Was 2018 a bad year for Siglent SDM3055 ? - Page 1
Forum section: electronics / testgear

author: EricG
author_rank: Contributor
timestamp: March 10, 2025, 06:25:37 pm
content: We have 4 Siglent SDM3055 DMMs that we purchased in 2018 as part of a test automation project. The project ended up being cancelled and the meters got relegated to non critical bench applications or being stored. We have another project that needs them now, so we sent them off to Transcat, who is Siglent's recommended lab, for calibration. 3/4 of them failed, and the 4th was on the edge.notes from Transcat:The unit failed calibration and repairs are not available. OOT inTemperature Measure K-Type @ -190.00 and 4W ResistanceMeasure @19kOhmThe unit failed calibration and repairs are not available. OOT inseveral parameters. DC Current 2A range and 4W in the 200 Ohmrange Zero Offset, DC Volts in the 20VDC, 200VDC, and 1000VDCRange, VAC 20 Volt range 19VAC@45Hz, and TemperatureMeasure K-type @-190 degrees celsius. Unable to adjust.The unit failed calibration and repairs are not available. OOT in VACin 200 volt range 190VAC @50kHz. Unable to adjustDid we just get very unlucky or was Siglent having quality problems during that time period? or did we just get what we paid for? We have HP/Agilent/Keysight and Fluke DMMs that are 20 years old and have never been out of tolerance. I took a chance with these and feel like I got burned.

author: tautech
author_rank: Super Contributor
timestamp: March 10, 2025, 06:34:29 pm
content: Quote from: EricG on March 10, 2025, 06:25:37 pmSimple manual adjustment is provided in the later firmwares but not in early versions from 2018.Go talk to your Siglent supplier or NA branch in Ohio.

author: bdunham7
author_rank: Super Contributor
timestamp: March 10, 2025, 06:52:08 pm
content: I'm not sure what they are saying in those notes. What does "unable to adjust" actually mean? Did they find the units OOT and attempted to adjust them and the adjustment failed for some reason? Or are they saying that they can only do a performance test and they don't have an adjustment procedure available? It would help if Siglent would release the calibration procedure. My worst fear would be that there isn't an actual adjustment procedure, or at least anything beyond this:https://www.youtube.com/watch?app=desktop&v=ToS--TvLWDs&t=98sSo, how far were these units OOT? Did they provide data? And did they explicitly say that they performed an adjustment procedure and if so, with what result? Did your people notice that these meters were off in any way prior to sending them?As for your bigger question, after hearing many similar stories it seems pretty clear to me that in the DMM department both Rigol and Siglent are just not quite up to professional standards. IMO, yes, you got what you paid for.

author: bdunham7
author_rank: Super Contributor
timestamp: March 10, 2025, 06:57:57 pm
content: Quote from: tautech on March 10, 2025, 06:34:29 pmIs there an adjustment procedure for HF AC response? That's a lot different than just entering scale and offset constants. Unless Siglent releases the actual cal procedures--and I've no idea why they keep them secret--we have no idea what is an is not adjustable.

author: tautech
author_rank: Super Contributor
timestamp: March 10, 2025, 07:07:36 pm
content: Quote from: bdunham7 on March 10, 2025, 06:52:08 pmThey have and the one you linked was their early User adjustment process , much improved and simplified in later firmware firmware versions.While Transcat has partnered with Siglent for Cal services I do not know to what level and if Siglent have shared their full calibration scripts with Transcat for use in Fluke universal calibrators, the same as used at the Siglent factory.https://siglentna.com/service-and-support/calibration-certificate/But I am aware Siglent Ohio have a Fluke universal calibrator in house and can fully calibrate/adjust the SDM range to the same standard as headquarters in Shenzhen.

author: EricG
author_rank: Contributor
timestamp: March 10, 2025, 07:25:54 pm
content: Quote from: tautech on March 10, 2025, 06:34:29 pmIs that the 1.01.01.27R2 update: "Add and optimize the manual calibration function" listed inhttps://siglentna.com/wp-content/uploads/dlm_uploads/2024/05/SDM3055-Firmware-Revise-History-and-Update-Instructions.pdf?

author: tautech
author_rank: Super Contributor
timestamp: March 10, 2025, 07:33:53 pm
content: Quote from: EricG on March 10, 2025, 07:25:54 pmYes, the last V 1.01 version.There have been further FW updates including an OS update but they must be done in a sequence.https://int.siglent.com/download/firmwares/?ProId=26

author: EricG
author_rank: Contributor
timestamp: March 10, 2025, 08:59:48 pm
content: Quote from: tautech on March 10, 2025, 06:34:29 pmI just talked to Transcat, and they were unaware that these units had the potential to be adjustable at all so they didn't try. given their status as Siglents "official" cal vendor that's really suspicious/irritating.

