EEVBlog #497 - Siglent SDG5000 Function Generator Teardown

[nitro2k01]

Inside the Siglent SDG 5000 series SDG5082 80MHz Arbitrary Function Generator.

[Short Circuit]

oops

[ddavidebor]

Dave, have you noted that this thing has not the EU CE mark, but the china export ones?

[Jebnor]

oops

Umm.. Ok.  What is the oops?

[nitro2k01]

6:47 What's the matter with that screwdriver? Is that dent intentional/useful for something?
8:40 (The cutout) Maybe they're super cheap and place two pieces in a zigzag pattern to save on the metal. Even so, the metal work is only going to cost a fraction of the electronics, so it should be a problem. Maybe they outsourced it completely, or don't communicate too much between the different departments?

oops

Umm.. Ok.  What is the oops?

Here's a hint.

[synapsis]

Looks like he forgot the ribbon cable between the CPU board and the output board?

Those marks are typical of deburring stamped sheet metal with a 90 degree die grinder (with an 80 grit nylock). The welds look like they were touched with a MIG.

[grego]

After watching Dave's video I opened up my new 5082 (I've had it about a week or so) and didn't have the rust issues he did.  Chassis is still a bit flimsy as he showed but I think the rust may have been a bum unit.

[EEVblog]

After watching Dave's video I opened up my new 5082 (I've had it about a week or so) and didn't have the rust issues he did.  Chassis is still a bit flimsy as he showed but I think the rust may have been a bum unit.

The EEVblog curse strikes again.
Was there any exposed metal from the punchout?

[Short Circuit]

oops

Umm.. Ok.  What is the oops?

The missing cable, but what surprised me is no error message at all. No wonder it boots so quickly...

[Rufus]

The EEVblog curse strikes again.

Just goes to show how much those golden QC and QA stickers are worth. Hard to believe all the rust occurred in the box. The bare metal and probably rust must have been visible during assembly and test.

[free_electron]

not rust. leftover from the sheet cutter ( plasma  ).

clockgen : 74HA04 hex inverters  Dave! 

grinded device is too large for fpga config memory.

[EEVblog]

not rust. leftover from the sheet cutter ( plasma  ).

Sure looks and feels like some sort of rust to me. How would a plasma cutter explain all the scrape marks, like the edges have been filed or ground down?

[synapsis]

When they ground the edge to deburr it, they probably took the galvanization off the sheet metal, which is why it rusted. If you look closely, you can see the edge of the coating right where the grind marks begin.

[free_electron]

you can see the backspray on the side in one shot. rust would not grow in perfect parrallel strokes.

12:36 when you talk about deburring.  they cut from the far side towards you. so the plasma exits towards you and causes the slanted strokes. that is spattering : streaks of hot metal. they are all in the same direction ( away from the direction the plasma cutter travels. )

it's too regular to look like grinding.

[TooOldForThis]

I just looked in my SDG5082.  No sign of any rust or grinding on the internal edges.  And yes, the inner case is not battleship armor but that frame just has to hold the guts together until you slide the thing into the heavier outer case.  A thicker inner case would just add weight.  It doesn't distract from having a AWG that can play out cardiac signal with a 20MHz pulse rate.  It's like what an ECG from a frightened hummingbird on meth would look like. 

[AmericanLocomotive]

Super, super minor surface corrosion. Whatever method they used to cut the metal, be it grinding, cutting, stamping, laser/plasma cutting chipped/burnt off the galvanization on that edge, leaving bare steel. Bare un-coated steel will get surface corrosion in a matter of hours just from humidity in the air. The spot welds look fine, and are a cheap and strong way to secure two pieces of metal. I can guarantee you that most of the metal in your car is held together by spot welds.

While the chassis does seem to be made of somewhat thin metal, if it feels solid with the cover on, then who cares?

[99tito99]

Rusty metal out of the box can be a big problem depending on your location.  Tucson 8% humidity not so big, New Orleans 95% could get a cancer and one day have problems with rust flecks all over the boards. Cheers, Mark

[EEVblog]

While the chassis does seem to be made of somewhat thin metal, if it feels solid with the cover on, then who cares?

I care.

