New SDS1104X-E missing calibration certificate  - Page 1
Forum section: electronics / testgear

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 08:21:51 pm
content: Today I received a SDS1104X-E brand new in box from a well-known (UK) authorized distributer. I'm frustated in finding that the calibration certificate was neither tucked into the Quick Start Guide, nor elsewhere in the box.Whilst I await a reply to emails sent to the distributor and Siglent's EU office, is the calibration date stored in the firmware? (A long shot, I know). Perhaps it can be inferred from the 2023-11-28 warranty expiry date?!Thanks in advance!

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 08:25:22 pm
content: We can get PDF copies of the original factory Cal from the factory. Siglent in Hamburg can get them after the factory kicks into gear again next week after CNY.

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 08:30:15 pm
content: Quote from: tautech on February 19, 2021, 08:25:22 pmThanks tautech, I was hoping you would reply! A PDF of the factory calibration would be perfect and I shall see if the Hamburg office (or UK distro) reply after CNY.Seems like a petty thing but it would do a lot to get rid of the bitter taste of not knowing if the scope has had any factory calibration. Perhaps the fact that I care so much is sickness I picked up working at a metrology company!

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 08:40:34 pm
content: LOL yes it's a sickness.I get Cal certs with every instrument and over the last while there has been a 6mth extension from cal date to sale date for the 1 yr cal period to start.

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 08:44:39 pm
content: Quote from: tautech on February 19, 2021, 08:40:34 pmHaha!I noticed the extension was mentioned herehttps://www.siglenteu.com/service-and-support/calibration-certificate/Again, it's greatly appreciated. Fingers crossed that I hear something from someone after the end of next week.

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 08:55:52 pm
content: If you get overlooked PM me the SN# and I get the Cal sheet for you. As we can't PM PDF's I'll need your email to send it to you.

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 08:59:41 pm
content: Quote from: tautech on February 19, 2021, 08:55:52 pmThank you very much indeed for the kind offer. I will drop you a PM if I end up banging my head against the wall!

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 09:24:50 pm
content: I really don't understand why Cal sheets aren't forwarded to customers as it seems suppliers don't think they will ever be needed for traceability.They really need to sharpen up their game.

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 09:30:15 pm
content: I figured from what you've written that distributors must get a PDF copy so you don't need to open the box(?) It seems a bit strange that the paper copy was missing from mine and whilst it was hard to be 100% sure, I am fairly confident the box was factory-taped shut. On first boot the scope registered 1 power up... Perhaps the paper sheet was lost in the factory? Who knows?!

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 09:41:24 pm
content: We distributors only see the paper copy unless we request a PDF copy however every reseller has a different dispatch system where in my case I open every unit to fit my company sticker, check FW version and compensate probes if it's a scope.At that time the boot count is 1 after I've done my PD checks and my customer sees 2 when they boot the unit for the first time.Anyways it's not a biggy as whenever I've requested a Cal sheet they have been available. Done that a couple of times for members here, one with new gear like you and another with a used unit and wanted to know date of manufacture/Cal for his own interest.Recently a customer wanted one too as he'd lost the original along with the manuals and CD.

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 09:47:13 pm
content: Quote from: tautech on February 19, 2021, 09:41:24 pmIt's good to hear that you make these pre-delivery checks and setup the instrument! Sounds like top-teir service.Quote from: tautech on February 19, 2021, 09:41:24 pmGood to know that these Cal sheets have been freely available for you. I feel happier knowing Siglent are likely to make the effort. Thanks!

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 09:55:59 pm
content: Be aware most sellers don't have a direct line to the factory but instead either must go through the Hamburg or Ohio divisions of Siglent.NZ is a small place of just 5M so here there is just me so I deal directly with Shenzhen.

author: 74HC04
author_rank: Contributor
timestamp: February 19, 2021, 10:05:11 pm
content: Quote from: tautech on February 19, 2021, 09:55:59 pmSounds like I'm more likely to get a reply from Siglent EU than my distro then. Thanks.I am hoping I don't have to bother you again but really do appreciate the offer!(p.s. if you think 5M is small, try a population of 105k. I no longer live on the mainland and it took a week for the scope to get here!. It must be good to deal directly with the factory).