author: tautech
author_rank: Super Contributor
timestamp: March 10, 2025, 09:27:47 pm
content: Quote from: EricG on March 10, 2025, 08:59:48 pmSure, however it's not Transcat's responibility to have units updated to the latest firmware that allows for User adjustment before calibration.It's sounding like Transcat don't have the equipment to make the automated adjustment anyways.Call Siglent Ohio and have a chat with them.https://siglentna.com/contact-us/

author: bdunham7
author_rank: Super Contributor
timestamp: March 10, 2025, 10:08:16 pm
content: Quote from: EricG on March 10, 2025, 08:59:48 pmNow that's some clown show! Unfortunately, that's also what I suspected. I doubt so many ranges on all those meters would be not only OOT but also out of the calibration adjustment range since that would presumably involve the meters being seriously off on multiple ranges. I'd call Siglent and explain that if they can't set up a system for users to get reliable professional service then they may as well close their shop and just sell on AliExpress. However, I'm still unsure what calibration capabilities are actually there as the "user adjustment" doesn't seem to me to be quite the whole potato. My understanding from what I remember of that video is that the original cal constants are retained and the user adjustment values are manually entered and then overlaid as scale correction factors. Let us know what they say.

author: KungFuJosh
author_rank: Super Contributor
timestamp: March 10, 2025, 10:52:32 pm
content: Quote from: bdunham7 on March 10, 2025, 10:08:16 pmI haven't attempted any whole potatoes, but what I did do seemed pretty darn good. My DAQ6510 was recently calibrated, and my 34465A agreed with it pretty well, but my SDM3065X was off. I used my SPD3303X as a voltage source with all 3 meters connected. I know. Anyway. It was good enough for government work, as they say. You can see in the 10 hour test things looked a little better in that one range I adjusted.Thanks,Josh

author: bdunham7
author_rank: Super Contributor
timestamp: March 10, 2025, 10:59:35 pm
content: Quote from: KungFuJosh on March 10, 2025, 10:52:32 pmOne of the OP's meters was OOT at 190VAC @ 50kHzQuoteAssuming you had an accurate source for 190VAC @ 50kHz, is there a relevant adjustment for the HF AC? Just adjusting the scale factor for the 200VAC range won't work very well because you'll throw off the reading for 190VAC @ 1kHz or 60Hz.

author: EricG
author_rank: Contributor
timestamp: March 10, 2025, 11:13:28 pm
content: Quote from: tautech on March 10, 2025, 09:27:47 pmIt's very true that it's not Transcat's responsibility to keep updated. I never really thought about it since this isn't an issue with Tek, Keysight or Fluke calibration, You just check a box that it's OK to update the FW if needed or they call and ask if it's ok, so I'll admit my laziness on that front. However, given that they are the named cal vendor of choice from Siglent in the US, I'm really surprised they don't get service bulletins or training on this, or that their in-house procedure doesn't spell this out. When when I got the notes on this from Transcat, they just offered to throw the units away for me, and when I called them they said that was routine on these meters, Which is BONKERS.I also never thought that adding the ability to adjust calibration was something that would require an update 8 years after the first FW date.

author: tautech
author_rank: Super Contributor
timestamp: March 10, 2025, 11:27:28 pm
content: Quote from: EricG on March 10, 2025, 11:13:28 pmTotally, complain to Siglent and recommend they get Transcat up to speed or give them the boot for a better US Cal institution.QuoteUser Cal capability was never part of the original design brief but got added later after requests for it to correct Vref drift as these models all use un-aged references.The first User Cal processes were unnecessarily cumbersome but now easy to use by way of padding the original Cal and saving it as the new User Cal to use but the original Cal is retained to revert to if/as required.OEM Cal is an automated process controlling the SDM and Fluke calibrator from a PC script where OEM also records and saves each Cal and we can get these if required.As mentioned, Ohio has the calibration gear to properly calibrate SDM models like they just came from the factory.

author: EricG
author_rank: Contributor
timestamp: March 11, 2025, 11:46:30 pm
content: I talked to transcat again today, and they let me come by and update the FW on the DMMs and they will run them through again now that they have the ability to adjust.

author: bdunham7
author_rank: Super Contributor
timestamp: March 12, 2025, 12:04:43 am
content: Quote from: EricG on March 11, 2025, 11:46:30 pmDid you ever talk to Siglent NA about this?

author: tautech
author_rank: Super Contributor
timestamp: March 12, 2025, 12:32:07 am
content: Quote from: EricG on March 11, 2025, 11:46:30 pmReally, that was nice of them....not...when you had already given them approval to update the FW.Will you send them your bill for your professional development services ?Watching from the cheap seats....unless they give you a really good deal I will never again be pointing anyone to Siglents NA website where they claim to be partnered with Transcat.

