Rigol DP832 - Firmware list and bugs

[mcinque]

no problem here with the banana plugs, with an April 2014 model .
I will check for the OVC issue.

[McBryce]

I bought my DP832 late last year and I can assure you that any amount of beating won't get a 4mm banana into the positive post. Must be a bad batch.

McBryce.

Gesendet von meinem Motorola DynaTEC 8000X mit Tapatalk 2.

[mcinque]

After the first OC trip, turn the channel back on, then try to trip it again. Instead of tripping, it current limits (it doesn't trip) using the OCP setting for current limiting, not the current limit setting.
Is this behaviour just me?

01.09 here and no OCP issue as you described

[Sparky]

Hi,
    just came across this thread (because it popped back up to the top). I haven't read the entire thread, because I assume all issues are listed in the first post, but you don't mention the rather annoying hardware bug that the positive connection posts are too small for standard 4mm banana connectors.

McBryce.

I don't have the issue myself, but I assume you're talking about this:
https://www.eevblog.com/forum/testgear/banana-plugs-don't-fit-in-positive-sockets-rigol-dp832/

Let me quote Sparky below, so that he adds this to the list

DP832 - Firmware versions and bugs/issues

Thanks McBryce and LaurentR -- I've added this info to the first post!

[Howardlong]

After the first OC trip, turn the channel back on, then try to trip it again. Instead of tripping, it current limits (it doesn't trip) using the OCP setting for current limiting, not the current limit setting.
Is this behaviour just me?

01.09 here and no OCP issue as you described

Thank you, is that the boot version, or the digital version?

[Owen]

For your list of bugs and design flaws in the DP832: Youtuber Jason Li investigated that Rigol's DP832 seems not to be isolated to earth. There's an AC coupling between earth and ground (exceed 32 Vac). Here's the video:

[SimonD]

Hi,
If anyone can confirm that, this is a serious bug ! It can realy destroy circuits under test ! So we have to find a quickly  solution.

[bson]

I see ~3.1V AC.  About 13.3uA DC, ~13.3uA AC (20Hz filter) measured with the Keysight 34465A.  Just noise.  I think the guy in the video has a problem with his earth...

This is with a cold instrument, didn't null it or anything -- it's just noise.

[Owen]

Hi,
If anyone can confirm that, this is a serious bug ! It can realy destroy circuits under test ! So we have to find a quickly  solution.

My DP832 shows ~5 V AC between earth and ground on Channel 1 and ~17 V AC on Channel 2/3.

[OldNeurons]

For your list of bugs and design flaws in the DP832: Youtuber Jason Li investigated that Rigol's DP832 seems not to be isolated to earth. There's an AC coupling between earth and ground (exceed 32 Vac). Here's the video:

Same here.
DMM: Metrix MTX3293, 10 MOhms impedance

DP832 power ON, CH1, CH2, CH3 OFF:
CH1 to earth: 37 Volts TRMS, 106 Volts PP
CH2, CH3 to earth: 39 Volts TRMS, 110 Volts PP

DP832 power OFF:
CH1 to earth: R>100 MOhms, C = 1.69nF
CH2, CH3 to earth: R>100 MOhms, C = 1.48nF

I don't have any schematic of that PSU, but we know that this PSU is equiped with a 'nice' toroidal transformer.
I would like to have the opinion of specialists, but at this stage, for me, this issue could be related to a bad design/wiring  of the transformer.
Please have a look to these papers.

http://coefs.uncc.edu/mnoras/files/2013/03/Transformer-and-Inductor-Design-Handbook_Chapter_17.pdf
http://sound.westhost.com/power-supplies.htm

Not sure to be on the right way, but I don't have any other idea ... Your comments are welcome.

[OldNeurons]

For your list of bugs and design flaws in the DP832: Youtuber Jason Li investigated that Rigol's DP832 seems not to be isolated to earth. There's an AC coupling between earth and ground (exceed 32 Vac). Here's the video:

Thanks Owen for bringing that to our attention. Thanks also to Jason Li.
I now realize and understand what happened to me a week ago ... Spent hours ...
I'am a bit tired spending time to debug my Rigol products (PSU, Gen. and scope) 
I will receive monday morning my Keysight 34461A. Hope that I will just spend time to enjoy ...

[dadler]

With the DP832 on but all channels off:

I see ~7.5VAC@60Hz between channel1+ and mains earth. The other channels show 7.5-8.5VAC. The current is .022uA according to my 34465a, >20Hz filter mode.

So voltage, but almost nil current. Much ado about nothing?

[economist]

On my DP832, on a Keithley DMM I'm seeing 4.4V AC @ 60Hz between CH1 and ground and 6.2 for channels 2 and 3, both at 60Hz. Confirmed (slightly different volts, but all at 60Hz) on a Fluke 289. The 289 is showing a little over 6.6V AC RMS from Ch1 positive to ground). Current is miniscule.

Here it is (CH1 off, power on, positive to ground on the DP832) on the scope.

[OldNeurons]

With the DP832 on but all channels off:

I see ~7.5VAC@60Hz between channel1+ and mains earth. The other channels show 7.5-8.5VAC. The current is .022uA according to my 34465a, >20Hz filter mode.

So voltage, but almost nil current. Much ado about nothing?