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 10:12:01 pm
content: LOL 3 days is normal for anywhere in NZ.Anyways you'd better get started with getting to know your scope as it will be a while before you get to be fully conversant with it !

author: Fungus
author_rank: Super Contributor
timestamp: February 20, 2021, 07:39:03 am
content: Quote from: tautech on February 19, 2021, 09:24:50 pmThink of the planet!PS: I imagine the first thing most customers do is press "auto-cal", thus invalidating the certificate.

author: tautech
author_rank: Super Contributor
timestamp: February 20, 2021, 07:49:13 am
content: Quote from: Fungus on February 20, 2021, 07:39:03 amPlant a tree, how many have you ?QuoteDo you even really know how that works ?Or Quick Cal for that matter ?

author: rf-loop
author_rank: Super Contributor
timestamp: February 20, 2021, 08:28:19 am
content: Quote from: Fungus on February 20, 2021, 07:39:03 amWhat is this random generator you use for generate these comments.

author: 2N3055
author_rank: Super Contributor
timestamp: February 20, 2021, 08:57:39 am
content: Quote from: rf-loop on February 20, 2021, 08:28:19 amLOL!good one..But seriously, this is from Keysight 3000T user manual:"Perform user-calibration:• Every two years or after 4000 hours of operation.• If the ambient temperature is >10° C from the calibration temperature.• If you want to maximize the measurement accuracy.The amount of use, environmental conditions, and experience with otherinstruments help determine if you need shorter User Cal intervals"and then:"User Cal performs an internal self-alignment routine to optimize the signal path inthe oscilloscope. The routine uses internally generated signals to optimize circuitsthat affect channel sensitivity, offset, and trigger parameters.Performing User Cal will invalidate your Certificate of Calibration. If NIST (NationalInstitute of Standards and Technology) traceability is required, perform the"Performance Verification" procedure in the Keysight InfiniiVision2000/3000 X-Series Oscilloscopes Service Guide using traceable sources."So self cal is needed for best accuracy, but invalidates Certificate of Calibration...Sinisa

author: Fungus
author_rank: Super Contributor
timestamp: February 20, 2021, 10:47:53 am
content: Quote from: tautech on February 20, 2021, 07:49:13 amAre Siglents so magical that a user can't mess them up by pressing "auto-cal"?(eg. before it warms up properly)

author: 2N3055
author_rank: Super Contributor
timestamp: February 20, 2021, 12:46:42 pm
content: Quote from: Fungus on February 20, 2021, 10:47:53 amIf you selfcal while internal temp is still low, you can always restart selfcal.User can also permanently decalibrate it by using hammer.I was pointing out the idiocy of lawyer talk in Keysight documents.There is a factory calibration/adjustment that defines real accuracy of the instrument.And self cal that is equivalent to bench multi-meter Autocal (that high precision meters have).Somehow in bench meters it is auto cal is improving specification, and on the scopes it invalidates traceability..There is a complete lunacy surrounding this topic, completely confusing bureaucracy of traceability with accuracy of instrument measurements.

author: rf-loop
author_rank: Super Contributor
timestamp: February 20, 2021, 02:46:10 pm
content: Quote from: 2N3055 on February 20, 2021, 12:46:42 pmPerhaps even more...Whole NIST traceable cal have many problems.One of simplest is something like this mechanism is build in this whole mess.Take example. I have some lab what make tests and all need do with NIST traceable instruments with valid certificate. Lab room temp is also measured with certified meter so that it is inside valid range. Think certificates valid period is 1 year. After instrument come from cal lab we continue measurements and write documents and every document have also info about instruments calibration cert.Year go and lot of things have done.Instrument go again to cal lab for certificate.In this process find it is off and can not write certificate, first need repair/adjust etc.But there is not any knowledge when this fault happen, if it happen just after last cal check or drifted until some day gone out of limits.There is lot of test reports around of world done with this instrument or it is part of test setup.Do you call back all test results made after last cal certificate because you do not know when it have failed. It can be failed whole year and all measurements can be just garbage.This is one small hole in this whole cal mess.

