EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: alank2 on June 28, 2020, 12:44:28 am
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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...
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Work around it by not having anything connected or initiate a return/replacement.
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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.
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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.
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Glad i did not buy this garbage, they did advice me to buy it.
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Glad i did not buy this garbage, they did advice me to buy it.
Don'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...
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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.
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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.
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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!
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Don't be an ass.. there are thousands of these out there that work just fine. He got broken one. It happens.
Happens alot in china.
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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.
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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!
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I hooked up all channels to a scope and this is what I see, when powering on the DP832:
[attachimg=1]
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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.
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Has anyone else got data on what other similarly priced PSUs do upon powerup?
Eg Siglent, GWInstek, Tenma, B&K etc
Never 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.
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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.
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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)
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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 1
Unit 3: It got a 20mV spike that smoothly ramp down to 0 after 300ms
6632A 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 580ms
I 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.
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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.
In 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.
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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.
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Discussed here: https://www.eevblog.com/forum/testgear/is-rigol-dp832-output-voltage-spikes-when-unit-is-turned-on-an-real-problem/ (https://www.eevblog.com/forum/testgear/is-rigol-dp832-output-voltage-spikes-when-unit-is-turned-on-an-real-problem/)
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 580ms
I 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.
I 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 250ms
CH2 - -400mV
CH3 - -400mV
CH1 is concerning, the others are not.
DP832A:
CH1 - 1.5V
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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.
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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.
That'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?
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Now anyone still disagree with me ?
garbage
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Now anyone still disagree with me ?
garbage
I disagree.
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Now anyone still disagree with me ?
garbage
|O
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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.
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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 280ms
24.90 V for 5.5s
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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.
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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.
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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?
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I got the same measurements on my Fluke 189's which are isolated.
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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.
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Has anyone else got data on what other similarly priced PSUs do upon powerup?
Eg Siglent
SPD3303X-E
3 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.
(https://www.eevblog.com/forum/testgear/new-dp832-voltage-when-powering-on/?action=dlattach;attach=1017754)
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tautech
I 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?
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tautech
I 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?
No 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........
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Thanks!
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Thanks!
No worries. :)
Try this one:
https://www.eevblog.com/forum/testgear/siglent-spd3303x-e/ (https://www.eevblog.com/forum/testgear/siglent-spd3303x-e/)
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Ah yeah, that's the one I found but I discounted it as being the "main" thread since it's only 4 pages long.
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Ah yeah, that's the one I found but I discounted it as being the "main" thread since it's only 4 pages long.
Dave 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.
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Ah yeah, that's the one I found but I discounted it as being the "main" thread since it's only 4 pages long.
Dave 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.
Yeah I can see how that third channel being fixed and no CC is hurting sales compared to the dp832
I'm just looking for a solid bipolar supply so I'm not too vexed about the 3rd channel limitations
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Ah yeah, that's the one I found but I discounted it as being the "main" thread since it's only 4 pages long.
Dave 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.
Yeah I can see how that third channel being fixed and no CC is hurting sales compared to the dp832
I'm just looking for a solid bipolar supply so I'm not too vexed about the 3rd channel limitations
When alank2 gets 2 duds in a row that's not too good for sales either. :P
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.
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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.
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Ah yeah, that's the one I found but I discounted it as being the "main" thread since it's only 4 pages long.
Dave 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.
These 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 (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....
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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.
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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...
I 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.
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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.
So the first channel voltage is more in line with what I've measured right? 1-2V or so?
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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 calibration
step 0, cal point: 0.2v, meas val: -0.0705v
step 1, cal point: 0.5v, meas val: -0.0720v
step 2, cal point: 1.2v, meas val: 0.4447v
step 3, cal point: 2v, meas val: 1.2543v
ch2 ADC-V calibration
step 0, cal point: 0v, meas val: -0.1565v
step 1, cal point: 0.05v, meas val: -0.0899v
step 2, cal point: 0.1v, meas val: -0.0228v
step 3, cal point: 0.5v, meas val: 0.4982v
step 4, cal point: 1v, meas val: 1.0005v
CH1 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.
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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:
Did 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.
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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.
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Here 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/#msg2975942 (https://www.eevblog.com/forum/testgear/dp832-calibration-using-python-pycharm-running-on-windows/msg2975942/#msg2975942)
It 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 (https://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg2965052/#msg2965052)
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Are you saying that the negative issue could be a normal issue and that there is a calibration method around it?
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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 calibration
step 0, cal point: 0.2v, meas val: -0.0705v
step 1, cal point: 0.5v, meas val: -0.0720v
step 2, cal point: 1.2v, meas val: 0.4447v
step 3, cal point: 2v, meas val: 1.2543v
Which 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.
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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?
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I kinda hate the fan noise from the 831. Makes testing audio stuff rather difficult.
I swapped the fans out on both my DP832s and now they are very quiet. The post I created on it is here (https://www.eevblog.com/forum/testgear/dp832-fan-replacement-2018/msg1453635/#msg1453635).
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I got it working now by modifying garrettm's script to skip multiple negative steps and only use the last one.
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I kinda hate the fan noise from the 831. Makes testing audio stuff rather difficult.
I swapped the fans out on both my DP832s and now they are very quiet. The post I created on it is here (https://www.eevblog.com/forum/testgear/dp832-fan-replacement-2018/msg1453635/#msg1453635).
Ah, 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.