EEVblog Electronics Community Forum

EEVblog => EEVblog Specific => Topic started by: EEVblog on August 30, 2013, 07:10:56 am

Title: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 07:10:56 am
Dave started out wanting to investigate the power-on spike on the Rigol DP832 Lab Power Supply, but ended up hunting down a reset bug that uncovered a bad thermal design mistake in the supply.
Watch Dave hunt it down step by step, and almost get duped by some marginal oscilloscope triggering.
How will Rigol respond to this?

EEVblog #512 - Rigol DP832 Bad Design Investigation (http://www.youtube.com/watch?v=y-KkPLWZJko#)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mikeselectricstuff on August 30, 2013, 07:52:59 am

If they can make such a fundamental mistake as dissipating 5W in a small package you have to wonder about the quality of the rest of the  design...
I wonder if maybe it was a feature-creep issue, where the reg originally supplied a lower current then someone added other stuff without telling the PSU guy.
 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mikeselectricstuff on August 30, 2013, 08:00:37 am
Do you have a variac? I so, try winding up the mains voltage to the max rating and see how hot the reg gets.
(if not, use a mains transformer as an autotransformer with LV secondary in series with mains to boost it up)

The obvious easy fix is to replace the reg with a switcher - there are plenty of drop-in 7805 replacements.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Kjelt on August 30, 2013, 08:10:52 am
If they can make such a fundamental mistake as dissipating 5W in a small package you have to wonder about the quality of the rest of the  design...
And the rest of their total product portfolio.  I was a Rigol fan but watching this makes me think twice next time  :palm:
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on August 30, 2013, 08:12:11 am
It might have originally been a switcher, but given how unusually sensitive the logic was (rebooting from such small ripple) maybe they swapped it out for the LM, and never upped the heat sink accordingly.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fabio on August 30, 2013, 08:22:32 am
Hi Dave,

The 317 dissipation looks crazy, but the increased ripple does not look that critical to me to justify a reset on the SoC.

On the other side, I had some bad experiences in the past with the i.MX28, caused by the poor efficiency of the integrated power supply that leaded to a really high operating temperature of the whole SoC.  My suspect would be that the front panel would suffer from the reduced airflow when operating without the chassis, the i.MX28 overheats and reset and the temporarily increased 5V ripple would be just a consequence of the integrated OS booting and initializing stuff.

Are you still able to check the temperature of that?  The back of the BGA may be accessible enough to measure.

Thanks for the video!

Fabio
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 08:27:35 am
Hi Dave,
The 317 dissipation looks crazy, but the increased ripple does not look that critical to me to justify a reset on the SoC.

Perhaps. But I cannot find anything else obvious to explain it. I'll leave that up to Rigol.

Quote
My suspect would be that the front panel would suffer from the reduced airflow when operating without the chassis, the i.MX28 overheats and reset and the temporarily increased 5V ripple would be just a consequence of the integrated OS booting and initializing stuff.

That would be an amazing coincidence that two parts are running super hot and overheating.
Also would not explain why pushing external air over the LM317 fixed the reset problem.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fabio on August 30, 2013, 08:33:29 am
Also would not explain why pushing external air over the LM317 fixed the reset problem.

Well... it's not that your bad-ass fume extractor was sharpshooting just at the regulator... :-)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 08:36:10 am
Well... it's not that your bad-ass fume extractor was sharpshooting just at the regulator... :-)

Yeah, but it was going nowhere near the front panel.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TerminalJack505 on August 30, 2013, 08:44:03 am
If Rigol wanted to be as cheap as possible then, as a hotfix, they could probably send all of the current users one of those 20W 8R power resistors that they use for testing audio systems.  Just stick that sucker inline between the +12V output and the LM317's input and it would probably dissipate enough heat to solve the problem.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: FrankBuss on August 30, 2013, 08:46:14 am
Perhaps. But I cannot find anything else obvious to explain it. I'll leave that up to Rigol.
I'm curious about Rigol's response. Sometimes shit happens, maybe first the CPU board needed much less power and then they enhanced it and forgot to check the supply. But the manufacturer should communicate it clearly and provide fixes for it (maybe a repair kit with a bigger heatsink, as you suggested) or do a product recall.

Agilent is a good example for very good customer support: Last time when I reported a trigger problem in auto-mode for a signal on my Agilent DSO, they reproduced the signal (which was not very difficult, just a digital burst sequence), confirmed the problem and fixed it with the next firmware release.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 08:49:33 am
Do you have a variac? I so, try winding up the mains voltage to the max rating and see how hot the reg gets.

I'm already not far off the max mains voltage here in the lab I think.
I'd have to do that for all mains voltage selection scenarios to be thorough.
It's not going to make a huge difference in dissipation anyway. Enough to cause units to fail?, maybe. But in the end there are many variables at play here, so I'll leave that up to Rigol to work out and fix.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mikeselectricstuff on August 30, 2013, 08:54:03 am
Without looking in detail, my guess is a lot of that power is going to the LCD backlight, which could just as easily have been run from the unregulated 12V supply (assuming they actually have a proper backlight driver and not just some Rs from 5V....!) 

..and I suppose there is a possibility that they have mis-configured the CPU to run in a much more power-hungry mode then intended - maybe they'll issue a firmware 'fix' that slows it down to a crawl so the UI then sucks ass...
Quote
they could probably send all of the current users one of those 20W 8R power resistors that they use for testing audio systems.  Just stick that sucker inline between the +12V output and the LM317's input and it would probably dissipate enough heat to solve the problem.

The heat still needs to go somewhere -  The R would need decent mounting where there's airflow. 5W is still 5W, whatever device you burn it in - it's mostly  about surface area.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: olsenn on August 30, 2013, 08:57:12 am
Quote
I'm already not far off the max mains voltage here in the lab I think.
I'd have to do that for all mains voltage selection scenarios to be thorough.
It's not going to make a huge difference in dissipation anyway. Enough to cause units to fail?, maybe. But in the end there are many variables at play here, so I'll leave that up to Rigol to work out and fix.

What does the mains voltage have to do with the 12-to-5 volt regulator? If a lower mains voltage means lower temperatures somehow, does that mean that a US (120V) system will be less likely to fail than your Aussie one?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tnt on August 30, 2013, 09:10:40 am
You could try feeding the 5V from another lab power supply to see if it's really the issue.

If it works, then maybe just put one of the cheap 5$ switcher between the bridge output and the LM317 input (or bypass the lm317 all together), this should allow to cut the dissipated power by more than half, hopefully bringing it to a more reasonable temp.

Cheers,

    Sylvain
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tinhead on August 30, 2013, 09:11:53 am
How will Rigol respond to this?

i bet they will tell you "Dave, this is high-end precission power supply" :P Sorry, but i couldn't resist :)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TerminalJack505 on August 30, 2013, 09:14:26 am
Without looking in detail, my guess is a lot of that power is going to the LCD backlight, which could just as easily have been run from the unregulated 12V supply (assuming they actually have a proper backlight driver and not just some Rs from 5V....!) 

..and I suppose there is a possibility that they have mis-configured the CPU to run in a much more power-hungry mode then intended - maybe they'll issue a firmware 'fix' that slows it down to a crawl so the UI then sucks ass...
Quote
they could probably send all of the current users one of those 20W 8R power resistors that they use for testing audio systems.  Just stick that sucker inline between the +12V output and the LM317's input and it would probably dissipate enough heat to solve the problem.

The heat still needs to go somewhere -  The R would need decent mounting where there's airflow. 5W is still 5W, whatever device you burn it in - it's mostly  about surface area.

Yep.  I'm envisioning a wiring harness that allows the resistor to be placed back by the fan, perhaps.  Also, I didn't really run the numbers so far as size goes.  It might need to be more like 4R.  Anyway, just thinking out loud.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 09:14:26 am
What does the mains voltage have to do with the 12-to-5 volt regulator? If a lower mains voltage means lower temperatures somehow, does that mean that a US (120V) system will be less likely to fail than your Aussie one?

This is a linear supply, not a switcher with PFC. So if you increase the mains voltage by 10%, from 220 V to 242 V, all the secondary voltages will also go up by 10%. So dissipation will go up by ~5%. Not really something that will make much of a difference, but it might just be enough to tip the scales and have the unit reset with the case fully assembled. For 120 V the taps would be configured differently, so you wouldn't see only 6 V secondary voltage with 120 V AC in ;).

PS: Nice video, Dave! I liked the combination of troubleshooting, review and tutorial.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on August 30, 2013, 09:15:36 am
Dave,

If you intend to investigate further, then one idea may be to stick a small, calibrated SMD thermistor on the tab of the 80N15 pass device for one of the 30V rails. Close the whole PSU fully up, load down all the rails, and measure the tab temperature.

At your mains voltage and 22V @ 3A output, just before the first tap switches, the 80N15 needs to dissipate 72W. With Rth,JC at 0.35 K/W you need the HS temp at 100oC or less, with no margin for error. You casually measured about 70oC or so at 48W dissipation (30V @ 3A load), so the large HS may seem slightly small as well. Particularly so if you load down all three rails, causing the transformer to 'pre-heat' the cooling air a bit before it reaches the large heat sinks.

PS: According to the IXYS datasheet I could quickly find, then the 80N15 MOSFET is housed in a TO-264 case, not a TO-220 as we see in the video.
PPS: The over temperature protection numbers I have seen, suggests the device in question usually shuts down when the die reaches roughly 175oC.

----
Edit. The IXYS 80N15 has a TJ,max of 150oC. Not sure I'd like to run it at that, but...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: quarros on August 30, 2013, 09:17:28 am
What does the mains voltage have to do with the 12-to-5 volt regulator? If a lower mains voltage means lower temperatures somehow, does that mean that a US (120V) system will be less likely to fail than your Aussie one?

No because of the tabs on the transformer it would still give out 12 volts no mater if it intakes 120V or 230V.
What he meant is that the mains voltage can go up and down around 5% or more depending on your area electric network.
Therefore the output voltage on the transformer can also be higher than 12V and that adds to the dissipated power altough not much I wager.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: KerryW on August 30, 2013, 09:46:52 am
If it was MY power supply, the first thing I'd do is replace the LM317 with an LM1085.  It has a theta J-C of 0.7 degC/W, a saving of over 20 degrees.
Next, I would stick a BGA heat sink on the front, such as an AAVID 375424B00034G.

My judgment might be colored by the fact that I have those parts in stock.  ;)

Kerry
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 09:50:26 am
It's a real shame, I was seriously going to buy one of these. But now, I've been put off.

So how many other Rigol units have a similar design where they are supplying 5v using a LDO at near 5Watt's? You would think that a company like Rigol would design reuse across the board and thus this might not be a one off.

Does it mean that their Oscilloscopes could potentially be doing the same? Makes you wonder.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mariush on August 30, 2013, 10:01:15 am
It's a shame you didn't bother to just replace the small heatsink with a larger one.  There is room for one both sideways and vertically, at least as far as I can see.

The heatsink in the picture below is a 7.6 C/w one and as you can see, it would accept a TO-220 just fine and would probably fit there.   

Yeah, it would still be 5 watts dissipated there, and those capacitors would slowly cook there... but at least it would decrease the chance of resetting.

(picture was made for someone else to show the rectifier, but it just happens the heatsink is in the picture so ...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 10:07:37 am
So how many other Rigol units have a similar design where they are supplying 5v using a LDO at near 5Watt's? You would think that a company like Rigol would design reuse across the board and thus this might not be a one off.
Scopes will have a switching power supply, so they're unlikely to use an LM317 to create a 5 V rail from 12 V. The Rigol DMMs could share this design, but they probably draw less power on the grounded 5 V rail, since the display is smaller. The LM317 is not generally regarded as low dropout, by the way.

I would definitely put any orders on hold until Rigol has come up with a solution and distributed this fix to their distributors. I wouldn't be surprised if they would indeed come up with a firmware bodge job like CPU power saving or fan speed.

I wonder how many DP832s are running in racks. Do people already trust Rigol for heavy-duty system applications? I would probably trust the scopes, but most of their other products are too new to be used for important jobs, in my opinion. Fine for design work where you just grab another supply if one dies (unless it sends out a spike and kills your DUT, but that would never happen :P), but not in an application where your production line grinds to a halt if the thing fails.

The heatsink in the picture below is a 7.6 C/w one and as you can see, it would accept a TO-220 just fine, and would go around the large capacitors and the rectifier on the left side of the LM317.
That's still not very nice for those caps in my opinion. They may be 105°C rated, but they will only survive a few thousand hours at that temperature, so even 60°C is not very nice.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: free_electron on August 30, 2013, 10:10:32 am
Hi Dave,
The 317 dissipation looks crazy, but the increased ripple does not look that critical to me to justify a reset on the SoC.

Perhaps. But I cannot find anything else obvious to explain it. I'll leave that up to Rigol.

one thing i noticed from watching the video again : the metal tab on that lm317 is very thin .... much thinner than normal ... fake lm317 ?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ashplant on August 30, 2013, 10:18:02 am
Dave, this was one of your best one's. I like the I like the way it combined teardown and theory.

I wonder how Rigol will react. The cynic in me says they'll come out with new firmware that speeds the fan and slows the digital. If they do it cleverly - and remember that responsive and fast are different - it might stop the resets without much UI pain. But it won't change the fact that you shouldn't have electrolytic caps nestling up to a hot spot.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 10:22:21 am
one thing i noticed from watching the video again : the metal tab on that lm317 is very thin .... much thinner than normal ... fake lm317 ?

I noticed that too, but there's not a whole lot to screw up for a fake here in my opinion. It's not like 100 mA is flowing through its adjust pin. If 700 mA flows through a linear regulator with a 7 V difference between Vin and Vout, it's going to dissipate at least 3.5 W no matter what you do. It may increase Thetaj-c, though. I have seen the thin tabs from legitimate sources before, not sure if it was from ST.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 10:22:41 am
It's a shame you didn't bother to just replace the small heatsink with a larger one.

I have not thought about the best fix for my unit yet.
I'd have to source a suitable heatsink in that case, I don't have suitable ones in the junk bin.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 10:29:07 am
Well it certainly looks a lot thinner than a not fake LM317.

Top LM317 by ST in malaysia
2nd LM317 by ST in morroco notice the tab difference
3rd 7812
4th 7805 by ST

So they are thicker. Or maybe mine are the fake ones!!!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on August 30, 2013, 10:31:00 am
Yeah, I've always found the ST TO-220 tabs to be nice and thick. Now, Fairchild, on the other hand...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 10:32:25 am
Or yours are older. What's the date code?

But even if it is a fake, what would a genuine LM317 do differently that makes this problem disappear? We saw it put out a fairly stable 5V DC, so it's not like a fake LM317 is going to magically have the LCD draw twice the current. Are you seriously blaming the LM317 for going into thermal shutdown at what might be a junction temperature in excess of 140°C?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 10:41:51 am
Yeah ok, mine are quite old, 97-99.

Maybe it's the old adage of "They don't make them like they use too"
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: staggerlee on August 30, 2013, 10:47:49 am
Transformer tap voltage too high or wrong tap?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 10:49:13 am
Dave measured 12v in so suspect that is correct input voltage.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: staggerlee on August 30, 2013, 10:53:29 am
Is it normal to use 12v and regulate it down to 5?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on August 30, 2013, 11:00:51 am
one thing i noticed from watching the video again : the metal tab on that lm317 is very thin .... much thinner than normal ... fake lm317 ?

Not fake, they call it a single gauge TO220 package, a drawing is in the ST data sheet.

Probably devised because of and definitely becoming popular with the rising price of copper.

It doesn't really change theta JC but there is less copper to spread heat across the tab so the effective case to heat sink thermal resistance is going to be a bit worse.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 11:20:28 am
Normal? Yes, if you want to put together something cheap and quick, but are powering a low wattage circuit, like a simple uController or low current circuit.

But at 700ma, no, pure power wastage madness.

I hope they don't want a Energy Star rating on this thing!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 11:30:06 am
I think the 5 V supply is only driving the digital logic, so I really see no reason why they didn't go for a buck converter. Would have been much more efficient and would have easily fitted in that space.

In Dave's scope measurements it seemed like only a few mV or so increase in ripple caused the system to reset, but I think there's more going on (like a fast transient) that the scope didn't capture or gets clamped. Their noise margin can't be that poor. This is not a mobile device running on an extremely tight power and cost budget. Unless someone screwed up and designed in a 3.3 V regulator with a 4.99 V dropout voltage, but that would be plain stupid. And I doubt anything sensitive gets powered directly from 5V.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 11:32:03 am
But even if it is a fake, what would a genuine LM317 do differently that makes this problem disappear?

Nothing. Fake or genuine, the die is still running at greater than the recommended max operating temperature.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 11:33:18 am
Is it normal to use 12v and regulate it down to 5?

Nope. Normally you pick something like a 9V tap for that.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 11:36:00 am
I assume the 12 V rail is also used for something like running the fan, so that would involve adding another winding to the already complex transformer.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on August 30, 2013, 11:37:59 am
Is the USB host port powered by this LM317 too? Then load it with an additional 500mA.>:D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on August 30, 2013, 11:40:05 am
At your mains voltage and 22V @ 3A output, just before the first tap switches

I was also going to mention worst case pass transistor dissipation will be at maximum current and a voltage just before one of the downwards tap changes.

On the reset problem - I'm not totally convinced that the regulator shutting down was resetting the processor without being able to see more than 100mV of ripple on the 5v rail. The ripple we did see was at 5Hz what is that from? Was there some high frequency oscillation the scope wasn't seeing? On the other hand air flow across the board stopping it and the crazy regulator temperature does point towards it.

On the regulator temperature yes it is crazy, the board ought to have a high temperature warning label if the regulator was intended to run that hot.

On the actual design issue I can see how it happens, the attraction of using a common heat sink, the load requirement being underestimated and creeping upwards. Maybe they decided minimum mains input voltage was too high and upped the transformer winding a bit. Maybe the fan was a bit loud and they turned down the minimum speed. What I don't understand is why it wasn't determined to be a problem and fixed before the went into production. I can't believe no one noticed there was a burn hazard on the boards they were developing then building and testing.

Rigol are competent enough to design a 5v regulator, if not their other products would be riddled with problems. Seems more like a management/quality/ethos failure.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 11:44:29 am
Is the USB host port powered by this LM317 too? Then load it with an additional 500mA.>:D

Oops, yeah, it would be. Good point!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on August 30, 2013, 11:48:33 am
Is the USB host port powered by this LM317 too? Then load it with an additional 500mA.>:D

Oops, yeah, it would be. Good point!

You can use it for remote reset. It's not a bug, it's a feature. ;D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on August 30, 2013, 11:48:59 am
The comments on firmware changes makes me think of what Canon have done with my SX280 compact zoom camera. A great camera let down by a basic design flaw.

When running in video mode, if you used the zoom it would immediately indicate 'low battery' and this would remain until a full power off/on reset. How that fault got past QC I will never know. It wasn't as if the issue was hard to replicate...they all do it.

Canon came out with a new firmware to 'fix' the problem. My brand new camera arrived with the old firmware so I installed the new patched version. The result is less occurrences of the low battery warning when using the Zoom, but the problem does still occur now and then.

Why am I telling this story ? well the firmware update changes just one thing....it slowed the zoom motor and effectively lowered its current consumption. It appears that the battery in the SX280 is overloaded by video and Zoom functions operating at the same time and drops its p.d. as a result. Oooops !

The camera takes great pictures and the video issue is not a concern to me, but it is yet another example of very poor design and testing.

I suspect Rigol will not like the idea of a recall or any hardware changes, so the comments regarding crippling the processor speed are a definite possibility. The early ASUS 700 netbook was the subject of such a 'fix'. The first release overheated so the firmware was updated to hobble the processor speed and so reduce heat production inside the case. It worked but was then awfully sluggish.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on August 30, 2013, 11:49:16 am
Is it normal to use 12v and regulate it down to 5?

Nope. Normally you pick something like a 9V tap for that.

An LM317 needs 3v across it so that's 8v, add on the ripple and line input range and a bit less than 12v input average at the high end of the line range isn't far out.

Is the 12v used for anything else? A lower voltage tap and LDO regulator would almost be a fix. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: twjtwj on August 30, 2013, 11:49:32 am
Maybe there is a software option upgrade to make it run cooler.  :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 11:53:58 am
Replacing all those transformers will be expensive, though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on August 30, 2013, 11:58:47 am
hmm,
noticed mine has a different transformer  500va not 400va and it has a 9v tap.
time to tear it apart again and measure I guess

http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/? (http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/?action=dlattach;attach=55776)action=dlattach;attach=55776[/url]
wrong link, trying again

http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/?action=dlattach;attach=55778 (http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/?action=dlattach;attach=55778)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 12:02:18 pm
An LM317 needs 3v across it so that's 8v, add on the ripple and line input range and a bit less than 12v input average at the high end of the line range isn't far out.

A nominal 9V RMS tap would give 12.7V peak. Subtract 1.2V for full bridge diode drops and say 1V for ripple, still leaves you with 10.5V.
BTW, I'm reading 10.5V RMS on the tap. It's marked 10V on the transformer label.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: edpalmer42 on August 30, 2013, 12:47:28 pm
Dave,

When you were trying to trigger the scope on the problem, you missed the biggest, boldest trigger signal possible - the output voltage!  Use channel 2 on your scope to monitor the output voltage and trigger a single shot capture when the output disappears.  Set the trigger to capture in the middle of the memory so that you've got the channel 1 signal before and after the output disappears.

As for whether the regulator caused the reset, you appeared to be using slow sweep speeds.  Depending on how the LM317 responded to the overloads, it could be causing a very narrow outage glitch.  You wouldn't have seen it at slow sweep speeds.

Ed
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on August 30, 2013, 01:21:16 pm

The obvious easy fix is to replace the reg with a switcher - there are plenty of drop-in 7805 replacements.

Maybe that explains how this happened in the first place.  Someone designed it with a switcher in mind, and a bean counter came along and said "wait, that part is 5 times the price of this other regulator - let's go with the cheaper one!"
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on August 30, 2013, 01:27:03 pm
If Rigol wanted to be as cheap as possible then, as a hotfix, they could probably send all of the current users one of those 20W 8R power resistors that they use for testing audio systems.  Just stick that sucker inline between the +12V output and the LM317's input and it would probably dissipate enough heat to solve the problem.


