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In this episode Shahriar attempts to repair an Anritsu MG3700A Vector Signal Generator. The instrument does not fully power on and suffers from several problems. The digital IF board as well as the main computer are presented. The power-on fault is traced to a faulty fuse on the 5V power supply which feeds the main CPU board. A new fuse enables the instrument to fully boot.
The unit also exhibits a failure for all signals above 3GHz. The instrument is equipped with a super hetrodyne mixer board which covers 3GHz - 6GHz output range. This RF board is examined and explored in details alongside the block diagram of the unit. The fault is traced to a unidentifiable component (potentially PIN diode switches). Bypassing these components allows the instrument to generate sufficient power. However, the repair must stop here for now until these parts can be identified.
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Пікірлер: 88

@GeorgeTsiros 3 жыл бұрын

For the level of video quality and, more than that, _content_ quality, you're so frequent with your uploads it is incredible.

@bakagaijin7452 3 жыл бұрын

Looks like HP/Agilent/Avago/Broadcom MiniPack's. Probably ATF-551[m4] (Vx marking, where x is a date code) or some PIN dual/quad

@Thesignalpath 3 жыл бұрын

This is promising! The voltages match up and connections makes sense. I bought a few of them from eBay. :)

@bakagaijin7452 3 жыл бұрын

@@Thesignalpath Great! As far as I understand, they are only there to gain back that insertion loss caused by the 3 stages of BPF and maintain a flat response. PS: Could you explain or give a hint on how those impedance matching networks work here? Usually it is 3 pages of intimidating math and a kung-fu roll of passives with no hope of understanding what this is all about .

@lmamakos 3 жыл бұрын

Very nice investigation! I really love how you demonstrate debugging and analysis techniques.

@Electronic.Repairs 2 жыл бұрын

در یک کلام بینظیری ، سپاس جناب مهندس شهریار عزیز برای همه ویدئوهای قشنگ ومفید وآموزنده ... موفق باشی 🙏❤️

@everythingquads 3 жыл бұрын

Love your channel. Very professionally produced and frequent uploads. How do you even manage to maintain this rate of content. Amazing.

@3ffrige 2 жыл бұрын

“Very very straight forward…” says the RF rocket scientist 😎. Actually, that’s one cool thing about these magical RF bricks in general…the insides reflect the published block diagrams almost exactly.

@matterickson5651 3 жыл бұрын

I used to work for a electronic recycling business and i remember breaking one of those down for scrap.

@R2AUK 3 жыл бұрын

Best repair video so far!

@Daybreakerflint 3 жыл бұрын

I do love your content! Thanks for sharing!

@sirousmohseni4 2 жыл бұрын

Another excellent video. Thanks Shahriar

@gregorymccoy6797 2 жыл бұрын

Thumbnail is to die for... Awesome troubleshooting.

@conconmervin 3 жыл бұрын

Very interesting and educational. Thank you very much.

@AissaAzzaz 3 жыл бұрын

Those thumbnails are just getting better and better Great video and explanation as usual

@ptronix 3 жыл бұрын

Thanks, always good to see some r f magic, hope you can eventually fix it

@ruhnet 3 жыл бұрын

Yay!!! Another repair!

@DaruoshAghajaney 3 жыл бұрын

You're videos thought m more than 6 years university studies bu a huge margin.

@RyanUptonInnovator 3 жыл бұрын

Very good video.

@priestblood 3 жыл бұрын

Thank you for another great repair video ,technology is getting smaller every year,how long until components are so small it's impossible for any repair to be completed without use of robotic micro hands.when you see how electronic parts are getting so small the right to repair bill will be worthless without expensive specialist equipment under super Magnification .How long until parts are so small they can fit them inbetween the different layers of the PCB,when you look at a pcb for modern phones or computers and see how small and compacted they are now what size will they be in 10 or 20 years.

@mengisi 3 жыл бұрын

Nothing to repair again and us will be replaced with Robot, sadly the end of electronic technician :(

@motherjoon 3 жыл бұрын

Some components can't get any smaller to the fundamental physical limitations. It's a matter of politics and legislation since research into self-diagnostics is progressing rapidly. Companies should just implement them and use off-the-shelf parts.

@vincei4252 3 жыл бұрын

Best thumbnail :-)

@projectartichoke 3 жыл бұрын

Could you measure one of the good pin diodes with a curve tracer and find another with the same characteristics?

@Aligreta 3 жыл бұрын

Its not a matter just curve tracer but characterize the parasitics

@Thesignalpath 3 жыл бұрын

Not really. The component’s I/V characteristics is important of course, but it doesn’t tell us about it’s high frequency model.

@willernst8376 3 жыл бұрын

Tough part to find, I wish manufacturers marked their parts better. I can't remember how many times I've been confounded by the same problem. I hope you find the part, maybe a lengthy mouser or digi key search will help, but I bet you already did that ;-)

@jfbeam 3 жыл бұрын

Why? The manufacturer knows exactly what it is. "Send it in. We'll fix it." (for 80% of the cost of new.)

