EEVblog #549 - Rigol DP832 Lab Power Supply Followup - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: November 18, 2013, 11:39:16 pm
content: An update on the Rigol DP832 lab power supply fix.

author: dr.diesel
author_rank: Super Contributor
timestamp: November 19, 2013, 12:24:25 am
content: Quote from: EEVblog on November 18, 2013, 11:39:16 pmIMO,

author: Andy Watson
author_rank: Super Contributor
timestamp: November 19, 2013, 01:21:31 am
content: Quote from: dr.diesel on November 19, 2013, 12:24:25 am+1I'm still not convinced about this design.So, they've fixed the over heating problem. This issue shouldn't have made it off the drawing board, how did it get through testing and development?Ditto the software bug - didn't they bother to test this design before putting it into production?"Precision" ? Where? This design doesn't have proper sense terminals. As you've just demonstrated in the video, it's easy to lose 20mV down a few cm of wire when you start pushing current through it - that's twice the claimed basic resolution! It makes a mockery of the 90 bucks you paid to check that the 1mV software switch worked.

author: RupertGo
author_rank: Regular Contributor
timestamp: November 19, 2013, 01:53:47 am
content: Is there a cap missing on the new board? When you have them side by side at around 7 minutes, there are two small electrolytics just to the right and above the three main caps on the old board, but I can see only one on the new. There is some odd perspective difference, in that a lot of the components visible on the new board to the immediate right of the big heatsink are almost entirely hidden on the old, but I don't think that explains the cap.

author: centon1
author_rank: Unknown
timestamp: November 19, 2013, 02:29:52 am
content: After cancelling my original unit and waiting for the latest revision of the board I ended up with a DP832A board V02.10 dated 2013-03-26, with the the 'short' black anodized heat sink.As Dave encourages I opened it up. I lifted the warranty sticker which had already been lifted on one side by whom ever upgraded it to the 'latest?'Once in for the penny I opted to replace the heat sink with a much larger one mounted on stand-offs fastened to the side and re-located the LM317 from the board to it similar to an earlier post in the forum.For me as a 'hobbyist' even with its shortfalls it has much more than I may require and for the cost of the DP832 I think it is a great deal.So I am happy.I could see how 'Lab' procurements & installations might be 'upset' if the higher priced units are based on the same design though.

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 03:23:32 am
content: Quote from: Andy Watson on November 19, 2013, 01:21:31 amThe unit easily meets in specs when used in the normal ground return mode.Yes, I don't like it any more than you do, but it is far from being a mockery, or useless. I now know the limitation and can avoid that if I require the precision.

author: jwm
author_rank: Regular Contributor
timestamp: November 19, 2013, 03:38:43 am
content: Does that mean that the entire return current when using the "wrong" jack is going through the sense wire? Is it of sufficient gauge to handle that without issue? usually sense wires are not very thick.It doesn't seem that unusual of a case to come up in practice as I often use my current supply to give +12 and +5 to the same device that share a common ground with some pretty beefy current going through the 12V line, I'd hate to think I could blow an internal sense wire by choosing the wrong ground plug.

author: Co6aka
author_rank: Unknown
timestamp: November 19, 2013, 04:21:46 am
content: Every "multiple output" PS I've ever used has had completely independent/isolated returns ("the black binding post") such that the outputs could be wired in series. I have and have used split ("bipolar" or "+/-" or whatever you wanna call 'em) supplies that have a common return with positive-referenced and negative referenced outputs. But this DP832 is just plain weird.AFAIC, that 5V output is NOT a third "multiple" output; it's a "split" output with the second...(Me smell chop phooey!) And, the true test of a "multiple output" PS is if its outputs can all be wired in series. So me no buy DP832!For V3.0, fix the returns, and make the "5V" output adjustable and/or with presets (1.8V, 3.3V, etc.)

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 04:37:27 am
content: Quote from: Co6aka on November 19, 2013, 04:21:46 amIt's not uncommon at all to have supplies with a shared common output like this. Especially a lower voltage rail like this one uses. It's a design/cost tradeoff.

