TSP

[@davidgustafik7968]

Interesting comment @34:00 - that they do not care all that much about the impedance of the IF, but there's an absolutely crazy amount of vias around it.

[@Thesignalpath]

Let me clarify a little. When I say they don't care about the impedance, I mean they can afford to have a higher impedance line because the frequencies are low and therefore losses are much less important. They can afford to make the lines narrower and deal with the skin effect. The vias are needed no matter what because isolation between traces is still very important. The impedance is still controlled.

[@davidgustafik7968]

@@Thesignalpath Thanks for the clarification! Anything above a few hundred MHz seems witchcrafty and I have no idea of what to expect :)

[@TomStorey96]

Anything beyond digital is witchcraft to me, even though digital is still analogue. I'm all 1's and 0's 😂

[@samihawasli7408]

Hate to break it to you, those fast switching digital signals have some super high frequency content. Remember, square waves need lots of odd harmonics to look square. Due to this , some digital systems operate at higher frequencies compared to most RF systems 🤷🏼‍♂️

[@djcok5315]

Catching up on some of these videos, having just recently become aware of them. I designed the TC745 doubler chip shown in the video. Just wanted to mention those are actually diodes, not FETs. Way back then we did not have an appropriate diode process, so those diodes are "FET gate diodes", diodes realized using gate-source/drain junctions of MESFETs. Keep up the good work!

[@googacct]

Nice repair video. Hopefully AllTest will continue to send you things to repair. Hopefully they also pay you for your work and you get some addittional funds to support the channel.

[@jianhuiluo]

Always pleasure to watch your professional analysis. I was able to repaired my E4407B after watch your Video. Thank you very much.

[@mohank4808]

Dr. Shahriar, Always very pleasure to watch the logical approach of fault section isolation. Stunning. Off the topic to this video. After watching TSP #120 - Rohde & Schwarz ZNLE 1MHz - 6GHz Vector Network Analyzer Review, was in the oscillation between R&S ZNLE vs Keysight 5063A. Finally went with Keysight ENA 5063A due to its additional lower and higher frequency bands. Also the price competitiveness.

[@FurkanBahadr]

That embeded band pass filter gave me microwavegasm. I have a lot to learn and practice. Feels like a mountain. Damn.

[@Impedancenetwork]

I am a patreon supporter. I took a microwaves and telecommunication courses in my electrical engineering curriculum, but I dropped both just before the drop date. Both of those courses are essential to understanding the details of what is going on in these videos. I find these videos fascinating. The way the microwave filters are constructed is so cool. That is stuff they don't teach you in school. All I did in my classes was mathematically mixing signals. You don't get to see the actual implementation of a microwave filter until you get in industry. The construction of these boards is so dam cool. I can't watch enough of these videos.

[@alexcesarpalma]

Pooch is obviously checking the job, I love it!

[@Thesignalpath]

Alejandro Cesar Nothing leaves the lab without Pooch seal of approval.

[@laser-on-off]

It's always a pleasure to watch. Thank you so much !

[@Daybreakerflint]

Hello there! I basically just have dipped my toes in RF-Engineering and maybe I'll become one in the near future. I find your explanations very easy to follow even if I still have to look up a couple of words and abbreviations. (Such as but not limited to IF ;) ) Thank you for the great breakdown and analysis! A bachelor electrical engineer student

[@sbreheny]

At 36:25, what is the out-of-focus object over part of the inductor at the center top?

[@dtiydr]

A gold wire as the others but it goes upwards in such a way its much out of focus.

[@Noubers]

Always fun to watch these MXA videos after having spent many hundreds of hours staring at the screens of 9020s and 9040s in the lab and wanting to tear them open. Thanks!

[@fixthetempo7276]

The owner of this instrument should send it to keysight for Adjustment tests because the frequency response is not perfect after A13 replacement. 90% of all failures related with input attenuators , low band switches or preselector path. Nice video, keep going on

[@Thesignalpath]

The unit will require calibration to meet factory specifications for sure.

[@xDevscom_EE]

Let's see follow up video on 3458A :) It can't be called fully repaired, unless it's nice and stable and verified to spec. I have some 5720A's to help with that.

[@Thesignalpath]

I would love to get my hand on a Fluke calibrator. I have been searching and searching, but they always become several thousands on eBay.