With such measurements, I agree with you. No need to worry about.
In case of my DP832, I confirmed the measurements with 3 other DMM + my oscilloscope. All show voltage above 30 Volts.
All measurements where made with an input impedance of 10 MOhms. I think that in your case (44465A), and for the Keithley, the AC input impedance is 1MOhms. But that does not explains the big difference between my DP832 and Jason's one.
I also measured the current with 4 DMM. All show over 30µA, which is much much higher than your value, and not negligible. I am not saying that it is a dramatic situation, but just wondering in which case(s) I should take that in account.

So, it seems that we are observing DP832 with different characteristics.
For information, my DP832 shows a calibration certificate dated September 2014.

Could you try to measure the capacitance between earth and output terminals, and return the values?

It is more than midnight here, and we are switching from winter time to summer time this night. So, time to sleep 
I will continue my investigations tomorrow.

P.S.: English is not my native language. Do not hesitate to ask for clarification if needed.

[economist]

I see 8 microamps of current from CH1 + to ground. Capacitance between + to ground and - to ground is very very small -- well under 1 nF.

[Owen]

I see ~5 µA on channel 1 and  ~15 µA on channel 2/3.

[lunxg]

Hi all,
I am Jason Li who posts the video on youtube.
First of all I have to make it clear that all of my instruments including DP832 are properly grounded( the same mearsuring result with DP832 grounding pole and my ESD ring ground)

My friend's DP832( total in 3) also showing this voltage but some show lower coupling voltage about 17Vac


And this voltage really makes a  lot of problems including generating noise into oscillscope and affects other instrument such as sig gen.
I know this voltage is very weak in current ( high impedance source ) I will try to measure the current later. But it really affects my testing and it seems kill some of my mcu already(cannot reprogram them again).

Should you have anything want to know or test on the DP832, please leave it, I will try to make it and post to the forum or youtube.

[Howardlong]

I see 35VAC at 25uA. I am wondering if this is induced current from the toroidal transformer.

If you stick a 0.1uF cap from the black terminal(s) to the green earth terminal, it reduces to 0.5V.

Whether that's a reasonable workaround or not I don't know, but I would be concerned if 25uA stray current was enough to blow up a design.

[lunxg]

As my point of view, just a voltage(without any current) will be enough to blow up the ICs, as stated in the specification.

[Howardlong]

As my point of view, just a voltage(without any current) will be enough to blow up the ICs, as stated in the specification.

While I understand your view, the ESD protection diodes should easily deal with that.

The reason I suggested this is that it is often very easy to blame external effects without considering one's own design enough.

I worked on a project where, for quite some time, the embedded computer guys were blaming the 3W of UHF RF radiation of a connected telemetry beacon for blowing up their MCUs. We put in a 30dB attenuator. The MCUs still blew up. We put on a dummy load. The MCUs still blew up. When it came to final check out, we were finally allowed to remove the dummy load to find that the slight mismatch by connecting to the antenna causing the RF PA to go into oscillation, but by then it was all conformally coated. As the unit was being shipped the next day, I had to fix it by using just the right RF electrical length of coaxial feeder to present an acceptable load to the PA. That is in a satellite that is now orbiting the Earth.

[Kevin.D]

Hi , In some bench power supplies you will find any floating output's (at both +,- sides) are ac coupled to mains earth at the output's by capacitors ~ 47n-100n, the job of these is to provide a low impedance path for any earth referred mains noise back to earth (so they form a Voltage divider with the source impedance and thus attenuate this noise) . From what was said by Howard in earlier post sounds like these are missing/not fitted here. If your not satisfied and you want to reduced this then you could fit some yourself ( 47nF caps would reduce it to ~1V). Maybe ask Rigol first why they did not fit them.

[lunxg]

Hi , In some bench power supplies you will find any floating output's (at both +,- sides) are ac coupled to mains earth at the output's by capacitors ~ 47n-100n, the job of these is to provide a low impedance path for any earth referred mains noise back to earth (so they form a Voltage divider with the source impedance and thus attenuate this noise) . From what was said by Howard in earlier post sounds like these are missing/not fitted here. If your not satisfied and you want to reduced this then you could fit some yourself ( 47nF caps would reduce it to ~1V). Maybe ask Rigol first why they did not fit them.

Yeah, I posted in other forum and some suggest the missing of the filter capacitor.
I have a 0.047uF(47nF) 300V  Y-cap which I brought an extra when I fixing my HP8920A.
It seems works and reduce the voltage to ~1.4Vac (But it still over 1V)
I will try to make some comparison for the capacitance measurement on  other lab power supplies tomorrow.

[Macbeth]

20VAC 26uA on CH1 and 22VAC 28uA on CH2+3 here. UK mains so I know all my earths are good 

[lunxg]

20VAC 26uA on CH1 and 22VAC 28uA on CH2+3 here. UK mains so I know all my earths are good 

For the video I made in YouTube, I am in Hong Kong and also using British standard plug. The main ground is so damn good and I have always no doubt with that

[dadler]

With the DP832 on but all channels off:

I see ~7.5VAC@60Hz between channel1+ and mains earth. The other channels show 7.5-8.5VAC. The current is .022uA according to my 34465a, >20Hz filter mode.

So voltage, but almost nil current. Much ado about nothing?

To correct my above current values, I was measuring current to actual mains with a shoddy alligator clip. With a solid connection, I measure 11uA AC. Voltages measure the same. I am in the USA with 120V@60Hz service.