author: Fungus
author_rank: Super Contributor
timestamp: February 20, 2021, 03:15:14 pm
content: Quote from: rf-loop on February 20, 2021, 02:46:10 pmYep. User error can invalidate a certificate ten minutes after it was issued. Even in a controlled environment it can mean the device is giving bad results for months/years before the next check.(I believe this is why Fluke and others make you disassemble the meter just to change a fuse).

author: 2N3055
author_rank: Super Contributor
timestamp: February 20, 2021, 06:53:41 pm
content: Quote from: Fungus on February 20, 2021, 03:15:14 pmNah, that is because Flukes are really made to contain explosion, and having one piece solid case makes it easier to make it safer...Fuses should be ones most armoured which interferes with easy to access...

author: 2N3055
author_rank: Super Contributor
timestamp: February 20, 2021, 07:03:04 pm
content: Quote from: rf-loop on February 20, 2021, 02:46:10 pmYou are so correct.Current calibration certificates actually kinda work in reverse, and you need two cals, to attest that whatever was measured ininterval betweentwo certificates was probably accurate...So you calibrate, measure for a year, than calibrate again, and you can say that measurements for the last year were OK.If you fail cal, everything going to last good cal is questionable.That is why for critical measurements they keep cal lab on site and calibrate on 30 days and 24 hour intervals...And that is why for critical measurements you measure with multiple instruments as a sanity check...It gets complicated and expensive quick..

author: tautech
author_rank: Super Contributor
timestamp: February 20, 2021, 08:40:25 pm
content: Quote from: 2N3055 on February 20, 2021, 12:46:42 pmYou wouldn't do that if you RTFM.....nobody can fully compensate for uninformed/careless use of an instrument.QuoteNo such claim of ruining calibration is even mentioned in Siglent documentation therefore the intelligent reader will assume there is no risk in running Self Cal which of course there isn't.To confirm this assumption the factory says:The user self cal will not destroy the calibration data.QuoteYes, and entirely separate to user cal. User Cal makes miniscule adjustments so to maintain best accuracy until the next verification of accuracy is performed at normally 1 yr intervals. (Calibration)Accuracy verification steps/tests are listed in the Service manual.

author: 74HC04
author_rank: Contributor
timestamp: February 21, 2021, 10:02:08 am
content: Quote from: tautechThanks for pointing this out. I was relucatant to run a self-cal, at least until I've seen a factory calibration certificate, in case I overwote that factory cal. I am seeing a ~1 pixel positive offset especially from CH1 and CH2, which tends to come and go with vertical position, even when the inputs are gnd coupled (is this a "real" ground anyhow?) and regardless of the volts / div setting. Probably just expecting too much from the front-end!Or is this a rounding artefact, perhaps?The lack of factory cal certificate in a Siglent tape sealed box worrys me (it's mentioned on the datasheet's packing list and looks as though it should be tucked into the Quick Start Guide), so I will wait to obtain a copy before drawing any conclusions.