author: bdunham7
author_rank: Super Contributor
timestamp: March 12, 2025, 01:20:16 am
content: Quote from: tautech on March 12, 2025, 12:32:07 amTranscat is not only Siglent's designated NA calibration partner, they are a Siglent equipment dealer.https://www.transcat.com/brand/siglent-store

author: tautech
author_rank: Super Contributor
timestamp: March 12, 2025, 01:26:09 am
content: Quote from: bdunham7 on March 12, 2025, 01:20:16 amAnd their Cal department advised binning of the SDM3055 that failed Cal.Crazy but HQ now knows about this and no doubt NA HQ will be advised to have a chat with Transcat.

author: EricG
author_rank: Contributor
timestamp: March 12, 2025, 05:14:07 pm
content: Quote from: bdunham7 on March 12, 2025, 12:04:43 amI was waiting to bottom out with transcat before I started with Siglent.Quote from: tautech on March 12, 2025, 12:32:07 amafter talking to them yesterday, they said they checked and aren't allowed to update software on customer units. So letting me come down and do it myself and running cal again i think counts as nice. I can see other companies telling me to go pound sand.

author: bdunham7
author_rank: Super Contributor
timestamp: March 12, 2025, 08:15:18 pm
content: Quote from: EricG on March 12, 2025, 05:14:07 pmWell, it should be interesting to see where you end up. One of the things I still don't understand is how the meters wereoriginallycalibrated (presumably with an automated system) but now they can't be recalibrated without a FW update? And I think there's no doubt that the more you complain, the more of a favor you are doing for Siglent. Simply discarding the units as advised and never considering their brand again in the future would probably be the most common response from commercial users.I can't believe the issue hasn't come up before. Surely people have been getting their Siglent meters calibrated (with adjustment) from time to time?

author: EricG
author_rank: Contributor
timestamp: March 18, 2025, 04:49:58 pm
content: so, apparently new FW wasn't enough. I received new quotes with the following comments:The unit failed calibration and repairs are not available. OOT - OOT inseveral parameters. DC Current 2A range and 4W in the 200 Ohmrange Zero Offset, DC Volts in the 20VDC, 200VDC, and 1000VDCRange, VAC 20 Volt range 19VAC@45Hz, and TemperatureMeasure K-type @-190 degrees celsius.Unable to adjust. Would you like the defective units returned to youor scraped at our facility?The unit failed calibration and repairs are not available. OOT in VACin 200 volt range 190VAC @50kHz. Would you like the defectiveunits returned to you or scraped at our facility?The unit failed calibration and repairs are not available. OOT - OOT inTemperature Measure K-Type @ -190.00 and 4W ResistanceMeasure @19kOhm. Would you like the defective units returned toyou or scraped at our facility?for reference the original comments were:Quote from: EricG on March 10, 2025, 06:25:37 pmThe customer service manager said that both the tech and the lab manager attempted adjustment with the FW provided controls, but couldn't get them back into tolerance. I'm picking them up this afternoon and will contact siglent about this.Rigol lists Transcat as their preferred Cal vendor as well. so we'll see what happens with out Rigol loads when I drop them off.

author: bdunham7
author_rank: Super Contributor
timestamp: March 18, 2025, 05:15:38 pm
content: Quote from: EricG on March 18, 2025, 04:49:58 pmThat one I'd expect to be non-recoverable because I presume this meter does not have a DAC-controlled AC pole or flatness section to compensate the HF response. It shouldn't need one given the relaxed 1% accuracy spec, but if it does go beyond that it lacks the hardware needed to adjust it. This would be an actual physical change to the AC response, not a calibration constant. This is not a Siglent-exclusive shortcoming, many other common 5.5-digit meters with closed-case calibration also would need a physical repair if their AC HF response was off.For the others, it really appears to me that Siglent has not released a true calibration procedure to Transcat and as odd as it sounds, there may not be such a procedure. IDK how they set them up at the factory, but I suppose they could use external devices to calculate and burn in the calibration constants and the meter may simply lack the ability to do it on its own. I'm curious as to how far these ranges were off, as well as what readings they got on the ranges that passed. I suppose they don't provide data?