I was thinking about the fix and the more I think about it, the more of a real shit-show this is for Rigol.  I don't think there is any way a company like Rigol would ever offer up a fix where the user is soldering anything.  Actually, if Dave said that heat sink is PCB-mounted with tabs, I don't even see how they could offer up a replacement heat sink because that would require soldering as well.  Not to mention they would have to agree to waive the "Warranty void" labels being broken in future warranty claims, and on top of that what if someone breaks their unit while attempting the fix? 

Really, all these units will need to go back to Rigol.  I have no idea how many they sell or have sold of the 832 series, but a recall is going to be unheard of for a test equipment manufacturer, I'd think.  I think Rigol is going to be extremely hesitant to do that, especially in light of the fact that we don't know any have actually failed.  On the other hand, we know it's an ST LM317 with a max junction temp of 125C and we know it's running above that, so Rigol can't really say the design is fine either.

I really hope they don't do what Dave suggested might happen, and distribute a bullshit firmware that runs the fan balls-out to compensate.

They really need to do a recall on this.  Sucks to have to do it, but what can ya do...  actually, a recall and a coupon for a healthy discount on another piece of Rigol gear bought factory direct might work out well...  they could make up the cost of the recall with that.  I'd love to get a DG4062 for $200 off, let's say :)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: talvor on August 30, 2013, 01:27:11 pm
Is it normal to use 12v and regulate it down to 5?

Nope. Normally you pick something like a 9V tap for that.

This is a newbie design question.

Dave said that it is not normal to use a 12v input to regulate down to 5v.  Would a voltage divider work to get the 9v out of the 12v input?

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 01:33:00 pm
You still have to dissipate the drop of 12v to 9v. Your now just doing it in the Resistor instead.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jon_joy_1999 on August 30, 2013, 01:42:30 pm
105c caps right next to a device that reaches 111c, smells like planned obsolescence (and boiled electrolyte) to me!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TerminalJack505 on August 30, 2013, 02:04:08 pm
I was thinking a dropper resistor would be a workable kludge too but if that same rail is expected to power any connected USB devices as well then it probably wont. 

Like someone else mentioned, some kind of active voltage dropper would have to be used.  It would need its own heat sink and the LM317 still might need a bigger heat sink for the worst-case scenario. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: pickle9000 on August 30, 2013, 02:12:33 pm
I have seen heat sinks doubled up, in one case a much larger one so the fins all came out in the same direction. No soldering required at least.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: johnnyfp on August 30, 2013, 02:59:43 pm
Ah hell, let's just replace it with water cooling  :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 03:01:43 pm
They really need to do a recall on this.  Sucks to have to do it, but what can ya do...

My guess is they will quietly fix the issue in new production units, and then honour the 3 year warranty claims as and when they come up, and hope it's not too many.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on August 30, 2013, 03:21:27 pm
The thin tab is indeed perfectly normal.

(https://lh4.googleusercontent.com/-Rkw9JbBuNDg/UdcAry1OcnI/AAAAAAAADFk/rgT_bBzOmio/w959-h719-no/IMG_20130705_182053.jpg)

Both of those are genuine ST parts, and the right hand, single-gauge one came from Farnell. Cost almost twice as much as the other, too.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bored@Work on August 30, 2013, 03:27:40 pm
Really, all these units will need to go back to Rigol.

Maybe they are lucky. The power is coming to the board via some connector. If the power from that connector is only going into the regulator they could device a fix that is supposed to be plugged in between the cable and the board connector. Like a pre-reglator, dropper resistor, etc. If they are lucky no soldering required.

But my bet is on Dave's suggestion. They might do nothing and just treat broken stuff under warranty, hoping there won't be too many. Hoping people won't find their receipt after a year or two, and probably playing the stupid game they played in the past: Service, support and warranty only for units bought via official distributors, screwing everyone who bought on ebay, or did use some other way of doing a gray import.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Laidukas on August 30, 2013, 04:45:05 pm
Does this video mean that higher end model that shares the hardware also has this issue?

Damn, I trusted RIGOL so much, I have a lot if RIGOL equipment and now they spoiled their reputation.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 04:47:52 pm
I have confirmation that the issue has already been fixed in a new board revision.
They changed the board to fit a larger heatsink, but it's not a huge amount bigger. See photo.
They measured the temp at 76C in a 28C ambient , but I'm not sure if this is free standing out of the case, or in the case with airflow.
They will be replacing all Australian units, I don't know about other countries.

I would not call this a proper belt'n'braces fix, as I think the heatsink still isn't big enough, but it probably now puts it into the (just) acceptable category.
They have also apparently made a few other fixes.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndyC_772 on August 30, 2013, 04:52:57 pm
It's rather sad that they didn't take the opportunity to increase the gap between the heat sink and those two electrolytic caps a bit further, it's not as though there's no room :(
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on August 30, 2013, 04:56:43 pm
I have confirmation that the issue has already been fixed in a new board revision.
They changed the board to fit a larger heatsink,…

so much for the claim that "defective parts" have been used.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 04:58:06 pm
It's rather sad that they didn't take the opportunity to increase the gap between the heat sink and those two electrolytic caps a bit further, it's not as though there's no room :(

Technically they are arse backwards. The airflow will come from the side vents, over the heatsink, and then out the back over the caps. The heatsink should have been toward the rear (left in image).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndyC_772 on August 30, 2013, 05:06:28 pm
Actually I take it back... I've just seen how bad they were on the first rev!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on August 30, 2013, 05:13:53 pm

They will be replacing all Australian units, I don't know about other countries.

I would not call this a proper belt'n'braces fix, as I think the heatsink still isn't big enough, but it probably now puts it into the (just) acceptable category.
They have also apparently made a few other fixes.
this restores my confidence a bit, but I think I owe you a thanks Dave.
Call me cynical but I don't think there would have been any action without your BS call
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on August 30, 2013, 05:17:12 pm

They will be replacing all Australian units, I don't know about other countries.

I would not call this a proper belt'n'braces fix, as I think the heatsink still isn't big enough, but it probably now puts it into the (just) acceptable category.
They have also apparently made a few other fixes.
this restores my confidence a bit, but I think I owe you a thanks Dave.
Call me cynical but I don't think there would have been any action without your BS call

I really don't think they sourced a heatsink, modified the board, and had it produced and tested in just two days..
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndyC_772 on August 30, 2013, 05:18:25 pm
They might have decided whose units get replaced with new ones, though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 05:26:00 pm
Call me cynical but I don't think there would have been any action without your BS call

I can't take credit.
They obviously knew about this and had this fix in place for some time.
How they found out, I don't know.
And I don't know if these new units are on shelves yet or not.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Redtailed on August 30, 2013, 05:54:00 pm
From the forum on video #509 (http://www.eevblog.com/forum/blog/eevblog-509-rigol-832-lab-power-supply/msg278445/#msg278445), I said:

Quote
I remain confident that if Dave opened up a Rigol product that reeked of oversight, bad design, or dangerous flaws, he'd have a field day showing them in all their glory and ask the manufacturer to respond.

I swear I didn't predict this.

Please no email asking for lottery ticket numbers. :)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: firewalker on August 30, 2013, 06:00:29 pm
Why a mosfet as a series pass element?

Alexander.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on August 30, 2013, 06:15:55 pm
So Dave, a 'fix' has already been implemented by Rigol. Is yours going to be replaced? Can you do another investigation on the new unit if you get one? Also 'some other improvements' you speak of would be interesting to know about.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: firewalker on August 30, 2013, 06:24:11 pm
They will be replacing all Australian units, I don't know about other countries.

Rigol or the distributer?

To bad you voided you warranty!!!  :P :P :P :P

Alexander.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: siklosi on August 30, 2013, 07:12:52 pm
Dave (and Chuck Norris) can't void warranty!!!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: quarros on August 30, 2013, 07:36:49 pm
Hmmm someone correct me if I'm wrong, but wouldn't be a much more cost effective and "elegant" solution to put a pre regulator on the 12V tap with a little standalone board. It could be even using a switching type reg, as the LM317 still would dissipate some excess (keeping the line clean) but the input would be around 8-9 volts, lessening the burden on the LM317.
Or is the 12V input goes somewhere else on the board and therefore needs to be 12V?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 08:01:33 pm
So Dave, a 'fix' has already been implemented by Rigol. Is yours going to be replaced?

Yes. The Oz distributor (Emona) has confirmed that Rigol are going to replace all units in Oz. Presumably through Emona who then would just charge Rigol whatever it costs. That's usually how these things are handled with most manufacturers.
I do wonder what happens to the old units?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 08:03:51 pm
Do Rigol use sequential serial numbers? Is there any reason not to post serial numbers here? I'm thinking we could try to establish the range that is affected.

I was asked for my serial number and digital version number, so maybe they can track based on these. But of course you'd expect any decent manufacturer to be able to track this sort of stuff.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on August 30, 2013, 08:07:25 pm
Well, this is an extremely unsatisfactory "solution". I expect expensive test equipment to last for much longer than three years. When I get home I'm going to see if I can see which type of heatsink is fitted to mine, i.e. if it has the fix or not. If not I'll be pushing for a replacement unit, or looking for a way to accelerate failure in the warranty period without breaking the warranty seal.

Hold up.. Rigol offer 3 years warranty, that is pretty damn good for the price point. I also doubt they build failure into their product. Any failure would be due to the fact they are making it to a price,a price which is appealing to you.
If you want top quality test gear that has a 20 year life expectancy you may want to spend more than $400.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on August 30, 2013, 08:11:05 pm
They obviously knew about this and had this fix in place for some time.

IIRC Corp just got his, probably others as well.  Means Rigol didn't bother to recall the unsold faulty units, probably just hoping the users of these just don't notice.

Another nail in their coffin of reliability and trustworthiness.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on August 30, 2013, 08:11:55 pm
the longer i think about it the angrier i get.

rigols "new solution" to the problem is still halfhearted. if they redesign the board to relocate the voltage regulator they could also have reserved mounting holes for a bigger heatsink - and with "bigger" i suppose the like ~2cm of height that should still be available. is that too much to ask for? 2cm *more* strand casted aluminium?
its about doing it right after spotting a design flaw, not about doing just whats necessary to avoid further breakdowns.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 08:14:16 pm
IIRC Corp just got his, probably others as well.  Means Rigol didn't bother to recall the unsold faulty units, probably just hoping the users of these just don't notice.

Yep, I'm a bit miffed that they shipped me one knowing it was like this. And mine wasn't old local stock, it came straight off the plane, I had to wait a bit for it.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Lefuneste on August 30, 2013, 08:35:55 pm
I think Rigol is seriously mishandling this design issue so far and they will be forced to update their board again after your review Dave. Seriously your videos are so well known by the community (including Rigol themselves posting your reviews on their website), that there's no way in the Universe that they will escape a proper thermal management of this part now... They will have to handle so many returns, so many complaints (with mysteriously broken warranty stickers), so many questions to support... It's a direct path to a shameful failure. It's true these supplies don't sell like Iphones volume-wise, but considering that Rigol wanted to set a new market standard with this supply, they won't escape this. So in a certain way, your video is going to cost them the money they avoided spending in the first place... There may be some justice in this world after all...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 30, 2013, 08:49:32 pm
I might wait asking for replacement if Rigol comes up with a second (or third :P) iteration of this fix. I'm not impressed either: almost 90°C heatsink temperature at 40°C ambient with presumably decent airflow. And presumably without the additional current draw from the USB port (which hasn't been tested). Not a lot of margin there. It's probably going to work without resetting under most conditions, but I still fear for the life of those caps.

Does any owner feel like hooking up a load to the USB port and measuring the increase in current or temperature of the '317?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on August 30, 2013, 09:07:39 pm
just got mail from the reseller i am buying the PS from.

they state that there were problems with the transformer and so also with the voltage regulator. the transformer has been changed in the second generation of the PS and the problems should be void.

thats for the 240V model they sell here in germany… we'll see.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 09:08:22 pm
Does any owner feel like hooking up a load to the USB port and measuring the increase in current or temperature of the '317?

It would be interesting to see if loading down the USB port can reset the unit...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: madires on August 30, 2013, 09:10:27 pm
105c caps right next to a device that reaches 111c, smells like planned obsolescence (and boiled electrolyte) to me!

Absolutely! I'd consider placing electrolytic caps directly besides a heatsink (>30-40 °C) in a lab grade device a show stopper. It's built to fail.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: manicdoc on August 30, 2013, 09:17:45 pm
Just out of interest - what was the no load power consumption on the device? Just wondering how much of that is down to the 5w going out as heat..

I had a similar situation on a robot  powering 5v from 12v and just ordered a little switcher circuit online to do the job.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: funfairEE on August 30, 2013, 09:25:46 pm
out of interest will they still exchange yours because you voided the warranty by opening it??
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: hikariuk on August 30, 2013, 09:27:45 pm
out of interest will they still exchange yours because you voided the warranty by opening it??

I get the feeling Dave gets a pass on voided warranties for test and lab equipment.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on August 30, 2013, 09:28:12 pm
out of interest will they still exchange yours because you voided the warranty by opening it??

I'm quite sure they will exchange Dave's, even if he modded a new heatsink, etc.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Oracle on August 30, 2013, 09:52:15 pm
unbelievable: how can rigol be so blind to make run a regulator to 120°?? It's insane. Good to know about this before buying rigol gears.... But, at least this confirm i was right to invest a lot of money on my lab power supply.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mikeselectricstuff on August 30, 2013, 10:13:13 pm
just got mail from the reseller i am buying the PS from.

they state that there were problems with the transformer and so also with the voltage regulator. the transformer has been changed in the second generation of the PS and the problems should be void.

thats for the 240V model they sell here in germany… we'll see.

Interesting - I wonder if maybe the issue was (partly) that the transformer wasn't supposed to put out 12V on that winding - if it had been designed to supply 8-9V after rectification, that may have been OK with that heatsink.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mikeselectricstuff on August 30, 2013, 10:15:12 pm
out of interest will they still exchange yours because you voided the warranty by opening it??
Depending on what country you are in, consumer law means goods must be as described and fit for purpose. Pulling it apart, warranty seals etc. have no bearing unless they can show you caused damage.
This supecedes any warranty condition.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 10:27:12 pm
Just a clarification.
There was some mistaken communication that Rigol would be replacing units in Oz. That does not appear to be the case, or at least was an incorrect assumption at this stage. The local rep will simply come good with whatever Rigol come up with (board replacement or whatever). Nothing is confirmed yet, talks are still in progress with Rigol.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: M0BSW on August 30, 2013, 10:29:33 pm
Personally I wont' buy anything New that comes with rust on it, for the price of the thing,it's not cheap. I think the rust issue is just pure shoddy, no matter how small, now I'm sitting back on the fence as I almost parted with money for a Rigol scope, now I'm wondering did they cut corners there too. I don't like shoddy Newly bought equipment, it's all about confidence.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on August 30, 2013, 10:38:45 pm
Hi,
I have just buy DP832A ,
will have the same problem?
 :palm:
Title: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ddavidebor on August 30, 2013, 10:44:50 pm
Hi,
I have just buy DP832A ,
will have the same problem?
 :palm:

Power it up and power all the channel.

Then go to drink a coffe, if you return and the channel had became all off, it has resetted.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on August 30, 2013, 10:51:52 pm
ok, i test it.
how many minutes should I wait?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: RupertGo on August 30, 2013, 10:57:14 pm
It's surprisingly common - or used to be, anyway - to find overstressed and under=cooled regulator or switching devices in production equipment. I sometimes wonder if some of those designers even understand what makes their soldering iron heat up, and how many production lines include proper snake-and-bake testing. (Oddly, some famous cheapie brand names take it really seriously - I guess that's because they understand about margins and post-sale costs, and have done the sums on the price of getting it right versus getting it wrong.)

The real shocker here is that this is a PSU Design Silly 101 error in a precision power supply from a relatively new brand that has spent serious money on getting things right in the past, and has perhaps done the most to shake off the Chinese rep for, as Dave says, howya doin'? Even top-notch equipment goes to market with bugs, and mostly you can sorta see how they got through design, production and test: the real world is impossible to simulate.

But this is much harder to explain. A last minute spec or component change that wasn't properly reviewed, followed by lack of production sample testing? A minor piece of design shucked off to a student engineer and not checked thereafter (seen that one)? Has Rigol outsourced this design, or given it to a new division that doesn't have the same oversight as its other test equipment? Something systematic is broken, and that has repercussions for future products. All good engineers know that if there's a failure, it's not enough to fix it - you want to know why it happened, and whether it could happen again.

At this point, I think it would be really good for Rigol to invite Dave on a factory visit and let him talk to the designers, engineers and management on camera. I know this would mean Dave taking a chunk of time out from his schedule, and what that means for a one-man band running a pretty tight ship. And I know that Chinese companies do not have the same approach to media interaction as Western outfits.  I don't pretend that this would be an easy thing for either him or Rigol to justify, even before dealing with the potential problems if Rigol's competitors wanted to do the same thing.

He could ask about the rust, too.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Oracle on August 30, 2013, 10:59:12 pm
Just a clarification.
There was some mistaken communication that Rigol would be replacing units in Oz. That does not appear to be the case, or at least was an incorrect assumption at this stage. The local rep will simply come good with whatever Rigol come up with (board replacement or whatever). Nothing is confirmed yet, talks are still in progress with Rigol.

maybe a big discount?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: firewalker on August 30, 2013, 11:04:57 pm
just got mail from the reseller i am buying the PS from.

they state that there were problems with the transformer and so also with the voltage regulator. the transformer has been changed in the second generation of the PS and the problems should be void.

thats for the 240V model they sell here in germany… we'll see.

Interesting - I wonder if maybe the issue was (partly) that the transformer wasn't supposed to put out 12V on that winding - if it had been designed to supply 8-9V after rectification, that may have been OK with that heatsink.

What the label on the transformer states?

Alexander.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: firewalker on August 30, 2013, 11:08:24 pm
Someone posted this image.

(http://i.imgur.com/4ksKYt6s.jpg) (http://i.imgur.com/4ksKYt6.jpg)

Alexander.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on August 30, 2013, 11:13:32 pm
Interesting - I wonder if maybe the issue was (partly) that the transformer wasn't supposed to put out 12V on that winding - if it had been designed to supply 8-9V after rectification, that may have been OK with that heatsink.

Someone already mentioned and previously posted photographs of the transformer in their DP832 being a 500VA unit with a 9v winding while Dave's unit has a transformer marked 400VA with a 10v winding.

LM317s are not specified with less than 3v across them, so with ripple and say a target 20% line variation tolerance 8-9v isn't realistic. Lowering the transformer voltage enough for that heatsink would require an LDO regulator.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AlfBaz on August 30, 2013, 11:21:22 pm
Hi,
I have just buy DP832A ,
will have the same problem?
 :palm:
The pcb Dave showed had DP832A written on it. So the internals seem the same except the 832 is software crippled.

Unless rigol publish serial numbers of before and after the pcb re-spin, you'll only really know by looking inside.
It appears to reboot with now air flow over the regulator so short of jamming the fan with a screw driver the only way to know is to open it up, unless it can be proven that drawing 500mA out of the USB can cause a reset even with the fan running

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on August 30, 2013, 11:29:11 pm
I think Rigol is seriously mishandling this design issue so far and they will be forced to update their board again after your review Dave. Seriously your videos are so well known by the community (including Rigol themselves posting your reviews on their website), that there's no way in the Universe that they will escape a proper thermal management of this part now... They will have to handle so many returns, so many complaints (with mysteriously broken warranty stickers), so many questions to support... It's a direct path to a shameful failure. It's true these supplies don't sell like Iphones volume-wise, but considering that Rigol wanted to set a new market standard with this supply, they won't escape this. So in a certain way, your video is going to cost them the money they avoided spending in the first place... There may be some justice in this world after all...

 :-+
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 30, 2013, 11:47:45 pm
What the label on the transformer states?

Mine states 10V and measures 10.5V (RMS)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: M0BSW on August 30, 2013, 11:49:30 pm
Now will be a goodtime to see how much their rivals will discount their prices !!!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on August 30, 2013, 11:52:17 pm
Someone posted this image.
(http://i.imgur.com/4ksKYt6s.jpg) (http://i.imgur.com/4ksKYt6.jpg)
Alexander.

mine hasn't been delivered jet. i'll post pictures.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Kjelt on August 31, 2013, 12:21:44 am
Anyway this thermal issue has shifted all attention from the previous bad problem: the voltage glitch at startup.
Adding it all up, i'll pass on this product, i'll stick with my three full analogue Delta power supplies. Some of them are now 20 yrs old, last year i have recapped the elco's and they still work like a charm. And best, no firmware onboard that over time will fail  ;) .
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 12:28:15 am
There's nothing wrong with analog power supplies if you don't need presets, computer control or programmability. Performance hasn't improved much: it's not like the ripple, transient response or regulation of the Rigol supplies is better than that of the old analog supplies. Plus those analog meters have much more bandwidth than that wanky fake analog dial of the DP832.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: free_electron on August 31, 2013, 12:31:13 am
Meanwhile, i am wondering about something toally different....

Why put in an lm317 where a 7805 would have done ....
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 12:34:11 am
I was wondering the same. My guess was that they use an LM317 somewhere else on the board, so it reduces BOM size. Haven't looked at the teardown pics to check, though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: G7PSK on August 31, 2013, 12:40:53 am
It's rather sad that they didn't take the opportunity to increase the gap between the heat sink and those two electrolytic caps a bit further, it's not as though there's no room :(

Technically they are arse backwards. The airflow will come from the side vents, over the heatsink, and then out the back over the caps. The heatsink should have been toward the rear (left in image).

Interesting that you should say that as I was thinking the same thing but for a different reason today about my scope the fan sucks air from the front and expels it out the back therefore sucking in any fume from soldering, this is a problem that manufacturers of welding equipment are aware of and the fans blow air from the back to the front thus lessening the amount of dust and fumes drawn over the insides, not such a problem with solder fumes I know but they still leave sticky residues on surfaces, equipment that is designed for industrial use should be made with industrial situations in mind, I don't do that much soldering but the scope I have could easily be used in an industrial situation it as it is not one aimed at the hobbyist. To my mind all fans on equipment should exhaust to the front and not the rear.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on August 31, 2013, 12:41:53 am
Meanwhile, i am wondering about something toally different....