author: Performa01
author_rank: Super Contributor
timestamp: February 21, 2021, 11:54:38 am
content: Quote from: 74HC04 on February 21, 2021, 10:02:08 amIsn't this funny? Folks buy a dirt-cheap entry level scope from a Chinese manufacturer and then rant about things that experienced professionals would not expect even from a midrange DSO manufactured by one of the "big boys" and costing more than 10 times as muchJust like the majority of modern DSOs, this one does not have a "real" input ground. So checking anything with input coupling set to GND is completely meaningless.If you want to check the offset with grounded input, you could use a BNC-Terminator for that (with DC coupling). Or just leave the input open, the difference is really negligible.If you do so, please check the specifications for offset and gain error in the data sheet (and compare these with even much more expensive instruments) before you start questioning the quality of the (excellent - high sensitivity, low noise) frontend, just because you spot a few pixels deviation somewhere.Self calibration is there to bring the instrument to the calibrated state. Specifications can only be guaranteed after a self-cal has been performed after at least half an hour warm-up of the instrument. You can bet your bottom dollar that the factory performs such a self-cal before checking the instrument cal state and then issuing the certificate if it's passed. Of course you won't need another self-cal anytime soon unless there were major temperature changes or the firmware has been updated. Yet the temperature in your lab might differ from the one used for the calibration, so a self-cal could improve things.Self-Cal cannot provide infinite accuracy though. It relies on an internal reference and a highly accurate DAC, but the adjustments don't have infinite resolution. This is true for the offset DAC (for offset calibration) as well as the PGA (for gain calibration). So especially if you look at the trace at high sensitivities (<5 mV, which are just "fake" software zoom in many other even much more expensive DSOs, but are very real in the SDS1000X-E series), the limited resolution of the offset DAC might leave us some visible offset in the realm of a couple 100 µV.The frontend of a modern DSO has to use an OpAmp for the DC/LF-path of the input buffer. Since it needs to be high impedance, it has to be (MOS)FET. But this means that it cannot be low offset with low TC - and you don't want a chopper stabilized amp in the frontend of a DSO. This is the reason why a DSO frontend cannot be compared to a multimeter, because the latter usually doesn't need a separate OpAmp and even if it did, it would be of the "zero offset" species. It's essentially the drift and temperature stability of this beforementioned OpAmp that causes the offset error (changing with temperature) in a DSO, hence makes the self-cal necessary. The SDS1000X-E can even provide a "quickcal" that kicks in automatically as soon as the instrument detects a condition that might increase the offset error. The gain on the other hand is much more stable anyway.If you are interested in an exemplary performance verification regarding DC and AC accuracy, you can have a look at the document "SDS1104X-E Review 50-70.pdf" that is attached in reply #1 of this thread:https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/In this document, at page 52 you will find a demonstration to measure a DC voltage of 205 V to an accuracy of better than 0.08 %.Compare this to the specifications and you will learn that this instrument can actually be vastly better than that, especially when it comes to offset accuracy. Still you'll have to live with a smalladditiveerror, only visible at high sensitivities.

author: Fungus
author_rank: Super Contributor
timestamp: February 21, 2021, 01:31:10 pm
content: Quote from: 74HC04 on February 21, 2021, 10:02:08 amThere's nothing to "overwrite", there's really no such thing as a "factory cal" in a device which recalibrates itself at the push of a button.The certificate only tells you about the numbers they saw on-screen after they pushed that button at the factory under controlled conditions, ie. if it was capable of calibrating itself properly or not.Your 'scope will give different readings in summer and winter, maybe even in morning/afternoon (depending on the climate control in your workplace). Any readings taken less than 15-minutes after power-on are invalid (try powering it on from cold and watch the DC offset change as it warms up).Numbers on DSO screens are only approximate, treat them as such. If a reading is really critical then do yet another self-cal just before taking it.

author: 2N3055
author_rank: Super Contributor
timestamp: February 21, 2021, 01:42:21 pm
content: Quote from: Fungus on February 21, 2021, 01:31:10 pmThere is absolutely factory adjustments that saves basic correction coefficients into instrument at manufacture time.Autocal is NOT full adjustment. It only compensates partially for some parameters, and that mainly for thermal drift.It is more important as a functional verification.It will compensate some for temperature related drift and make most accurate measurements.

author: Fungus
author_rank: Super Contributor
timestamp: February 21, 2021, 02:06:58 pm
content: Quote from: 2N3055 on February 21, 2021, 01:42:21 pmOn modern DSOs? Have watch the auto-cal do its thing? You can see it doing binary searches to find the offsets/scales and it they're not tiny adjustments, they can go way off screen.I know that there are posts here about "lost calibration" on older 'scopes but I doubt modern DSOs need that (it would cost money...)Let's see...sds1104X-e lost calibration- zero resultsds1054z lost calibration- zero results

author: 2N3055
author_rank: Super Contributor
timestamp: February 21, 2021, 02:18:06 pm
content: Quote from: Fungus on February 21, 2021, 02:06:58 pmThey go off the screen because full range on A/D is off the screen...And most of the new scopes don't carry any calibration in battery backed RAM.. And they are new.. Old scopes had time to die in numbers so that statistics is skewed by definition

author: Fungus
author_rank: Super Contributor
timestamp: February 21, 2021, 03:41:31 pm
content: Quote from: 2N3055 on February 21, 2021, 02:18:06 pmObviously.ie. They have a particular starting point and they have plenty of adjustment built in, no need for "basic correction coefficients".

