NEW DP832 - 33V !!! voltage when powering on... - Page 1
Forum section: electronics / testgear

author: alank2
author_rank: Super Contributor
timestamp: June 28, 2020, 12:44:28 am
content: I got this yesterday. CH1 is outputting a voltage as soon as I flip the switch while the rigol logo comes up. It was connected to a 5V project and I think it was outputting 6V, then 7V. I disconnected it and connecting a meter it outputs 33V at power on. Any thoughts? I can try to reflash the latest firmware. My other DP832 does not do this.Updated firmware/analog board update. no change. During power up channel 1 goes to 33V for a few seconds...

author: maginnovision
author_rank: Super Contributor
timestamp: June 28, 2020, 01:21:24 am
content: Work around it by not having anything connected or initiate a return/replacement.

author: alank2
author_rank: Super Contributor
timestamp: June 28, 2020, 01:45:25 am
content: Yep, CH2/CH3 do not do it, but I'll be calling for a replacement. I just wondered if anyone else has seen this fault before.

author: alank2
author_rank: Super Contributor
timestamp: June 28, 2020, 01:51:29 am
content: For kicks I wanted to see what it would deliver - I put a 25W 25ohm load on it and this brought the 33V down to 1.95V with 80mA delivered across the load during power on. I'll get a replacement.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: June 28, 2020, 04:27:55 pm
content: Glad i did not buy this garbage, they did advice me to buy it.

author: 2N3055
author_rank: Super Contributor
timestamp: June 28, 2020, 04:41:07 pm
content: Quote from: Jan Audio on June 28, 2020, 04:27:55 pmDon't be an ass.. there are thousands of these out there that work just fine. He got broken one. It happens.It's not like when they made a PSU that on powerup destroyed 1500 USD development system, and after investigation it was discovered it was like that by design and they had to create new version of PSU with different suffix to fix it and recall old ones...No wait, that wasn't Rigol, it was Keysight...

author: alank2
author_rank: Super Contributor
timestamp: June 28, 2020, 05:10:29 pm
content: Good find PeDre - that is the exact issue I am having on CHA (presumably power board 1). It would be nice to figure out what the fault is so someone could fix it themselves if their unit is out of warranty, but maybe it is a defect that it either comes with or doesn't - hopefully.I really do love the DP832, this is my second one and my first one is 4 years old. I'll contact tequipment on Monday to get a replacement.

author: sequoia
author_rank: Unknown
timestamp: July 01, 2020, 12:36:53 am
content: I just got a DP832 (also from tequipment), so first thing was to test if it has this issue.... Luckily my unit doesn't have this problem.Factory calibration date appears to be from late April, so unit was manufactured relatively recently.

author: alank2
author_rank: Super Contributor
timestamp: July 01, 2020, 12:39:58 am
content: Thanks for the report -tequipment shipped me a replacement and it should be here Friday. I know the first thing I'm going to test as well!

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 01, 2020, 01:32:58 pm
content: Quote from: 2N3055 on June 28, 2020, 04:41:07 pmHappens alot in china.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 02, 2020, 04:10:14 pm
content: For one extra data point, I bought a new DP832 from TEquipment.net about a month ago; I just tested it and it doesn't have any voltage surge on Ch1 during power up.

author: alank2
author_rank: Super Contributor
timestamp: July 02, 2020, 06:18:18 pm
content: I'd check all three channels at power up to make sure! My replacement is coming tomorrow, that is the first thing I plan to test!

author: sequoia
author_rank: Unknown
timestamp: July 03, 2020, 05:32:42 am
content: I hooked up all channels to a scope and this is what I see, when powering on the DP832:

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 03, 2020, 02:24:17 pm
content: I just re-ran the test. I do get a 250 mS period of 3V on Ch1 on about 2 out of 3 power ups. Are you sure that you haven't got a x1 vs x10 setting error when you say it's 33V?This should not be happening but it's not a big enough deal for me to return the DP832.

author: aristarchus
author_rank: Regular Contributor
timestamp: July 03, 2020, 02:57:58 pm
content: Has anyone else got data on what other similarly priced PSUs do upon powerup?Eg Siglent, GWInstek, Tenma, B&K etcNever tested that since I always have the PSU disconnected and connecting it only to perform specific tasks.Having said that, I do like my DP832 as it has proven reliable and doing its job for 3 years now.