Why put in an lm317 where a 7805 would have done ....

Perhaps a 7805 was going into thermal shutdown. >:D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 12:45:30 am
In general it's more efficient for the fan to be blowing out than blowing in. It also gives a more diffuse airflow across the components. So that would involve mounting fans on the front panels, something that's not feasible for most equipment where front panel real estate is extremely limited. It's also less comfortable for the operator.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on August 31, 2013, 12:57:56 am
Perhaps a 7805 was going into thermal shutdown. >:D

The sad bit is that you are probably correct.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on August 31, 2013, 01:03:03 am
If hack with switching regulator ?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 01:03:23 am
The problem is probably that they were supposed to use counterfeit LM317s without a working thermal shutdown. But some idiot at the assembly house bought genuine LM317s.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: free_electron on August 31, 2013, 01:13:31 am
Why put in an lm317 where a 7805 would have done ....

Probably because the 7805 drifts much more with temperature than an LM317 and low temp co. resistors.
Irellevant. This the logic supply. A 7805 will do perfectly fine.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndyC_772 on August 31, 2013, 01:41:12 am
I still find it odd that the CPU was resetting even though we never actually see the 5V supply drop out - just a fairly minor increase in the (frankly awful) ripple voltage on the 5V supply.

Is the amount of ripple already marginal in terms of what the CPU can tolerate? Could it be approaching the brown-out trip point even under normal operation? If so, the thermal problem really isn't the only problem.

How much voltage margin is there between the output of the LM317 toaster and the minimum the CPU requires in order not to reset? How does this vary from unit to unit and over time and temperature?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: LoyalServant on August 31, 2013, 02:10:19 am
Perhaps a 7805 was going into thermal shutdown. >:D

The sad bit is that you are probably correct.

And if THAT tidbit got past them then it's a worse fail than it is now.
I am sure that detail would never make the light of day because that would confirm they knew something was up...

I am still trying to get my head around the that xformer having a 12 volt tap for a 5 volt supply.
Must have had a shitload of those xformers laying around :D

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ResR on August 31, 2013, 02:23:53 am
I suspect some grid noise causes resets, is there any mains noise filter (for ex. 15SRB1-Q) in that PSU? I also have seen too many times where the capacitors are too close to the heatsink, like just to make sure it brakes eventually within few years.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: IanJ on August 31, 2013, 02:28:38 am
I still find it odd that the CPU was resetting even though we never actually see the 5V supply drop out - just a fairly minor increase in the (frankly awful) ripple voltage on the 5V supply.

Thats what I was thinking......can only think that there's a watchdog circuit in there that trips the Cpu at the smallest thing. Either that or it's a bad watchdog design.......didn't Rigol state they had fixed a number of things?.....so maybe more than the reg and possible transformer winding.

Ian.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: free_electron on August 31, 2013, 02:44:16 am
its even more off since that motorola thing is not a 5 volts part .... it is designed to run on much lower voltages. so there must be an additional regulator on the front panel . probably a switcher ...

and there is ...

so that could be the trouble. the lm317 starts to buckle , the switcher is drawing pulsed currents , the input voltage droops enough so the switcher goes in protection , starving the cpu , the brownout detector trips and slams on the brakes-> reset.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 03:00:12 am
Your theory sounds likely, but that still doesn't explain why the +5 V rail appeared to be perfectly stable.

It would be kind an odd choice: use a switcher to go from 5 V to 1.8-3.3 V at 100 mA or so, but use a linear regulator from 12 V to 5 V at 700 mA. Would they have been worried about interference on the analog power supply board?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on August 31, 2013, 03:12:05 am
Someone already mentioned and previously posted photographs of the transformer in their DP832 being a 500VA unit with a 9v winding while Dave's unit has a transformer marked 400VA with a 10v winding.

Can anybody measure their 500VA transformer and post the dimensions, please? Dave already provided the height and diameter for the 400VA unit. I'm curious to know if this is just a 'cosmetic' change of a sticker and one of the secondaries, or if the toroid core is actually somewhat larger in the 500VA units.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: LaurenceW on August 31, 2013, 03:25:56 am
A couple of points.

Dave, where are all the twelve year old trolls, who only a couple of videos back were claiming that you were somehow in the pay of the equipment suppliers, such as Rigol? Hellooooooooooo??? Nah, can't hear 'em... :-DD

Five watts is five watts, no matter how big the heatsink which dissipates it. This is poor design in the age of higher efficiency equipment. A very simple (LM2575?) switcher would have done the job much better. Less heat all round, and could have probably saved themselves the price of any heatsink, at all.

Dave, to get MAX heat dissipation in the main heatsinks, you'll have to measure the supply running at the LOWEST output voltage corresponding to the highest (Triac) transformer tap <you knew that!> - I think you said it was 22V. Then (~50v-22V) x 3A is 54W. And then all this from one output device??? Hmmm - my old school TTI Thurlby Thandor supply outputs up to 3A at 30V and spreads that load across no fewer than SIX 2N3055's - luverly :-+ I think you Oz folk have a saying including the words "Brick" and "Dunney" to describe this construction style...?

Last thing - check your blood pressure, mate. We worry about you.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: pickle9000 on August 31, 2013, 03:49:15 am
So in this particular case assuming Rigol fixes the supply problem (and a few of the other software issues and poweron spike), how many people will buy the unit? Personally I prefer to know the faults my equipment has (within reason of course). What I don't like is to find an equipment fault after a major investment. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on August 31, 2013, 03:50:38 am
So in this particular case assuming Rigol fixes the supply problem (and a few of the other software issues and poweron spike), how many people will buy the unit? Personally I prefer to know the faults my equipment has (within reason of course). What I don't like is to find an equipment fault after a major investment.

is what happened to me !!  :palm: |O |O
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on August 31, 2013, 04:00:16 am
This is poor design in the age of higher efficiency equipment. A very simple (LM2575?) switcher would have done the job much better. Less heat all round, and could have probably saved themselves the price of any heatsink, at all.

Yes, this is bizarre to me as well. Why in god's name would you put 800mA or whatever it was through a linear regulator in 2013? It's obviously not in the output path, so who cares if it's "supposed to be a linear supply"? Dear lord, with a little care in design, a decent switcher isn't going to put any appreciable noise on the output...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Phantomix on August 31, 2013, 04:12:31 am
LOL

ROFL


without reading the whole thread, i can exactly say why they designed it like that

They're sitting in the US, where they only have half the input voltage! So, in the design process this was fully OK and wouldn't justify a switching regulator. Then, when it's gone to production, noone looked again at it, as it basically works. Maybe, some software developer had "random software resets" on his todo list before they finally found it... :D

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on August 31, 2013, 04:14:56 am
LOL

ROFL


without reading the whole thread, i can exactly say why they designed it like that

They're sitting in the US, where they only have half the input voltage! So, in the design process this was fully OK and wouldn't justify a switching regulator. Then, when it's gone to production, noone looked again at it, as it basically works. Maybe, some software developer had "random software resets" on his todo list before they finally found it... :D

No, that'll have nothing at all to do with it.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: free_electron on August 31, 2013, 04:15:21 am
LOL

ROFL


without reading the whole thread, i can exactly say why they designed it like that

They're sitting in the US, where they only have half the input voltage! So, in the design process this was fully OK and wouldn't justify a switching regulator. Then, when it's gone to production, noone looked again at it, as it basically works. Maybe, some software developer had "random software resets" on his todo list before they finally found it... :D

what have you been smoking ?

- RIGOL is chinese
- China is 220 volts...
- the machine has a switch to select 110 /220 ...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Phantomix on August 31, 2013, 04:29:38 am
what have you been smoking ?

- RIGOL is chinese
- China is 220 volts...
- the machine has a switch to select 110 /220 ...
just wanted to be funny

You're right, they sit in china, but also in the US and Germany, according to their website.
Quote
RIGOL Headquartered in Beijing, China, with the branch offices in Cleveland, OH,and Munich, Germany,
Yes, maybe they have developed it in China, I would not bet on this.


About the 110/220 switch:
Oookay, maybe. With such a design flaw, I wouldn't be surprised to find out about a 2nd design flow and the problem still having to do with 110/220
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Paul Moir on August 31, 2013, 04:41:02 am
Maybe I'm being naive, but how do you blow 700ma on a power supply user interface?  I mean, I understand that it's a benchtop power supply and that low power consumption would be just about the last thing to strive for, but to me that's seriously getting up there.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: FrankBuss on August 31, 2013, 04:44:09 am
Maybe I'm being naive, but how do you blow 700ma on a power supply user interface?  I mean, I understand that it's a benchtop power supply and that low power consumption would be just about the last thing to strive for, but to me that's seriously getting up there.
The display and background light can use quite a lot of power, if powered from the same 5V.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on August 31, 2013, 04:48:54 am
Maybe I'm being naive, but how do you blow 700ma on a power supply user interface?

Well, that's another option. Base model works for five minutes. $100 more and it shuts off the 500mA dummy load...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on August 31, 2013, 04:50:38 am
The display and background light can use quite a lot of power, if powered from the same 5V.

Is CCFL still that widely used for LCD backlight purposes? I'm surprised they haven't switched to white LEDs exclusively by now.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: SeanB on August 31, 2013, 05:12:58 am
Most likely RGB LED's or white ones. Not going to save much power wise, you still need about 200mA at 5V to light them on a display of that size.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Galaxyrise on August 31, 2013, 05:37:56 am
Dave, to get MAX heat dissipation in the main heatsinks, you'll have to measure the supply running at the LOWEST output voltage corresponding to the highest (Triac) transformer tap <you knew that!> - I think you said it was 22V. Then (~50v-22V) x 3A is 54W.

I was wondering the same thing.  And why tap 50V when the max output is 30V? That seems like a needless voltage drop across the transistor.  It's almost as if the person specifying the transformer voltages was speaking peak-to-peak but they got implemented as RMS.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on August 31, 2013, 05:48:18 am
I was wondering the same thing.  And why tap 50V when the max output is 30V? That seems like a needless voltage drop across the transistor.  It's almost as if the person specifying the transformer voltages was speaking peak-to-peak but they got implemented as RMS.

Lower mains voltage. It should still works at ~200V.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: IanJ on August 31, 2013, 05:49:22 am
With these design issues I wouldn't be surprised if the 220/120vac sticker is reversed....... :scared:

.............ok, I'll get my coat.

Ian.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on August 31, 2013, 05:50:16 am
Maybe they use a 50v transformer tap for yet another model. I believe I've seen a DP811 or DP821 which has a 60V dc output.

It seem more and
Ore likely they use identical hardware for their entire model range.

Edit: dp821a
http://www.rigol.com/prodserv/DP821A/ (http://www.rigol.com/prodserv/DP821A/)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ant452 on August 31, 2013, 06:21:52 am
A lab power supply in which its power supply has a design issue....  Not good.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dread on August 31, 2013, 06:48:32 am
A couple of points.
Dave, where are all the twelve year old trolls, who only a couple of videos back were claiming that you were somehow in the pay of the equipment suppliers, such as Rigol? Hellooooooooooo??? Nah, can't hear 'em... :-DD

While I was not one of those "twelve year old trolls" and I have made No such accusations about Dave, I would point out that this Video certainly had a different feel about it than Dave’s normal video's and I am pretty sure it was partly meant to address those people directly! You can read into that what you want, in any case I liked the teardown a lot.

Since this whole DP832 series started I have been saying that I would rather have my 2x (HP E3615A) power supplies any day of the week over a DP832 and that was met with a few negative replies.  The fact is that Dave and many of you guys talk a lot about the building things to a price point, using a $1 part versus $2.50 part but then the whole notion of that seems to go out the window when your buying equipment.  You need to use that same logic when buying test gear and reflect that same logic onto the company your thinking of buying from.

If your Rigol and your making a power supply, the first thing you do is work out a basic list of features and then you set a price point per unit so the engineers know what kind of budget they are designing around.   If you put that into a nice Pie chart and start to slice it up, in the case of the DP832 you need to take out a nice little slice for the microcontroller related section and include the costs involved for all the software development and the extra shielding etc.  For a power supply that sells for around $420 it probably costs about $220 to manufacture and at this low a price point once you take out the expenses involved in all the Microcontroller stuff and that nice Toroid your not left with a whole lot of money to make a proper linear power supply with high margins and a solid interior and exterior construction.

When you compare that to say an older HP/Agilent supply they used most of that pie chart on the Voltage/Current regulation design and put in a crap load of money testing those designs under all sorts of conditions.  The rest of the money was used on making a solid exterior.  On top of that your talking about a $800 unit in early 1990's money.

Every time I look at a piece of gear from China I look at how many bells and whistles they have added and I try to subtract that from what I figure the cost price is and then calculate out how much money they must have spent on the core engine of the device.

To me the Core is what really matters, what’s the point of having a Precision Lab Power supply with 100 bells and whistles if it’s output is not really precise or reliable?

When I saw the DP832 I knew the core engine had to be made on a very low budget, the rotary encoder knob was the first indication that money was very tight and it only got worst as I saw more.  I think if Dave was to look around further I think he would find that regulator is probably just one of many shortcuts they took to save money.  I would bet good money that almost every part in that unit from the regulators to the Caps are all picked from the lowest bidder and very little margin is built into the overal design.

BTW it was nice to see the Fluke 87V were it belonged, front and center.

Great Video Dave.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndyC_772 on August 31, 2013, 07:45:24 am
Your theory sounds likely, but that still doesn't explain why the +5 V rail appeared to be perfectly stable.

It would be kind an odd choice: use a switcher to go from 5 V to 1.8-3.3 V at 100 mA or so, but use a linear regulator from 12 V to 5 V at 700 mA. Would they have been worried about interference on the analog power supply board?
There are plenty of very small and efficient dc-dc converters which are designed for low voltage use and which can only accept inputs up to 5V or thereabouts. I use them all the time as my 'standard' way to generate all the low voltage rails needed for CPUs, FPGAs and the like, and other than that the QFN packages are a swine to solder and inspect properly, they do a superb job.

Check out www.enpirion.com (http://www.enpirion.com) for some good examples. The larger parts that can run off 12V are new, and over sized for many applications. The smaller parts, which have been around for longer and which are ideal for powering logic, can only tolerate up to 5.5V or so - hence the need for a linear pre-toaster.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: envisionelec on August 31, 2013, 07:56:25 am
Hey Rigol - I'll gladly buy dozens of these power supplies....for YOUR cost!

:)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tom66 on August 31, 2013, 08:17:36 am
Why am I telling this story ? well the firmware update changes just one thing....it slowed the zoom motor and effectively lowered its current consumption. It appears that the battery in the SX280 is overloaded by video and Zoom functions operating at the same time and drops its p.d. as a result. Oooops !

Reminds me a little of the "infamous" HP dv6000 fix... these laptops are prone to having the lead-free solder on the GPU fail due to the laptop running hot. The HP "fix" makes the fan run at 100% all the time, which probably puts failures just outside of the warranty period and turns the laptops into miniature jet engines.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: centon1 on August 31, 2013, 09:09:03 am
Dave I can't thank you enough for everything and especially these reviews. My DP832 was to ship this coming Tuesday Sept. 3rd.
I've canceled it.
 
http://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif (http://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 31, 2013, 09:19:39 am
While I was not one of those "twelve year old trolls" and I have made No such accusations about Dave, I would point out that this Video certainly had a different feel about it than Dave’s normal video's and I am pretty sure it was partly meant to address those people directly!

As always, those who try and read intent into my videos fail miserably, every time.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: xrunner on August 31, 2013, 09:24:09 am
I watched the whole video yesterday, now there is 11 pages of posts, so forgive me if this has been asked.

I was wondering why they just didn't mount the regulator on a much bigger heat sink? Seems like there is enough room. That doesn't excuse the shitty electrical design, but metal isn't real expensive and if they had settled on the electronic part already seems like an easy way to buy more thermal capacity.

But you guys are better at this than I am.  :-//
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AlfBaz on August 31, 2013, 11:08:41 am
I don't know much about these matters but given a precision power supply board that goes to the trouble of using guard traces and stress relief on the reference, why would you then want to go and place a switcher on the same board to produce nearly an amp?

Not only would they have to contend with noise on the supply board but those gulps of current are being drawn from the same transformer that's supplying the DC out. Seems to me that using a switcher here would almost defeat the purpose of designing a linear lab supply in the firs place

Edit: oh and using only that one pissy series pass element seems a bit dodgy as well
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on August 31, 2013, 11:17:57 am
It's all to a price level.
Lots of companies have issues from time to time due to oversights and mistakes.. This is built to a very nice price level and they have worked towards fixing it. They provide a 3 year warranty, pretty good for this price level. There is too much risk of issues for them to be purposefully cooking the capacitors.

If you aren't content or don't understand what you are buying here then go spend $2000+ on a different brand, or grab the siglent.

I'll be putting an order in for one when I can be guaranteed the newer model board and I suspect that it will perform more than adequately for my purposes.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TerminalJack505 on August 31, 2013, 11:20:42 am
I watched the whole video yesterday, now there is 11 pages of posts, so forgive me if this has been asked.

I was wondering why they just didn't mount the regulator on a much bigger heat sink? Seems like there is enough room. That doesn't excuse the shitty electrical design, but metal isn't real expensive and if they had settled on the electronic part already seems like an easy way to buy more thermal capacity.

But you guys are better at this than I am.  :-//

That's what they wound-up doing.  Somewhere in this or the other thread Dave posted a picture of a new board layout.  The heatsink is bigger and has been moved away a bit from the caps.

And, yes, it should take care of the problem so long as it's big enough.  I've been applying the thermal modeling information Dave taught in one of his videos.  I pretty much just guessed at some of the numbers but they're probably pretty close.  Making the heat sink's thermal resistance smaller has a dramatic effect.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on August 31, 2013, 12:37:48 pm
[While I was not one of those "twelve year old trolls" and I have made No such accusations about Dave, I would point out that this Video certainly had a different feel about it than Dave’s normal video's and I am pretty sure it was partly meant to address those people directly! You can read into that what you want, in any case I liked the teardown a lot.


I think you (or rather they, if you are not one of them) flatter yourself if they think Dave is adjusting the tone or content of his videos to address one or two outspoken trolls.

I have a much more reasonable explaination - occam's razor.  Dave really liked the power supply.  Dave really didn't like the power supply thermal issue.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fsck on August 31, 2013, 01:23:18 pm
well, the rest of the PSU looks pretty good.
But that restarting thing is really crippling
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on August 31, 2013, 02:05:29 pm

They will be replacing all Australian units, I don't know about other countries.

I would not call this a proper belt'n'braces fix, as I think the heatsink still isn't big enough, but it probably now puts it into the (just) acceptable category.
They have also apparently made a few other fixes.
this restores my confidence a bit, but I think I owe you a thanks Dave.
Call me cynical but I don't think there would have been any action without your BS call

I really don't think they sourced a heatsink, modified the board, and had it produced and tested in just two days..
no, not the fix, I can bodge a new heatsink or switching regulator myself- this is what I wanted to hear "They will be replacing all Australian units" interesting a sales slime somewhere else knee jerk reaction was to blame counterfeit part - without this sort of publicity it would have been swept under the carpet. "Dave Nader"  :-+
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: SeanB on August 31, 2013, 02:59:12 pm
Probably there were a range of boards in stock with some being V2.0 and some V2.1 or later ,and as the cost of scrapping the existing V2.0 stock is high, and they will do the job for basic use with the likelyhood of failing in the warranty period being small ( few people will draw 500mA from the USB to drive a flash drive, at load it will run cooler with a high fan speed, most will be in a cool airconditioned environment) some bean counter calculated the chances of failure are small, and this would be within the allowed warranty return value. However now they have had it shown, so have to do something to either replace the boards, or to have a field modification kit to add a bigger heatsink or a small modification board to replace the whole power supply.

I hope as well they have fixed the swapped colours on the power leads to the front panel, it can be confusing to the authorised service centre people that have to repair them.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dread on August 31, 2013, 04:02:08 pm
[While I was not one of those "twelve year old trolls" and I have made No such accusations about Dave, I would point out that this Video certainly had a different feel about it than Dave’s normal video's and I am pretty sure it was partly meant to address those people directly! You can read into that what you want, in any case I liked the teardown a lot.


I think you (or rather they, if you are not one of them) flatter yourself if they think Dave is adjusting the tone or content of his videos to address one or two outspoken trolls.

I have a much more reasonable explaination - occam's razor.  Dave really liked the power supply.  Dave really didn't like the power supply thermal issue.

This power supply as noted by the numerous posts and the original video has so many issues that the thermal issue is just the icing on a rather nasty cake!  What Dave thought after the first video only Dave knows. I know that I was completely turned off by the terrible rotary knob design and its tracking, the ergonomics of the unit as a whole and the voltage display not showing the exact set voltage plus that nasty spike.  The list goes on but surmise to say it was pretty clear to me from the original video that the power supply even before the tear down was not that good, of course that's just my opinion.  I guess we will know for sure what Dave was thinking if he keeps the repaired revision as his main bench supply.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 31, 2013, 04:57:01 pm
What Dave thought after the first video only Dave knows.

I thought I said what I thought?
It seemed like a pretty decent supply for the money. I liked (mostly) the way it worked, I liked (mostly) the features, I liked (most of) the build quality. It had a couple of small issues, plus the small power on spike, but overall, no show stoppers. It wasn't bad, esp compared to the POS Atten it replaced. As always, YMMV.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on August 31, 2013, 04:59:22 pm
this is what I wanted to hear "They will be replacing all Australian units"

As I clarified, that statement was incorrect, due to a mis-communication.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on August 31, 2013, 05:49:33 pm
this is what I wanted to hear "They will be replacing all Australian units"

As I clarified, that statement was incorrect, due to a mis-communication.
bugger missed that. wait patiently I guess, still has warranty, but would rather be preemptive , Mr Murphy says it will fail at the worst possible time otherwise
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: eksund on August 31, 2013, 05:56:50 pm
I was in the mode of ordering the DP832 after Dave:s review. The price is right and the functionality is to my need.
Then I saw the follow up and decided to wait for answers.
I can´t buy a power supply who has a fault in its power supply.
I have now asked the dealer to verify that the units they have are of later edition.

I can´t wait for Dave to update with a video about the new boards performance.