@c4t4l4n4 3 жыл бұрын

Ha, I know the answer. This is only part 1, so Shahriar is going to find a solution and repair the unit.

@artursmihelsons415 3 жыл бұрын

Nice fault localization video! 👍 Didn't find that component marking in my book with smd markings.. I think, that this unknown part is, probably, some transistor (RF FET) or dual transistor.. 🤔 One idea, even, was ATF54143, but wrong marknigs and pinout.. Sad, that by picture, isn't possible to get package dimensions.. I missing times, when manufacturers published schematics.. 😢 Update: ATF-551M4 have similar package and product code is V, but W may be data code..

@Thesignalpath 3 жыл бұрын

I bought a few AFT-551M4 transistors from eBay!

@willud 3 жыл бұрын

Hello! ATF 554 transistors . I have not been able to eliminate the cause. It is in the filter after the HMC441 driver. Sorry for the English. (

@saintfather7757 2 жыл бұрын

How do you know?

@willud 2 жыл бұрын

@@saintfather7757 I have repaired this device.

@brainbuginfestation8548 3 жыл бұрын

The diode (if it is a PIN diode indeed) might be an HMPP-386x or HMPP-389x type with an odd marking on it.

@stonail665 3 жыл бұрын

I think you are on the right track, that could be it.

@Thesignalpath 3 жыл бұрын

Its close, but these components have two of their diagonal pads internally connected.

@brainbuginfestation8548 3 жыл бұрын

@@Thesignalpath The HMPP-389T has internal connections from pins 1 to 3, and 2 to 4. So both of the diagonals are connected. Hmm...

@hotcheeksoreilly 3 жыл бұрын

Yay, an MG3700A! Many on the used market report ALC errors in the low-frequency range. Mine does, and I was hoping yours would, too, so you'd explain what all the bits in the low-frequency module are and I could figure out how to fix mine. BTW, you *might* also have the same ALC problem in the low-frequency range. Mine only reports an ALC alarm in CW mode, but also only after it's been running for a while. Not too long, maybe a few 10s of seconds. I've assumed that's the time scale on the ALC loop low-pass filter. Anyway, give it a chance to think about it and it might complain. And the power is only just a little bit too low on mine, maybe 20% low. With a 1.23 MHz bandwidth white Gaussian noise modulation applied (one of the stock waveforms that should be pre-loaded), the ALC alarm goes away. So it has a problem, in particular, with high spectral power density, it's OK if the requested power is spread out.

@Emerson1 3 жыл бұрын

I’m here for cat scan pooch, - much more fun than smith charts .

@MrDehicka 3 жыл бұрын

VW marking - maybe Vectrawave GaAs LNA? I'd try to replace it with 4-pin wide band LNA from RFMD for example.

@garybevis8691 3 жыл бұрын

Love your work, sorry for the non common/unidentified parts that failed. I hope someone can donate a board or schematic.

@DoingSomethingHere Ай бұрын

Have You managed to repair it? Maybe dissolving resin and reading markings on silicon will be an option?

@dtiydr 3 жыл бұрын

18:30 That via stitching would have had any PCB fab to kill you.

@gacherumburu9958 3 жыл бұрын

👍

@NaudioElectronics 3 жыл бұрын

I think you could ask Anritsu for support. Also, show him this video. I'm sure you will get the right part number from them

@Thesignalpath 3 жыл бұрын

Not a chance. They don’t even share their firmware.

@NaudioElectronics 3 жыл бұрын

@@Thesignalpath Just try :)

@jhpyle2 3 жыл бұрын

Pooch in the thumbnail but not in the video itself -- that's what I call clickbait!

@paulpaulzadeh6172 3 жыл бұрын

now the price of Anritsu on eBay goes up , Shahriar do you have some secret channel so we can in advance find out which machine you going to repair ?!

@procactus9109 3 жыл бұрын

Is there a connection between those hair filters and a YAGI, design wise ?

@shaungoda2633 2 жыл бұрын

Can anyone explain how the various geometry in the RF frontend pcb's signal path effects the signal? What can I look into to learn more about it?

@kiwisdr7038 3 жыл бұрын

Is it a packaged die of a VWA5000048AA PHEMT LNA MMIC from VectraWave?

@MrBleulauneable 3 жыл бұрын

Maybe a stupid suggestion but : What about decaping the dead component ? Is it possible to identify the part with the stuff engraved around the chip circuits ?

@AndrewZonenberg 3 жыл бұрын

You might see a vendor logo but IC dies (and especially discrete transistors/diodes) usually just have a mask ID code (or sometimes a code name) and not an actual part number, which is decided by marketing long after the chip is taped out. So it won't get you much closer to actually identifying the part itself.

@davidjereb 3 жыл бұрын

@@AndrewZonenberg You could always try contacting the manufacturer afterwards and requesting the part number. I have a feeling that sending an email from the Bell Labs domain would also be helpful. 😁

@ToniT800 3 жыл бұрын

I would like to see a tutorial on how to design and build own mixer.