author: tom66
author_rank: Super Contributor
timestamp: July 03, 2020, 04:03:52 pm
content: IMO anything other than switch arcing and 100mV DC is unacceptable on a PSU when it turns on. My GW Instek PSP-603 has a relay isolator so no glitch happens at all when powered on. My EA-PS 2042-10B is similar, output no higher than 100mV when turning on.There are many applications where you might have a sensitive component attached to your PSU. When the output or PSU is off, the output should be zero.

author: PeteH
author_rank: Unknown
timestamp: July 03, 2020, 04:12:13 pm
content: I've seen this happen on a GW GPS4303 when you click off the physical power switch... Kicks the output...I think it's only with a certain series/parallel config (internally, with the buttons on the front of the unit)

author: NoisyBoy
author_rank: Frequent Contributor
timestamp: July 03, 2020, 06:12:59 pm
content: I tried it on a few Agilent bench and system supplies at my hobby lab:E3615A, there is no output off, so I have to set the output to zero and turn the unit on:Unit 1: 0 spike at power on, I had to turn up the voltage just to make sure everything is connected properly.Unit 2: Same as unit 1Unit 3: It got a 20mV spike that smoothly ramp down to 0 after 300ms6632A System Supply, it default to output on, but also default at 0V:0 spike at power on.6643A System Supply, it defaults to output off at power on:Unit 1: 0 spike at power on.Unit 2: 0 spike at power on.E3631A bench supply, it defaults to output off at power on at all 3 outputs:6V output: There is a -280mV voltage that lasted for 550ms+25V output: 0 spike-25V output: There is a 330mV voltage that lasted for 580msI expected the system supplies to be at a much higher standard than the bench supply, so their results is what I expected. The E3615A are my go to supplies for bench work, those are rock solid and the results bear that belief. I did learned something for the E3631A, I definitely will not leave it attached to sensitive DUTs while powering it up.Back to the Rigol, I have to think the turn-on spike is excessive, you have to be careful not to leave delicate DUTs attached to it during power up.

author: JxR
author_rank: Unknown
timestamp: July 03, 2020, 08:18:23 pm
content: Quote from: NoisyBoy on July 03, 2020, 06:12:59 pmIn certain situations not even this is adequate. For instance, if you had a quick power interruption for your entire premise. I had almost an entire year in which additional housing was being built around my location. So quick power interruptions were regularly occurring. If I was in the middle of powering a circuit, it would then receive this input spike every time the power was momentarily interrupted. I ended up having to get rid of the DP832 solely due to this issue.

author: alank2
author_rank: Super Contributor
timestamp: July 04, 2020, 12:02:04 am
content: Replacement DP832 came in today - sadly CH1 outputs 24V when powering on.I have 3 Fluke meters connected to each of the channel outputs.Everyone should be checking their DP832 outputs when turning on - clearly Rigol has a batch of ones with an issue - this is two in a row for me.

author: thm_w
author_rank: Super Contributor
timestamp: July 04, 2020, 12:06:09 am
content: Discussed here:https://www.eevblog.com/forum/testgear/is-rigol-dp832-output-voltage-spikes-when-unit-is-turned-on-an-real-problem/Quote from: NoisyBoy on July 03, 2020, 06:12:59 pmI can't think of any part that would be damaged from 330mV? Maybe you are working on some cutting edge electronics.edit: checked a DP832 here, on power on:CH1 - 3V for 250msCH2 - -400mVCH3 - -400mVCH1 is concerning, the others are not.DP832A:CH1 - 1.5V

author: NoisyBoy
author_rank: Frequent Contributor
timestamp: July 04, 2020, 01:23:17 am
content: thm_w, thanks. No, nothing ultra sensitive, just precautionary more than anything else, as I have not blown anything with any of these supplies.I hope Rigol is able to correct the issue quickly, I hope those are just manufacturing defects and not caused by design updates, 25 and 33V spikes are very high for any bench supply.

author: sequoia
author_rank: Unknown
timestamp: July 04, 2020, 05:05:09 am
content: Quote from: alank2 on July 04, 2020, 12:02:04 amThat's pretty bad luck, or Rigol has a problem.... I guess I was lucky, since mine doesn't spike over 0.5V. Something to be aware off, but I don't think I'll return power supply for that. Did you check the (factory) calibration dates for your units?