[synapsis]

Rusty metal out of the box can be a big problem depending on your location.  Tucson 8% humidity not so big, New Orleans 95% could get a cancer and one day have problems with rust flecks all over the boards. Cheers, Mark

I built a 1931 Chevy car chassis out of bare steel. Never painted it, and it never rusted in three years of sitting in my garage in Tucson. The only place that got surface rust was where my arm touched it while leaning over it.

[orin]

Super, super minor surface corrosion. Whatever method they used to cut the metal, be it grinding, cutting, stamping, laser/plasma cutting chipped/burnt off the galvanization on that edge, leaving bare steel. Bare un-coated steel will get surface corrosion in a matter of hours just from humidity in the air. The spot welds look fine, and are a cheap and strong way to secure two pieces of metal. I can guarantee you that most of the metal in your car is held together by spot welds.

While the chassis does seem to be made of somewhat thin metal, if it feels solid with the cover on, then who cares?

The welds don't look like spot welds to me.  They look more like TIG welds which are an entirely different and much more expensive proposition.  I'd hazard a guess that those welds have lower resistance than a spot weld or screw connection.  I've done TIG welding on far thinner metal than that chassis FWIW.

The rust at this point in time seems to be cosmetic.  My guess is they ground it down to bare metal to make a good connection with their RF gasket material... bad decision as it seems to have rusted almost instantly.

Orin.

[Paul Moir]

Well, there's spot welds and then there's spot welds.  Clearly these are not resistance spot welds.

I'm inclined to agree on the TIG.  There's a lot of undercut there for MIG, and not enough filler.  Never mind there's no evidence of spatter.  Betcha they're plenty strong enough to hold a signal generator together...

At first I thought the rust was the result of a wire wheel deburring, but plasma cutting explains it better.  It's very regular.


 

[staxquad]

invisible inner chassis (for the unDaves)

(MIG or TIG,  , could have been spot  )

can't wait for the review, where true value should be revealed (or not)

[Towger]

Dave, have you noted that this thing has not the EU CE mark, but the china export ones?

That was the first thing I saw on the back. China Export, Siglent will not be able to legally sell the model in Europe.

[tinhead]

i don't see any rusty metal here

https://www.eevblog.com/forum/testgear/tests-siglent-sdg5082-waveform-generator/

but the way how to chassis/enclosure has been made seems to be the same.

[rf-loop]

Dave, have you noted that this thing has not the EU CE mark, but the china export ones?

That was the first thing I saw on the back. China Export, Siglent will not be able to legally sell the model in Europe.

They can sell in europe normally.
Btw, Dave live in Au and there  ChinaExport is just ok or what ever there need. EU directives are not valid in Australia. 

I have also full report documentation about these, other is 52 sides and other 75 sides. Very detailed documents including of course all data how tested and results etc with laboratory  document pictures but these stay behind my body. These can try ask from Siglent, they may give these or not.
------------

About rust or what ever.  I have here opened and documented one SDG5082. No signs of this level of rust what Dave show. But, I can see also very very thin signs of "rust" on some metal cutting. This metal is somehow coated but cutted borders have open iron and it may slightly rust in some environment. Also I can see extremely light signs about this.
I suspect that it have happend in Shenzhen what is sometimes extremely humid/wet place. Perhaps in some time theu have been outside and wet before they arrive to Siglent electronic factory.

Outer case is aluminium.
Rf shielding seals are?
Internal body metal coating is undefined?

It may be better if do galvanic (electrolysis) coating after all metal work is ready and before use these in product line. But more this is like cosmetic problem and only inside unit  -- UNTIL it is used in environment where where condensation may occur.

Internal can do also as old HP, aluminum casting and then the metal machining. But this body is then more expensive than whole this equipment now.

Btw, I did not see front panel teardown..
(oh yes but it can see in my images)
-------------------


But here certificates

[AmericanLocomotive]

While the chassis does seem to be made of somewhat thin metal, if it feels solid with the cover on, then who cares?

I care.

But there is no reason to. That metal is more than thick enough for the intended purpose. I've seen structural components of automobile bodies stamped out of thinner steel. Having super thick steel in a product like this is only good for making it heavier and increasing the wank factor. It offers no real benefits.

