TSP

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In this episode Shahriar takes a look at a R&S SMBV100A Vector Signal Generator which does not produce the correct output level. Despite passing all self-tests and ALC checks, the output power level is far below expectation. The output also shows a high-pass frequency response.
The (heavily simplified) block diagram of the instrument is examined and discussed. The teardown of the unit reveals the output RF board which is presented in details. Since the instrument cannot detect the failure internally, it is very likely that the fault is part of the RPP output RF relay. The circuitry as well as the datasheet of the components are examined. Measurements show that the output RF relay is never activated due to a faulty PMOS transistor. After transistor is replaced, the unit shows the correct output level. The baseband generator functionality is also verified.
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Пікірлер: 81

@MIsam-fv9kb 4 жыл бұрын

Like the new intro , and I give like even before watching. quality is guaranteed here in the signal path with Dr.Sharihar. thank you for your time and effort to share your knowledge.

@pilifx 4 жыл бұрын

I love the new Logo. Pooch is such an integral part of your production. It’s only fair he is part of the logo too

@pnjunction5689 4 жыл бұрын

Thumbs up for including the cat in the new intro. When I saw the fault, I thought it was just a loosely conneced coax inside the device :-)

@benmodel5745 4 жыл бұрын

New Keysight meter? It was a bit easier to read on camera than the Fluke, even more so with the back light on. If there's one good thing to come from the Coronavirus, it's more TSP videos. Glad Pooch is getting more attention.

@t1d100 4 жыл бұрын

I am a novice electronics hobbyist. You explain things so extremely well that even I can understand what you are doing and learn. Thank you for sharing your time, effort and expertise!

@LarrysMachineShop 4 жыл бұрын

Another perfect demonstration and learning video. Awesome job as usual. Many Thanks. With you being home for a while we may get lucky with a few more videos

@KF7JO 4 жыл бұрын

What a treat with a teardown and repair of a 1 generation old vector generator and current gen combo VNA+VSA. Regarding the LO feedthrough at the end of the video: Internal alignment on the SMBV100A is under 15 minutes. After that, IQ Modulator > change optimization mode to high quality and then Adjust IQ Modulator to current frequency. That should significantly improve LO feedthrough. You can also use baseband frequency offset to move the LO out of band, up to half of the baseband bandwidth.

@PoLoMoTo2 4 жыл бұрын

New intro is looking great!

@WillArtie 4 жыл бұрын

New intro!! With CatScan included!! Edit: and just a little P-Channel to replace. Amazing. Never ceases to amaze me how swiftly you zero in on the problem, especially when faced with such complex instruments.

@heathwellsNZ 4 жыл бұрын

Needs to get a dog as well so we can have a LabReport

@WillArtie 4 жыл бұрын

@@heathwellsNZ ha! Nice

@tedvanmatje 4 жыл бұрын

So the failure of a two-cent component potentially rendered this high-end device as scrap? Now it's working, it'll make a nice addition to the Lab.....but I bet the original owner is a little bit peeved. Nice new intro and thanks for uploading!

@stargazer7644 4 жыл бұрын

You forgot to include the $1500 repair fee.

@dtiydr 4 жыл бұрын

And if it would have been sent to an ordinary repairer they would have quoted for a main moderboard swap, since they don't have any logic to think or even the education as usual.

@dtiydr 4 жыл бұрын

@@stargazer7644 He changed a mosfet and after that the output worked as it should, what the hell are you talking about?

@user-zx2vw8wc3l 4 жыл бұрын

The new logo in intro is great, but the old music was better :)

@toastedcrumpets 4 жыл бұрын

Another nice repair, its great to see new content when we're trapped at home with the virus, hopefully it lets you get some more work done. I'm always put off buying second-hand R&S gear as I think they're not very good with service manual/information but I do like the "German" design. Great new logo too, but I miss the lo-fi video recording of a computer screen of the early videos :-P

@Darieee 4 жыл бұрын

22:30 amazing camera placement work ❤️

@IxIVVI 4 жыл бұрын

Super cool stuff - can't wait for the patreon to finally hit the lecture style tutorials :)

@davidv1289 4 жыл бұрын

Very nice explanation and repair as always. I had a problem with an RF generator using mechanical attenuators that gave similar indications during troubleshooting - near normal output at 2 GHz but rolled off significantly at low frequencies. One attenuator section switch was not making contact when switched out but was OK when switched in.

@ahmedalshalchi 4 жыл бұрын

My friend , I envy you for being in this heaven lab of hi-tech TMIs....