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 04:38:34 am
content: Quote from: Co6aka on November 19, 2013, 04:21:46 amThe 5V outputisadjustable.

author: Co6aka
author_rank: Unknown
timestamp: November 19, 2013, 05:05:28 am
content: Quote from: EEVblog on November 19, 2013, 04:37:27 amI have a couple, but they're "split supplies" not "multiple output supplies." (Maybe I'm "spoiled" in the PS department? Anyway...)Quote from: EEVblog on November 19, 2013, 04:38:34 amJust checkin' to see if you paytention...(I gotta go crash... It's bloody midnight already!)Cheers!

author: Bored@Work
author_rank: Super Contributor
timestamp: November 19, 2013, 06:19:30 am
content: Quote from: RupertGo on November 19, 2013, 01:53:47 amYes, they removed one smaller cap.Edit:Regarding that current sensing in the ground connection, shame on Rigol. Every serious article about power supply design tells you not to do it on the ground connection, unless the channel is completely isolated. With that current sensing their claim to a precision power supply is just hogwash.

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 07:56:52 am
content: Quote from: Bored@Work on November 19, 2013, 06:19:30 amOnlyfor the usage case demonstrated. Otherwise itisa precision supply and meets its spec.So in the 4 possible connection usage cases:1) Single supply = meets precision spec2) Dual isolated supply = meets precision spec3) Dual isolated + 3rd channel (separate return grounding) = meets precision spec4) Dual isolated + 3rd channel (shared return ground) = may not meet it's precision spec (depending upon output current)

author: BravoV
author_rank: Super Contributor
timestamp: November 19, 2013, 08:20:12 am
content: Quote from: EEVblog on November 19, 2013, 07:56:52 amI guess Rigol also needs to update their advertising/brochure with a small footnote ...."Specification on the precision is not guaranteed and not applicable at certain connection"

author: rs20
author_rank: Super Contributor
timestamp: November 19, 2013, 08:52:40 am
content: Quote from: Bored@Work on November 19, 2013, 06:19:30 amExcept putting the sense resistors low here has caused no problem, and nor would I expect it to. It'd work just fine if they strongly tied the two common terminals together, and just had one voltage sense wire sampling the potential at this "one true ground". The thing that I find really interesting and original (to my newbie eyes) about this schematic is that CH2 and CH3 are completely isolated, except for the one connected ground sense point (let's just pretend they commoned them properly, not via sense wires). In particular, they have completely separate coils on the main transformer, separate rectifiers, etc etc, all the way out to the outputs,and all the way back again. That makes the location of the current sense resistors completely irrelevant according to your basic Kirchoff's Voltage Law. Rigol just put them low because it's easier to measure there.I'm a bit tired and what I wrote above might not make sense, but let's at least agree on this point:ifthey moved the current sense resistors to the high side, but left the messed up commoning-via-sense-wires, then the voltage error with "incorrect connections" would still exist. Nothing to do with that problem at all.

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 08:59:26 am
content: Quote from: rs20 on November 19, 2013, 08:52:40 amIndeed, the effect of which I showed in the video.I'll probably mod my own unit to fix that.

author: RobB
author_rank: Contributor
timestamp: November 19, 2013, 09:25:59 am
content: You are going soft Dave, this is a lazy Claytons fix. As you said the correct solution would have been to reduce the voltage coming from the tranny. I guess Rigol already have a stock of trannies they need to shift. IMHO there is still far too much power going into heating the lab. As you would say, you can fly to the moon on a few hundred milliwatts. Have you considered adding a contra winding the secondary to reduce the tranny output voltage? Yes it's a dirty hack but an effective hack all the same.

author: akanowitz
author_rank: Contributor
timestamp: November 19, 2013, 09:32:00 am
content: Well have to say, it's looking more attractive every day, but I do not like the round keypad.Al

author: rs20
author_rank: Super Contributor
timestamp: November 19, 2013, 09:35:52 am
content: Quote from: RobB on November 19, 2013, 09:25:59 amNah bro, add contra windings to theprimary!! Thenallof the secondary side circuitry will think it's in the USA(modulo frequency)