If you can't twist, distort, or otherwise bend or flex the device fully assembled with the cover on, then the chassis and cover were properly designed as a system to work together.

[EEVblog]

But there is no reason to.

Yes, there is.
It is totally unprofessional, and not found in any other professional brand test gear that I am aware of. If they cut corners there, what else are they willing to cut corners on?, or simply not care about?
It does not instill a not confidence in the QA and manufacturing processes.
Can you imagine if Agilent, Tektronix, or Fluke offered up rusty exposed metal chassis on their latest gear? Their arse would be hauled over the coals.
If Siglent want to play with the big boys and be taken seriously like for example Rigol are now, this is not the way to do it. Small things matter, engineers are naturally pedantic.

[ddavidebor]

and of course, if is rusted now, what will it be in ten year?

[Short Circuit]

Dave, have you noted that this thing has not the EU CE mark, but the china export ones?

That was the first thing I saw on the back. China Export, Siglent will not be able to legally sell the model in Europe.

They can sell in europe normally.

Towger and ddavidebor are correct, and the generator as-is is not legal to sell in europe.
Yes, they (Siglent) can sell it, but buyers can not legally put the device in operation or sell it to others.

As already explained, the CE marking is wrong. Also, there appears no identification of manufacturer or importer on the machine.
Easily fixed with a small label containing the correct CE mark and the name+address info of the entity which imports the machine into the EU.

Of course, it's all not that bigga deal. Nobody really cares about this kind of violations, especially not on specialized low-volume equipment like T&M.
On the other hand, it's sooo easy to do it right...

Directive 2004/108/EC, articles 8.1 and 9.2

Each apparatus shall be accompanied by the name and
address of the manufacturer and, if he is not established within
the Community, the name and address of his authorised representative
or of the person in the Community responsible for
placing the apparatus on the Community market.

[rf-loop]

If Siglent want to play with the big boys and be taken seriously like for example Rigol are now, this is not the way to do it. Small things matter, engineers are naturally pedantic.

Agree.

Chassis internal finishing can be better without high costs. It is more like it only need simple cheap things and someone who care this in product design (and when they make order to metal work company who make this. Just "command" that if you want sell chassis works for us, you need follow these standards or we find other who make deal for these parts.

I do not classify this as big fail but just as I like see old HP internals good finishing is part of product "quality feel" and these feels are important in markets.

And more, if there is (specially in some environments) generated heavy rust after some aging, it is also reliability question. (example dropped rust powder may in worst case lead to failures.)

I hope I can see next generation where this  metal work are also made some amount better.
Even as I have not seen rust there what individual SDG5000 equipment I have inspected, but I can also see that this is possible.

[rf-loop]

Dave, have you noted that this thing has not the EU CE mark, but the china export ones?

That was the first thing I saw on the back. China Export, Siglent will not be able to legally sell the model in Europe.

They can sell in europe normally.

Towger and ddavidebor are correct, and the generator as-is is not legal to sell in europe.
Yes, they (Siglent) can sell it, but buyers can not legally put the device in operation or sell it to others.

As already explained, the CE marking is wrong. Also, there appears no identification of manufacturer or importer on the machine.
Easily fixed with a small label containing the correct CE mark and the name+address info of the entity which imports the machine into the EU.

Of course, it's all not that bigga deal. Nobody really cares about this kind of violations, especially not on specialized low-volume equipment like T&M.
On the other hand, it's sooo easy to do it right...

Directive 2004/108/EC, articles 8.1 and 9.2

Each apparatus shall be accompanied by the name and
address of the manufacturer and, if he is not established within
the Community, the name and address of his authorised representative
or of the person in the Community responsible for
placing the apparatus on the Community market.

You habve seen David video.
Note that this equipment is for marketing area what is not EU.

I have EU localised SDG5000 and sure it is legal for sell inside EU.
Also CE marking is ok. And if mark is not ok, it is also legal to add this CE mark there if need.

There is full documentation of certificates and and also documents behind these certificates.
 
Edited: After I go to my workshop and take one to my hand, and measure, there is small error in CE logo. (before I look only my one picture and there was angle si that can not get right dimensions, proportions.