[@xDevscom_EE]

@@Thesignalpath I have 50% of one, sitting as spare boards, could be a cool project to build, just like I did twice. I'm sure alltest have few dead 5700s somewhere.

[@gammarayflash1170]

Oh yes, please! A collaboration between TSP and xdevs (TiN)! I would really appreciate this. Please, go ahead with that idea guys. :-)

[@DrFrank-xj9bc]

I'm still waiting for experiments you'd do with the 3458A. Wonderful analysis and interim repair!

[@Iceteavanill]

Do you never worry that your cat destroys some of your equipment? Very interesting video. Thank you for sharing.

[@Thesignalpath]

Not really, he doesn't damage anything. I have to make sure all the equipment is securely placed so he can't topple them over. Given how heavy most things are, it has not been an issue.

[@s3sebastian]

​@@Thesignalpath Could Pooch's fur cause ESD damage to open instruments though? The first picture in the 'triboelectric effect' Wikipedia article actually shows what I mean.

[@tommihommi1]

he's a well trained cat who doesn't nibble on cables

[@s3sebastian]

Looks like it was a good choice of AllTest to entrust you with the repair, there surely aren't that many people who would have another front end module and a X-ray machine on hand to do the troubleshooting so well in this case. (And not to forget the synthesizer as well as the other spectrum analyzer which also go up to 26.5GHz and the knowledge of course.) So the video discourages someone who lacks any of these to buy similar broken instrument off eBay and waste a lot of money on an instrument one probably can't fix. 😉

[@GadgetUK164]

Excellent work reverse engineering that against the diagram!

[@colinstu]

I wonder why they removed comb?

[@marcin_szczurowski]

Cool, one of my daily used analyzers. Good to know what's inside :)

[@visionofwellboyofficial]

The oddity is the N-connector works up to 18GHz, whereas the spectrum analyzer is rated up to 26.5GHz. How did they make it work up to higher frequencies? Very interesting. Could be better using K-compatible connector

[@jianhuiluo24]

What kind of X-ray machine do you have to take those clear X-ray pictures?

[@douro20]

I saw that they have some R&S FSU26s. I wonder if those are also Transputer-based.

[@diegogmx2000]

I've never worked with stuff as fast as this, it's impressive to see the boards which also have edge plating to avoid radiating too much do you know if they also do enig before solder mask?

[@sverreh]

So my gess for how the instrument detects it is fault is: they want to calibrate away the aliasing/mirroring/harmonics from the mixers and so when the sweep does not detect the signals it is trying to calibrate away it knows it does not work correclty... something like that??

[@glenslick2774]

Around 31:40 in the X-Ray view of the PCB to the left of the band-pass filter and below the mounting hole there appears to be an 8-pin package that is not visible on the normal view of the top of the PCB. Is that a die that is embedded in the inner layers of the PCB?

[@Danilo_Djokic]

Looks like it's on the other side of the board ?

[@catalinalb1722]

The Razavi Videos are still on my Watch Later list (for ✌️ years 🤔)

[@thecrikster]

Those xrays are so pretty you could frame and mount them on the wall ;)

[@saintfather7757]

Omg thank you. I am drunk and its the best thing for today’s evening)

[@vaualbus]

It use the sub harmonics of the reference signal to detect if the path is missing? Any way I would be interested to see what is behind the third block!

[@ronniepirtlejr2606]

I would hate to imagine the cost and hard work it took to achieve your level of knowledge on electronics! It is a pleasure watching your videos. For some reason you kind of remind me of the Young wise Daniel in the Bible. He was a highly educated , sought-after wise man. :-)

[@dtiydr]

22:00 Via stitching just got a name, holy shit. Its understandable of course though for the frequency involved.

[@electronic7979]

Helpful repair video

[@ahmedgaafar5369]

spare parts availability Magic, can you repair any device with zero knowledge, given all the spare parts of that device? the answer is Yes of course, but might be a lengthy repair process. as usual, it's a high quality knowledge in every signal path episode...thank u.

[@jonka1]

Not sure that's as true as you think. Sometimes (don't ask me how I know) devices can have cascading failures from one part into lots of others. If you just stick good parts in you are risking damage from trouble further up the line. Simple power supply problems are potentially deadly. Given the cost and availabilty of these parts I think your assumption needs more work.