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 10:17:32 am
content: Quote from: RobB on November 19, 2013, 09:25:59 amThere also may be a margin issue on worldwide voltages at play, perhaps there isn't much to be gained here. I have not run the numbers...QuoteI agree, but this is a linear lab supply, perhaps the most inefficient bit of gear in any lab. So pissing away a few watts here isn't a big deal.QuoteI'm not that fussed to bother with doing that.

author: woox2k
author_rank: Regular Contributor
timestamp: November 19, 2013, 10:51:04 am
content: Hmm considering that so far all people have got black anodized heatsinks on their PSU, would it be possible that they just put in custom (much larger) heatsink just for you?

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 11:55:11 am
content: Quote from: woox2k on November 19, 2013, 10:51:04 amNope. All the boards shipped to Emona had that larger heatsink.

author: dr.diesel
author_rank: Super Contributor
timestamp: November 19, 2013, 12:01:10 pm
content: Don't ask me how, but I've got a couple pictures of Rigol's newest power supply, code named the DP92:

author: woox2k
author_rank: Regular Contributor
timestamp: November 19, 2013, 01:32:09 pm
content: Quote from: dr.diesel on November 19, 2013, 12:01:10 pmI would have guessed they would just use some water cooling on that next time.But seriously talking how can they fail 2 times in a row with such... quite easy task. Okay they got it wrong the first time around... no big deal, they fixed it and then it still wasn't enough and they had to fix the fix. (Reminds me one of Dave's teardowns where he found bodges on bodges)Who would have guessed that they fail to calculate the size requirement for that heatsink, twice.

author: madires
author_rank: Super Contributor
timestamp: November 19, 2013, 02:15:16 pm
content: Any news on the reset and the power-on (voltage spikes while output is disabled) issues?

author: Cdngreybeard
author_rank: Contributor
timestamp: November 19, 2013, 02:27:27 pm
content: I checked my replacement DP832A and it still has the power on voltage spikes. My question to theForum is, do your other power supplies also exhibit power on spikes? I own a Hameg triple power supply that also shows power on spikes.

author: sprocket
author_rank: Regular Contributor
timestamp: November 19, 2013, 06:10:40 pm
content: Some times I really wonder.Why do some people insist on a 300dollar rigol PSU to be at the same high standard as a +1300 dollar agilent PSU?Sure this PSU had a bad design flaw. BUT THEY FIXED IT. Many companies wouldn't give a flying toss about it, sweep it under the rug and fix it on a later board revision, and just the fact that rigol have acknowledged this design fault and fixed it, proves to me they are serious about becoming a reputable brand company, and not just the regular copy-paste knock off shit products that constitutes 90% of everything that comes out of china. Agilent, Tektronix, lecoy etc. etc. needs to keep an serious eye out for rigol. I remember when I was a kid in the 80's when electrics that came out of Korea and Taiwan was utter garbage, I dont think any one thinks that any more.I for one had no problem what so ever in buying the rigol DP832 after they changed the lay out for the LM317. Sure it has a few quirks you probably wouldn't see in a +1300 dollar agilent PSU, but for hobbyist use and even for most small companies, schools and universities a PSU like this is a no brainer. There is nothing on the marked that I have seen that gives you this much bang for the buck as this PSU does.

author: Unknown
author_rank: Unknown
timestamp: November 19, 2013, 06:30:43 pm
content: There's no indication that Rigol would have fixed the existing instruments if Dave didn't complain about them publicly. The old supplies were still in the distribution channels, even though the flaw appeared to have been discovered at Rigol. So it seems that they would also have swept it under the rug and silently released a new version if not for Dave. From the forums it seems that communication about replacement of existing power supplies is still quite poor. Other forum users reporting issues (DG1022 software support, some DM3068 issue) have generally been ignored or brushed off. Korad also fixed their power supplies after Dave's damning review. I think this is more a matter of the marketing department figuring that Dave complaining about their product is bad publicity than genuine customer service.People often consider the new Rigol scopes to be close to or even in the same league as the Agilent scopes. This is clearly not the case for power supplies, although they might offer decent bang/buck for hobbyists.