[Eliminateur]

btw Dave, you described the Cypress SRAM as "Cirrus Logic" @24:29

[EEVblog]

btw Dave, you described the Cypress SRAM as "Cirrus Logic" @24:29

Yep. I spent a decade working with Cirrus Logic chips, one of those mistakes that pops up every time.

[grego]

So, just for folks reading this thread lets summarize about the "rust" and welds Dave saw.

1. So far as we can tell he's the only one with the issue (at least 3 others of us have them, have looked and don't see it).
2. There is some disagreement if it is actually rust instead of the results of plasma cutting the frame.  I would say this is slightly supported by the fact that only the outer edges (e.g. the "top") of the sheet metal seem to have it, none of the cutouts do/did.
3. The welds (and I am NOT a welder here, just reading a few earlier comments) appear to be perfectly acceptable TIG welds for their purpose.  Unconfirmed and I will leave that to others who have a heck of a lot more knowledge about it to discuss.

I just hate to see a decent piece of kit get panned erroneously.  I'm not saying it isn't rust, but there seems to be a fair amount of evidence it's a one-off problem and/or not rust at all.

This is no way endorses the choice of such flimsy sheetmetal for the frame or the lack of any insulation below the power supply (which I found disappointing).

[EEVblog]

2. There is some disagreement if it is actually rust instead of the results of plasma cutting the frame.  I would say this is slightly supported by the fact that only the outer edges (e.g. the "top") of the sheet metal seem to have it, none of the cutouts do/did.

Nope, the "rust" is all down the sides, and on the cutouts too.

3. The welds (and I am NOT a welder here, just reading a few earlier comments) appear to be perfectly acceptable TIG welds for their purpose.  Unconfirmed and I will leave that to others who have a heck of a lot more knowledge about it to discuss.

I did not mean to imply they aren't decent welds, just that it looks cheap and unprofessional to me.

I just hate to see a decent piece of kit get panned erroneously.

To me some things look very unprofessional compared to other similar class instruments from other manufacturers. That can't be erroneous, but can of course be a matter of opinion.
If I'm wrong on the rust/corrosion, so be it, but it still looks like crap!

[Eliminateur]

that weld is horrible and inappropiate(even if it's TIG) for simply holding the shape, a correct one would be a single spot weld on the excess metal(or a stitch of 2/3 small spot welds) which doesn't add material and only leaves the usual black spot we're all used to see

[Sine]

Well, it al comes down to cost doesn't it.
The keithley and agilent instruments use aluminum, no problems with rust there.

[grego]

Nope, the "rust" is all down the sides, and on the cutouts too.

I didnt notice it on the cutouts - hence my comment.  Probably I wasn't paying close enough attention!

I did not mean to imply they aren't decent welds, just that it looks cheap and unprofessional to me.

I was just pointing out that there were folks who have more knowledge about them is all.  I don't disagree necessarily that "normally" I would see riveted/bolted metal on those angles.

To me some things look very unprofessional compared to other similar class instruments from other manufacturers. That can't be erroneous, but can of course be a matter of opinion.
If I'm wrong on the rust/corrosion, so be it, but it still looks like crap!

I was more just trying to sum up what's come out since the video (a whole day <grin>).

BTW Dave you'll probably find when you review the 5000 a couple of annoyances in its user interface -- I won't spoil the fun for you but I'm interested to see if you trip over the same silly things I did.

[rf-loop]

I have carefully inspected agen (with measurements) CE logo and  it is not as typical China Import logo. Distance between C and E is more. But not enough for CE logo. So, there is error in CE logo.

Is it acceptable or not, who can give official answer? Then he need also give same answer for many other "brands" products. Even some products made inside EU - how we stop these to EU border?.


Then fun, it use same proportional dimensions as my Hewlett-Packard counter (it was near my hand) and also even more fun, in EU produced medical nurse equipment have exactly same distance proportionally.  But then, my one Epson printer have exatly right logo. HP laser printer have same as Siglent, Agilent made  system power supply have wrong CE mark, C and E distange same as Siglent, but C and E too thin. So... what to do. Make note and ask they stop these Agilent sell in Europe? Or HP printers etc etc.. so perhaps they have copied this CE logo from wrong place?

btw, difficult to find real tolerances what are accepted. If someone give dimensions or proportions what need follow, he need normally also give tolerances for dimensions or proportions.