author: EricG
author_rank: Contributor
timestamp: March 18, 2025, 06:38:05 pm
content: for failed units they don't provide data.just sent this to Siglent North America:"Hello,We have 4 SDM3055 DMMs purchased in 2018 that have been in storage or reference only use for a while and we wanted to put them back into service. As part of good practice and to fulfill our ISO 9001 requirements, we needed to have them calibrated. Siglent lists Transcat as your calibration partner in the US. ¾ of the units failed calibration and Transcat was unable to adjust them to be in tolerance (more on this below) and the 4th one barely passed. For equipment that still should be well with in expected service life this is concerning. I’m hesitant to put the remaining unit into service because I see it as likely to drift out of tolerance within the calibration interval, creating a quality management issue. Given the scope of this, it also casts doubt on whether Siglent should be considered in future equipment purchases.When we sent these into Transcat for calibration, all of them failed and Transcat noted that they were unable to adjust them and they were effectively scrap now. I found out that the ability to adjust calibration is a relatively new feature, only added in 2023 with the 1.01.01.27R2 firmware. This Is quite surprising to me, the ability to adjust calibration outside of the factory seems like it should be a given, and not a feature that you should have to check on. Transcat was unaware of this feature as well and when the units failed calibration they suggested scrapping them. They mentioned that it is common to tell customers this. Since Transcat will not update the FW on units in for cal (quite reasonably) I went to their cal lab and updated the FW and they attempted calibration and adjustment again. Adjustment was attempted but they could not bring them into tolerance. Given their status as Siglent’s named calibration partner, the fact that they did not know that this equipment was adjustable, suggests that Siglent is not keeping them informed as to capability and best practice.A second part of this issue is that if such a high proportion of equipment becomes useless in such a short period that there is likely a quality or design problem with these DMMs. Are there known quality issue with units of this vintage? Since most of these units were in storage it’s not possible to know when they went out of cal."

author: tautech
author_rank: Super Contributor
timestamp: March 18, 2025, 08:05:41 pm
content: Quote from: EricG on March 18, 2025, 06:38:05 pmSuggesting they are adjusting units manually so don't get a Fluke calibrator output.They don't need OEM script to setup a calibrator for automated Cal checks.....only the knowledge of how to write one and the accuracy specs from the datasheet.QuoteDo you still have the OEM Cal sheets ? Check them for clues.....Are they consecutive SN#'s ?There is a very small possibility the OEM Cal was wrong due to expired Cal equipment.....thinking out loud....Interested in NA HQ response.

author: bdunham7
author_rank: Super Contributor
timestamp: March 18, 2025, 08:24:16 pm
content: Quote from: EricG on March 18, 2025, 06:38:05 pmThat seems very odd to me. What particular service did you request (ISO17025, Z540 w/ data, etc?) I haven't used Transcat, but typically the lowest service I've been offered by others (Z540 w/ OOT data only or something like that) will provide at least the as-found data for any range found to be out of spec. You need that in case review and/or remediation is needed due to the out-of-tolerance condition. In your case that obviously isn't an issue.It's mind boggling that the SOP would be to scrap these meters because they are not only non-repairable but also non-adjustable. I wonder where the scrapped units go? I haven't seen them show up on eBay as "pulled from a working environment".

author: EricG
author_rank: Contributor
timestamp: March 18, 2025, 10:01:46 pm
content: Quote from: EricG on March 18, 2025, 06:38:05 pmI was wrong about this, when I picked them up, they gave me complete data. I'll see if i can dig up the original paperwork for theseQuote from: tautech on March 18, 2025, 08:05:41 pmthey are all within ~400 of each otherif Siglent responds I'll update this post

author: bdunham7
author_rank: Super Contributor
timestamp: March 18, 2025, 10:13:47 pm
content: Quote from: EricG on March 18, 2025, 10:01:46 pmIf it is permissible, could you post the data or at least the OOT results? I'd be curious to see if they are off by an amount that should be fixable with calibration or if they're so far off that they're broken.I'm glad to hear that they provided data. I've not used them, but Transcat has a very good reputation and I hope they don't go to the dogs as some companies have.

author: EricG
author_rank: Contributor
timestamp: April 15, 2025, 08:20:40 pm
content: Quote from: bdunham7 on March 18, 2025, 10:13:47 pmIt's been a while so I thought I'd update this. After going back and forth, it has come to light that even after the firmware update, no adjustment was performed. So the data won't be useful to problem solve.I've been attempting to engage the manager of that particular lab about why and how this broke down and he's stopped returning email. I'm too busy to keep trying to problem solve on this, but this has been very, very disappointing.I've been in contact with Siglent NA I wont reproduce the full emails here, but this is the most relevant quote:"I appreciate the response. I will work on them having better information and using it better. They contact us all the time and request quotes for their customers. We have several instruments in house now that went to transcat first, had an issue, and are getting an adjustment at our facility."So Siglent is at least paying lip service to make this better. they also mentioned that they have been working more with Trescal lately. I've gotten an RMA from Siglent to ship these back to Ohio to be adjusted.

author: bdunham7
author_rank: Super Contributor
timestamp: April 15, 2025, 09:00:28 pm
content: Quote from: EricG on April 15, 2025, 08:20:40 pmThanks for the update.