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 04, 2020, 01:50:08 pm
content: Now anyone still disagree with me ?garbage

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 04, 2020, 01:56:23 pm
content: Quote from: Jan Audio on July 04, 2020, 01:50:08 pmI disagree.

author: 2N3055
author_rank: Super Contributor
timestamp: July 04, 2020, 03:51:46 pm
content: Quote from: Jan Audio on July 04, 2020, 01:50:08 pm

author: aristarchus
author_rank: Regular Contributor
timestamp: July 04, 2020, 05:06:26 pm
content: Have not seen any oscilloscope evidence from others for similarly spec'd, 3 output, and similarly priced PSUs as said eg Siglent, GWInstek, Tenma etc.Instead reported on premium brand eg HP, Agilent, Keysight and all without any oscope verification.@alank2 can you post any oscilloscope capture of your DP832 PSUs? (and of course to have in mind @Gandalf_Sr commend regarding X1 and X10 setting mixup)For what is worth it, on CH2 and CH3 it seems that there is no issue but in general the CH1 which is the 'floating' output, exhibits that behaviour.I'm really interest to see if this is just to DP832 or it is a generic low priced PSUs issue.

author: alank2
author_rank: Super Contributor
timestamp: July 04, 2020, 06:13:45 pm
content: All of my measurements before have been a Fluke 189 connected directly to the CH1 output. Power up goes immediately to either 24V or 33V depending on which unit.The 33V unit is in the box and ready to go back, I haven't boxed the 24V one yet, so here is a capture from it. 10X probe / scope set to 10X. It has a small bump at 2.117V and then ramps up to the 24.90 V until it is fully booted. The first one did the same thing, but at 33V instead of 24V.2.117 V for 280ms24.90 V for 5.5s

author: aristarchus
author_rank: Regular Contributor
timestamp: July 04, 2020, 06:40:52 pm
content: Yep, not a good one.It looks that when the others settle after the 2V for 300msec, this one does not, goes high and stays full voltage for a really long time.And two of those came to you, its a bummer indeed.

author: alank2
author_rank: Super Contributor
timestamp: July 04, 2020, 07:33:52 pm
content: Here is a shot from my good DP832 (4 years old). It has the similar 280ms period, but if I zoom in on it, it is -230 mV which is fine.There is an instantaneous blink where it goes to -2V, but you have to zoom in to its almost max to even see it because it is so quick.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 04, 2020, 09:28:06 pm
content: My scope is running through an isolation transformer so I'm truly measuring the voltage across the DP832 - + terminals. I wonder if folks testing with a grounded scope are seeing ground transients?

author: alank2
author_rank: Super Contributor
timestamp: July 04, 2020, 09:42:03 pm
content: I got the same measurements on my Fluke 189's which are isolated.

author: tom66
author_rank: Super Contributor
timestamp: July 04, 2020, 09:44:55 pm
content: The spike you're seeing at the start is a relay or switch arcing producing high frequency wideband noise. Almost every PSU is going to show that - the reality is that it only exists (for most purposes) on your scope screen.

author: tautech
author_rank: Super Contributor
timestamp: July 06, 2020, 05:36:22 am
content: Quote from: aristarchus on July 03, 2020, 02:57:58 pmSPD3303X-E3 isolated channels......well until you connect a probe reference lead to the negative of each.Power ON....NO, repeat NO noticeable spike at mains ON as channel outputs are manually switched.All channels ON button, channels 1 and 2 set to 1V and ch3 set to 5V and triggered from.It can be seen each channel is staged to ON from the below screenshot.

author: Ctrlocti
author_rank: Regular Contributor
timestamp: July 07, 2020, 07:25:30 am
content: tautechI can't find the main SPD3303X-E thread so I'm just going to post here, is it not possible to limit the 3rd channel current output to lower than 3.2A?

author: tautech
author_rank: Super Contributor
timestamp: July 07, 2020, 07:34:36 am
content: Quote from: Ctrlocti on July 07, 2020, 07:25:30 amNo it’s not, they are fixed current and 3 switchable voltage settings for the 3rd channel.Normally you would prove a DUT or design rail was safe with ch1 or ch2 using current limiting then transfer it onto ch3.I’ll come back with a link to the thread when I get off this iPad soon........

author: Ctrlocti
author_rank: Regular Contributor
timestamp: July 07, 2020, 07:47:25 am
content: Thanks!

author: tautech
author_rank: Super Contributor
timestamp: July 07, 2020, 07:52:01 am
content: Quote from: Ctrlocti on July 07, 2020, 07:47:25 amNo worries.Try this one:https://www.eevblog.com/forum/testgear/siglent-spd3303x-e/

author: Ctrlocti
author_rank: Regular Contributor
timestamp: July 07, 2020, 07:56:15 am
content: Ah yeah, that's the one I found but I discounted it as being the "main" thread since it's only 4 pages long.