[firewalker]

Just a dust particle?



Alexander

[tinhead]

sure, that logo on the back looks more CE than China Export logo:

The middle line in E sign have to be shorter than the top/bottom lines -> and that's the case for the logo on Siglent
The distance between C and E have to be that long as the length of middle line in E sign -> and that's almost the case here

http://www.ce-zeichen.de/ce-zeichen-und-faq.html

[rf-loop]

sure, that logo on the back looks more CE than China Export logo:


http://www.ce-zeichen.de/ce-zeichen-und-faq.html

Or it is something like intermediate between China Export logo and official European C E
Problem is not big but there is some possibility to accept or reject, and arbitrary decision may be possible because there is no given tolerances. (specially if there is some pedant pettifogger officer and bad day. European Commission's instructions in this case is unworthy poor quality and allow for arbitrary interpretations.

But also, whu it is so difficult for manufacturers copy these ready made official logo images? They are available in many places, they do not need copu from some other manufacturer, they can copu directly from official source.

But, lot of talking, In reality I do not think this any problem.
Hand up who can not regognize this is C E  but it is CE

There is also full report documents behind published certificates, made by accredited independent laboratory.

[Rubi]

Hi

The metals is anodised which acts as an insulator. To get the shielding electrically connected they filed the coating away.
Of course then it loses its protection and starts to rust. A good workaround would be the use of aluminium.

Cheers Rubi
http://rubines.blogspot.co.at/
 

[JackOfVA]

Hi

The metals is anodised which acts as an insulator. To get the shielding electrically connected they filed the coating away.
Of course then it loses its protection and starts to rust. A good workaround would be the use of aluminium.

Cheers Rubi
http://rubines.blogspot.co.at/

I thought that ferrous metals are difficult to anodize, and when they are the most common process is a black ferric oxide finish - commonly seen with screws and hardware, but not common at all for steel sheet.

[Smokey]

Well, it al comes down to cost doesn't it.
The keithley and agilent instruments use aluminum, no problems with rust there.

Just because aluminum doesn't "rust" doesn't mean you can leave it unprotected.  It still corrodes and starts to look crappy if it's untreated.  Anodize or Alodine are good protection for aluminum without adding the bulk of powder coating or something.

[DarlingtonPear]

I'm surprised that Siglent haven't responded yet. Lot's of discussion, but they have yet to weigh in. The rust sure surprised me.

[Greg J]

I'm sure they are busy seeking and firing the culprit

[Bored@Work]

I'm surprised that Siglent haven't responded yet.

Really?

[andersendr]

It looks like the case was made from one giant sheet of pre painted metal.  It then looks like it was cut out with a CNC punch machine and then some clean up either before or after it went through the press brake to get its shape.  I did not see any paint on the edges where there were cutouts.  It is easier, cheaper, and quicker to paint a giant flat sheet than individual formed boxes. 

[Alexei.Polkhanov]

The middle line in E sign have to be shorter than the top/bottom lines -> and that's the case for the logo on Siglent
The distance between C and E have to be that long as the length of middle line in E sign -> and that's almost the case here

Ohhhhhh, common guys, are you serious? Legal, illegal, legal, illegal, legal .... this is EE forum not of some stupid Bar association I have whole bag of those labels around somewhere for all countries - they were included as "extra" with project box I ordered online from China. You can print any labels as much as you wish but your your brand reputation is not printable and that what matters.

[skycarl]

Plasma or grind,,, that shouldn't be there period.

[hobbs]

Re the cutouts in the ground planes--there are a lot of misconceptions about that.  The designer of thiis instrument seems to have fallen into the most elementary one: making  the cutout the same size as the pad.

The parallel plate capacitance formula breaks down really badly when the dielectric thickness is comparable to the pad size.  The fringing capacitance dominates so much in that case that the true capacitance can be several times the parallel-plate value. 

In order to really reduce the capacitance from a pad to the ground plane, you typically have to extend the cutout one or two dielectric thicknesses in both directions.

I do a lot of high-Z front ends, so I run into this problem all the time.

Cheers

Phil Hobbs

[dentaku]

Has Dave ever reviewed a function generator other than way back in episode #5?

