EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: papo on July 28, 2014, 08:52:17 am
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Hello
I asked this over on reddit (http://www.reddit.com/r/AskElectronics/comments/2bruur/new_rigol_dp832_out_of_cal/) already 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 you
Matt
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Hello
I asked this over on reddit (http://www.reddit.com/r/AskElectronics/comments/2bruur/new_rigol_dp832_out_of_cal/) already 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 you
Matt
Sounds like you got an New Old Stock unit, but more important to know what the dealers name is, so that others avoid this dealer
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Sounds like you got an New Old Stock unit, but more important to know what the dealers name is, so that others avoid this dealer
I 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.
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Hello
Sounds like you got an New Old Stock unit, but more important to know what the dealers name is, so that others avoid this dealer
Yeah I promise to tell who the dealer is as soon as I get a reply from them. The
reason 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. If
I were not confident in making a simple current measurement, I should probably
look for another job, but still. From your reply I get that something is
wrong as I suspected.
Second, seeing how they react is more important to me than them shipping a
faulty unit. From what I described in my initial post, I can't possibly see how
a simple mistake can lead to this but still, I'd like to see how they react
first. You can expect a progress report here and a wrap-up on my youtube
channel. 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 and
suggested 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 what
they have to say.
Best regards and thanks
Matt
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Hello
I 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.
I fully agree, that's why I didn't post it yet (see my other comment).
Regards and thanks
Matt
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It sucks for hobbyists but most companies just get their kit calibrated as soon as it arrives anyway, because policy requires all calibrated instruments to have a sticker and record.
Interesting... 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.
The big issue is that they shipped you one with a broken PCB. They should have returned all stock for replacement. You should mention who you bought it from, and the outcome if you contact them.
Can 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 regards
Matt
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Buyers beware... they are still in the sales channel.
I just received a DP832A today purchased new from an authorized source in the US and it is the "Bad Design" revision. I am especially frustrated as I asked pre-sales if the units they had in stock were the newer revisions and was assured this was the case.
It came with firmware 1.05 and the "Certificate of Calibration" is dated 13-Jul-2013 so not surprising it’s the old revision after reviewing this topic.
I purposely haven't mentioned the supplier as I haven't notified them yet and didn't want to potentially bad mouth them before they have had a chance to act on my complaint. Mistakes happen and at this stage I am more interested in how they respond.
I 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/0 (http://beyondmeasure.rigoltech.com/acton/fs/blocks/showLandingPage/a/1579/p/p-0011/t/page/fm/0)
I 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. ;D
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.
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Hello and thank you for digging into this.
I 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.
It'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.
I 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. ;D
I 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
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I 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.
Same here... the "Cal Time" on my unit is 2013-7-10 so 3 days before the certificate.
Did you notice any offsets like the ones I described in the original post?
No 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.
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It is common for kit to come with out of date calibration certificates, and even be out of calibration.
HP Agilent Keysight 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. :-DMM 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. :bullshit: If it's ever going to lose calibration, that's a good time to do it.
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Hello
HP Agilent Keysight 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.
Interesting, that has never happened to me either, but I don't doubt what you are writing. For example, I got a HP Agilent 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: The dealer (http://electronic.maxdata.ch/) contacted 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 everyone
Matt
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On a related note, this just took a pleasant turn: The dealer (http://electronic.maxdata.ch/) contacted 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.
That'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".
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Hello
That'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".
Yeah 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 you
Matt
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Hello
That'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".
Yeah 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 you
Matt
I 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.
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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 (here (http://youtu.be/fuze5sY-UfI) it 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 regards
Matt