Thanks!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: JoeO on August 31, 2013, 06:21:19 pm
Maybe the DP832 was released as a way to get rid of the dodgy DP832A boards.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Harvs on August 31, 2013, 07:16:57 pm
As a complete aside to this linear reg issue, here's the bit I don't get.  You go to all this trouble to build a 0.05% spec PSU, then don't put separate sense terminals on it?  What's the point in having all that accuracy if you still need a separate meter to know what voltage your DUT is getting?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on August 31, 2013, 07:23:30 pm

This power supply as noted by the numerous posts and the original video has so many issues that the thermal issue is just the icing on a rather nasty cake!  What Dave thought after the first video only Dave knows. I know that I was completely turned off by the terrible rotary knob design and its tracking, the ergonomics of the unit as a whole and the voltage display not showing the exact set voltage plus that nasty spike.  The list goes on but surmise to say it was pretty clear to me from the original video that the power supply even before the tear down was not that good, of course that's just my opinion.  I guess we will know for sure what Dave was thinking if he keeps the repaired revision as his main bench supply.

You had your conclusion in mind before you ever saw the video, and before you ever knew the specs of this supply.  I noticed you have an irrational hatred of it and inflate every criticism to be the worst thing ever, and gloss over every benefit as useless.

Case in point... "terrible rotary design".  I don't know what is terrible about it?  It is better than the knob on my Agilents.  There is nothing wrong with it's tracking.  It works great.

Case in point... you say "as noted by many posts has numerous issues".  The comments from owners have been overwhelmingly positive. 

Case in point... you say "what Dave thought, only he knows".  No, we all know what he thought because he told us. 

Case in point... you say "pretty clear to me it was not that good". 

You have hated this power supply from day one... I have no idea why.  But it clearly has very little to do with this power supply itself.  The thermal problem IS a deal breaker, but your complaints predated that discovery by a long time.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on August 31, 2013, 07:25:00 pm
this is what I wanted to hear "They will be replacing all Australian units"

As I clarified, that statement was incorrect, due to a mis-communication.

Do you know if Rigol are still looking into this (or at least your distributor is) and expecting to get back to you? 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on August 31, 2013, 07:30:30 pm
Let me comment on the voltage readback-lag a little. Some argue this needs to be fixed and is a flaw in the design. Although the voltage readback from the outputs is a little laggy when you rotate the adjustment wheel and change the set output voltage, if you actually measure the change of output voltage and watch the smeller indicator of the set-voltage you are adjusting, it pretty much adjusts instantly. At least as quick a my 87V display readback shows me.

So yeah, although the readback on the supply is annoyingly laggy, it's good to know the voltage adjustment responds quickly to user input, and corresponds nicely with the smaller voltage-set readout on the display.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: open loop on August 31, 2013, 08:12:06 pm
I think the main point of the video was "how did this get past design review!" Dave was going to have this power supply as a "keeper" in the lab as that this is a nice supply for the money. Ok it had some small issues but this would not have mattered to most users. The worst of which was the voltage power spike which I think he wanted to look into.

What really upset him was what we all now know, the 5v power circuit overheated which somehow caused a reset and closely placed smoothing caps to a very hot heat sink. In short poor design - something that is garanteed to get David ranting.

Rigol were obviously aware of this well before David's PSU was shipped because a fix was emailed back 5 minutes after David's question. And that fix would have taken a week or two at least to design and verify. So the key questions to my mind are,

1. How did this get past design review or the first, second round of product verification and testing?

This I have no answer for this as only Rigol can answer this, all of my guesses would be meaningless drivel.

2. Why was the product not pulled before first shipments?

The answer to this only Rigol can know but we can only guess and there are several reasons that come to mind, we only just noticed the problem (see question 1), or wanting to "save face" and not admit it publicly and deal with any issues with warranty as I would have imagined that they have a warranty fund provided by the bean counters.

3. Does the fix address the original problem?

Can't answer this until we see a news from Rigol and somebody independently verifies this. Again Rigol is key to this.

And finally

4. How is Rigol going to handle this with existing customer's?

This is key for Rigol and if they handle this well then this will put them at an advantage above their competitors. But as we have seen they have spent many thousands of man hours building a reputation and one silly design mistake can ruin all of that.

This is where the company needs say "I don't want to save some money, I want to save my reputation, I will do all this needed to make this right". They could learn something from the way Microchip responded to Dave's review of the PIC kit 3.

Imagine being the design engineer where you had several projects on the go and this was somehow missed. As I am sure David would verify that part of being the design engineer is to having to fix errors that you did not foresee or were not listened to during the design review. And this impacts on your current 6+ projects. This even worse when the damn thing is the field all over the world.

Anyway I get the feeling that Rigol is a relatively new company and this maybe the first time they have had such a serious issue. It will be interesting to see how this turns out.

BTW The hello kitty version of this PSU doesn't have the reset issue ;-)

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ali80 on August 31, 2013, 08:14:25 pm
I think the maximum power dissipation in the pass transistor should occur at output voltage of 22v and not 30v, just before the tap changing by the triac.
and by the way, why using discrete taps like the old relay based designs while you can have a continuous tap by using the triac?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on August 31, 2013, 08:58:27 pm
I think the maximum power dissipation in the pass transistor should occur at output voltage of 22v and not 30v, just before the tap changing by the triac.
and by the way, why using discrete taps like the old relay based designs while you can have a continuous tap by using the triac?

I think it would be much harder to get rid of the noise you get by regulating AC with a triac (basically, you're chopping off more or less of the middle section of the sine wave, while keeping its peaks). Plus, chances are there would be annoying audible noise (ever had a triac-based lights dimmer?)

EDIT:
Furthermore, I don't think that short, intermittent current pulses (which you'd get by regulating secondary's output with a triac) is an optimal way of loading the transformer.

EDIT 2:
Basically, if you chose to go that route, I think you'd be better off just designing a proper switching mode supply as essentially you've just offset all the benefits of a linear supply anyway.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Mikey on August 31, 2013, 09:32:15 pm
This is awesome, even if it is a stupid mistake. That mistake just teached me how to read the datasheet on a heatsink! :D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: electrocat on August 31, 2013, 09:39:34 pm
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on August 31, 2013, 09:45:17 pm
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

If you mean lowering the currently used transformer tap output, that would mean re-winding the transformer (basically, making a new one). Hardly an optimal solution. If you mean using another tap which is already there used for the main output, well, the point is to have the logic supply (and the interface ports) separate and galvanically isolated from the main outputs. Anyway, most fans are rated 12V and I strongly assume this one is 12V as well.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on August 31, 2013, 09:57:57 pm
If I happened to have one of those earlier version Rigols, I think I'd switch the regulator for this fella: http://www.jm.pl/karty/AMSR178NZ.pdf (http://www.jm.pl/karty/AMSR178NZ.pdf)

I'm already using this part in a one-off hobby project of mine and couldn't be happier with its performance. Well, it's 1A only so USB port loading with 500 mA would be a no-go but I'm pretty sure these Aimtec guys are making beefier ones as well (no longer 7805 pin-compatible but that's not that big of a deal given the available board space, I guess).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on August 31, 2013, 10:05:09 pm
what a disappointment! rigol  |O
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: H.O on August 31, 2013, 10:23:02 pm
Hi,
I've currently got mine loaded down as follows:
Ch1: 23V, 3A  (E-Load)
Ch2: 23V, 2.95A (Resistive load)
Ch3: 5V, 1A (Resistive load)

It's been going for ~90 minutes so far, the air comming out the back is barely warm. I'll leave it untill either it shuts down, blows up, I get bored or need to leave the house.

Clearly the overheating voltage regulator is an issue and I'm sure glad it's been brought up. I've contacted my supplier regarding my particular unit and I think what happens next will say more about RIGOL than the actual issue itself. If they won't do anything about it now I'll be a bit dissapointed but I'll just use the thing and hope it breaks down or start acting up within the warranty period. If it doesn't I'll go in and replace the caps and either apply a bigger heatsink or a switcher when the warrant period is comming to an end (if I'll remember).

The power on glitch/spike MIGHT be an issue for SOME people. Personally I don't think it matters for me and now I AM aware of it thanks to Daves video.

The front panel layout is different, sure. But really, it's not that bad to actually USE.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 10:28:48 pm
Loading the supply will likely increase the fan speed, making the 5 V regulator less likely to overheat than without load.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on August 31, 2013, 10:39:41 pm
It's been going for ~90 minutes so far, the air comming out the back is barely warm. I'll leave it untill either it shuts down, blows up, I get bored or need to leave the house.

Any particular reason for not loading the 5V rail to 3A? May as well go for broke. :D

Also, according to Dave's video, the heat generated in the 30V regulators will be at a maximum at 22V output voltage, not 23. The first tap switched between 21 and 22V.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on August 31, 2013, 10:44:50 pm
Just a clarification.
There was some mistaken communication that Rigol would be replacing units in Oz. That does not appear to be the case, or at least was an incorrect assumption at this stage. The local rep will simply come good with whatever Rigol come up with (board replacement or whatever). Nothing is confirmed yet, talks are still in progress with Rigol.

The messages at the thread drops like a rain!

I have order one of this from 10th August, via my local distributor in my country, but I haven't received yet.
Is there any information about from what serial number there is the correction?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tom66 on August 31, 2013, 10:48:15 pm
Is Dave going to do a video on the start-up spike/voltage, or is that going to be missed in light of this serious problem?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on August 31, 2013, 10:50:01 pm
It would be good if Rigol put a sticker on every power supply and its box with the fix. Unmodified supplies may very well stay in the distribution channels for a while, and it would inspire confidence in the customers if they (or the seller) can easily verify that the power supply has been fixed.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: H.O on August 31, 2013, 10:55:02 pm
Quote
Loading the supply will likely increase the fan speed, making the 5 V regulator less likely to overheat than without load.
Yes, but mine doesn't seem to reset without load and I beleive neither does others - as long as they aren't taken apart.

Quote
Any particular reason for not loading the 5V rail to 3A? May as well go for broke.
Ideally I'd like to put it at 0.5V and 3A or something but I didn't have any suitable load at hand.

Quote
Also, according to Dave's video, the heat generated in the 30V regulators will be at a maximum at 22V output voltage, not 23. The first tap switched between 21 and 22V.
Yeah, yeah but I wanted some margin to be sure I was on the correct winding.

It's still going (~2h), the ambient temp is ~21C and the air comming out the back is ~35C. I need to go out for a bit so I'll disconnect the loads but leave the outputs on, will see if it resets. Later tonight I'll see if I can find something to load Ch3 properly and lower the voltage of Ch1 and Ch2 closer to 22V, not that I think it'll make a huge difference.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on August 31, 2013, 11:20:41 pm
Also, according to Dave's video, the heat generated in the 30V regulators will be at a maximum at 22V output voltage

For a constant load. It's about 70W.

With a repetitive pulsed load it could be higher, e.g. 9ms shorting the output and 1ms no load. This will keep the big smoothing caps at high voltage, eg. 45V. Then the power dissipation will be about 120W.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on August 31, 2013, 11:39:25 pm
Yeah, yeah but I wanted some margin to be sure I was on the correct winding.

Sorry. :)

It's still going (~2h), the ambient temp is ~21C and the air comming out the back is ~35C. I need to go out for a bit so I'll disconnect the loads but leave the outputs on, will see if it resets. Later tonight I'll see if I can find something to load Ch3 properly and lower the voltage of Ch1 and Ch2 closer to 22V, not that I think it'll make a huge difference.

The cooling air temperature rise is not a good indicator of what is happening inside, as most of the cooling air will not have been in contact with the hot heat sinks and the transformer. The only reliable method for testing whether there are other temperature related issues, is to measure the tab temperatures of the regulator pass devices. Your stress test would only reveal any catastrophic design issues, of which there are hopefully none.

There may also be components or heat sinks, which are not cooled appropriately due to the air flow being partially blocked by 'upstream' structures creating air 'shadows'.

Even if the capacitors or power semiconductors are run well above their recommended maximum operating temperatures, they may still last literally for months of continuous operation. High temperatures are usually a long term reliability problem, not something you'd expect would kill anything in a few hours or days (unless the problem is really, really bad).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: bktemp on September 01, 2013, 12:21:53 am
The worst situation for the mosfet used as regulator is, when the output is shortet at maximum voltage and the junction is already hot. If it does not fail then, it is unlikely that it will ever fail.
The mosfet is marked 80N15, I think it is a SUP80N15 which has a specified maximum power dissipation of 300W (@25°C) and is 175°C rated. This is why a single TO220 device is enough for such a power supply and should have no problems even at short circuit conditions at maximum input voltage. Unfortionatly the datasheet does not give any information for thermal derating.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on September 01, 2013, 12:40:41 am
If I happened to have one of those earlier version Rigols, I think I'd switch the regulator for this fella: http://www.jm.pl/karty/AMSR178NZ.pdf (http://www.jm.pl/karty/AMSR178NZ.pdf)

The 5v powers the RS232 interface, USB, and Ethernet. Stick cables into those ports and your power supply could double up as a broadband rf noise source.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 01, 2013, 12:58:22 am
The worst situation for the mosfet used as regulator is, when the output is shortet at maximum voltage and the junction is already hot. If it does not fail then, it is unlikely that it will ever fail.
The mosfet is marked 80N15, I think it is a SUP80N15 which has a specified maximum power dissipation of 300W (@25°C) and is 175°C rated. This is why a single TO220 device is enough for such a power supply and should have no problems even at short circuit conditions at maximum input voltage. Unfortionatly the datasheet does not give any information for thermal derating.

The derating is 2W/K. Dave measured already ~70°C heatsink temperature at a medium load (3A@30V -> 48W dissipation). The transistor case will be considerably hotter.

The transistor is maybe enough. It's maybe barely enough. The poor LM317 works with a closed case too. I missed a temperature sensor near the transistor for thermal protection. It would not surprise me if you can kill it with the right load.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 01, 2013, 12:59:06 am
If I happened to have one of those earlier version Rigols, I think I'd switch the regulator for this fella: http://www.jm.pl/karty/AMSR178NZ.pdf (http://www.jm.pl/karty/AMSR178NZ.pdf)

The 5v powers the RS232 interface, USB, and Ethernet. Stick cables into those ports and your power supply could double up as a broadband rf noise source.

Not sure I got your point... are you suggesting that this DC-DC converter has so bad ripple, etc.? Well, I haven't measured those but then again I see no reason for it to be significantly worse than other DC-DC switching converters out there. And the +5V on the USB in your laptop/desktop is most probably provided by a switcher anyway, so...  :-//
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: SeanB on September 01, 2013, 01:34:59 am
That converter will work there, just need to do a little pin shuffling to get it to fit and give it a ground pin. You probably will need a 1.5A version though, as with 700mA for the onboard micro and 100mA for Ethernet along with 500mA for the USB this will be more than the 1A limit of it. There is enough capacitance there to keep the regulator happy though.

As to the pass devices, I would think they are running very close to the max allowable, any with poor mounting or a loose screw will fail rather spectacularly.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on September 01, 2013, 02:13:47 am
And the +5V on the USB in your laptop/desktop is most probably provided by a switcher anyway, so...  :-//

Yes and they paid a great deal of attention to filtering the switcher input and output and board layout and I/O filtering with lots of expensive EMC emission testing to see how they were doing and after all that they still had to mould a big ferrite bead on the PSU cable.

You can't just replace a linear regulator with a switcher especially when it powers I/O interfaces which are going to have antennas plugged into them.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tom66 on September 01, 2013, 02:17:29 am
You could replace it with a switcher, but it wouldn't be a drop in job. It would be a re-layout of that part of the board. I'd probably use a switcher which had a switch frequency above 500kHz, which simplifies some parts of the EMC design.  I've had some luck using LM2734's, but their output current is limited to around 1 amp.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 01, 2013, 02:33:45 am
Yes and they paid a great deal of attention to filtering the switcher input and output and board layout and I/O filtering with lots of expensive EMC emission testing to see how they were doing and after all that they still had to mould a big ferrite bead on the PSU cable.

You can't just replace a linear regulator with a switcher especially when it powers I/O interfaces which are going to have antennas plugged into them.

Sure, I understand those are all valid considerations. But have you actually checked this regulator's datasheet? It's not your average SMPS driver chip requiring external inductors, etc. It's a hybrid, all-in-one solution with inductors and everything sealed in one package. It's not the cheapest thing around, either. I'd expect it to be an "end-to-end" solution, with proper thought given to the EMI and noise issues as well. But maybe that's just the wishful thinking on my side. I have neither the equipment nor the knowledge necessary to back my assumption. I only know I've designed it into my microcontroller based project and it's all dandy so far, some rudimentary scoping on the output haven't revealed anything worrisome, either.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on September 01, 2013, 02:34:58 am
As to the pass devices, I would think they are running very close to the max allowable, any with poor mounting or a loose screw will fail rather spectacularly.

The SUP80N15 has pretty impressive SOA curves if that is what it is.

If you want to try to kill it set maximum output voltage and current and short the output. The pass device then has to dump most of the energy in the reservoir capacitors initially at about 50v and 3A (or worse if the current limit is slow).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on September 01, 2013, 02:45:41 am
I was in the mode of ordering the DP832 after Dave:s review. The price is right and the functionality is to my need.
Then I saw the follow up and decided to wait for answers.
I can´t buy a power supply who has a fault in its power supply.
I have now asked the dealer to verify that the units they have are of later edition.

I can´t wait for Dave to update with a video about the new boards performance.

Thanks!

Who is selling this in Sweden, and for what prices?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: H.O on September 01, 2013, 05:05:29 am
Wow, you guys are great, I'm sure that if we all give it our best we can come with a way to kill it. Seems like that's what we're trying to do anyway....

I'm not saying the thing doesn't have issues but I'll wait for RIGOLs response before making up my mind about what to really think about it. Apart from the LM317 issue I actually like it so far, especially considering the price - it's $400 for crying out loud... And, it's not like they (RIGOL) are the first ones to have issues with devices in the field, it's how they handle it that matters IMO.

Anyway, for those who might be interested. I came back roughly 5 hours after leaving the unit with its outputs ON but no load connected. The outputs where still on so no reset here. Again, I'm not denying the issue, just saying that unit works fine with the lid on - only time will tell for how long.

So I set Ch1 and Ch2 in tracking mode, parallelled the ouputs, set the voltage to 22.25V and the current limit to 3.2A. Then I set the electronic load to pull 6.3A. Ch3 is loaded with a couple of resistors and is sitting at 0.8V @3.2A. It's been going like that for over an hour now. Case is cold, air out the back is barely warm. The e-load is getting warmer though....
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 01, 2013, 05:39:50 am
Wow, you guys are great, I'm sure that if we all give it our best we can come with a way to kill it. Seems like that's what we're trying to do anyway....

I thing it's an important question for a lab power supply. Can it be killed? Under which circumstances? What's happen then? Does it output 50V without any current limitation? Look at the Korad review.

The Rigol has a terrible failure in it's thermal design. Why should i trust the design regarding this small pass transistor?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lilshawn on September 01, 2013, 05:59:55 am
i'm not seeing a really big deal here...worse comes to worse, open 'er up and if you have the first revision board... put a big ass heatsink on it. relocate it if you have to. 20 minutes out of your life tops.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: madires on September 01, 2013, 06:10:44 am
You could replace it with a switcher, but it wouldn't be a drop in job. It would be a re-layout of that part of the board. I'd probably use a switcher which had a switch frequency above 500kHz, which simplifies some parts of the EMC design.  I've had some luck using LM2734's, but their output current is limited to around 1 amp.

I'm using the LM2576 (52kHz, 3A) with an additional output ripple filter without any problems for several toys with "antennas" attached. EMI tests are done with a shortwave receiver :-) The EMI is so low it's really hard to detect any or distinguish it from background noise. But that would add about 5 bucks to the BOM.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: FatalError3141 on September 01, 2013, 06:22:56 am
i'm not seeing a really big deal here...worse comes to worse, open 'er up and if you have the first revision board... put a big ass heatsink on it. relocate it if you have to. 20 minutes out of your life tops.

Yea, granted its not a large problem to fix. But you don't expect to buy a £400 Supply that you have to "fix" before using it. 

I found another issue with this supply, could someone else confirm it?  Turn the outputs off while in the storage menu and they will remain active  :wtf:
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: brainwash on September 01, 2013, 08:39:50 am
Just watched the video and short of replacing the LM317 with a bigger regulator and/or bigger heatsink the better solution would be to replace it with a switched supply (those 2$ ones on ebay should work well after a thorough check) as a preregulator to 6.5-7V and the heatsinked LM317 after it. It's a 15 mins and 3$ job compared to sending the unit over or causing it to fail and having to wait for another.
At least that's what I would do.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tom66 on September 01, 2013, 09:29:41 am
The LM317 doesn't have particularly good ripple rejection though, so you've still got the wideband noise problem that a cheap switcher will give.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on September 01, 2013, 10:08:00 am
Dave, can you say your serial number ?

My power supply not have problem with noise when reset the dp832.

s/n: DP8C1512XXXX

I live on brazil and the cost to send was 200 u$ and 200u$ of taxes, i not pay this again to send for warranty.

:S
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dread on September 01, 2013, 12:53:01 pm

This power supply as noted by the numerous posts and the original video has so many issues that the thermal issue is just the icing on a rather nasty cake!  What Dave thought after the first video only Dave knows. I know that I was completely turned off by the terrible rotary knob design and its tracking, the ergonomics of the unit as a whole and the voltage display not showing the exact set voltage plus that nasty spike.  The list goes on but surmise to say it was pretty clear to me from the original video that the power supply even before the tear down was not that good, of course that's just my opinion.  I guess we will know for sure what Dave was thinking if he keeps the repaired revision as his main bench supply.

You had your conclusion in mind before you ever saw the video, and before you ever knew the specs of this supply.  I noticed you have an irrational hatred of it and inflate every criticism to be the worst thing ever, and gloss over every benefit as useless.

Corporate666 do you work for Rigol or are you the forums official attack dog when anybody has something negative to say?

First of all how could I have had a conclusion about the 832 before I even saw the first video?  I had never even heard of the DP832 until Dave did the first video!   Based on that video I made it very clear that I did not like the "DP832 Precision Power Supply" and stated my reasons why.  How do you then come to a conclusion that I have an "irrational hatred" of it when my initial reasons are not even under dispute?