[Bored@Work]

The middle line in E sign have to be shorter than the top/bottom lines -> and that's the case for the logo on Siglent
The distance between C and E have to be that long as the length of middle line in E sign -> and that's almost the case here

Ohhhhhh, common guys, are you serious? Legal, illegal, legal, illegal, legal .... this is EE forum not of some stupid Bar association I have whole bag of those labels around somewhere for all countries - they were included as "extra" with project box I ordered online from China. You can print any labels as much as you wish but your your brand reputation is not printable and that what matters.

You stop making fun of it if customs holds and then rejects your import and you are asked if you (a) want to pay for the destruction  of it or (b) want to pay for the return to the sender.

[rf-loop]

Re the cutouts in the ground planes--there are a lot of misconceptions about that.  The designer of thiis instrument seems to have fallen into the most elementary one: making  the cutout the same size as the pad.

You can now show how this affect this signal generator output signal quality?
It do not work? Do you thisnk they have tried minimize capacitances as low as possible? No, they have not and next I ask why they should. They have designed output circuit and in practice it works without problems.   I have also true measured data from it. So, what exactly is now wrong there? 

I'm interest about what problems you find in output signal now (related this PCB layout) and what changes exactly need do and what is improvement in signal quality after your designed changes.
 

[Rubi]

Hi

The metals is anodised which acts as an insulator. To get the shielding electrically connected they filed the coating away.
Of course then it loses its protection and starts to rust. A good workaround would be the use of aluminium.

Cheers Rubi
http://rubines.blogspot.co.at/

I thought that ferrous metals are difficult to anodize, and when they are the most common process is a black ferric oxide finish - commonly seen with screws and hardware, but not common at all for steel sheet.

Honestly I have no idea, maybe it is just a protective coating.
But imho there must be some insulation layer, because otherwise the file marks would make no sense.

Would be interesting if grandmaster David Jones could tell us if the no rusting portions of the metal frame have an isolation layer.

Cheers
Rubi

[Orange]

But there is no reason to.

Yes, there is.
It is totally unprofessional, and not found in any other professional brand test gear that I am aware of. If they cut corners there, what else are they willing to cut corners on?, or simply not care about?
It does not instill a not confidence in the QA and manufacturing processes.
Can you imagine if Agilent, Tektronix, or Fluke offered up rusty exposed metal chassis on their latest gear? Their arse would be hauled over the coals.
If Siglent want to play with the big boys and be taken seriously like for example Rigol are now, this is not the way to do it. Small things matter, engineers are naturally pedantic.

I agree Dave,
Those gold AQ stickers made me suspicious.
Anyhow, can someone confirm that the used TxDAC is genuine Analog Devices. Its missing the AD logo on it. They might be cutting corners here as well.

[EEVblog]

Anyhow, can someone confirm that the used TxDAC is genuine Analog Devices. Its missing the AD logo on it. They might be cutting corners here as well.

It would have to be. I doubt you'd be able to get a fake that worked like the real thing.

[tinhead]

You can print any labels as much as you wish but your your brand reputation is not printable and that what matters.

but Siglent's brand reputation is good enought for LeCroy, that matters Alexei.

[tinhead]

Anyhow, can someone confirm that the used TxDAC is genuine Analog Devices.

yes, i can confirm, they are genuine.

[flolic]

I thought that ferrous metals are difficult to anodize, and when they are the most common process is a black ferric oxide finish - commonly seen with screws and hardware, but not common at all for steel sheet.

Only aluminium and magnesium can be anodized, ferrous sheet metals are either hot dip galvanized or electrogalvanized.


 

[hobbs]

Re the cutouts in the ground planes--there are a lot of misconceptions about that.  The designer of thiis instrument seems to have fallen into the most elementary one: making  the cutout the same size as the pad.

You can now show how this affect this signal generator output signal quality?
It do not work? Do you thisnk they have tried minimize capacitances as low as possible? No, they have not and next I ask why they should. They have designed output circuit and in practice it works without problems.   I have also true measured data from it. So, what exactly is now wrong there? 

I'm interest about what problems you find in output signal now (related this PCB layout) and what changes exactly need do and what is improvement in signal quality after your designed changes.

