Rigol DP832 still shipping faulty (I think) - Page 1
Forum section: electronics / testgear

author: papo
author_rank: Regular Contributor
timestamp: July 28, 2014, 08:52:17 am
content: HelloI asked thisover on redditalready but I only had moderate feedback there, hence I'm trying it here now.The unit was ordered through an authorized dealer and was delivered 3 days ago. The first problem I have is that the calibration certificate is 13 months old. While I don't really care too much about that because I don't have my private home-lab gear calibrated regularly, this really strikes me as unusual. If I had this ordered for work, I'd feel tempted to return it/ask for a current cal cert. This unit must be so old that it originally suffered from the thermal issue discussed on Dave's blog -- I can see the large, silver heatsink from the side. As far as I know, these were retro-fitted after June 2013, which means that even after the modification, nobody bothered to re-take the calibration. As I said, that alone would be a minor issue but I'm still wondering whether I should be expecting a current certificate or not.That's question 1.Second, I don't think the unit is within cal. The datasheet specifies an annual current programming accuracy of 0.2% + 10 mA and an annual current readback accuracy of 0.15% + 5 mA. If I hook up an amp-meter to channel 1 directly or in series with a resistor and set the supply to 9 mA, I measure 34 mA and the readback is 0.08 A. The readback issue is well known and fixed in later firmware revisions. This was shipped with 00.01.04 -- a very old firmware revision with multiple arguably serious bugs; they didn't bother to upgrade the firmware. If I program the current to 10 mA, the readback is "correct", but I still have the 25 mA offset. I don't think this instrument is within spec.Question 2 is on whether I am wrong on this.(The other channels are fine, by the way).I'll call the dealer later today and respectfully complain, but before I do that I'd like to know what others think.Best regards and thank youMatt

author: Orange
author_rank: Frequent Contributor
timestamp: July 28, 2014, 09:45:32 am
content: Quote from: papo on July 28, 2014, 08:52:17 amSounds like you got an New Old Stock unit, but more important to know what the dealers name is, so that others avoid this dealer

author: idpromnut
author_rank: Unknown
timestamp: July 28, 2014, 02:55:20 pm
content: Quote from: Orange on July 28, 2014, 09:45:32 amI would contact the dealer as the OP is intending and see if they will resolve it without hassle before dragging their name through the mud.

author: papo
author_rank: Regular Contributor
timestamp: July 28, 2014, 03:45:26 pm
content: HelloQuote from: Orange on July 28, 2014, 09:45:32 amYeah I promise to tell who the dealer is as soon as I get a reply from them. Thereason I'm not doing it right now is two-fold:First, I don't want to call them out publically in the event that I am wrong. IfI were not confident in making a simple current measurement, I should probablylook for another job, but still. From your reply I get that something iswrong as I suspected.Second, seeing how they react is more important to me than them shipping afaulty unit. From what I described in my initial post, I can't possibly see howa simple mistake can lead to this but still, I'd like to see how they reactfirst. You can expect a progress report here and a wrap-up on my youtubechannel. For now, I called them and while the lady on the phone was super nice,she had absolutely no clue what I was talking about, said so right upfront andsuggested to send an email to the guy who is supposed to know about this stuff.I'm not sure whether that is supposed to instill confidence but let's see whatthey have to say.Best regards and thanksMatt

author: papo
author_rank: Regular Contributor
timestamp: July 28, 2014, 03:46:23 pm
content: HelloQuote from: idpromnut on July 28, 2014, 02:55:20 pmI fully agree, that's why I didn't post it yet (see my other comment).Regards and thanksMatt

author: papo
author_rank: Regular Contributor
timestamp: July 28, 2014, 05:28:53 pm
content: Quote from: mojo-chan on July 28, 2014, 03:47:47 pmInteresting... I've seen this happen with the really expensive gear, but then a proper service manual with calibration protocols was available. In the case of this Rigol supply, this does not seem to be readily available and the manual states that "Calibration by users themselves is not recommended". I'm not sure whether I should interpret this as "the hobbyist is not supposed to do this" or "Rigol and certified cal labs are the only ones to calibrate this thing". Most likely, I have access to the gear required to perform a calibration, but I was wondering whether this should be expected. Your reply answers that, thank you for that.Quote from: mojo-chan on July 28, 2014, 03:47:47 pmCan you elaborate on that? The thread on that supply is really long but I went through all of it and I came across at least three kinds of boards: The original one with the wimpy power supply, the same board with a larger, shiny heat sink and a later revision with the electrolytics moved away from the heat sink. For sure I have a large shiny heat sink that can bee from the side... would you consider that to be broken because of potential issues with caps? I'm just wondering... By extension, I'm wondering which board I should have if everything went well and whether there is an official statement from Rigol on the recall.Thanks again and best regardsMatt

author: geekGee
author_rank: Unknown
timestamp: July 28, 2014, 11:04:25 pm
content: Quote from: geekGee on July 26, 2014, 04:05:51 amI am quoting myself from the EEVblog # 512 topic and as you can see I am having a similar issue except my board appears to be the Revision 2.0 version which has the fault the best I can tell. I can see the two capacitors with the small black heatsink behind them.I have gone through EEVblog # 512 and it sounds like you do have the updated board based on your description but here is the URL of Rigol's FAQ regarding the issue anyway.http://beyondmeasure.rigoltech.com/acton/fs/blocks/showLandingPage/a/1579/p/p-0011/t/page/fm/0I am being told from my supplier that the board in mine was replaced in the first quarter of this year in Rigol's Ohio office at which time it was recalibrated but no new certificate was issued. This sounds consistent with your experience in that no new certificate was issued assuming both were actually recalibrated.I am still dealing with my board revision issue. Needless to say, I am a little disillusioned with Rigol and/or my supplier. This may be the first and last time I buy from both.