author: bronson
author_rank: Regular Contributor
timestamp: November 19, 2013, 06:31:58 pm
content: I love how Dave wonders "is that hot?" and reaches right in and grabs the heat sink. You'd think he'd know better by now. I know I've done that a bunch... "hm, is current flowing in thYEAOUCHHH!! Yes. Yes, it is. BRB bandaid."I guess there's still hope for me. I did finally learn that about catching falling soldering irons.

author: Jon86
author_rank: Frequent Contributor
timestamp: November 19, 2013, 06:37:57 pm
content: What really grinds my gears is all that output capacitance. Imagine if you had something that you were running on constant current at 10mA, then you disconnect it and connect it again, and all that cap just entirely discharges into the load...

author: Unknown
author_rank: Unknown
timestamp: November 19, 2013, 06:47:42 pm
content: That's actually pretty standard and something to be aware of in all bench supplies, although well designed power supplies tend to be stable and have reasonable noise levels with smaller output caps. Does anyone remember the capacitance from the teardown or calculated it using I/C=dV/dt? I believe that TTi manuals do a good job of explaining this issue.

author: robrenz
author_rank: Super Contributor
timestamp: November 19, 2013, 06:53:51 pm
content: That is a 2 edged sword, what about full current transient response without the output cap? Some old hp supplies have the output cap connected thru rear terminal straps so you can unstrap the cap when you don't want it.

author: sync
author_rank: Frequent Contributor
timestamp: November 19, 2013, 07:23:04 pm
content: Quote from: Jon86 on November 19, 2013, 06:37:57 pmUse a constant current source then.

author: Unknown
author_rank: Unknown
timestamp: November 19, 2013, 08:00:25 pm
content: A fast regulation loop with fast settling times can have good transient response without huge caps. Bob Pease published the design of a power supply without any caps on the output for this purpose. The basic problem is that a good bench supply is a voltage and a current source in one. An ideal voltage source has a zero output impedance, so caps improve the voltage source by reducing the output impedance. An ideal current source has an infinite output impedance, so caps degrade the current source. Most bench supplies, especially the cheap ones, are better voltage sources than current sources.

author: jahonen
author_rank: Super Contributor
timestamp: November 19, 2013, 08:37:41 pm
content: I can't understand why it is so difficult to do a proper fix for such a simple issue; an obvious one is that if the output voltage goes just into MCU & mostly digital stuff, then why not just put a switch-mode regulator and be done with it. Instead of putting that enormous heatsink. I also noticed that there are traces running just below the heat sink, I can't see if there are any free space between the PCB traces and the heat sink, but I afraid that only insulator between those traces and heat sink is just the solder mask. If that is the case, it is only matter of time when solder mask gives up and heat sink produces a short in those traces. Solder mask should not be used as an electrical insulator.I can understand that the efficiency does not matter, but in this case it causes components to run unnecessarily hot. And regarding to potential EMI effects, I think that they are quite often easier to take care than the heat problems if you take the time to think about it. Besides, i.MX CPU already contains an internal switcher (I don't believe that they run it with internal LDO).Regards,Janne

author: sprocket
author_rank: Regular Contributor
timestamp: November 19, 2013, 08:52:19 pm
content: yea well. SMPS PSU have their use. But they also have downsides, so depending on your application you have to choose. I know a liniar is not very efficient, but I don't care, I want some thing that is 100% noise free.One of the places I worked when I was in the army, we gave up on using SMPS pus to drive the VHF and HF radios when we ran tests on them. All the SMPS based PSU's we had simply put out to much noise for us to actually make decent testing on the radio's. One particular Agilent SMPS psu thats actually still in production totally blanked out the radios aroudn the 42-43MHz range. So we dusted off our old liniar PSU's and voila problems solved.

author: EEVblog
author_rank: Unknown
timestamp: November 19, 2013, 08:52:40 pm
content: Quote from: woox2k on November 19, 2013, 01:32:09 pmYes, it's pretty silly.The first time they realised it themselves (or had someone else find it?) and changed from the small one to the larger black anodised one. Then due to my video they doubled the size again with the same footprint.