Wow, guy, take a pill--I wasn't the one that slapped yo' mama.   

 I haven't tried one of these things out, myself, but watching the review, I thought it was an interesting observation.  It's amazing how little actual thought people put into things like decoupling strategy and minimizing capacitance. 

If you don't believe me, try doing some measurements of how large a hole you need in the ground plane to reduce the capacitance of a small pad by as much as half.  (Hint: it's a lot bigger than the pad.)

Cheers

Phil Hobbs

[robrenz]

Only aluminium and magnesium can be anodized,

Plus stainless steel, titanium and zinc.  meaning they will form a useful oxide layer with the correct procedure.

[ddavidebor]

Yep, only metal with a coerent oxyde can be anodized.

[Short Circuit]

Re the cutouts in the ground planes--there are a lot of misconceptions about that.  The designer of thiis instrument seems to have fallen into the most elementary one: making  the cutout the same size as the pad.

You can now show how this affect this signal generator output signal quality?

He's not saying that it affects output quality. Actually, he tells those cutouts do next to nothing at all.

[PA0PBZ]

He's not saying that it affects output quality. Actually, he tells those cutouts do next to nothing at all.

If the cutouts should do something but they don't it could affect output quality 

[RupertGo]

That rust won't just be fugly, it's got the capability of introducing a large number of non-linear junctions into the device shielding. Which, if there's any amount of RF energy floating about (in an 80 MHz arbitrary waveform function generator with GHz clocks, that isn't much of an if at all), could create some interesting side-effects with a very high fun factor in the tracking down thereof.

At least it proves that Siglent and its suppliers are honest and don't cherry-pick or hand-tune units to go out to reviewers. Every cloud has a silver - or oxidised - lining.

[free_electron]

Re the cutouts in the ground planes--there are a lot of misconceptions about that.  The designer of thiis instrument seems to have fallen into the most elementary one: making  the cutout the same size as the pad.

The parallel plate capacitance formula breaks down really badly when the dielectric thickness is comparable to the pad size.  The fringing capacitance dominates so much in that case that the true capacitance can be several times the parallel-plate value. 

In order to really reduce the capacitance from a pad to the ground plane, you typically have to extend the cutout one or two dielectric thicknesses in both directions.

I do a lot of high-Z front ends, so I run into this problem all the time.

Cheers

Phil Hobbs

rule of 3

[free_electron]

You can print any labels as much as you wish but your your brand reputation is not printable and that what matters.

but Siglent's brand reputation is good enought for LeCroy, that matters Alexei.

pot calling kettle ?

[komet]

Did I miss it or did Dave forget to say "ta-da" on this occasion?

[tinhead]

pot calling kettle ?

yeah, probably. The point is however what means reputation and who deserve it.

[tinhead]

How can you confirm it?

confirm what?

[WattSekunde]

yeah, probably. The point is however what means reputation and who deserve it.

Reputation arises from the user community and discussions like this. Mostly, reputation decide on the amount of the sales.

[LDM]

With the full external part of the chassis mounted it doesn't seem like mechanical stability would be a problem.

But still, rust is never good...


LDM

[maiakaat]

1.Chassis: The solution seems easy enough, they investigate the supply chain, and switch to chassis more typical of the quality expected, add $20 to cover the costs, and re-release as a revised version of the current brand, issuing an apology and agreeing to replace the chassis for anybody who has problems within 3 years specifically with the chassis who bought from approved dealers.

2. C E, I feel this has been answered and ignored, the C E certificate is available for this device on this thread, and China should be investigated by the EU for creating a virtually identical sticker which may have been deliberate

As an additional note, all countries should do something to stop unsafe electronics coming into our respective countries, to increase local sales, as clearly the current customs processes are not adequately funded, Ebay and Amazon pay no tax, and neither do any of the sellers, and this is undermining quality of goods, salaries, national and economic balance and well-being, not to mention safety where goods are dangerous (ie cheap chargers and things)

[SeanB]

I can see the reason for this chassis being like it is. The die used to punch it out of the sheet makes both the inner case and the central power supply divider out of the same sheet, complete with cutouts and the broaches for the cable ways. Then a second machine finishes the broaches to make non sharp edges so as not to cut cable insulation, and does the bends to make the case assembly. A third die then finishes the bends, so that the case is basically finished. Sharp edges are a given with new dies, so somebody went over them with a file to dull them, though this would have been better with a different method after welding. Then they were welded most likely with a MIG welder, and then a spot of protective paint was applied over the welds. Better would have been to have welded, then tumbled to smooth them then wash, acid etch and electrogalvanise them in a bath to provide a complete cover that would not rust easily. Then the stand off posts were placed and riveted in in a press.