author: 74HC04
author_rank: Contributor
timestamp: February 21, 2021, 04:35:58 pm
content: Quote from: Performa01 on February 21, 2021, 11:54:38 amThanks very much. Self calibration seems to have helped.I appreciate your in-depth review and have a lot of reading to do.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 07:11:09 pm
content: Quote from: Fungus on February 21, 2021, 01:31:10 pmOh FFS what BS your random reply generator is creating this time only this time it's absolute BS !Pretty obvious you have never seen a calibration certificate or even know about the processes used in modern closed box calibration.Traceable calibration certificates arerequiredto list the instruments SN# and the instruments used for the calibration process,theirSN#'s and the expiry date oftheircalibration.All this is included on Cal certs accompanying Siglent instruments.Please disable random reply generator and enable any critical thinking residing in that space between ears.

author: Fungus
author_rank: Super Contributor
timestamp: February 21, 2021, 07:18:47 pm
content: Quote from: tautech on February 21, 2021, 07:11:09 pmFactory Calibrationcertificates, exist, obvously. I've seen one. There's samples on the Siglent web site.eg.https://siglentna.com/wp-content/uploads/2018/09/SIGLENTCoCSample.pdfNote that they don't give any numbers, it's just pass/fail.What doesn't exists is some burned-in "factory cal" parameters inside the 'scope that could be 'overwritten'. Factor calibration isn't some magical process, they just pressed the self-cal button at the temperature/humidity stated on the certificate and unless you're working at that exact temperature/humidity you should reallyrecalibrate it as soon as you receive it.Try reading the words on the screen before rushing to insult me.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 07:40:49 pm
content: Quote from: Fungus on February 21, 2021, 07:18:47 pmSo lets review information already presented in this thread as it seems this has yet to be enabled:Please disable random reply generator and enable any critical thinking residing in that space between ears.Posted by: tautech« on: Yesterday at 09:40:25 am »To confirm this assumption the factory says:The user self cal will not destroy the calibration data.Quote from: Fungus on February 21, 2021, 07:18:47 pmThenumbersthatmust be metare in the datasheet and in greater detail in the Performance Verification section of the Service manual.

author: Fungus
author_rank: Super Contributor
timestamp: February 21, 2021, 08:34:08 pm
content: Quote from: tautech on February 21, 2021, 07:40:49 pmYep, that'd be how they do the "pass/fail" part.(or maybe you think they do it randomly?)You finally seem to be getting the complete picture.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 08:47:05 pm
content: Quote from: Fungus on February 21, 2021, 08:34:08 pmOh really, do you think so ?Service manual P23 Performance Testhttps://int.siglent.com/upload_file/user/SDS1000X-E/SDS1000X-E_ServiceManual_SM0101E-E01A.pdf

author: Fungus
author_rank: Super Contributor
timestamp: February 21, 2021, 09:11:31 pm
content: Quote from: tautech on February 21, 2021, 08:47:05 pmYou haven't actually disagreed with any of my "random" replies so I'm starting tohopeso.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 09:20:16 pm
content: Quote from: Fungus on February 21, 2021, 09:11:31 pmRTFM

author: 74HC04
author_rank: Contributor
timestamp: February 23, 2021, 01:22:54 pm
content: Update: The distributor sent me a jpeg scan of the front page of the Calibration Certificate.The distributor in question is Telonic. As you will see from the few pages of the following thread leading to the one linked below, this is not the first time they've sent a Siglent instrument without it's Calibration Certificate. I can only speculate as to what happened to the document but would recommend that anyone ordering from Telonic that values their Cal Cert insists that it is included within the scope of delivery!https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/1650/.Thanks all for your input and advice.

author: 74HC04
author_rank: Contributor
timestamp: February 23, 2021, 01:25:14 pm
content: Quote from: 74HC04 on February 23, 2021, 01:22:54 pmFreudian slip!