author: jahonen
author_rank: Super Contributor
timestamp: November 19, 2013, 09:01:50 pm
content: Quote from: sprocket on November 19, 2013, 08:52:19 pmBut then, the whole thing must be considered as a whole, not just the regulator that powers the processor. There is a i.MX processor running on 100's of MHz along with an internal switching regulator, DDR memory and wide parallel bus going into LCD, I'd think that is already quite far from 100% noise free analog stuff anyway. Small switch-mode regulator doesn't change EMI properties that much anymore. It would be a different thing if there weren't any digital electronics in that thing.Regards,Janne

author: sprocket
author_rank: Regular Contributor
timestamp: November 19, 2013, 09:19:58 pm
content: Quote from: jahonen on November 19, 2013, 09:01:50 pmgranted, MCU's are obviously not "noise free", but MCU's dont radiate any thing of significance, not in the real life cases that I have delt with any ways. Where as a 30amp agilent switcher blanked out an entire work shop. And bare in mind this agilent unit is still being made if I recall correct.

author: ZeroAviation
author_rank: Contributor
timestamp: November 20, 2013, 12:08:39 am
content: Quote from: EEVblog on November 19, 2013, 08:52:40 pmSorry if I missed this answer somewhere. I did read all of this thread.Is the larger black anodised one still ok? I measured 63C at 25C ambient on the side of the heat sink with the fins. It was powered on for about 20 minutes. I should also mention it was with the case on, I stuck my thermocouple through the holes.Thanks!-Matt

author: Rigby
author_rank: Super Contributor
timestamp: November 20, 2013, 02:36:22 pm
content: Quote from: ZeroAviation on November 20, 2013, 12:08:39 amhttp://www.fairchildsemi.com/ds/LM/LM317.pdfIf I remember from the video, that LM317 is dissipating 7W. According to the datasheet, if I'm reading it correctly, that means the physical package will be 35°C cooler than the junction temperature. The maximum for the junction is 125°C, so take your 63°C + 25°C to get the junction temp = 88°C. That's well under 125°C, so you're good.PLEASE correct me on any of this if I'm wrong. I'm still very much a newbie to this.EDIT: oh, you're measuring the heatsink. Measure the LM317 itself to get a better reading.

author: Zbig
author_rank: Frequent Contributor
timestamp: November 20, 2013, 03:24:26 pm
content: Quote from: Cdngreybeard on November 19, 2013, 02:27:27 pmI have a Siglent SPD3303S. It had no power-on spikes on neither of its two main 0-30V channels 1 or 2 but exhibited a "hard power-on" (with a mains switch, not with a soft-enable switch) spike on auxiliary 2.5V/3.3V/5V channel 3. User FrankBuss of this forum has worked with the support and they've provided afixself-repair solution which Frank described here:https://www.eevblog.com/forum/testgear/siglent-spd3303d-review/msg299246/#msg299246Reportedly, they've revised the PCB already.

author: Unknown
author_rank: Unknown
timestamp: November 20, 2013, 04:11:00 pm
content: Too many issues on this thing, don't worth buying.

author: Rigby
author_rank: Super Contributor
timestamp: November 20, 2013, 04:19:12 pm
content: Quote from: Oracle on November 20, 2013, 04:11:00 pmI don't think that's true at all. Every bit of test gear will have something that any given user won't like.Just be aware of the issues your equipment has and you'll be fine.I'll be buying one of these soon. I am aware of the issues, and given the price and features, this is a pretty awesome power supply.

author: madires
author_rank: Super Contributor
timestamp: November 21, 2013, 02:46:24 pm
content: Quote from: Rigby on November 20, 2013, 04:19:12 pmYep, that's the point! As long as there's no real show stopper, the price is fine and you know about limitations and smaller issues you can buy it without any worries. If you've got a delicate circuit connect it to the PSU after powering it on. Also follow the wiring recommendation for ch2 and ch3 regarding the interconnected ground and current sensing. I would be more concerned about the reset issue if it's not fixed by fixing the voltage regulator overheating.