Dave did not like the rotary encoder design or the numeric pad, I did not like the rotary encoder or Pad.

Dave did not seem pleased with the way the encoder responded, I did not like it at all.

Dave did not like that Nasty glitch, I did not like it either.

During the video it was clear that the set voltage versus the output voltage under no load did not correspond, I said I did not like that at all, is something wrong with that opinion.

The video showed one of the outputs having a small current draw when nothing was connected, that's another issue I did not like.

No sense voltage on a precision power supply, whats a person supposed to do, dedicate a precision meter to monitor the DUT?

And my main reason was that I did not like the ergonomics of the design and the incorporation of so many rarely used features because I knew it was just a selling point distraction that would mean less design money would be available for making a supply that was actually going to be precise and reliable.  The Teardown and the First video proved that to be correct.

Quote
Case in point... "terrible rotary design".  I don't know what is terrible about it?  It is better than the knob on my Agilents.  There is nothing wrong with it's tracking.  It works great.

Yes it is terrible and for the reasons I stated above!
My agilent knob fits nicely between my two fingers and I can turn it very slowly and precise while looking at my other equipment, something that seems very difficult to do with that encoder.  It also tracks my movements perfectly and the display matches my every movement, the 832 does not do that.

Quote
Case in point... you say "as noted by many posts has numerous issues".  The comments from owners have been overwhelmingly positive.

Really!!  They sound either upset or worried and several have pointed out other issues. 

Quote
Case in point... you say "what Dave thought, only he knows".  No, we all know what he thought because he told us.
I assumed Dave opened the box for the first time while filming the video, he made many positive remarks and some negative remarks.  Most people don't make up their mind about anything that they see for the first time until they mull it over for a few hours, sometimes days. That's why snap purchases are typically regretted.  So it was logical to assume that Dave's opinion could be in Flux so I had no way of knowing what he thought the next day, his mind might have changed. That's why I simply stated only Dave knows.

Quote
Case in point... you say "pretty clear to me it was not that good". 

You have hated this power supply from day one... I have no idea why.  But it clearly has very little to do with this power supply itself.  The thermal problem IS a deal breaker, but your complaints predated that discovery by a long time.

Yes; it is pretty clear to me!  That's my opinion, in your world is there no room for people to have opinions that differ from yours?

"You have no idea why I hate it":  I stated the reasons in every post |O

"The thermal problem is a deal breaker for you":  For some people they may not see it as a deal breaker at all, they may just stick a bigger heat sink on it or just keep the Lid on and sell it in 2 years.  Once again "Deal Breaker" is your opinion and it's not shared by everyone.  My opinion was formed from the first video because I have already been reemed up the arse buying equipment that had lots of dazzling features at the expense of being really bad at doing the core thing it was designed to do.

Whats the bloody point of having a Blinged out Linear Precision Power Supply if it's not Precise and it's not reliable?  :palm:

And all those "Benefits" you think I should be praising are bloody useless if it's primary functions don't work properly :-//

Corporate666 why don't you spend your time on the bloody rude people I see making posts on this forum instead of hammering people like me who are just trying to have a civil discussion.

You seem to be tracking my posts, so tell me how many times have I said a reviewed piece of equipment was a POS?  It would also be helpful to know if that's not allowed on the forum because it sure feels that way.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: teda on September 01, 2013, 01:20:25 pm
Dave will probably get an official fix from Rigol and if I paid 400$ for a piece of equipment I would want one too.

In a pinch instead of adding a bigger heat sink or adding a switcher regulator, another solution could be a 4 ohm / 5watt resister in series with the regulator input to bleed off some of the input voltage.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 01, 2013, 02:36:37 pm
Yes; it is pretty clear to me!  That's my opinion, in your world is there no room for people to have opinions that differ from yours?

I am not attacking you at all - but I call it like I see it, and when I see bullshit, I call it bullshit.

I don't know what you mean "tracking your posts"?  I just remember that you and that Citizen guy seemed to have a beef with the supply (and/or Dave) and have been grinding out that beef in the threads on it.  You overstate every negative aspect of the unit and downplay every positive aspect to fit your conclusion that it's shit and Agilent is better.  You don't even own one of these PSU's and have never used one but you are arguing with folks that own both, and you seemed to get very offended when people criticized Agilent.

One of my other hobbies is racing cars, and the same thing happens on all the car forums.  The Mustang guys spend eons arguing with the Corvette guys that their car is better.  The Corvette guys argue the same to the Viper guys.  The Viper guys argue the same to the Ferrari guys.  And the Ferrari guys argue the same to the McLaren guys.   

There are some who just appreciate all the cars (or power supplies), and when those folks see someone waging a war against a product, it's pretty clear.  As it is in this case.  You don't like this PSU - we get it, so don't buy one.  But feel free to keep telling us all how it's total shit and only an Agilent is worth buying and every feature the Agilent lacks is unnecessary and every feature the Rigol has is unnecessary  :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on September 01, 2013, 03:00:20 pm
Yes; it is pretty clear to me!  That's my opinion, in your world is there no room for people to have opinions that differ from yours?

I am not attacking you at all - but I call it like I see it, and when I see bullshit, I call it bullshit.

I don't know what you mean "tracking your posts"?  I just remember that you and that Citizen guy seemed to have a beef with the supply (and/or Dave) and have been grinding out that beef in the threads on it.  You overstate every negative aspect of the unit and downplay every positive aspect to fit your conclusion that it's shit and Agilent is better.  You don't even own one of these PSU's and have never used one but you are arguing with folks that own both, and you seemed to get very offended when people criticized Agilent.

One of my other hobbies is racing cars, and the same thing happens on all the car forums.  The Mustang guys spend eons arguing with the Corvette guys that their car is better.  The Corvette guys argue the same to the Viper guys.  The Viper guys argue the same to the Ferrari guys.  And the Ferrari guys argue the same to the McLaren guys.   

There are some who just appreciate all the cars (or power supplies), and when those folks see someone waging a war against a product, it's pretty clear.  As it is in this case.  You don't like this PSU - we get it, so don't buy one.  But feel free to keep telling us all how it's total shit and only an Agilent is worth buying and every feature the Agilent lacks is unnecessary and every feature the Rigol has is unnecessary  :-DD

kind of agree and it nearly as annoying as this Monty Python "I scratched the record" for 10 minutes and 2 seconds (http://www.youtube.com/watch?v=pA6155YveK0#)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 01, 2013, 03:07:41 pm
Yes; it is pretty clear to me!  That's my opinion, in your world is there no room for people to have opinions that differ from yours?

I am not attacking you at all - but I call it like I see it, and when I see bullshit, I call it bullshit.

I don't know what you mean "tracking your posts"?  I just remember that you and that Citizen guy seemed to have a beef with the supply (and/or Dave) and have been grinding out that beef in the threads on it.  You overstate every negative aspect of the unit and downplay every positive aspect to fit your conclusion that it's shit and Agilent is better.  You don't even own one of these PSU's and have never used one but you are arguing with folks that own both, and you seemed to get very offended when people criticized Agilent.

One of my other hobbies is racing cars, and the same thing happens on all the car forums.  The Mustang guys spend eons arguing with the Corvette guys that their car is better.  The Corvette guys argue the same to the Viper guys.  The Viper guys argue the same to the Ferrari guys.  And the Ferrari guys argue the same to the McLaren guys.   

There are some who just appreciate all the cars (or power supplies), and when those folks see someone waging a war against a product, it's pretty clear.  As it is in this case.  You don't like this PSU - we get it, so don't buy one.  But feel free to keep telling us all how it's total shit and only an Agilent is worth buying and every feature the Agilent lacks is unnecessary and every feature the Rigol has is unnecessary  :-DD

kind of agree and it nearly as annoying as this Monty Python "I scratched the record" for 10 minutes and 2 seconds (http://www.youtube.com/watch?v=pA6155YveK0#)

 :-DD

I am soooo going to log into my computer remotely on Monday, crank the volume up and play that clip when I leave for work.  Everyone will hear it but won't want to go into my office and mess with my computer  :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: free_electron on September 01, 2013, 03:45:33 pm
in itself there is nothing wrong in useing that lm317. they just should have bolted on amuch larger heatsink. okay you are burning off 7 watts.. so what ? its a 300 watt+ power supply. who cares ...

agilent uses the same lm317 in their 363x supplies. but , they bolt them to the main pass transsitor heatsinks. and those things are huge , fan cooled and never heat beyond 50 degrees c , even under full supply dissipation

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on September 01, 2013, 04:00:32 pm
yep, the LM317 gets too hot. I'm bored about now
Let replace it with this http://bursonaudio.com/DIY_Super_Regulator.html (http://bursonaudio.com/DIY_Super_Regulator.html)

the audiophools vouch for them so they must be good  >:D

that being said enough trolling for today from me.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TMM on September 01, 2013, 05:12:38 pm
I can't see how Rigol can get out of replacing affected units. Back when the XBOX 360 was having overheating issues and MS were only offering an extended warranty the standard advice was to wrap your console in a towel to force it to overheat so you could make a claim.
The towel method was a dodgy way of reflowing the solder on the BGA lol which could actually fix it temporarily.

Every time I look at a piece of gear from China I look at how many bells and whistles they have added and I try to subtract that from what I figure the cost price is and then calculate out how much money they must have spent on the core engine of the device.

To me the Core is what really matters, what’s the point of having a Precision Lab Power supply with 100 bells and whistles if it’s output is not really precise or reliable?

When I saw the DP832 I knew the core engine had to be made on a very low budget, the rotary encoder knob was the first indication that money was very tight and it only got worst as I saw more.  I think if Dave was to look around further I think he would find that regulator is probably just one of many shortcuts they took to save money.  I would bet good money that almost every part in that unit from the regulators to the Caps are all picked from the lowest bidder and very little margin is built into the overal design.

BTW it was nice to see the Fluke 87V were it belonged, front and center.

Great Video Dave.
What about the DS2000 series scopes and DG4000 function gens which happen to be both cheap and well designed? There is hardly a corner cut in those products. Rigol usually pick brand name parts. So what if they pick an ST reg over Linear Tech? ST is still better than some unknown chinese reg.

I think the issue in the DP832 was a genuine design oversight, not the result of cost cutting. The person responsible for the powersupply board with the 5v reg may have only ever been intended it to supply something like 200mA and the team designing the digital board just asked what kind of regulator was on the board, got the answer of it being an LM317 and assumed that they were fine because their board only drew 700mA.
The surprise is that no one picked up on it before the product went out the door.

Regardless of the LM317 issue, upon seeing Dave's first review video of the DP832 i felt that Rigol had dropped the ball a bit. Particularly ergonomics which is one thing they usually do well. Clearly the design team that did the DP832 is not of the same calibre as the team(s) which have engineered other Rigol products such as the scopes and function gens.


Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Salas on September 01, 2013, 07:48:08 pm
Why a mosfet as a series pass element?

Alexander.

Safer-easier. No secondary breakdown.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: eternal_noob on September 01, 2013, 08:20:36 pm
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

If you mean lowering the currently used transformer tap output, that would mean re-winding the transformer (basically, making a new one). Hardly an optimal solution. If you mean using another tap which is already there used for the main output, well, the point is to have the logic supply (and the interface ports) separate and galvanically isolated from the main outputs. Anyway, most fans are rated 12V and I strongly assume this one is 12V as well.

If a buck winding will fit on the transformer without any problems physically, it should do the trick. Plus an extension on the heat sink of course.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: eternal_noob on September 01, 2013, 08:26:08 pm
The LM317 doesn't have particularly good ripple rejection though, so you've still got the wideband noise problem that a cheap switcher will give.
I believe the datasheet says something about 70db rejection and that should be pretty good.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Steffen on September 01, 2013, 08:35:35 pm
Is the USB host port powered by this LM317 too? Then load it with an additional 500mA.>:D

For what you need 500mA on that PSU to power USB devices? Is there any need to plug in a 2,5" HD to save few lousy KiB for some settings or configuration data? I think flash drives are more handy in this case - and even cheaper!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on September 01, 2013, 08:41:39 pm
For what you need 500mA on that PSU to power USB devices?

To charge my cell phone.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: con-f-use on September 01, 2013, 09:49:04 pm
500mA is the USB specification on max. current draw so the PSU better provide it!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on September 01, 2013, 09:58:48 pm
who designed this product is an intern?
 :--
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on September 01, 2013, 10:00:54 pm
Dave, please, hack your 832 , how to resolve these bug?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: brainwash on September 01, 2013, 10:13:20 pm
The LM317 doesn't have particularly good ripple rejection though, so you've still got the wideband noise problem that a cheap switcher will give.

If you look at Dave's video you can see there is actually plenty of ripple after the LM317; the ripple seemed to increase with temperature.

Sure, you can stick a larger TO220 and heatsink to the whole thing but any added consumer (like USB) will force the part some more and result in high inefficiency. I would still stick a switched preregulator before the LM317.

Rigol has agreed in the comments that there has been an oversight in the design. Admitting to the error or issuing a "fix" might result in a class lawsuit so they would likely try to avoid that and instead say something about "stability improvement modification".
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 01, 2013, 10:21:31 pm
Is the USB host port powered by this LM317 too? Then load it with an additional 500mA.>:D

For what you need 500mA on that PSU to power USB devices? Is there any need to plug in a 2,5" HD to save few lousy KiB for some settings or configuration data? I think flash drives are more handy in this case - and even cheaper!

It's not about using a HD or not. The power supply should not reboot if the USB port is loaded. Like a computer. What do you think of a computer which will crash when a USB port is loaded/overloaded?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on September 01, 2013, 10:24:28 pm
For what you need 500mA on that PSU to power USB devices?

It's very simple: you should not be able to thermally stress and possibly damage, or crash, any device with a USB port by plugging in a perfectly valid USB device. Ports are external, they should be able to take a bit of abuse.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: brainwash on September 01, 2013, 10:24:55 pm
Reminds me of my cheap car stereo that reboots if I plug in the phone but works fine with a stick. Hmm... I might try to do a mod on that.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rs20 on September 01, 2013, 10:26:34 pm
How about replacing the linear reg with one of these switching-regulators-in-a-TO-220-footprint devices?:

http://www.murata-ps.com/data/power/oki-78sr.pdf (http://www.murata-ps.com/data/power/oki-78sr.pdf)

Less than US/AU$10 from digikey. Now of course, switching noise is always a concern with any switching regulator, but I get the impression that nothing sensitive/analog is being powered off this line?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 01, 2013, 10:37:25 pm
If you look at Dave's video you can see there is actually plenty of ripple after the LM317; the ripple seemed to increase with temperature.

Sure, you can stick a larger TO220 and heatsink to the whole thing but any added consumer (like USB) will force the part some more and result in high inefficiency. I would still stick a switched preregulator before the LM317.

A adequate cooled LM317 can handle 1.5A @ 7V dropout with out problems. With low ripple and noise. It's just 10W.

This is a linear power supply. It's not about efficiency. It's wasting 10s or 100s watts anyway. Saving 3W with a switching preregulator doesn't change that.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: brainwash on September 01, 2013, 10:42:14 pm
It's not about power consumption nor ripple: the LM317 now takes raw rectified input anyway so a switching preregulator will probably reduce the ripple.
That additional 3-7 watts count towards the thermal characteristic of the entire unit causing the fan to rev a lot of the time and reduce unit life by a few percents. Plus, the bigger heatsink is not free so that money is better spent on something more efficient.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nigel53 on September 01, 2013, 11:04:33 pm
The LM317 doesn't have particularly good ripple rejection though, so you've still got the wideband noise problem that a cheap switcher will give.
I believe the datasheet says something about 70db rejection and that should be pretty good.

Look at datasheet, 70dB will not be at typical switching frequencies! ;D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 01, 2013, 11:05:04 pm
It's not about power consumption nor ripple: the LM317 now takes raw rectified input anyway so a switching preregulator will probably reduce the ripple.
Unlikely. A proper used LM317 has orders of magnitude lower mains ripple that needed. But a switching regulator is a RF transmitter and a LM317 is not good at filtering RF. It doesn't make sense to use a preregulator. Just replace the LM317 with a proper switcher then.

Quote
That additional 3-7 watts count towards the thermal characteristic of the entire unit causing the fan to rev a lot of the time and reduce unit life by a few percents. Plus, the bigger heatsink is not free so that money is better spent on something more efficient.
A better thermal design will give you more than a few percents more life time. Just bold the dammed LM317 on the main heatsink - done. If this makes thermal problems then the design is broken anyway.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Steffen on September 01, 2013, 11:06:19 pm
The power supply should not reboot if the USB port is loaded. Like a computer. What do you think of a computer which will crash when a USB port is loaded/overloaded?
No joke, i've seen computers rebooting when a USB device has been plugged in. Reason: Broken USB connector on the motherboard and shorted out pins when plugging sth. in. I found such computers in my school.
For those cellphone chargers: I've also seen measurement devices in the 4-5 digit price sector with USB ports specified for max. 100mA. This was written in the spec. and in the manual. For thumb drives and mice/keyboards this is totally ok. If you need more ports than the typically 1-2 you get, there is always the possibility to use an active usb hub.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 01, 2013, 11:17:56 pm
For those cellphone chargers: I've also seen measurement devices in the 4-5 digit price sector with USB ports specified for max. 100mA. This was written in the spec. and in the manual. For thumb drives and mice/keyboards this is totally ok. If you need more ports than the typically 1-2 you get, there is always the possibility to use an active usb hub.

It's ok when an USB port limits the current to 100mA. But surely the poor LM317 in the Rigol doesn't withstand additional 100mA.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: FrankBuss on September 01, 2013, 11:43:09 pm
It's ok when an USB port limits the current to 100mA. But surely the poor LM317 in the Rigol doesn't withstand additional 100mA.
The USB 2.0 specification is very clear in chapter 7.2.1: "Systems that obtain operating power externally, either AC or DC, must supply at least five unit loads to each port. Such ports are called high-power ports."

Battery-powered systems are allowed to supply only one unit load (a "unit load" is 100 mA) and for bus-powered hubs, up to five unit loads are allowed after configuration (the device requests the amount of power it needs and the hub allows it only, if the sum is not greater than the five unit loads from upstream). So it is not an USB standard-conforming host, if the current is limited to 100mA.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nigel53 on September 02, 2013, 12:18:17 am
The fitting of a switching regulator, either as a complete replacement or pre-regulator, must be carried out with caution. It is not just a question of hf noise on the output, but hf noise introduced back onto the input supply; this could have impact on the EM compliance of the unit. If I had one of these, then I'd be looking at fitting a discrete linear pre-regulator (any npn TO-220 device with suitable specs) onto the main heatsink, leaving the LM317 as is, but handling less volt drop.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sync on September 02, 2013, 12:32:33 am
If I had one of these, then I'd be looking at fitting a discrete linear pre-regulator (any npn TO-220 device with suitable specs) onto the main heatsink, leaving the LM317 as is, but handling less volt drop.
Then you can just move the LM317 to the main heatsink. Much easier. You will have the isolation issues with both solutions. But it's not really a problem.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nigel53 on September 02, 2013, 12:58:55 am
If I had one of these, then I'd be looking at fitting a discrete linear pre-regulator (any npn TO-220 device with suitable specs) onto the main heatsink, leaving the LM317 as is, but handling less volt drop.
Then you can just move the LM317 to the main heatsink. Much easier. You will have the isolation issues with both solutions. But it's not really a problem.

Very true, but as stated 'if I had one of these' then I would over-engineer (always been sad like that!), total dissipation split between 2 devices will always be more reliable than 1 device
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsjsouza on September 02, 2013, 01:03:26 am
I was lurking at this thread for a while and I can't help but think that, if this is the first power supply designed by Rigol, it may be suffering from the well known "Rev 1.0" syndrome... Or maybe it is their major first redesign aiming to cut costs, as they have a much higher cost power supply that yields less than half the output power and similar noise/ripple/regulation specs... (I did a quick glance at both specs).

In any case, it becomes a hard sell after all this flak... I wonder if they will leave the model as it is or will slap a "Rev B" or "Mk II" or something else to differentiate the previous faulty products...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nigel53 on September 02, 2013, 02:20:37 am
Looking at the price/performance of this unit are we getting a bit paranoid! The switch-on pulse, only occurs with the 'hardware' power switch, is this really a problem? I have a TTI Electronic Load, that has a slow-start facility, this does not function with the 'hardware' power switch. I am now aware of this and ensure the unit is powered on before enabling any 'soft' controls, not a problem.
Yes, the LM317 issue could be a long term problem, only time will tell, but in normal use appears to be at the moment a non-issue. Now we are aware of it, then we could take steps to improve the overall reliability if we really felt the need. This is not the first time, and will not be the last, that a piece of equipment (of any manufacturer) has been produced with an obvious design flaw. To state that the DP832 is a faulty device, is at the moment rather an exaggeration.

I use a Farnell LT-30-2 PSU, big analogue meters, heavy duty mechanical input/output switches & not a digital device in sight!!! Any damage caused by using this is my stupid fault only!!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: edpalmer42 on September 02, 2013, 04:24:36 am
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

If you mean lowering the currently used transformer tap output, that would mean re-winding the transformer (basically, making a new one). Hardly an optimal solution. If you mean using another tap which is already there used for the main output, well, the point is to have the logic supply (and the interface ports) separate and galvanically isolated from the main outputs. Anyway, most fans are rated 12V and I strongly assume this one is 12V as well.

If a buck winding will fit on the transformer without any problems physically, it should do the trick. Plus an extension on the heat sink of course.

I'm surprised that this idea hasn't had any more discussion.  It's potentially the cleanest and easiest DIY solution to this problem.  If the center area of the transformer is open, you might only need 10 to 15 turns of wire to make a buck winding to drop the voltage to the proper level.  You might even be able to thread the new wire in without disconnecting all the other windings.

Has anyone checked this out?

Ed
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nigel53 on September 02, 2013, 05:20:52 am
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

If you mean lowering the currently used transformer tap output, that would mean re-winding the transformer (basically, making a new one). Hardly an optimal solution. If you mean using another tap which is already there used for the main output, well, the point is to have the logic supply (and the interface ports) separate and galvanically isolated from the main outputs. Anyway, most fans are rated 12V and I strongly assume this one is 12V as well.

If a buck winding will fit on the transformer without any problems physically, it should do the trick. Plus an extension on the heat sink of course.

