100A service manual and it has a module-level diagram, explosion diagrams for the mechanical parts, etc, etc.

[@KF7JO]

@@Thesignalpath FSEA/FSEB scanned service manual with block diagram starting on page 88 of ko4bb.com/getsimple/index.php?id=download&file=Rohde_Schwarz/Rohde_Schwarz_FSEAB_2030_Service_Manual.zip. Circuit level diagrams unfortunately either don't exist or aren't distributed outside of the product team. The microwave path (YIG filter, upconversion) path is different, but joins up with the rest of the RF front end.

[@johng8pef11]

@@KF7JO - You're more than likely correct when you say that detailed circuit info isn't available for most of R&S's product line... I'm not sure how it works in USA, but here in the UK, even the UK R&S service centre don't have the information (I have a friend who works for them) - the FSEx series are now effectively obsolete, but if you do send one in for service/repair, they have to send it back to Germany. If parts are still available, then you may be offered a repair, but spares are very thin on the ground, and there's every chance that they won't be able to fix it. I love the older R&S gear, but, it's a nightmare if it ever breaks... unless it's something 'simple' you have no chance, as a lot of the modules/ICs are custom marked and you have no idea what they are without circuit info or block diagrams (there's a certain amount you can glean from the labelling of internal connections and sections of circuit on the lids of the modules, but it's often infuriatingly close to being helpful, without actually helping, lol). I have a friend who runs an EMC pre-compliance test lab, and he has an FSP series analyser, which has a front-end problem; R&S can't fix it (no spares) and can't or won't give him any technical information to enable him to source something to fix the problem himself. I spent a very long time trying to source a tracking generator module for my FSE, and gave up in the end - I resorted to making my own, which might not have been quite up to R&S performance standards, but it worked well enough for me :)

[@tocsa120ls]

I'd call Munich a lot stuff, but... "beautiful"? ;)

[@ptronix]

Surely you mean preselector rather than prescaller ?

[@Thesignalpath]

Yes of course. :)

[@electronic7979]

I like it 👍

[@saintfather7757]

Today, September 2, 2019 I saw a guy, that looked like you at Penn Station, NY. But I was to shy to ask the name(

[@Thesignalpath]

Saint Father It wasn’t me. :) Hopefully we will meet some other time.

[@585585MC]

I appreciate your efforts in producing good content but may I ask why didn't you invest in a good microphone? The whole audio sounds muffled and it's a little bit distorted. It's a matter of levels instead microphone?

[@W8ASA]

I have no problems whatsoever with his audio. It's clear on my speakers.

[@585585MC]

Ken it’s quite strange, the same settings with eevblog or sdg electronics sound crystal clear and only this sound bad. Shouldn’t be an issue on my side.

[@585585MC]

Ken maybe a KZbin audio encoding issue for certain datacenters?

[@friedmule5403]

WOW!! 20,000$ used, not the cheapest one:-)

[@ttkoh123]

Did you use thinner to clean the front panel? Schwarz blurred. kzbin.info/www/bejne/pZqXmqOdbtZ7iJY

[@Thesignalpath]

Sadly the logo came off partially. I used alcohol.

[@etelmo]

You tested high frequency, but it also goes down to 40hz... is such a low frequency ever really useful? It's probably a case of curiosity killed the cat and a terrible idea... but the low end rating also made me wonder about the spectrum of the mains power... Is there even a way of safely connecting a spectrum analyzer such as this to the mains power, do they make high voltage probes for them or is that just silly foolishness? haha

[@etelmo]

@LabCat Ah cool, makes sense, thanks :D

[@REALIVH]

I love this channel but to bad youtube only show 360p for many first viewers

[@garci66]

Usually takes some minutes for the video to be distributed to the local caches which allow high bandwidth streaming to you. If you start watching as soon as it's published you can get the 360p stream from the main datacenter until it switches over to a regional cache with the full hd stream.

[@REALIVH]

@@garci66 yes some of my KZbin friends also have the same problem when they make premierer or line but not all my KZbin friends. that why I sometimes also wait some hours after it has gone public

[@mohammadr797]

Perfect as always! But the video quality is low!

[@JohnDoe-ot7wv]

Did you clean your glasses before watching the video?

[@mohammadr797]

@@JohnDoe-ot7wv At that time, the quality was only 360p! I don't know maybe it was because of my isp. Now is good.

[@diatomsaus]

@@mohammadr797 Likely because YT was still rendering the HD version.

[@garci66]

@@diatomsaus indeed. Or it's still spreading out to the local cache closer to you. Takes a little while

[@visionofwellboyofficial]

Looks very expensive

[@user-vw6gv6xu6t]

The YTF's main function is to reject the image frequency, other than the harmonics.