author: Fabio
author_rank: Newbie
timestamp: November 21, 2013, 06:20:34 pm
content: Quote from: madires on November 19, 2013, 02:15:16 pmI'm also curious about the reset issue... Has it been fixed with the new revision?

author: Rigby
author_rank: Super Contributor
timestamp: November 21, 2013, 07:18:05 pm
content: Quote from: Fabio on November 21, 2013, 06:20:34 pmYes, the spontaneous reset is fixed. The heatsink was the remedy for that. The LM317 was overheating, shutting down, causing the scope to reboot. The larger heatsink prevents overheating, therefore the regulator does not shut down, therefore the logic whose voltage is supplied by that regulator does not reset.All of this information is in the videos.

author: jrgandara
author_rank: Contributor
timestamp: November 23, 2013, 11:35:59 am
content: I´m looking for a new PS for my bench and, in general, I liked this DP832. Obviously those circular keys are ridiculous, but the features and the display looks very nice. But 42 cm deep is too much for my bench. Why so deep?Two questions:Any other option with similar features and maximum 32cm deep?What is the model or where to buy this temperature sensor Dave uses in his Fluke? I have one Fluke 187 and would be nice to have this probe.Thank you!

author: dr.diesel
author_rank: Super Contributor
timestamp: November 23, 2013, 11:44:21 am
content: Quote from: jrgandara on November 23, 2013, 11:35:59 amI bought this mostly because of it's shallow depth:https://www.eevblog.com/forum/testgear/gw-instek-gpd-4303s-4-channel-ps-review/

author: Rigby
author_rank: Super Contributor
timestamp: November 23, 2013, 02:08:33 pm
content: Quote from: jrgandara on November 23, 2013, 11:35:59 amIt's a simple K-type thermocouple with a multimeter adapter.http://www.adafruit.com/products/270?gclid=CMDdgMyK-7oCFcZDMgodqlIAsQ

author: Unknown
author_rank: Unknown
timestamp: November 23, 2013, 02:10:53 pm
content: Note that you either need one terminated in banana jacks or a type K to banana jack adapter to use the 187's built-in temperature function.

author: olsenn
author_rank: Frequent Contributor
timestamp: November 23, 2013, 04:23:37 pm
content: I contacted Rigol about getting the new top board replaced, but they insist I have to send in my full DP832 for them to fix it, and they won't just send me a new board like they did for Dave. What a bummer -- it's not worth all the shipping and customs fees, plus waiting to get my PSU back.Has the overheating issue bricked anyone's DP832 yet? It it's only left on for an hour or two at a time, is it likely that the board will fail in short time (I'm in North America if that makes a difference)? Would fixing it be as simple as putting a new 317 in (or will it break down the caps and surrounding circuitry as well)?

author: jrgandara
author_rank: Contributor
timestamp: November 23, 2013, 06:42:16 pm
content: Thank you guys for all info!The Insteak PS looks nice, but no separated on/off switches is a no no for me. I liked a lot the features and interface of the Rigol 832, but it is damn deep! I still think if I can manage to live with this size, but for now I will wait.Some time ago I made a product and the heat of the 7805 is way too much to low 12V to 5V. So I replaced with a LM2575-5. This IC is over 90% of efficiency and worked cool. Why Rigol prefer heat in a lab PS?

author: Zbig
author_rank: Frequent Contributor
timestamp: November 23, 2013, 09:23:39 pm
content: Quote from: jrgandara on November 23, 2013, 11:35:59 amAt the risk of sounding like a broken record (or scratched CD, for all the youngsters), yes, there actually is. It's called Siglent SPD3303D or SPD3303S, and it's about 30 cm deep. And no, contrary to the popular belief, I don't work for them

author: Rigby
author_rank: Super Contributor
timestamp: January 20, 2014, 04:07:55 am
content: Quote from: robrenz on November 19, 2013, 06:53:51 pmThe rear strapping configuration of those old HPs is possibly their most under-used and under-rated feature. The ability to slave supplies and configure them this way is excellent, IMHO.