I'm surprised that this idea hasn't had any more discussion.  It's potentially the cleanest and easiest DIY solution to this problem.  If the center area of the transformer is open, you might only need 10 to 15 turns of wire to make a buck winding to drop the voltage to the proper level.  You might even be able to thread the new wire in without disconnecting all the other windings.

Has anyone checked this out?

Ed

If you have access around the core, looking at the mounting in Dave's video, I doubt it. You then need the specification for the toroidal fitted (Max temp. rise above ambient, max ambient temp etc.) to even spec. the added winding correctly for temperature, will it pass the insulation tests as per original? I wouldn't class this as the easiest DIY solution, any modifications involving any items connected to the mains supply are fraught with potential hazards
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dread on September 02, 2013, 05:42:54 am
Yes; it is pretty clear to me!  That's my opinion, in your world is there no room for people to have opinions that differ from yours?

I am not attacking you at all - but I call it like I see it, and when I see bullshit, I call it bullshit.

I don't know what you mean "tracking your posts"?  I just remember that you and that Citizen guy seemed to have a beef with the supply (and/or Dave) and have been grinding out that beef in the threads on it.  You overstate every negative aspect of the unit and downplay every positive aspect to fit your conclusion that it's shit and Agilent is better.  You don't even own one of these PSU's and have never used one but you are arguing with folks that own both, and you seemed to get very offended when people criticized Agilent.

One of my other hobbies is racing cars, and the same thing happens on all the car forums.  The Mustang guys spend eons arguing with the Corvette guys that their car is better.  The Corvette guys argue the same to the Viper guys.  The Viper guys argue the same to the Ferrari guys.  And the Ferrari guys argue the same to the McLaren guys.   

There are some who just appreciate all the cars (or power supplies), and when those folks see someone waging a war against a product, it's pretty clear.  As it is in this case.  You don't like this PSU - we get it, so don't buy one.  But feel free to keep telling us all how it's total shit and only an Agilent is worth buying and every feature the Agilent lacks is unnecessary and every feature the Rigol has is unnecessary  :-DD

Unfortunately once again you don't get it.  I don't have any particular love of Agilent as a matter of fact I jokingly rubbed Dave when I said he uses that Agilent meter instead of the Fluke when he's taking certain measurements, why don't you go back and read my original post again.

The point you keep missing is that I am just saying to people to first make sure that anything you buy is a piece of gear that does it's core function precisely and accurately and then look at Ergonomics and build.  If that checks out then look at all the bells and whistles because none of the other stuff matters if it's not precise, reliable and comfortable to use.

And BTW I am also into Racing, in this case Rally Car racing. I use to sponsor a rally car and am very familiar with the wars, especially the ones between the Mitsubishi drivers and the Toyota drivers.  That's also a good example of this problem because the Mitsubishi EVO 8 & 10 guys keep pointing out how great their Cars are and how much HP they have.  The EVO Guys always start out the rally with the best run times but by the third run they always keep blowing up the engines and losing the rally to the Toyota's. (And yes the car I sponsored was a Mitsubishi VIII)
BTW If you think this hobby is expensive try paying $7000 USD for a set of shock absorbers.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dread on September 02, 2013, 05:57:35 am
This is just my opinion.   I admire the fact that so many of you guys want to fix it yourselves but any such action will most likely void your warranty.  I know the pain some of you must be feeling, when I bought my scope for $800 I wanted to return it but I had already paid Fedex $150 in shipping along with $300 in customs duty so it was not an option.  In this case your problem is a factory fault you should just write to Rigol, file a complaint and then just use the PS as normal until Rigol comes up with a revised board.  Then follow up and make sure they ship you a upgraded board.  It's not like the thing is unusable in it's current state!   If Dave had not done a teardown most of you would have merrily kept on using it feeling very happy.

Just my 2 cents.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dave on September 02, 2013, 06:55:13 am
This design reminds me very much of the Agilent E3631A. The distribution of components throughout the case, the case itself, the way they arranged the heatsinks, how things are connected,...
It's like they took E3631A's design, made it super ugly and messed up the circuit in every way imaginable. :palm:

I would definitely like to see Rigol's other power supplies (DP1116 and DP1308) torn down. Shahriar from The Signal Path blog already made an in-depth review of them a while ago, but unfortunately there was no teardown. Any chance you could get your hands on those, Dave?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: edpalmer42 on September 02, 2013, 07:24:51 am
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

If you mean lowering the currently used transformer tap output, that would mean re-winding the transformer (basically, making a new one). Hardly an optimal solution. If you mean using another tap which is already there used for the main output, well, the point is to have the logic supply (and the interface ports) separate and galvanically isolated from the main outputs. Anyway, most fans are rated 12V and I strongly assume this one is 12V as well.

If a buck winding will fit on the transformer without any problems physically, it should do the trick. Plus an extension on the heat sink of course.

I'm surprised that this idea hasn't had any more discussion.  It's potentially the cleanest and easiest DIY solution to this problem.  If the center area of the transformer is open, you might only need 10 to 15 turns of wire to make a buck winding to drop the voltage to the proper level.  You might even be able to thread the new wire in without disconnecting all the other windings.

Has anyone checked this out?

Ed

If you have access around the core, looking at the mounting in Dave's video, I doubt it. You then need the specification for the toroidal fitted (Max temp. rise above ambient, max ambient temp etc.) to even spec. the added winding correctly for temperature, will it pass the insulation tests as per original? I wouldn't class this as the easiest DIY solution, any modifications involving any items connected to the mains supply are fraught with potential hazards

That's a surprisingly cautious attitude on this forum!  :)  You can't tell from the pictures if there's room or not.  Someone would have to undue the mounting nut and look.  Temperature rise is a non-issue.  We're only talking about a few watts on a transformer that's rated for 400 or 500 watts.

Insulation testing is also a non-issue.  The transformer has all the necessary insulation.  The extra winding will be outside everything else and so, protected by the existing transformer insulation.  Even though it will be connected in series with one of the existing windings, that winding already has the necessary ratings.

Ed
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 02, 2013, 09:39:35 am

Unfortunately once again you don't get it.  I don't have any particular love of Agilent as a matter of fact I jokingly rubbed Dave when I said he uses that Agilent meter instead of the Fluke when he's taking certain measurements, why don't you go back and read my original post again.

The point you keep missing is that I am just saying to people to first make sure that anything you buy is a piece of gear that does it's core function precisely and accurately and then look at Ergonomics and build.  If that checks out then look at all the bells and whistles because none of the other stuff matters if it's not precise, reliable and comfortable to use.

And BTW I am also into Racing, in this case Rally Car racing. I use to sponsor a rally car and am very familiar with the wars, especially the ones between the Mitsubishi drivers and the Toyota drivers.  That's also a good example of this problem because the Mitsubishi EVO 8 & 10 guys keep pointing out how great their Cars are and how much HP they have.  The EVO Guys always start out the rally with the best run times but by the third run they always keep blowing up the engines and losing the rally to the Toyota's. (And yes the car I sponsored was a Mitsubishi VIII)
BTW If you think this hobby is expensive try paying $7000 USD for a set of shock absorbers.

I get what you are saying just fine.  I am simply saying it's bullshit.  You were complaining about this power supply before the thermal issue was discovered, and your basis for that complaining was the feel of the rotary knob, the layout of the keypad, having a big color screen, etc, etc.  In other words, the "ergonomics and build" which you just claimed are unimportant next to basic functionality.

So like I said, you are drastically overstating the issues of this supply as being dealbreakers, and ignoring it's positive aspects as being irrelevant and unnecessary in a power supply.

And you don't even own one.  Apparently a lot of people disagree with your take because many of us have bought one and enjoy many of the features that you say are crap and we don't need. 

The great thing about free markets is that you are not required to buy one of these PSU's.  But don't think you should be immune from criticism when you want to lord your opinions over us all and tell us that a power supply you don't own and have never used is crap and we bought them because we were fooled by useless features that we don't need, and we should be more like you and buy good equipment that is lacking in features and overpriced but has things you consider more important.

I think after your many posts about this power supply that you don't own, your stance on the matter has been made perfectly clear.  Maybe we can now get back to discussing the relevant issue in this thread and look for a fix... or are you not done yet telling us all how shit this supply is and how it's essentially a paperweight in comparison to the real stuff you buy?   :-DD





Back OT.  I had gotten a call from Chris @ Rigol a couple of weeks back after we had bought a few pieces of Rigol equipment to ask what our plans were going forward for test equipment and such.  He gave me his contact info and said to keep in touch.  So I did!  I contacted him and asked him to chime in on this issue.  I hope we get a reply.  I noticed TEquipments return policy is 7 days, so this is something that will need to be fixed by Rigol directly, and I intend to hold them to fixing it - especially considering it's an issue they knew about (as evidenced by them having already made a version 3 board while they were *still selling f-ing defective units knowingly*).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AlfBaz on September 02, 2013, 01:49:54 pm
So, playing the devils advocate for a minute, I'm curious about the train of thought that the unit is defective, I mean, is it really?

I'm working on fixing an old crt DSO right now and I have about 10 minutes before the crt overheats as I have it I pieces on the bench to fault find, so the air flow from the fan is not getting to where it's supposed to.

People seem to be advocating (including the actual rigol fix) to install a larger heatsink but isn't the unit shunting enough heat away from the regulator with the current air flow?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stonent on September 02, 2013, 03:52:34 pm
105c caps right next to a device that reaches 111c, smells like planned obsolescence (and boiled electrolyte) to me!

Absolutely! I'd consider placing electrolytic caps directly besides a heatsink (>30-40 °C) in a lab grade device a show stopper. It's built to fail.

I guess if you come into your lab one day and your power supply is off and it smells like cat pee, you'll know.  :palm:
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stonent on September 02, 2013, 03:55:28 pm
Meanwhile, i am wondering about something toally different....

Why put in an lm317 where a 7805 would have done ....

I thought the same thing, 7805 would be cheaper, no?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stonent on September 02, 2013, 04:00:29 pm
Why am I telling this story ? well the firmware update changes just one thing....it slowed the zoom motor and effectively lowered its current consumption. It appears that the battery in the SX280 is overloaded by video and Zoom functions operating at the same time and drops its p.d. as a result. Oooops !

Reminds me a little of the "infamous" HP dv6000 fix... these laptops are prone to having the lead-free solder on the GPU fail due to the laptop running hot. The HP "fix" makes the fan run at 100% all the time, which probably puts failures just outside of the warranty period and turns the laptops into miniature jet engines.

I've seen more of those than I'd care to count. It was the ones with AMD cpus with Nvidia chipsets. Pretty much any of their laptops made with that combo during that time had it.  Also Dell D630 and E6400 laptops had overheating Nvidia chips.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stonent on September 02, 2013, 04:01:56 pm
"Dave Nader"  :-+

Unsafe at any current!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on September 02, 2013, 04:03:21 pm
… isn't the unit shunting enough heat away from the regulator with the current air flow?

the airflow, the amount of air, the heatsink size and the amount of heat to be transported away from the lm317. so… which parameter you'd like to change for better performance?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: FrankBuss on September 02, 2013, 04:04:19 pm
People seem to be advocating (including the actual rigol fix) to install a larger heatsink but isn't the unit shunting enough heat away from the regulator with the current air flow?
No, Dave demonstrated that it heats up to 109°C, even with the air flow from the fan and closed case, see minute 13:46 in the video. The voltage regulator and capacitors will age very fast at this temperature. If the regulator dies, it can even short the 12V input to the output and destroy the digital electronics, and it could catch fire, if the fuse is not tripping.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stonent on September 02, 2013, 04:11:50 pm
I'd be curious if you could either put a capacitor to smooth the ripple when it starts overheating to see what happens, or find a way to reproduce that rippling current with function generator feeding into a transistor. So not really overheat it but simulate the effect on the 5V rail to trigger the logic to reboot it again.

Did you also ask them about the reversed color on the + and - ?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 02, 2013, 07:29:02 pm
the airflow, the amount of air, the heatsink size and the amount of heat to be transported away from the lm317. so… which parameter you'd like to change for better performance?

There's nothing that can be done, I'm afraid:

- You were made as well as we could make you.
- But not to last
- The light that burns twice as bright burns half as long. And you have burned so very very brightly, Rigol


Sorry, but I just couldn't help myself after realizing that's a "Blade Runner" owl as your avatar!  ;)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on September 02, 2013, 08:29:56 pm
There's nothing that can be done, I'm afraid:

- You were made as well as we could make you.
- But not to last
- The light that burns twice as bright burns half as long. And you have burned so very very brightly, Rigol


Sorry, but I just couldn't help myself after realizing that's a "Blade Runner" owl as your avatar!  ;)

you're welcome :)
now its time to squish home heads and poke some eyes!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on September 02, 2013, 10:29:24 pm
I had a reply from my supplier:

Quote
this topic is already past. The 2nd series with the transformer, there was DP832 and thus problems with the voltage regulator, because the supplier had supplied the wrong transformer. This problem is already fixed and the affected devices have been replaced or changed the transformer. So was immediately known and has been fixed.

(translated from German)

seems we both have the same supplier.
on the other hand… rigol may have been aware of the problem, but they sold the defective units anyways. so i'm going to check which revision the upper board has when my unit arrives.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: gilbjd on September 03, 2013, 12:04:28 am
I doubt whether there are DP832 power supplies with Rev 3 boards in the supply chain yet. Correct me if I'm wrong.

I bought my DP832A on 20 August this year. Its serial number starts DP8B1529XXXXX (29th week of 2013) and its factory calibration date was 8 August 2013. It clearly has a Rev 2 board as the 2 electrolytic capacitors, the LM317 and its heat sink are visible through the ventilation holes in the Rev 2 positions. The heat sink runs at just over 100 degrees Celsius as judged by sticking a thermocouple through the ventilation holes.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: FrankBuss on September 03, 2013, 01:14:47 am
For what it's worth I am in the UK but bought the PSU from Germany. Out mains seems to be about 240V still, and Germany is probably still 220V, but Europe is supposed to be harmonized on 230V. So any 230V transformer they ship to Europe could be producing +/- 0.4V on a 9V tap, but that should be okay.
I've just measured it: 226.7V here in Cologne with my HM8012 (0.4% accuracy for the 500V AC range, true RMS).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: madires on September 03, 2013, 01:27:48 am
For what it's worth I am in the UK but bought the PSU from Germany. Out mains seems to be about 240V still, and Germany is probably still 220V, but Europe is supposed to be harmonized on 230V. So any 230V transformer they ship to Europe could be producing +/- 0.4V on a 9V tap, but that should be okay.
I've just measured it: 226.7V here in Cologne with my HM8012 (0.4% accuracy for the 500V AC range, true RMS).

Had anything from 225 up to 235V over the last years. Some seconds ago it was 227V (north of Frankfurt/Main).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: gilbjd on September 03, 2013, 01:37:44 am
I bought my DP832A on 20 August this year. Its serial number starts DP8B1529XXXXX (29th week of 2013) and its factory calibration date was 8 August 2013. It clearly has a Rev 2 board as the 2 electrolytic capacitors, the LM317 and its heat sink are visible through the ventilation holes in the Rev 2 positions. The heat sink runs at just over 100 degrees Celsius as judged by sticking a thermocouple through the ventilation holes.

Interesting. You are 230V 50Hz, same as Europe. That implies that the problem isn't fixed. I will try to do a better thermocouple reading on my unit.

We're 240V 50Hz here in Australia. Where I live the mains is usually around 245V RMS.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 03, 2013, 02:01:50 am
I don't think the difference in mains voltage is enough to account for the overheating. What we really need to know is if European units have a different transformer to Australian units, and what supply voltage the 7805 is supposed to be on.

The mains voltage selector on the back would suggest they don't.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 03, 2013, 02:15:43 am
Which in turn reminded me to provide a hint for the Rigol (well, any dual-voltage PSU for that matter) owners. When I got my Siglent SPD3303S it turned out the distributor remembered to switch the primary to proper voltage (230V) on the back but forgot about the fuse. Siglent specifies 6.3A for 120V and 3.15A for 230V operation respectively, which of course makes perfect sense, but the dealer forgot to switch the fuses so I was on 6.3A one for some time. I was positively surprised to find that there's a convenient spare fuse storage space in the IEC socket/fuse socket combo which contained the 3.15A fuse for me to switch. So check yours, 230V guys, just to be on the safe side.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Tepe on September 03, 2013, 02:27:59 am
For what it's worth I am in the UK but bought the PSU from Germany. Out mains seems to be about 240V still, and Germany is probably still 220V, but Europe is supposed to be harmonized on 230V. So any 230V transformer they ship to Europe could be producing +/- 0.4V on a 9V tap, but that should be okay.
I've just measured it: 226.7V here in Cologne with my HM8012 (0.4% accuracy for the 500V AC range, true RMS).
I just measured 240.3 V here (north of Germany).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nigel53 on September 03, 2013, 03:04:43 am
Hi

A better fix for the voltage regulator would be to change the transformer winding, from the hunt for the problem there looks to be +8v a drop across the regulator, no reason to have so much voltage drop, 4 volts would give lots of margin while dropping the power dissipation in half. With the larger heat sink things would be be just right.

If you mean lowering the currently used transformer tap output, that would mean re-winding the transformer (basically, making a new one). Hardly an optimal solution. If you mean using another tap which is already there used for the main output, well, the point is to have the logic supply (and the interface ports) separate and galvanically isolated from the main outputs. Anyway, most fans are rated 12V and I strongly assume this one is 12V as well.

If a buck winding will fit on the transformer without any problems physically, it should do the trick. Plus an extension on the heat sink of course.

I'm surprised that this idea hasn't had any more discussion.  It's potentially the cleanest and easiest DIY solution to this problem.  If the center area of the transformer is open, you might only need 10 to 15 turns of wire to make a buck winding to drop the voltage to the proper level.  You might even be able to thread the new wire in without disconnecting all the other windings.

Has anyone checked this out?

Ed

If you have access around the core, looking at the mounting in Dave's video, I doubt it. You then need the specification for the toroidal fitted (Max temp. rise above ambient, max ambient temp etc.) to even spec. the added winding correctly for temperature, will it pass the insulation tests as per original? I wouldn't class this as the easiest DIY solution, any modifications involving any items connected to the mains supply are fraught with potential hazards

That's a surprisingly cautious attitude on this forum!  :)  You can't tell from the pictures if there's room or not.  Someone would have to undue the mounting nut and look.  Temperature rise is a non-issue.  We're only talking about a few watts on a transformer that's rated for 400 or 500 watts.

Insulation testing is also a non-issue.  The transformer has all the necessary insulation.  The extra winding will be outside everything else and so, protected by the existing transformer insulation.  Even though it will be connected in series with one of the existing windings, that winding already has the necessary ratings.

Ed

Adding another winding of a few watts is not the point! You are adding a winding around an item that could be specified for a typical temp. rise above ambient of 50 deg C, this thing could run at 100 deg C.
The extra winding would indeed be outside everything else, including the existing transformer insulation; were talking about insulation to chassis, not just to the mains input.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: SeanB on September 03, 2013, 04:06:51 am
If I bought one I would put a bigger heatsink on it, and as well change the little 100uF 35V capacitor on the output of the 317 to a 470uF 16v unit. Add a 6V8 1W zener across it as well as a sacrificial device in case of failure of the 317, as there is a 2A PCB mount fuse there ( thanks for including that and not skimping Rigol, very useful to actually not rely on the big mains fuse for protection only) that will blow as the zener dies a horrible death as well, saving the digital board.

As well I would bend those fins of the heatsink further to allow airflow along it, and turn them to restrict airflow less.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Kjelt on September 03, 2013, 05:05:14 am
If Rigol has fixed this issue they can better rename the v2 to  DP833 or higher since no-one is gonna buy this hot number anymore .
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: plesa on September 03, 2013, 05:46:06 am
I quite impressed how many of members who purchased this crappy power supply is going to repair it by yourself.
I really do not understand why not to return unit to Rigol distributor, this will make the pressure on them.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: bitwelder on September 03, 2013, 05:52:47 am
I don't think the difference in mains voltage is enough to account for the overheating. What we really need to know is if European units have a different transformer to Australian units, and what supply voltage the 7805 is supposed to be on.
Would it make sense to compare the weight of the PSUs (for those who don't want to break the warranty seals)? It seems there are at least two transformers used with with this unit, a 400VA and a 500VA. I would guess that the units with a 500VA transformer are sensibly heavier.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on September 03, 2013, 06:03:21 am
I quite impressed how many of members who purchased this crappy power supply is going to repair it by yourself.
I really do not understand why not to return unit to Rigol distributor, this will make the pressure on them.
Quote from this page on cognitive dissonance (http://psychology.about.com/od/cognitivepsychology/f/dissonance.htm):

"(...) A more common example of cognitive dissonance occurs in the purchasing decisions we make on a regular basis. Most people want to hold the belief that they make good choices. When a product or item we purchase turns out badly, it conflicts with our previously existing belief about our decision-making abilities. (...)"

Also see irate comments directed at anyone trying to discuss the bigger issues behind these minor technical problems.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on September 03, 2013, 06:08:10 am
Not necessarily cognitive dissonance. If I bought a power supply that had a problem, I'd probably want to fix it myself just because I can do it faster. Who wants to wait for warranty repair on something like a power supply? It's not like it's some whiz-bang Agilent scope, there's nothing in there I can't repair by myself.

And even if it's faulty, there's a lot of stuff in there that's not faulty. I would still consider it worth the $400 even if I had to take an hour to fix a regulator.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 03, 2013, 06:24:12 am
I quite impressed how many of members who purchased this crappy power supply is going to repair it by yourself.
I really do not understand why not to return unit to Rigol distributor, this will make the pressure on them.
Quote from this page on cognitive dissonance (http://psychology.about.com/od/cognitivepsychology/f/dissonance.htm):

"(...) A more common example of cognitive dissonance occurs in the purchasing decisions we make on a regular basis. Most people want to hold the belief that they make good choices. When a product or item we purchase turns out badly, it conflicts with our previously existing belief about our decision-making abilities. (...)"

Also see irate comments directed at anyone trying to discuss the bigger issues behind these minor technical problems.

I think people get frustrated because of assumptions like in this post.