author: papo
author_rank: Regular Contributor
timestamp: July 28, 2014, 11:26:33 pm
content: Hello and thank you for digging into this.Quote from: geekGee on July 28, 2014, 11:04:25 pmIt's in the middle of the night, but I'll take a picture tomorrow or actually even shoot the video. Looks like I'm at least a little bit better off; Dave has a video in which he shows how the shiny large heat sink can be seen from outside, through the vent holes. It is exactly as he shows in the video in my case.Quote from: geekGee on July 28, 2014, 11:04:25 pmI just checked, if I query the calibration date on the device, it gives me a date that is 3 days prior to what is written on the cal cert. I don't know whether that date is supposed to change to the date of the recalibration once it is done, but I would certainly expect it to. Which would mean that in my device, the board was swapped but not recalibrated. It is interesting that the official link you posted explicitly states that a recalibration is done after the board is swapped. Currently, this looks like they swapped the board but forgot to recalibrate. But I don't know for sure.Did you notice any offsets like the ones I described in the original post? In any case, thanks and good luck!Matt

author: geekGee
author_rank: Unknown
timestamp: July 29, 2014, 04:30:43 am
content: Quote from: papo on July 28, 2014, 11:26:33 pmSame here... the "Cal Time" on my unit is 2013-7-10 so 3 days before the certificate.Quote from: papo on July 28, 2014, 11:26:33 pmNo but really haven't done anything with it yet other than get frustrated over the old board revision.I do hope to be proven wrong and the board was replaced but based on the information in the blog and what I am seeing through the cooling holes, I suspect not.

author: Len
author_rank: Frequent Contributor
timestamp: July 29, 2014, 02:37:17 pm
content: Quote from: mojo-chan on July 28, 2014, 03:47:47 pmHPAgilentKeysight has an interesting way of handling this. At least some of their products come with a cal certificate and a separate note that says to assume it's in cal for an extra year if the initial calibration is stale.They justify that by saying that it shouldn't go out of cal while it sits in a warehouse, but I don't really buy that, mainly because it has to undergo the stress of shipping to the customer.If it's ever going to lose calibration, that's a good time to do it.

author: papo
author_rank: Regular Contributor
timestamp: July 30, 2014, 08:56:57 am
content: HelloQuote from: Len on July 29, 2014, 02:37:17 pmInteresting, that has never happened to me either, but I don't doubt what you are writing. For example, I got aHPAgilent DSOX3000 last year, I bought it pretty much 12 months ago and the cal cert was just a couple of days old.On a related note, this just took a pleasant turn: Thedealercontacted me this morning and told me that assessing what exactly is wrong would take longer than expected. Yesterday, I had sent them a detailed description of how I acquired the weird measurement, but didn't even include pictures. Hence, they offered to come by, pick up the unit (or send me stickers to return it by mail) and deliver a fresh one. I'm still not quite sure what exactly went wrong, and in an ideal world you would pick the dealer that delivers impeccable units and takes them back in the case they fail nonetheless. But if I can choose between a dealer that delivers a malfunctioning unit by mistake and goes through hoops to address the issue quickly and comfortably for the customer, and a dealer that doesn't care and claims everything is fine while it obviously is not (like the experience somebody posted in this thread), I'd clearly go with the first dealer. That said, I have to wait and see how this ends, but if they live up to what they just promised I would buy from this dealer again in the future.Best regards and thanks to everyoneMatt

author: geekGee
author_rank: Unknown
timestamp: July 30, 2014, 12:53:10 pm
content: Quote from: papo on July 30, 2014, 08:56:57 amThat's excellent!!! This could turn out to be a initially frustrating but ultimately positive experience for you.As the "somebody" you mentioned, I am still working on my issue but an engineer at Rigol has confirmed with me that my board is the "old design".

author: papo
author_rank: Regular Contributor
timestamp: July 30, 2014, 01:08:34 pm
content: HelloQuote from: geekGee on July 30, 2014, 12:53:10 pmYeah it's fairly nice indeed. Let's hope this goes as smooth as they make it look. And sorry for the "sombody", I didn't mean to be impersonal, I wrote my posting off-line while commuting and didn't bother to look up your user name. Let me know if you need pictures or anything to help you make your case, but as far as I understand the forum is full of pictures already.Best regards and thank youMatt

author: geekGee
author_rank: Unknown
timestamp: July 30, 2014, 01:27:27 pm
content: Quote from: papo on July 30, 2014, 01:08:34 pmI wasn't offended... I just take any opportunity to make a little joke even if a bad one. I assumed you were just posting in haste.Ya... I just took a screen shot from Dave's #512 video and told Rigol that this is what I am seeing through the holes. Thanks for offering.

author: papo
author_rank: Regular Contributor
timestamp: October 10, 2014, 09:00:01 am
content: OK so here's the conclusion: After I contacted the dealer, they offered a refund or swapping out the faulty unit with a new one. They told me the second option might take some time since they have to wait for Rigol to ship new units. I went for it anyway and, now have a new unit (firmware version 1.10) and am returning the old one.That wraps it up for me. It would have been great to get a working unit in the beginning, but given that I did not, the dealer's response has been great. Since I promised a video on this (hereit is) although it's fairly boring since you can see me demonstrating the issue as well as blabbering about what happened.Thanks again for all your insights and best regardsMatt