Good way to do a case though, as it uses the outer thicker case to provide rigidity, all the internal frame has to do is to keep the boards in line and transfer the forces to the outer shell.

[Rasz]

Better would have been to have welded, then tumbled to smooth them then wash, acid etch and electrogalvanise them in a bath to provide a complete cover that would not rust easily. Then the stand off posts were placed and riveted in in a press.

but that would cost them an equivalent of a big mac, cant do that! Just like washing soldered PCBs before shipping costs something like 0.2 cents so they stopped doing it and almost all Chinese products look inside like someone fished them out of a piss pond.

[GoosHänchen]

Differential DAC output converted to single-ended by the Intersil EL5166 then entering the relay selected reconstruction filter (Elliptical for sin output and Bessel for everything else I would guess). 

Looks like they left room on the PCB for increasing the order of the elliptical filter (currently populated is 7th order) in case it was needed or maybe they use a 9th order for the high frequency models.

Interesting design choice as opposed to filtering deferentially. 
Definitely costs less and doesn't seem to hurt their distortion specs.

[ByteMe]

Just to sum up the whole rust point. They obviously used a painted sheet of metal and did punching and folding directly onto that. If you ever want to play with the big boys, EVER, then just don't do any surface coating before all the mechanical forming was done. I don't care if the case is stainless steel, aluminium, magnesium, galvanized or even spray-painted. It just doesn't make any sense to form cases from surface treated metal. And Siglent is just embarrassing themselves by not reacting on this issue! Microchip has shown how to win the EEVBLOG's flying pig award, Siglent better put in some effort too!

[Rufus]

If you ever want to play with the big boys, EVER, then just don't do any surface coating before all the mechanical forming was done.

From what I have seen and read it is common to punch and form steel sheet with no further processing provided the sheet has some form of coating offering cathodic protection (galvanising or zinc loaded paint).

I have had a cheap GW Instek generator for several years which is of similar construction. The sheet is a bit thicker with screwed not welded fastenings. I looked at it carefully and the punched edges are bare steel. In one place there was a slight hint of discolouration which might have been rust otherwise it was fine.

Plasma cutting (if it was plasma cut) is supposed to leave a more resilient surface than shearing, but, I wonder about the risk of burning away the protective coating.

The problem is probably crap protective coating (cutting the proportion of zinc because it is expensive and it doesn't look any different would be very typical Chinese cost saving mentality) and poor finishing where they manually ground off burrs from blunt punches or plasma recast and ground off more of the crap protective coating.

Bottom line is it shouldn't rust in the future and it sure as hell shouldn't be rusty out of the box. Siglent quality control is crap.   

[Rasz]

From what I have seen and read it is common to punch and form steel sheet with no further processing provided the sheet has some form of coating offering cathodic protection (galvanising or zinc loaded paint).

Yes, most if not all cheap computer cases are like that, but they ARE NOT SHIPPED PRE RUSTED, whats more they dont even rust after few years.

[EEVblog]

UPDATE:
I have been informed that Siglent took the rusting issue seriously and have retooled their process to fix it. They are sending me the new production model so I can show the differences. 

[IvoS]

Nice. My SDG5082 is on its way. I will have a peek inside as soon as I get it to see how the chassis looks like these days.

[Smokey]

TheSignalPath did a tear down of a current production unit and they really cleaned up the internals since the EEVBlog review teardown.

[IvoS]

A few weeks old unit SDG5082 I purchased from Tequipment.  Rust, rust.....,  left me with rusty taste in my mouth. Another thing I noticed was pinched wire against the chassis. So, I am kind of glad I opened it up and caught it. This pinched wire could have the insulation deteriorating with the heat and one day it would leave me with blank screen.
I don't think I would be buying anything from Siglent any time soon.