For example, what are the "biggest issues" behind these problems?  Rigol designed a PSU with an idiotic bug that should never have left the QC room.  But how is that symptomatic of bigger underlying issues?  The PSU works as advertised and performs within spec.  That's what I expect of a PSU.

As for people not returning them, it's a rash assumption to say it's because people want to believe they are good.  In my case, the power supply still works and performs the job I bought it to do.  It's not actually defective.  It's just that we disagree (with Rigol) with the way in which the PSU was designed.  I don't think Rigol (or their distributors) would accept the units back on the basis that we don't like how something was designed, at least not without a restocking fee.

In my case, I bought from TE and their return policy is 7 days with a restocking fee for non-defective units.  Good luck arguing the case that a PSU which performs as sold is defective because one does not agree with a design decision that may cause it to fail earlier than we would like.  That's not going to happen.  And even if they did take it back, what do we ask for in exchange?  A refund?  A different PSU?  A version 3 of the DP832?  Until and unless Rigol acknowledges this as a warranty issue, no resellers are going to preferentially sell customers Rev3 models.

There's not even any indication that if any units fail, they will be fixed/replaced with the Rev3 model.

Isn't the smart choice, at this moment, to wait to hear an official response from Rigol, and then users can choose to either A) wait until it breaks and send it for repair B) Preventatively fix it themselves or C) "encourage" it to fail within the warranty period, after the Ver.2 units are gone so they will get it repaired/replaced with a Ver.3 unit instead?



Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on September 03, 2013, 06:37:54 am
Not necessarily cognitive dissonance. If I bought a power supply that had a problem, I'd probably want to fix it myself just because I can do it faster. Who wants to wait for warranty repair on something like a power supply? It's not like it's some whiz-bang Agilent scope, there's nothing in there I can't repair by myself.

And even if it's faulty, there's a lot of stuff in there that's not faulty. I would still consider it worth the $400 even if I had to take an hour to fix a regulator.

I don't entirely disagree. However, I at least (this crowd is a bit unusual here) don't have the ability at home to fix or perhaps even just diagnose potential issues with BGA solder connections, or if for instance the transformer was found to be fundamentally flawed. Many people won't be able to get warranty repairs nor replacements, once they have opened a product. In this case it seems we are lucky in that a fix to a few problems are easily DIYable, but you cannot rely on this always being the case.

Which to me would suggest people are better off in the long run to tell the manufacturer to fix their stuff, so it performs as advertized. Even if it takes longer.

I think people get frustrated because of assumptions like in this post.

For example, what are the "biggest issues" behind these problems?  Rigol designed a PSU with an idiotic bug that should never have left the QC room.  But how is that symptomatic of bigger underlying issues?  The PSU works as advertised and performs within spec.  That's what I expect of a PSU.

The bigger issue is the one I and others have raised on various occasions recently (and got thoroughly told off for doing so): People need to focus on basic performance of the test equipment they buy first, bells and whistles secondly. Otherwise the manufacturers will focus on making more (inexpensive) bells and whistles, instead of focusing on basic performance (which can be costly to implement correctly).

The reason why I in particular mentioned this some days ago, is that I have seen a scenario very similar to this one play out before, almost 30 years ago. To me what happens here feels a bit like a deja vu slow motion train wreck.

I had decided to let the subject rest for a bit, in the hope that I might be wrong. But there you go...

As for people not returning them, it's a rash assumption to say it's because people want to believe they are good.  In my case, the power supply still works and performs the job I bought it to do.  It's not actually defective.  It's just that we disagree (with Rigol) with the way in which the PSU was designed.  I don't think Rigol (or their distributors) would accept the units back on the basis that we don't like how something was designed, at least not without a restocking fee.

In my case, I bought from TE and their return policy is 7 days with a restocking fee for non-defective units.  Good luck arguing the case that a PSU which performs as sold is defective because one does not agree with a design decision that may cause it to fail earlier than we would like.  That's not going to happen.  And even if they did take it back, what do we ask for in exchange?  A refund?  A different PSU?  A version 3 of the DP832?  Until and unless Rigol acknowledges this as a warranty issue, no resellers are going to preferentially sell customers Rev3 models.

There's not even any indication that if any units fail, they will be fixed/replaced with the Rev3 model.

Isn't the smart choice, at this moment, to wait to hear an official response from Rigol, and then users can choose to either A) wait until it breaks and send it for repair B) Preventatively fix it themselves or C) "encourage" it to fail within the warranty period, after the Ver.2 units are gone so they will get it repaired/replaced with a Ver.3 unit instead?

I would agree, that in the current situation the smart move for any buyers would be to do nothing right now, while we wait for Rigol's next move.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: c4757p on September 03, 2013, 06:51:20 am
Not necessarily cognitive dissonance. If I bought a power supply that had a problem, I'd probably want to fix it myself just because I can do it faster. Who wants to wait for warranty repair on something like a power supply? It's not like it's some whiz-bang Agilent scope, there's nothing in there I can't repair by myself.

And even if it's faulty, there's a lot of stuff in there that's not faulty. I would still consider it worth the $400 even if I had to take an hour to fix a regulator.

I don't entirely disagree. However, I at least (this crowd is a bit unusual here) don't have the ability at home to fix or perhaps even just diagnose potential issues with BGA solder connections, or if for instance the transformer was found to be fundamentally flawed. Many people won't be able to get warranty repairs nor replacements, once they have opened a product. In this case it seems we are lucky in that a fix to a few problems are easily DIYable, but you cannot rely on this always being the case.

I agree about the BGA part. No matter how much I try I cannot properly remove and solder a BGA chip. |O But does this even have any BGAs? (I don't remember from the teardown.) They're probably the least likely part to fail in something like this, so even though I'd be up the creek without a paddle if I voided my warranty and one of those broke, I doubt it would.

I'd probably cuss a lot about having to fix the transformer, but I'd do it. Another unlikely problem. (Yes, I see it's part of the problem here, but I'd probably just replace the 317 with a bodge board containing an LM2575.)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tom66 on September 03, 2013, 09:46:17 am
The main processor and RAM are BGAs. i.MX plus what looks to be at least 16MB of SDRAM going by the package type.

Frankly, you can drive an LCD like that (~320x240 colour 16-bit, non-memory type) from an STM32F4 + 512K of SRAM, so I'm not sure why they bothered with an i.MX... seems a little overkill. My guess is they have a lot of code written for that, and the engineering cost being the main driver of the instrument cost, meant it worked out cheaper. I know they use i.MX in the DS1074Z, and I expect they're slowly moving away from Blackfins as they put more of the processing load in their scopes on FPGAs, or maybe the i.MX has good enough DSP anyway.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: MacAttak on September 03, 2013, 10:33:39 am
It seems like simply offering an extended warranty (at no charge) to owners of models with specific serial numbers would also solve the problem. More or less. Yes, some subset of units would still fail (but not all). Those customers would be able to get a warranty repair. And Rigol wouldn't have to issue a full recall. From a customer perspective, this is no worse than a recall... you still have to send the thing back and wait on a replacement either way. And what if some other problem is found in between now and when that regulator finally dies? You get a two-for repair in that case :-+

This is what Microsoft did with the RROD on the original revisions of the 360 if I recall correctly. We just got a few extra years on the warranty - which was more than enough for most people. And even post-warranty, they still would take care of it just to avoid the bad press.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on September 03, 2013, 10:39:54 am
From a customer perspective, this is no worse than a recall... you still have to send the thing back and wait on a replacement either way.
Except that it might die a week before a deadline, or some other unfortunate time. In the case of a recall the customer has at least some control about when to send it back, and they can even rent a replacement in advance if needed.

And what if some other problem is found in between now and when that regulator finally dies? You get a two-for repair in that case :-+
Then they deserve to have to do a second recall. That might inspire them to fire those monkeys doing testing and QA and get some actual humans to do it.

This is what Microsoft did with the RROD on the original revisions of the 360 if I recall correctly. We just got a few extra years on the warranty - which was more than enough for most people. And even post-warranty, they still would take care of it just to avoid the bad press.
The Rigol DP832 claims to be a professional tool, not a consumer toy. Being without an X-box for a few weeks is not an emergency for most people. Being without a power supply that was part of a product demonstration might be.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 03, 2013, 10:45:44 am
Quote
The bigger issue is the one I and others have raised on various occasions recently (and got thoroughly told off for doing so): People need to focus on basic performance of the test equipment they buy first, bells and whistles secondly. Otherwise the manufacturers will focus on making more (inexpensive) bells and whistles, instead of focusing on basic performance (which can be costly to implement correctly).

Ok, but what basic functionality does not operate correctly?  It delivers power within spec and I have loaded it up on my electronic load and it didn't burn up or overheat.  I don't see what Rigol has sold us that the supply is incapable of achieving?  Sure, the power spike at turn-on is unfortunate, but I think it is being overblown.  I measured 1.6V on CH1 and -600mV on CH2 - which IMO makes the PSU unsuitable for only a very small subset of users.  On the other hand, for me, being able to see the output of all 3 supplies is quite important, especially in an R&D/prototyping environment.  I don't think that is ignoring basic functionality in favor of bells and whistles, it's just assigning more value to the features that are helpful to me.

I would agree, that in the current situation the smart move for any buyers would be to do nothing right now, while we wait for Rigol's next move.

I hope we will get it soon.  I got a cheerful call from Rigol's North American customer support/technical sales guy a few weeks ago after I got my DP832 - he was quite interested in making sure we were totally happy since we bought several bits of Rigol gear in the past few weeks.  Let's see if he is equally interested in making sure we are totally happy now that there is a real problem :)

I fear Rigol's response will be to refuse to exchange units with this thermal issue... and I intend to do my best to compel them to exchange my unit.  Hopefully they do the right thing on their own. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 03, 2013, 03:37:59 pm
I have heard back from John South at Emona about the issue. And I'll quote a few parts:
Quote
we will be getting a detailed response from Rigol in the next day or so . Even with the old boards they have only just today been able to replicate your rebooting . The board out of the case and the higher Aust. Voltage apparently contributed. (As much as working out a solution for existing customers they needed to see what was happening on the original boards

They will be coming up with a fix for existing customers with older boards and it will be sooner rather than later (I expect an answer in
the next couple of days).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 03, 2013, 03:44:52 pm
We're 240V 50Hz here in Australia. Where I live the mains is usually around 245V RMS.

No, we are officially now 230V + 10% -6%
However, a nominal 240V is still very common, and is what I get at home and the lab.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: gilbjd on September 03, 2013, 03:46:43 pm
I have heard back from John South at Emona about the issue. And I'll quote a few parts:
Quote
we will be getting a detailed response from Rigol in the next day or so . Even with the old boards they have only just today been able to replicate your rebooting . The board out of the case and the higher Aust. Voltage apparently contributed. (As much as working out a solution for existing customers they needed to see what was happening on the original boards

They will be coming up with a fix for existing customers with older boards and it will be sooner rather than later (I expect an answer in
the next couple of days).

Thanks for chasing this up with Emona, Dave.

As a recent purchaser from Emona (DP832A 2 weeks ago), I would like to get this design flaw eliminated from my unit. Therefore it would be great if you could keep us up to date with Rigol's response and Emona's response for Australian customers.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 03, 2013, 04:20:03 pm
I have heard back from John South at Emona about the issue. And I'll quote a few parts:
Quote
we will be getting a detailed response from Rigol in the next day or so . Even with the old boards they have only just today been able to replicate your rebooting . The board out of the case and the higher Aust. Voltage apparently contributed. (As much as working out a solution for existing customers they needed to see what was happening on the original boards

They will be coming up with a fix for existing customers with older boards and it will be sooner rather than later (I expect an answer in
the next couple of days).


Ipad typing sucks..

Dave, how much (or all?) of this info applies only to Australian units?  Is Emona dealing with Rigol china on this or Rigol Australia?

Just wondering if we need to do our own badgering for USA units or if this pending solution will be all-encompassing... Thx!!!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: gilbjd on September 03, 2013, 04:32:14 pm

Ipad typing sucks..

Dave, how much (or all?) of this info applies only to Australian units?  Is Emona dealing with Rigol china on this or Rigol Australia?

Just wondering if we need to do our own badgering for USA units or if this pending solution will be all-encompassing... Thx!!!
[/quote]

Unlike their presence in the EU and the USA, Rigol has no office in Australia. Emona is their Australian distributor.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on September 03, 2013, 04:32:36 pm
We're 240V 50Hz here in Australia. Where I live the mains is usually around 245V RMS.

No, we are officially now 230V + 10% -6%
However, a nominal 240V is still very common, and is what I get at home and the lab.

more to it than that, as always the power companies give themselves wiggle room.
http://www.ausgrid.com.au/~/media/Files/Network/Documents/ES/ENOS_Oct2011.pdf (http://www.ausgrid.com.au/~/media/Files/Network/Documents/ES/ENOS_Oct2011.pdf)
my daytime average is above 245, I strongly suspect neighbours tweaking overvoltage cutout on solar to get max $$$
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on September 03, 2013, 04:35:38 pm
good to see Emona involved  but I got mine from Eyou http://www.eyou.com.au/ (http://www.eyou.com.au/)
guess that may be a separate battle.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 03, 2013, 04:39:35 pm
Unlike their presence in the EU and the USA, Rigol has no office in Australia. Emona is their Australian distributor.

thanks for the info.

Dave when you hear back could you maybe ask if this is a fix for Ozzie units or all DP832?  I think the tests that the yanks have done show its not a 240v only issue.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: John South on September 03, 2013, 05:12:42 pm
Hi - Just to let you know I am speaking with Rigol China and have passed that info on to Dave. I was on the phone to them today and they will have a resolution within a couple of days. I look after Australia and New Zealand so I will be looking after customers who have purchased from us here but I am sure that there will be similar options (whatever form that will take) available elsewhere . Whatever people think or like/dislike about their product they do take quality issues seriously.

mickpah - We can organise your unit as well. I will send you a pm.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tru on September 03, 2013, 05:26:51 pm
I don't know where you live but in the EU the minimum warranty period is 2 years. Beyond that the UK has something called the Sale of Goods Act, which states that anything you buy must last a "reasonable length of time". For example a laptop computer is generally said to have a five or six year lifespan by the courts. If it dies before then the shop (not the manufacturer) has to either replace or repair it, or can offer you a partial refund based on the amount of time you had it. So for example if your laptop dies after three years you might get 50% of the purchase price back because it only lasted half has long as it should have.

Price is mostly irrelevant. It doesn't matter if the laptop was £150 or £1500, it has to last a reasonable length of time for a laptop. In the case of lab equipment like a £350 PSU a decade would seem like a reasonable period to me. Lab use would be at least 8 hours a day, five days a week.
What are you smoking? (joke), but seriously what you're saying is untrue in the UK. Uk is no exception, UK Courts are held on an individual basis and results are also and are not automatic, final results depends on the judge, etc. Also it is not free, you would need to hire a Solictor (£££) to conduct the legal work and it most likely costs more than buying the new product.

Where is this link/reference of such 5 to 6 years law claim?

Warranty void labels do hold in the UK as it is not even mentioned in the "Sales of Goods Act".
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 03, 2013, 06:31:42 pm
The sticker may help them to show you opened the device, but they still have to prove that the specific fault was caused by you and was not there when the item was sold to you.

"I present as evidence to you your honour, this 45min video from a crazy aussie bloke that proves it is a design oversight"  ;D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tru on September 03, 2013, 07:25:04 pm
I guess you have no experience of this. You don't need a solicitor, you can use Small Claims Court. It costs £30 but you get that back if you win.

The warranty label is meaningless. The burden is on the shop to prove, on a balance of probabilities, that the fault was not a manufacturing problem. The sticker may help them to show you opened the device, but they still have to prove that the specific fault was caused by you and was not there when the item was sold to you.
Nope, I've never used Small Claims Court, and where does it say it costs £30?  In their link:
https://www.gov.uk/make-court-claim-for-money/going-to-court (https://www.gov.uk/make-court-claim-for-money/going-to-court)
All I see is:
"If there is a hearing, you can:.... pay for a solicitor to represent you"
Suggests paying yourself which most likely more than £30 if it goes further.

Yes, I'm not saying that warranty void label will stop you from particular case of manufacturing problem claim, but I disagree that it is meaningless in a court system.  In cases such as wear & tear/breakdown/accidental damage goods and under warranty, a warranty void broken seal will lower your chances.

Dave's case is about manufacturing problem/design fault, not your every day general case.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on September 03, 2013, 07:33:53 pm
We're 240V 50Hz here in Australia. Where I live the mains is usually around 245V RMS.

No, we are officially now 230V + 10% -6%
However, a nominal 240V is still very common, and is what I get at home and the lab.

more to it than that, as always the power companies give themselves wiggle room.
http://www.ausgrid.com.au/~/media/Files/Network/Documents/ES/ENOS_Oct2011.pdf (http://www.ausgrid.com.au/~/media/Files/Network/Documents/ES/ENOS_Oct2011.pdf)
my daytime average is above 245, I strongly suspect neighbours tweaking overvoltage cutout on solar to get max $$$

However, Ausgrid aims to maintain supply within the target steady state supply voltage range for at least 98% of the time when measured over a period of one week.
Which equals up 210 minutes consecutive or in intervals allowable above 253 v to meet targets - they are likely better than that, prudent design would need to take this into account
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on September 03, 2013, 08:52:35 pm
I have confirmation that the issue has already been fixed in a new board revision.
They changed the board to fit a larger heatsink, but it's not a huge amount bigger. See photo.
They measured the temp at 76C in a 28C ambient , but I'm not sure if this is free standing out of the case, or in the case with airflow.
They will be replacing all Australian units, I don't know about other countries.

I would not call this a proper belt'n'braces fix, as I think the heatsink still isn't big enough, but it probably now puts it into the (just) acceptable category.
They have also apparently made a few other fixes.
(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=59166;image)


Do you know from what serial number done this new board revision?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 03, 2013, 09:44:44 pm
Do you know from what serial number done this new board revision?

That is unknown at this stage.
Should be visible through the vent holes though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AlfBaz on September 03, 2013, 11:08:30 pm
...They have also apparently made a few other fixes.
(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=59166;image)
From that picture it looks as though they have moved those other caps (just visible on the left) further away from the rectifier heatsink

EDIT: Just looked back at Dave's video, the gap was bugger than I remembered, so no...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: HackedFridgeMagnet on September 03, 2013, 11:17:56 pm
Quote
EDIT: Just looked back at Dave's video, the gap was bugger than I remembered, so no...
Freudian slip maybe, nice one.
probable version: "bugger the gap was bigger than I remembered"
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AlfBaz on September 03, 2013, 11:20:36 pm
Freudian slip maybe, nice one.
probable version: "bugger the gap was bigger than I remembered"
LOL, took me a minute to see what you meant :)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 04, 2013, 12:06:16 am
EDIT: Just looked back at Dave's video, the gap was bugger than I remembered, so no...

Ah, so you're really a New Zealander  :P
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nquantum on September 04, 2013, 03:04:19 am
After read topic since 1st page up to now. Wondering who already own this unit and confirm this heat problem? More important is what u gonna do next? U wait for Rigol to respond or u will modify by yourself/how.

I'd also specially ask Dave. What u gonna do with your unit? Since u already break the seal so u break warranty right? Or if u don't break the seal yet. What u will do with this heat issue? I'm in Thailand. I also interest to have this unit in next 2-3 month also.
Thank
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Kjelt on September 04, 2013, 05:05:09 am
The Rigol DP832 claims to be a professional tool, not a consumer toy. Being without an X-box for a few weeks is not an emergency for most people.
Tell that to your kids and see what happens  :D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on September 04, 2013, 08:35:43 am
I've yet my super nes, twenty years old and work very well. :)

In my case the recall will be very expensive and sure i'll has fix this alone.

How i dont know yet, but i think that will need design other small pcb just to the lm317 and integrate this with wired of 2 mm (750v) in your the original place.

But the better is learn with the new releases of rigol.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dread on September 04, 2013, 01:43:53 pm
I quite impressed how many of members who purchased this crappy power supply is going to repair it by yourself.
I really do not understand why not to return unit to Rigol distributor, this will make the pressure on them.
Quote from this page on cognitive dissonance (http://psychology.about.com/od/cognitivepsychology/f/dissonance.htm):

"(...) A more common example of cognitive dissonance occurs in the purchasing decisions we make on a regular basis. Most people want to hold the belief that they make good choices. When a product or item we purchase turns out badly, it conflicts with our previously existing belief about our decision-making abilities. (...)"

Also see irate comments directed at anyone trying to discuss the bigger issues behind these minor technical problems.

Bingo!
And that's why certain people get so personal about it. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 04, 2013, 02:06:14 pm
I quite impressed how many of members who purchased this crappy power supply is going to repair it by yourself.
I really do not understand why not to return unit to Rigol distributor, this will make the pressure on them.
Quote from this page on cognitive dissonance (http://psychology.about.com/od/cognitivepsychology/f/dissonance.htm):

"(...) A more common example of cognitive dissonance occurs in the purchasing decisions we make on a regular basis. Most people want to hold the belief that they make good choices. When a product or item we purchase turns out badly, it conflicts with our previously existing belief about our decision-making abilities. (...)"

Also see irate comments directed at anyone trying to discuss the bigger issues behind these minor technical problems.

Bingo!
And that's why certain people get so personal about it.

Exactly.

People for whom half their posts are in threads complaining about one brand of equipment (scopes, PSU's, etc) and who own the competing brands :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 04, 2013, 04:42:37 pm
On Sunday night I ordered the DP832 from www.eyou.com.au (http://www.eyou.com.au) an Australian provider in Victoria.
Before proceeding I asked if they could provide the new model, with the fix. They said they had no way of knowing without opening the box but would be willing to exchange when Rigol responds.

Today it arrived; I quickly unboxed it and can confirm that the regulator is in the position shown on the image Rigol provided dave. (Clearly visible through the side grill)

It is the new revision of the board.

I will now have to find a way to measure the temperature.


Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 04, 2013, 05:30:34 pm
On Sunday night I ordered the DP832 from www.eyou.com.au (http://www.eyou.com.au) an Australian provider in Victoria.
Before proceeding I asked if they could provide the new model, with the fix. They said they had no way of knowing without opening the box but would be willing to exchange when Rigol responds.

Today it arrived; I quickly unboxed it and can confirm that the regulator is in the position shown on the image Rigol provided dave. (Clearly visible through the side grill)

It is the new revision of the board.