author: tailwheel
author_rank: Newbie
timestamp: March 04, 2014, 04:53:07 am
content: I've newly acquired a DP832A power supply. After watching Daves video, I was curious about the rampup time on the voltage with current limit set low.Doing what Dave did - set voltage to 32V and current to 1mA, I compared CH1 and CH2 ramp up times from 0V to 32V...CH1 takes < 5 secondsCH2 takes 17 secondsThe 17 second time seems to agree with what I was seeing in the video.The large discrepancy in ramp up times between CH1 and CH2 doesn't seem right to me.Coincidentally, I am also unable to calibrate CH1 VADC (output voltage reading) to be within the ballpark of spec. Although I was foolish enough to try the calibration using a Fluke 87V, I am able to get the calibration on CH2 to within at least a few hundred mV. Of course, this is still well out of spec., and I guess expected given I'm dong the cal with my 87V, but the difference in the results between CH1 and CH2 is concerning.So to my eyes, there seems to be an issue with CH1 on this power supply.Any thoughts on this from anyone? Much appreciated.

author: Rigby
author_rank: Super Contributor
timestamp: March 04, 2014, 05:00:00 am
content: why are you calibrating a new supply? don't dink with calibration unless you know what you are doing and you have the proper equipment.somewhere I believe there are calibration instructions for the dp832. if you don't have them, find them, and if you can get an inexpensive voltage standard on eBay (they can be had) you might be able to make something happen with it, such as finding out how far your 87V is out.

author: tailwheel
author_rank: Newbie
timestamp: March 04, 2014, 05:25:20 am
content: Quote from: Rigby on March 04, 2014, 05:00:00 amWell, yes, lesson learned. CH1 seemed slightly out of cal so I tried. I do have the documentation on calibration procedure and I willfully ignored the recommendation to use a 6 1/2 digit DMM.But the calibration is really beside the point of my post. I am concerned about the difference btwn CH1 and CH2 regarding the ramp up test I described. Seems concerning.

author: Rigby
author_rank: Super Contributor
timestamp: March 04, 2014, 06:28:49 am
content: try ch3, too.I'm wondering if ch2 and ch3 being common has anything to do with it.besides, if your calibration is out, you can't really trust anything about it until it is calibrated again. it might think it is sending 1ma into ch1 but actually be sending 3ma. if cal is out, you cannot trust those times.

author: tailwheel
author_rank: Newbie
timestamp: March 06, 2014, 03:25:28 am
content: Quote from: Rigby on March 04, 2014, 06:28:49 amfollowup... First, I'm not very smart, and second, you are correct, current limit on ch1 is off by 2-3 ma. I set the limit to 1mA, it actually limits to 3-4ma. I suppose that's within the spec for that. Don't know if it has anything to do with what I did. Thanks for the feedback.

author: stormbr
author_rank: Regular Contributor
timestamp: March 17, 2014, 10:52:38 am
content: Hi all,Sorry for repeat my problem, but i lost two channels (2 and 3) of my dp832, after that i install the new top board (version 2.01).I can calibrate just the channel 1 and him works fine, i have sure that follow all steps recommended by rigol correctly.I updated the firmware and bootloader of version 1.03 to 1.09.Somebody have any idea to help me solve this problem ?Thanks.

author: ted572
author_rank: Frequent Contributor
timestamp: September 16, 2014, 12:44:57 am
content: Quote from: stormbr on March 17, 2014, 10:52:38 amHave you seen the new Rigol 2014 Calibration Guide attached here?

author: T2
author_rank: Newbie
timestamp: May 03, 2020, 08:55:03 am
content: For those observing intermittent reboots of their RIGOL DP832 (as Dave has observed as well), check this thread:https://www.eevblog.com/forum/testgear/rigol-dp832-random-reboots/25/It may be relatedindirectlyto overheating the regulator (probably increases the chance to trigger it), but IMHO it's simply bad/wrong design of the digital power supply circuitry of the embedded controller.@EEVBlog: might be something to look into?/Thomas