[@DmitriIvanov]

Fantastic video man, really interesting! Thanks for sharing!

[@rodrigogarcia8180]

nice video and instructions , but I have a a question for you.... if rf front end A13 IS OK, IS POSIBLE that ytf preselector is bad and can you let me know if w32/w33 connections are ok if measure shorted?

[@inwin8799]

Follow the signal you understand

[@ddlsmurf]

So how did the instrument detect its failure without calibration signals in the failure ranges? I can't stand the suspense !

[@Thesignalpath]

I've got to give people a chance to guess!

[@ddlsmurf]

@@Thesignalpath How about a hint ? maybe one we have to click to get so there's no spoilers ? Even guessing at it is beyond my pay grade but I'm very intrigued!

[@paulmoir4452]

@@Thesignalpath My RF cave-man guess is it uses the harmonics of the test signals. But I feel it's a wooden club and there's something far more elegant. If I'm right though then 9:00 on shows Shahriar's mad teaching skills! "Oh, those harmonics suddenly appear in the band that is actually working..."

[@amciaapple1654]

What! You did not put a probe on the doubler and the amp to see which one failed ?

[@Thesignalpath]

Amcia Apple I may still do that. If can source the parts then it would be worth doing that.

[@tejeshwvardhan1165]

Are these Teflon pcb?

[@SaabFAN86]

Can you try to upgrade your MXA to the fully specced version with the firmware of the defective device? Maybe even make a video on how to calibrate it. Would make for an interesting video, I think.

[@Thesignalpath]

A lot of features should work in theory. But not everything. Calibration of these units is not easy.

[@BruceNitroxpro]

@@Thesignalpath , and you would be doing an upgrade... they call that an "optimization calibration." Good luck with THAT.

[@Vintaginside]

This would be highly interesting but I think it wouldn't work. There are many instruments which "tie" the software/firmware to the PCBs internal serial numbers. If something doesn't match, the device usually goes to the lowest spec'd version or gives an error message. Anyway something worth trying.

[@witeshade]

@36:13 what is that mark on the pad in the bottom right? It almost looks like something was attached there before but is now missing.

[@TomStorey96]

Probably left behind by a test probe. Presumably they design in extra pads that can be probed during the manufacturing process so they don't have to disturb pads which will be bonded during assembly.

[@jonka1]

It's on the video soundtrack, he talks about factory test probe marks.

[@witeshade]

@@jonka1 ahh I must have missed that, thanks!

[@saarike]

This is really interesting... Thanks

[@glenwoofit]

Another great video...

[@DC177E]

Does anyone happen to know why the bandpass filter at 33:00 has those 'spokes'?

[@bblod4896]

Need to win lotto before purchasing anything like that. Thanks for the video.

[@juanyamasaki9930]

hi i am new to this matter ,can someone tell me what means LO?

[@Thesignalpath]

Local Oscillator. In this case it is the signal used for the mixers.

[@hamidk4772]

Afarin

[@pahom2]

Finally an xray come useful

[@Thesignalpath]

It has been useful quiet a few times already.

[@daveblane6442]

Will it be an obvious DEAD CAP? ?????

[@Thesignalpath]

Only if.

[@dktr2]

Magic microwave stuff.

[@juniorprt-s2262]

brazil!!

[@PaulHigginbothamSr]

This is almost alien hardware to me. The fact you cannot even repair the component shows just how difficult on the F-35 the replacement of a damaged external panel is with this high frequency component failure. When I study the integrated circuit on the alien craft from rosewell in 1947 and see the circuit path of this spectrum analyzer and you having to xray the board to find a filter I just wonder what a spectrum analyzer will look like 100 or 1000 years from now. I can see what they looked like with a tube type with a motor on a variable condenser from a radio for the sweep circuit leading all the way to phased array radar panels on the Arliegh Burke destroyers looking much like the components in this spectrum analyzer And my antenna on my Raytheon radar with a vga signal from the antenna to the processor being able to paint targets and shorelines clearly and you reading this garbled data on a screen to read which component failed that in my lifetime we have become the aliens.

[@companymen42]

Good old windows XP😂

[@cda32]

They can send me one too :(