author: tautech
author_rank: Super Contributor
timestamp: July 07, 2020, 08:10:09 am
content: Quote from: Ctrlocti on July 07, 2020, 07:56:15 amDave did a teardown thread when they first were released but it's got a lot of background noise in it.Add the word teardown and you'll find it easy enough.In the nearly 5 years since release they have been a solid performer despite that they don't meet some buyers requirements.

author: Ctrlocti
author_rank: Regular Contributor
timestamp: July 07, 2020, 08:34:49 am
content: Quote from: tautech on July 07, 2020, 08:10:09 amYeah I can see how that third channel being fixed and no CC is hurting sales compared to the dp832I'm just looking for a solid bipolar supply so I'm not too vexed about the 3rd channel limitations

author: tautech
author_rank: Super Contributor
timestamp: July 07, 2020, 08:42:24 am
content: Quote from: Ctrlocti on July 07, 2020, 08:34:49 amWhen alank2 gets 2 duds in a row that's not too good for sales either.You can see from previous scope screenshots they have some power ON glitch of various amplitudes which a lab PSU shouldn't have at all. Period !Even the cheap MCH K305D's SMPS that I marketed here for a while were perfectly behaved at power ON and they didn't have switchable outputs.

author: alank2
author_rank: Super Contributor
timestamp: July 07, 2020, 12:48:23 pm
content: I spoke with Rigol yesterday and they say they have not seen this issue. Chris there pulled a new unit and tested it and it is fine so he is shipping me that one. Hopefully I'll have a good one then.

author: sequoia
author_rank: Unknown
timestamp: July 10, 2020, 09:17:40 pm
content: Quote from: tautech on July 07, 2020, 08:10:09 amThese Siglens PSUs seems all but abandoned, since firmware has not been updated for years and firmware is really buggy (easily can find years old reports on buggy behaviour, but no firmware updates....)Doesn't look like any kind of QA/testing had been done on the firmware, since for example these PSUs don't respond to most commands, if command is terminated with NL character (as specified by SCPI specs). Also when using USB (USBTMC) unit requires long delay (100ms or more) between sending command and reading the response, or unit won't respond at all... (https://www.eevblog.com/forum/testgear/siglent-spd3303d-failures-on-linux-via-usbtmc/msg788184/#msg788184)What makes things worse is that SPD3303X/X-E are being advertised supporting SCPI ,when units cleary don't implement even basic SCPI commands. Not sure if this is Siglent specific or do other manufacturers similarly advertise SCPI when their units don't come even close conforming to the specification?I gave a SPD3303X-E try, since it seemed good on paper (and looked like it was based on same design as GW-Instek GPD-3303D unit that I have used and been happy with). This Siglent performed ok if using it as stanalone PSU and not controlling it over USB or LAN, but I needed reliable "programmable" PSU and couldn't live with the buggy firmware, so I ended up returning the unit to the seller.Last straw was LAN interface repeatedly crashing, unit kept dropping off the LAN randomly, sometimes after few days and sometimes after few hours (after powering on the unit...). Decided to try a DP832 next, and so far happy with it, seems to have real SCPI support and no issues with LAN interface crashing....

author: alank2
author_rank: Super Contributor
timestamp: July 17, 2020, 03:54:18 pm
content: Update - Chris @ Rigol got me all set, it took awhile for FedEx to deliver it (it should have been Wednesday), but it arrived today and all 3 channels startup without any large voltages.

author: Bassman59
author_rank: Super Contributor
timestamp: July 17, 2020, 08:50:16 pm
content: Quote from: alank2 on June 28, 2020, 12:44:28 amI have had a DP831 for about a year and a half. I haven't noticed this sort of issue but then again, I have not looked. I will test it tonight and report back.I kinda hate the fan noise from the 831. Makes testing audio stuff rather difficult.

author: thm_w
author_rank: Super Contributor
timestamp: July 17, 2020, 09:58:08 pm
content: Quote from: alank2 on July 17, 2020, 03:54:18 pmSo the first channel voltage is more in line with what I've measured right? 1-2V or so?