@garybevis8691 4 жыл бұрын

Hi Shahriar I love your videos as always and I like your new logo at the beginning with a cat and RF symbols, so cool. Have a great day Shahriar! I hope can find some day a Rohde & Shcwarz piece of test gear on ebay some day I can afford!..lol

@dosgos 4 жыл бұрын

Learning so much here! Thank you.

@encryptededdy 4 жыл бұрын

Love the new intro!

@BruceNitroxpro 4 жыл бұрын

Nicely done.

@OldePhart 4 жыл бұрын

you added pooch... genius.

@largepimping 4 жыл бұрын

In the new opening, the cat's tail is connected to the circuit - can you please explain how that affects the circuit impedance?

@stargazer7644 4 жыл бұрын

It is obviously the schematic for a cat scanner.

@michaelhawthorne8696 4 жыл бұрын

largepimping Some sort of CAT 5 interface

@jonka1 4 жыл бұрын

This connection opens up a whole world of pussibilities

@heathwellsNZ 4 жыл бұрын

I see people cannot resist...

@405line 4 жыл бұрын

It prevents Cat-astrophic failure of electrolytic capacitors, that's how.

@PapasDino 4 жыл бұрын

Ahhh, if if only I were your neighbor and you could help me troubleshoot my ancient R&S FS300 spectrum analyzer that simply died the other day! Guess I'll get used to the new intro but think I liked the old one better! ;-)

@steve_case 4 жыл бұрын

Nice to see the ZNLE in action

@Thesignalpath 4 жыл бұрын

The ZNL! ;)

@steve_case 4 жыл бұрын

@@Thesignalpath opps! My bad. :-)

@trickyrat483 4 жыл бұрын

Awesome that you could get U2 to record you a new intro. :)

@bfx8185 4 жыл бұрын

As usually good video and lot of luck ;) thx

@tonysfun 4 жыл бұрын

Very nice! I need you to move next door to my house! But you would not like that, since I would bugg you every day! ha ha ha I think you can make a more basic video for beginners that start repairing electronics, or at least try to repair them. But keep making interesting videos also! Thanks again!

@thekaduu 4 жыл бұрын

Nice intro!

@lijuab 4 жыл бұрын

New intro，cool！

@mdbssn 4 жыл бұрын

I'm curious what made you think of the relay as a primary area for the fault - when I saw the high pass response on the output I immediately thought of the connectors or just a solder joint being broken. Was something about the way it responded a telltale sign? Did you just check the connections off camera? Is it just very unusual to get a mechanical fault between the front panel connector and the board when there's no physical damage to the unit? In any case, another nice repair and addition to the lab!

@CABohol 4 жыл бұрын

Nice

@FUNKLABOR_DL1LEP 6 ай бұрын

❤

@NiHaoMike64 4 жыл бұрын

Those electric screwdrivers are pretty nice, having got to use one at work, I understand why the technicians refer to them as "magic wands". That said, the charger is really bulky for what it is, it would be nice if it had a USB charging port built into the battery.

@rogeronslow1498 4 жыл бұрын

Great job there. I did notice that the coil voltage was a little low and wonder if it was due to the replacement mosfet's on resistance being higher than the original.

@stargazer7644 4 жыл бұрын

Any mosfet's on resistance will be thousands of times smaller than the 80 ohm relay coil, so its contribution to the voltage drop will be insignificant.

@gacherumburu9958 Жыл бұрын

👍👍

@maurosobreira8695 4 жыл бұрын

I'm a patreon of this channel on a dollar per episode basis and I recommend as one of the best investments if you like electronics (as he can buy more interesting stuff) - you will not find much better on youtube! Thanks for another lesson Shahriar!

@lorenzol.8798 4 жыл бұрын

You should also check if the reverse power protection still works. Perhaps what zapped the MOSFET could also have zapped something else!

@amciaapple1654 4 жыл бұрын

That's really unusual for the MOSFET to fail like that. I'd wager it got destroyed by the inductive voltage kickback from the relay's coil because the kickback protection diode has failed...or was absent in the design.

@TheDefpom 4 жыл бұрын

I need a few more Patreons so I can buy gear like that to fix, nice work as always.

@timballam3675 4 жыл бұрын

I need to build my new workshop so I can start making some videos....