@pocoapoco2 3 жыл бұрын

Your cat got Tron-ed.

@GeorgeTsiros 3 жыл бұрын

Is that a catode?

@hamidsk2573 3 жыл бұрын

thanks for the amazing video, do you have a special video for designing a radio?

@SidneyCritic 3 жыл бұрын

Ignore this if it's stupid as I'm a dummy - lol -, but can you measure the characteristics of a good diode and cross ref it with the package - the package might not be comvential so there might not be many - aand guess at it.

@ToltecMerc 3 жыл бұрын

That's what I was wondering. Would it be possible to pull another device with the same marking and attempt to characterize its response.

@wonderbars36 3 жыл бұрын

Kinda learned this same little trick from CuriousMarc when he was looking for a transistor for that Alto restoration awhile ago in the power supply. However I get that was probably nowhere near as demanding of a sub as this is going to be. And of course setting up something reasonable to attempt a measurement but I would think I/V characteristics would get one on a very close path. Is there a good one to pluck off the board?

@stazeII 3 жыл бұрын

Guessing not, but any hope in contacting Anritsu and asking what the part is (or a schematic)?

@TheFool2cool 3 жыл бұрын

I can type the reply for you now, "Dear Sir, thank you for contacting anritsu, this unit is out of support but we are more than happy to sell you a new one"

@danmenes3143 3 жыл бұрын

A Volkswagen PIN diode?

@henryD9363 2 жыл бұрын

Finally something I can understand

@jjoonathan7178 3 жыл бұрын

Cool! I have a MG3700A too! It had the same problem with janky buttons but the responsiveness cleaned right up after taking the pad out and washing it. Soap and water was enough. Re: the PIN diodes -- what's the basis for those being PIN diodes rather than amplifiers/transistors? I've seen a bunch of amplifiers gang-biased to boost the well-behaved variable gain range and this sort of reminds me of that, besides, it seems like a long way, a lot of filters, and a lot of pads to go without amplification at 9GHz -- but I've been fighting noise figure recently so maybe my intuition isn't in the same place as theirs. Anyway, just a thought. Love the content, as always! EDIT: Oh, right, the voltages. Then again... maybe the bias voltages are wrong?

@Thesignalpath 3 жыл бұрын

I agree that they can also can be amplifiers. They are very small, but they probably don't need to produce a lot of power.

@AndrewZonenberg 3 жыл бұрын

@@Thesignalpath If you want to send me one, I can decap it and send you a few photos. Should at least help you determine amplifier vs diode, even if it doesn't get you closer to a positive ID.

@paolomonai9511 3 жыл бұрын

@@Thesignalpath No, it is not an amplifier...you measured the bias voltage at around 0.5V. No amplifier would work with a such low volrage...insted 0.5V can be the right voltage drop across a PIN diode junction. Regards from Italy.

@erikbertram6019 3 жыл бұрын

I agree, I like them being amplifiers. The mixers are passive as well I think, if I found the right datasheet.

@paolomonai9511 3 жыл бұрын

@@erikbertram6019 Could you be so kind to show the complete part number or a link to the datasheet? Thanks in advance. Regards.

@johannilsson389 3 жыл бұрын

Is it a 4-pin package?

@Thesignalpath 3 жыл бұрын

Yes. Two are GND.

@BruceNitroxpro 3 жыл бұрын

Dear God, he talks fast... and my daddy always said, "Fast mouth, fast brain."

@Dtasaka1 2 жыл бұрын

Do you have Anritsu 54111A

@byronwatkins2565 3 жыл бұрын

Are you sure that is not "M Lambda" on that diode. en.wikipedia.org/wiki/Lambda_diode

@jean-louisbezombes7135 9 ай бұрын

Hi, I have a MG3700 with the same problem. I confirm that the 3 components in the 8.8GHz chain are active transistor ( HEMT?) with about 12dB gain, not pin diode. In my case all 3 seeems to operate but I have a level about 25dB lower than expected at 3 to 6 GHz output. All 3 amplifiers are operationnal but the signal is quite low befire the second mixer.....

@RuslanStashkevich 6 ай бұрын

Were you able to solve the problem? I have the same thing as yours, all cascades work, but the signal on the mixer is weak. The problem is something else.

@jean-louisbezombes7135 6 ай бұрын

@@RuslanStashkevich I did not find the cause of the problem. To solve the trouble I inserted a 25dB amplifier in the 8.8GHz ampli chain after the third transistor. The amplifier is a connectorized model in SMA and I drilled two holes in the module to insert semi rigide cables.

@RuslanStashkevich 6 ай бұрын

@@jean-louisbezombes7135 Oh, that's great. I solved the problem another way, by adjusting all the bandpass filters. They had too much attenuation coefficient in the band.

@jean-louisbezombes7135 6 ай бұрын

@@RuslanStashkevich that's ok. How did you adjust the bandpass filters ? It is quite strange that the passive BP filters have change with time.