author: alank2
author_rank: Super Contributor
timestamp: July 17, 2020, 10:13:29 pm
content: Yes, I've only viewed the channels with a multimeter and not a scope, but nothing of any consequence shows up.Now...frustratingly I did find a CH2 issue where it has a calibration problem at low voltage. It is fine at 500mV and higher, but at 150mV it is 0 and below that it goes negative. I calibrated it like I did my other DP832 and it will not correct it. The meter shows the correct value as long as it is above zero, so it isn't the meter side, but the DAC side.Here is a cut from the calibration that is odd:ch2 DAC-V calibrationstep 0, cal point: 0.2v, meas val: -0.0705vstep 1, cal point: 0.5v, meas val: -0.0720vstep 2, cal point: 1.2v, meas val: 0.4447vstep 3, cal point: 2v, meas val: 1.2543vch2 ADC-V calibrationstep 0, cal point: 0v, meas val: -0.1565vstep 1, cal point: 0.05v, meas val: -0.0899vstep 2, cal point: 0.1v, meas val: -0.0228vstep 3, cal point: 0.5v, meas val: 0.4982vstep 4, cal point: 1v, meas val: 1.0005vCH1 also had an issue with the step 1 also being more negative than step 0, but it doesn't have the problem for some reason.

author: thm_w
author_rank: Super Contributor
timestamp: July 17, 2020, 11:51:00 pm
content: Quote from: alank2 on July 17, 2020, 10:13:29 pmDid you check the output voltage at 150mV before calibrating? I guess its hard to know if it was actually in CAL when sent to you or not.Another user had added some additional CAL points to get greater accuracy in the low voltage ranges, might apply here.Can also try playing with manual cal, see if the DAC is actually capable of outputting 150mV. Although that doesn't directly fix the issue.

author: JDubU
author_rank: Frequent Contributor
timestamp: July 18, 2020, 01:28:05 am
content: Quote from: alank2 on July 17, 2020, 10:13:29 pmHere is a link to my forum post with a Python calibration script that prevents negative outputs at low calibration values:https://www.eevblog.com/forum/testgear/dp832-calibration-using-python-pycharm-running-on-windows/msg2975942/#msg2975942It is a modified version of one file in a Python calibration script originally created by others. Look back in that thread for more details on how to use it.Edit: Here is a link to my forum post that has an earlier version of the complete DP832 calibration script:https://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg2965052/#msg2965052

author: alank2
author_rank: Super Contributor
timestamp: July 18, 2020, 02:00:24 am
content: Are you saying that the negative issue could be a normal issue and that there is a calibration method around it?

author: alank2
author_rank: Super Contributor
timestamp: July 18, 2020, 02:47:01 am
content: I don't know Python, so take my questions with that in mind.Why go through the work of finding the first positive to the millivolt? When iterating through the calibration steps, first_positive is used to skip them, right? Why not just wait until you encounter the first one that is not negative and start writing calibration values from that point?Also, in my example:ch2 DAC-V calibrationstep 0, cal point: 0.2v, meas val: -0.0705vstep 1, cal point: 0.5v, meas val: -0.0720vstep 2, cal point: 1.2v, meas val: 0.4447vstep 3, cal point: 2v, meas val: 1.2543vWhich points would you want to skip? Just 0? 0 and 1?Does it make any sense that cal point 0.5V is LOWER than cal point 0.2V? Should that be possible?Let's say I skip cal points 0.2V and 0.5V and start with 1.2V. How does it possibly know how to extrapolate where 0 is?Or is there a calibration point entered that is not on their list, for example, if 0V was a 0.6V, would 0.6V be a calibration point at 0?EDIT - ok - I see it entering the first_positive as a calibration point.

author: alank2
author_rank: Super Contributor
timestamp: July 18, 2020, 02:50:27 am
content: My DMM is a Fluke 8845A, but I think it has an Agilent Mode for control. Would the python script work if I switch the DMM to Agilent mode?

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 18, 2020, 11:35:55 am
content: Quote from: Bassman59 on July 17, 2020, 08:50:16 pmI swapped the fans out on both my DP832s and now they are very quiet. The post I created on it ishere.

author: alank2
author_rank: Super Contributor
timestamp: July 18, 2020, 05:51:48 pm
content: I got it working now by modifying garrettm's script to skip multiple negative steps and only use the last one.

author: Bassman59
author_rank: Super Contributor
timestamp: July 20, 2020, 06:55:12 pm
content: Quote from: Gandalf_Sr on July 18, 2020, 11:35:55 amAh, thanks for the tip. I have to check on warranty status of the power supply, and once it's out of such I'll do the swap.