@Fusionx916 4 жыл бұрын

NICE NEW INTRO

@martinpope8963 4 жыл бұрын

What is the input mains voltage for the electric screwdriver charger. I'm looking for a 230v version for a friend. I have the Milwaukee version and the look the same in basic design but diferent molding on the plastic housing. Great tool to have with auto stop clutch

@pa4tim 4 жыл бұрын

I repaired a R&S VNA, to get in the powersupply I needed to remove 84 screws. I need such an electric screwdriver too. About the relais, is that good ? if I understand it well it was not turned on. But it only attenuated the signal while I would expect it to completely cut off the signal. What is the use for it if it only attenuates the signal some dB instead of totally cut it off. I love it how you diagnose the problem. A request, can you do the repair of a complex switching powersupply or if you can not find one, make a video about how to diagnose one. Like the ones used in instruments like this ( not the simple ones used in consumer stuff)

@methusalah2 4 жыл бұрын

Thanks for the upload! During the close-up of the input section (e.g. time 13:22), I notice a gap in the ground, just to the right of the input connector - is this truly a disconnect in the grounding? if this is intentional, what is the motivation?

@DavidNadlinger 4 жыл бұрын

To me, it looks like it's just a sliver of solder mask (which might have been part of the CAD footprint, but didn't print on the other side), that is, there is actually connectivity still. The metal case would also provide a ground path.

@yaghiyahbrenner8902 4 жыл бұрын

Like the new video intro, its shorter.

@xDevscom_EE 4 жыл бұрын

Nice, Pooch made it into logo :) But I will miss the old TSP classic music... @23:15 series impedance perhaps, not resistance? ;)

@paulpaulzadeh6172 4 жыл бұрын

Shariar, why you don't explain all other harmonics comes from , or why noise level is high, the signal integrity compare between keysight and R/S would be nice too, Anyway new logo better now we have your assistant too ( the cat) But i like the legacy music more , Some marketing stuff you should never change. ,

@SABTelecom 4 жыл бұрын

Is it possible to make a modification to the Agilent 8960 so that it works from 100KHz to 3GHz? I was interested in using it to work with radios for amateur 1.6Mhz to 1.2Ghz.

@enriquegonzalez2802 4 жыл бұрын

Great! Do you know where I can get a service manual for my Rohde & Schwarz UPL audio analyzer? Thanks!

@davet111 4 жыл бұрын

gloris.rohde-schwarz.com/ You'll have to register for an account.

@CraigPetersen12f36b 4 жыл бұрын

Is that a Keysight U1282A? If so how do you like it compared to the Fluke 289? Nice new intro, Pooch approved!

@marcin_szczurowski 4 жыл бұрын

The next one I use daily. Hmmm, suspicious ;)

@Sixta16 4 жыл бұрын

Lol, new intro. Love the cat but hate the music :D

@renesandbote3356 4 жыл бұрын

I wonder if the previous owner had a go at that relay, the soldering doesn't look that factory to me...

@Thesignalpath 4 жыл бұрын

René Sandbote I don’t think so. The seal was there. I also probed a few places, so you are seeing probe marks.

@linhlharfm1801 Жыл бұрын

Hi Shahriar Thank you very much for your videos. Do you know the part number of SPDT RF Switch which die packing type on RF board of SMB100A? I need it but don't know its part number :( Please help me! Thanks

@TrevorsBench 4 жыл бұрын

I prefer your old intro to the new one

@AynkaranRamachandiran 4 жыл бұрын

Does TheSignalPath logo always had a poose or is it a new logo? Just noticed it.

@BenjaminEsposti 4 жыл бұрын

Wow, these units, even USED, are like $10,000 .... and a few-cent part caused it to fail and get tossed. Someone has deep pockets or deep debt, LOL.

@ahmedgaafar5369 4 жыл бұрын

at last new better music...

@patcypatcy2797 4 жыл бұрын

Awesome. But... Shouldn't YOU be preparing for COVID19. Nobody is going to need a vector scope anymore...

@Thesignalpath 4 жыл бұрын

I am prepared. Bought one thousand rolls of toiler paper.

@Ziferten 4 жыл бұрын

I'm a Patron who is happy to support you, your outstanding content, and free education in general. That said, I don't appreciate the use of an Amazon affiliate link without disclosure. Whether you mention it in the video or next to the link itself makes no difference to me, but I think the fact that you have something to gain from the use of that link needs to be explicitly stated.

@Thesignalpath 4 жыл бұрын

The description of the video was temporary at the time of upload. It is updated now.

@Ziferten 4 жыл бұрын

@@Thesignalpath Thank you. It didn't seem like something you would do, so I'm glad to see it fixed.