I will now have to find a way to measure the temperature.

That was fast!

I am sure a lot of us are VERY interested in your temp readings.  Thanks!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 04, 2013, 07:37:35 pm
Today it arrived; I quickly unboxed it and can confirm that the regulator is in the position shown on the image Rigol provided dave. (Clearly visible through the side grill)

It is the new revision of the board.

I will now have to find a way to measure the temperature.

It looks like you could get an infrared reading through the side grill. To me, it looks like the thermal resistance from heatsink#1 to heatsink#2 has been reduced by at least 100 - 200% (without taking into account the new placement of the caps).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: unnecessarynitpicker on September 04, 2013, 10:45:43 pm
Does the new board still have the power on bug or did they just fix the overheating regulator?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 04, 2013, 10:56:59 pm
I won't be able to get my infrared on there. I was planning on getting a thermocouple anyway.

Should be able to get some readings tomorrow night.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: twjtwj on September 05, 2013, 02:10:04 am
I just received mine today from tequipment.net (US model).  I shined a light into the side and it appears I have the "Dave Jones" model.  I've had it on for about 15 minutes with all channels on, but it hasn't rebooted yet. This is a fresh from the box trail.

I'll run some temperature probe tests when I get a chance tonight (unless my 5 month year old thinks otherwise).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Ericho on September 05, 2013, 03:24:48 am
Dave,

Should I go for one of these ? after all its just a 10$ fix ones it runs out of waranty to make it reliable for the next 10 years.

It still seems like good value for money even if I end up with the "Dave Jones" model.

I will use it an hour or 2 a week at most.

The new picture version is good enough as is for me, I don't realy expect more then what I pay for. Rigol fits nice in what I need and willing to pay category.

Anyone have some advice as where to buy a DS2072 and maybe a PS, I live in Belgium Europe.

brgds,
Eric

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on September 05, 2013, 03:56:06 am
It still seems like good value for money even if I end up with the "Dave Jones" model.

Unless you need something today I'd wait for the revision.  Yeah what we've seen so far is an easy fix, but who knows where else they cheapened out, needs a bit more time to be trusted, right now they are sitting at 0% trustworthiness.

Good and reasonably priced power supplies come up on ebay often.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Ericho on September 05, 2013, 04:44:04 am
Nope, I donn't need it today. My PS's are just old and have no presets etc. I Always seem to run out off DDM's when I'm fideling around and thats anoying.

It make sense to wait a bit and just buy a DS2072 for now and a user frendly PS later. After all it's just the shipping costs.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 05, 2013, 05:05:28 am
Anyone have some advice as where to buy a DS2072 and maybe a PS, I live in Belgium Europe.
Batronix (http://www.batronix.com/shop/index.html) is the obvious Rigol supplier in the EU (30 day trial period) - but you can also send EEVBlog member drieg (http://www.eevblog.com/forum/profile/?u=343) (Petr Smid - Silcon Electronics (http://silcon.cz/)) an email or PM, and see if he might have a better deal for you than Batronix.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 05, 2013, 05:38:37 am
Or you can get Siglent SPD3303S/D from http://www.futu-tech.de/ (http://www.futu-tech.de/)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 05, 2013, 05:43:20 am
Or you can get Siglent SPD3303S/D from http://www.futu-tech.de/ (http://www.futu-tech.de/)
He was asking about a DSO.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 05, 2013, 06:25:50 am
For those asking for the serial number: DP8C1532014XX
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on September 05, 2013, 06:44:49 am
Do you know from what serial number done this new board revision?

That is unknown at this stage.
Should be visible through the vent holes though.

For those asking for the serial number: DP8C1532014XX

@ wizzy = this is the serial number that from this and after they fixed the issue?

Today I received the DP-832 that I have ordered before one month.

I can't break the warranty tape to see inside and I can't to see well inside via the side holes because it was afternoon.

I worked with this without any load for an hour and push the sense of temprature from the side holes. I write maximum temperature 65°C with ambient 27-28°C.
For the next two hours with loads and no loads the temprature was 58-65°C.
The serial number is DP8C1533014XX.
Before I receive the psu, ask from Owon Dealer to my country to confirm me that this psu hasn't this issue. They contacted with Owon Service Depatrment in Germany and the answers that gave them was "We have fixed that problem and your mentioned product has not that problem".

Tomorrow with the light of day, I'll try to see better via the holes and perhaps take a good photo from this area of board.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TerminalJack505 on September 05, 2013, 07:08:21 am
I have an original style one, with the heatsink behind the caps. Makes them difficult to measure but mine reached 80C as best I can tell after 20 minutes. No crashes.

80C seems high to me. I expect that the regulator is a lot higher... But maybe not 40C higher. Still, the caps are only 105C rated.

Zeitech claims that this model is "fixed" because it has the correct transformer in it. Perhaps they used a 9V tap or something. I'm not sure how to proceed, since I don't really want to open it when I know there may be a manufacturing defect. For reference my serial number is DP8C152400672.

I hope you mean the case is getting to 80C and not the heatsink.  Even with the case at 80C the die is running at 105C, assuming 5 watts of heat.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 05, 2013, 08:08:34 am
For those asking for the serial number: DP8C1532014XX

@ wizzy = this is the serial number that from this and after they fixed the issue?

I believe I have a new board. Looking in through the vent on the right hand side I can see the black heat sink clearly and it is in the location shown in the image Rigol provided.

I should be able to get a temp on it tonight.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: twjtwj on September 05, 2013, 10:14:43 am
My unit has not rebooted yet, but I was able to touch the regulator with a heat probe though the case (Fluke temperature probe hooked up to a Fluke 289).  The temp made it up to 98 degrees Celsius with all of the inputs on. :(  It's confirmed that I have a "Dave Jones" model.  :palm:

Again. This a US unit I bought from tequipment.net and it shipped last week.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on September 05, 2013, 10:17:42 am
Again. This a US unit I bought from tequipment.net and it shipped last week.

Which further proves they are shipping known defective equipment, on purpose, deliberately, hoping their customers just don't happen to notice. 

Pathetic....    :--
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: twjtwj on September 05, 2013, 10:28:10 am
Well to be fair it may have been on a boat for a week or two to get here (tequipment said they arrive by boat, or at least my oscilloscope did). They said it was one of about 300 units shipped to them. If it means anything the calibration time (I think they meant date) is "2013-7-1". So it may be almost 2 months old.

Is there anyone out there with a "fixed" board that can tell me the calibration date of their unit (Utility menu -> next 2/2 -> Test/Cal)?

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 05, 2013, 12:27:37 pm
I have borrowed a k type thermocouple probe from a work colleague and will measure the temp of the heat sink tonight.

Is there anyone out there with a "fixed" board that can tell me the calibration date of their unit (Utility menu -> next 2/2 -> Test/Cal)?
I will post my calibration date when I get home.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: warp_foo on September 05, 2013, 12:53:03 pm
For those asking for the serial number: DP8C1532014XX

For those looking to narrow down the affected serial number range, my unit is DP8C15230058X, and I have the 'broken' version. The heatsink appears to be the same as in riconette's photo in post #84.

Purchased late July, delivered first week of August.

m
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 05, 2013, 01:06:23 pm
Mine is DP8C152600824
Factory cal'ed on 9th July.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 05, 2013, 03:15:26 pm
UPDATE:

From John South at Emona:
Quote
Rigol will be replacing the Analog boards in units globally . With Emona (and I would imagine other distributors) we will be sent the new boards with some calibration software and instructions . I don't yet know what is involved with the board replacement and calibration etc but most likely we will be performing the replacement at our service center . I'm also not sure of a timeframe due to the large logistics involved but at least it is very good news for all existing users of the DP power supply.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fsck on September 05, 2013, 03:19:55 pm
at least they have a solution, but god that's going to be painful logistics.
who pays for transport to and from?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on September 05, 2013, 03:28:22 pm
UPDATE:

From John South at Emona:
Quote
Rigol will be replacing the Analog boards in units globally . With Emona (and I would imagine other distributors) we will be sent the new boards with some calibration software and instructions . I don't yet know what is involved with the board replacement and calibration etc but most likely we will be performing the replacement at our service center . I'm also not sure of a timeframe due to the large logistics involved but at least it is very good news for all existing users of the DP power supply.

Awesome, thanks for the follow-up Dave.

I am actually quite impressed with Rigol.

Every company makes mistakes.  Every company eventually ships something they wished they hadn't.  What separates the men from the boys is how they handle it.

As for shipping, I know people will complain about having to ship their units to Rigol, but nobody has a god-given right to not be inconvenienced in any way.  If my TV breaks, I don't expect Sony to cover the fuel cost to drive it to them or to compensate me for my time driving back to the store... as we say "shit happens".  Yeah, it's an inconvenience, but at least Rigol is taking care of it - reflects very well on them, IMO.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 05, 2013, 07:27:48 pm
I measured the heat sink temperature in my power supply. (Fluke 179 + k type thermocouple)

Ambient temp:                    22C
10min idle:                          44C
30min idle:                          44C
90min idle:                          46.5C

Idle is all channels on, no load, voltage 1:32v 2:32v 3:5.3v

I will update as the night goes on.

Mains voltage:                    244Vac
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 05, 2013, 07:30:26 pm
10min idle:                          44C

Seems a bit low compared to what Rigol themselves measured.
Are you getting nice firm pressure on the heatsink?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 05, 2013, 07:50:46 pm
I'm holding it firmly against the side of the heat sink, the one facing the vent. I have to hold it there for about a minute before it stops moving. Its possible the readings are being interfered with by airflow around the thermocouple.

I don't feel like taking the unit apart. It would be a difficult one to explain to the boss.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on September 05, 2013, 08:09:49 pm
UPDATE:

From John South at Emona:
Quote
Rigol will be replacing the Analog boards in units globally . With Emona (and I would imagine other distributors) we will be sent the new boards with some calibration software and instructions . I don't yet know what is involved with the board replacement and calibration etc but most likely we will be performing the replacement at our service center . I'm also not sure of a timeframe due to the large logistics involved but at least it is very good news for all existing users of the DP power supply.

Aces, Rigol!  If you read this, a big THANKS for addressing this issue in a professional manner.  I have three Rigol products I'm really happy with --- I will easily buy more if this hardware fix pans out.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: madires on September 05, 2013, 08:54:36 pm
Zeitech are saying contact Rigol directly. EU law says they have to deal with it. Hmm.

I'll contact Rigol, see what they I suppose.

Since Zeittech is located in DE they have to obey the BGB (basic law about contracts). If the toy you just bought has a known defective you may ask the seller to get you a working unit, fix the problem or take it back and refund you. Some sellers try to intimidate buyers to contact the vendor for warranty to save money & time for honouring your BGB rights. In that case tell them that you know about the BGB and wouldn't hesitate to involve your lawyer. But if you bought the unit for a/your company it's a little bit different, but the seller is still accountable for that he sold you a good unit.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 05, 2013, 08:59:50 pm
Seems a bit low compared to what Rigol themselves measured.
Are you getting nice firm pressure on the heatsink?

Perhaps Rigol's measurements were with the board outside of the case, as in your video?

When I saw the photo of the new heatsink, I also thought it should be bigger - but maybe once Rigol discovered the initial mistake, they actually figured out the optimum size for a balance between heat transfer and good airflow in the case.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Omicron on September 05, 2013, 09:10:34 pm
I measured the heat sink temperature in my power supply. (Fluke 179 + k type thermocouple)

Ambient temp:                    22C
10min idle:                          44C
30min idle:                          44C
90min idle:                          46.5C

Idle is all channels on, no load, voltage 1:32v 2:32v 3:5.3v

I will update as the night goes on.

I received a DP832A earlier this week from Batronix in Germany. It has the revised PCB in it. I measure very similar temperatures, also using a thermocouple pressed against the heat sink through the ventilation holes. I waited until the temperature didn't seem to rise anymore and got something around 47 C.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: HackedFridgeMagnet on September 05, 2013, 09:41:26 pm
The other obvious thing to measure is the supply voltage.
This would also have a significant effect if it was near the peak of it's allowable range.
In Australia it is 230V + 10% or -6% = 253Vac - 216Vac.

If for example at 230vac the voltage rectifies to 12Vdc on load which causes a voltage drop of 7volts and power loss of 4.9 watts at 700mA.
Then at 253vac the voltage would rectify to 13.2Vdc on load which causes a voltage drop of 8.2volts and power loss of 5.74 watts at 700mA.
Which is an increase of 17% power over an already stressed system.

I recommend any heat measurements also have maybe ambient temp and supply voltage too.


Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 05, 2013, 10:14:56 pm
I recommend any heat measurements also have maybe ambient temp and supply voltage too.

I've updated my post but it was 244Vac.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: studio25 on September 05, 2013, 11:06:20 pm
KeyGen for dp832 available.

http://www.eevblog.com/forum/testgear/sniffing-the-rigol%27s-internal-i2c-bus/msg287042/#msg287042 (http://www.eevblog.com/forum/testgear/sniffing-the-rigol%27s-internal-i2c-bus/msg287042/#msg287042)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: BravoV on September 05, 2013, 11:24:59 pm
KeyGen for dp832 available.

http://www.eevblog.com/forum/testgear/sniffing-the-rigol%27s-internal-i2c-bus/msg287042/#msg287042 (http://www.eevblog.com/forum/testgear/sniffing-the-rigol%27s-internal-i2c-bus/msg287042/#msg287042)
Looking at the timing in this crowded and huge discussion thread, this particular post made me chuckle.  :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jzoeller on September 05, 2013, 11:55:54 pm
I purchased the "A" model of this supply about a month ago. I can verify that I have the model with the revised board. I'm in Cincinnati Ohio, USA.

Jesse
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on September 06, 2013, 12:39:13 am
Do you know from what serial number done this new board revision?

That is unknown at this stage.
Should be visible through the vent holes though.

For those asking for the serial number: DP8C1532014XX

@ wizzy = this is the serial number that from this and after they fixed the issue?

Today I received the DP-832 that I have ordered before one month.

I can't break the warranty tape to see inside and I can't to see well inside via the side holes because it was afternoon.

I worked with this without any load for an hour and push the sense of temprature from the side holes. I write maximum temperature 65°C with ambient 27-28°C.
For the next two hours with loads and no loads the temprature was 58-65°C.
The serial number is DP8C1533014XX.
Before I receive the psu, ask from Owon Dealer to my country to confirm me that this psu hasn't this issue. They contacted with Owon Service Depatrment in Germany and the answers that gave them was "We have fixed that problem and your mentioned product has not that problem".

Tomorrow with the light of day, I'll try to see better via the holes and perhaps take a good photo from this area of board.

Update
I looked via the holes and  I can verify that I have the model with the revised board.
It has DP8C1533014XX serial number, digital version 00.01.06 and Cal Time 2013-8-17.

With the probe cable sense (not very accurate like Fluke) measures via holes, after 80 minutes temperatures btw 47-68°C according to heatshink point (look at the attachment photo). Of course the case was closed and the ambient temperature was 27-28°C.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: DarkPrince on September 06, 2013, 12:59:20 am
Good to see things turning around for the Rigol PSU. Though also unfortunate to me because now I have that itch to acquire one. Something to accompany my Mastech power supply which is a pain to dail to within 100mV possibly? I'll have to ponder thee.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bored@Work on September 06, 2013, 03:04:51 am
Zeitech are saying contact Rigol directly. EU law says they have to deal with it. Hmm.

I'll contact Rigol, see what they I suppose.

If you are in the EU, find your local (not the German, unless you are in Germany)  ECC http://ec.europa.eu/consumers/ecc/index_en.htm (http://ec.europa.eu/consumers/ecc/index_en.htm) Contact them, tell them you have an issue with a retailer in another EU country and ask them for their advice.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 06, 2013, 04:04:37 am
With my main at 207V (I know, it's low!), I've recorded 67°C after 6 min. idle (all outputs on with no load).

Edit: "buggy" REV 2 board, agilent probe through holes with closed case, 25°C ambient temperature
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: wizzy on September 06, 2013, 06:16:39 am
With the probe cable sense (not very accurate like Fluke) measures via holes, after 80 minutes temperatures btw 47-68°C according to heatshink point (look at the attachment photo). Of course the case was closed and the ambient temperature was 27-28°C.

This is as I suspected. Would be nice to get temps directly on the regulator but far too difficult without pulling it apart.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: studio25 on September 06, 2013, 06:36:12 am
The password for the DP832 "ManualCal" menu is "2012".
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 06, 2013, 06:52:21 am
I suspect that the fix that Rigol has showed was not specifically planned for ours buggy DP832s.

I mean that it's NOT their quick reply to what Dave has discovered.

Since Rigol have recently released a couple of new models in China (811A (http://www.rigol.com/prodserv/DP811A/) 40V/5A?+ 20V/10A and 821A (http://www.rigol.com/prodserv/DP821A/) 60V/1A + 8V/10A) I bet that instead a quick response, the new REV3 corrections for the DP800 series was originally implemented for that new models.

Now that they have no excuses about bad design, they are replacing the buggy boards with the new production.

It doesn't change the fact that we could have a fix, but it sounds different to me than "a quick response to an issue".



Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on September 06, 2013, 06:59:37 am
Dave never stated that the PCB fix was a response to his findings.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 06, 2013, 07:06:02 am
Dave never stated that the PCB fix was a response to his findings.

Neither me.

I was criticizing Rigol, not Dave.

It was only my feeling reading some congratulations posts to the DP832's fix.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: hikariuk on September 06, 2013, 05:51:15 pm
Is the only difference between the DP832 and the DP832A simply that the A has all the features enabled and that it has a multi colour display, instead of mono coloured display (despite, I suspect, being the same TFT).

I'm Tempted to buy once the dust has settled and the chances of it needing immediate warranty attention have reduced.  On a related note, where do people tend to snag Rigol kit from in the UK?

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on September 06, 2013, 06:10:47 pm
Is the only difference between the DP832 and the DP832A simply that the A has all the features enabled and that it has a multi colour display, instead of mono coloured display (despite, I suspect, being the same TFT).

Quick answer: YES.  Suggest you read through this thread (http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/) for many similar questions.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: hikariuk on September 06, 2013, 08:10:13 pm
Quick answer: YES.  Suggest you read through this thread (http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/) for many similar questions.

Ta.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TooOldForThis on September 07, 2013, 08:45:05 am
I heard from Tequipment that Rigol has asked them to return all their stock for rework.  There was mention that units already sold would be recalled too.  Tequipment had additional DP832s arriving from Rigol in 3 weeks but Rigol couldn't say if those units would need to be returned for rework too.  I'm not sure if that means Rigol isn't sure if the units mid-shipment had the new or old style heat sinks or if that meant that Rigol hadn't determined if even the units with the new heat sink and layout needed to be recalled.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: etc6849 on September 07, 2013, 01:02:56 pm
Is Tequipment going to contact the purchasers?  Sucks as mine just got here yesterday :(

I measured through the case with a k-type thermocouple after leaving it on a few hours.  No reset, but the temperature was 200*F+ (93* C) on the backside of the lm317's heat sink.  Pretty disappointing.  I hope I don't have to pay for return shipping...  It's good Rigol is making things right though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 07, 2013, 02:28:16 pm
I purchased the "A" model of this supply about a month ago. I can verify that I have the model with the revised board. I'm in Cincinnati Ohio, USA.

Wow, that's a wile ago.
How did I (and others) get a fresh shipment with the old design?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: SeanB on September 07, 2013, 03:52:47 pm
Assorted versions of the boards at the assembly plants will do that. If one was a little behind in the production schedule, but still in the delivery spec, and with a large consignment of boards to assemble, that would account for the differing spec levels of the boards.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 08, 2013, 12:41:02 am
Rigol Europe are not even responding. I'll wait until Monday but it looks like I'll have to force Zeitech to deal with it.
I confirm that they (both Beijing and Europe) are not responding, even if I'm only asking firmware updates.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Hydrawerk on September 08, 2013, 01:37:25 am
What to do. Rigol intruduces a new product. Then you must wait one year. Now it's time to buy, when the HW and SW bugs are not appearing...  :--
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 08, 2013, 01:50:00 am
Rigol Europe are not even responding. I'll wait until Monday but it looks like I'll have to force Zeitech to deal with it.

I'm curious as to why you bought it via Zeitech instead of Batronix? Looking through the two websites, it seems that all of the advantages are for Batronix (30 day return policy, free shipping over €400, no surcharge for different payment methods, etc). Also, when I bought Rigol goods via Batronix in the past - and had issues with it - Batronix got on it immediately and communicated with Rigol.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 08, 2013, 01:55:01 am
What to do. Rigol intruduces a new product. Then you must wait one year. Now it's time to buy, when the HW and SW bugs are not appearing...  :--

Man, you overreact quite often. There was a design mistake - Rigol has acknowledged it and is dealing with it. It's not like Agilent has never had to recall or fix a problem in one of their instruments, is it?

My DS2000 has worked perfectly from the moment I got it. Yes, there were some FW issues I wanted fixed/changed - but nothing that got in the way of me using it for my work.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: gmit77 on September 08, 2013, 04:50:34 am
from next monday RIGOL Europe is able to reply and support.
please contact your reference RIGOL distributor to know what to do.
thanks
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Hydrawerk on September 08, 2013, 11:29:22 pm
It's not like Agilent has never had to recall or fix a problem in one of their instruments, is it?
I don't know.
------------------------------------
Well, the DS2000 is quite good scope when compared to GW Instek GDS-2000A or that weird Owon TDS series. Especially when it comes to intensity grading.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 08, 2013, 11:32:08 pm
It's not like Agilent has never had to recall or fix a problem in one of their instruments, is it?
I don't know.

Well, they have.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 08, 2013, 11:59:09 pm
Because it was much, much cheaper. The whole point of the EEC is that you can buy from anywhere and have full consumer rights. I'm sure Zeitech will deal with it.

Cheaper? You mean they gave you a discount over the listed price (which is exactly the same as Batronix's)?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Hydrawerk on September 09, 2013, 12:06:08 am
It's not like Agilent has never had to recall or fix a problem in one of their instruments, is it?
I don't know.

Well, they have.
OK, it is possible. What was the problem?
BTW in every firmware update of my scope Agilent fixes some minor bugs, they are there! But i never noticed any...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: marmad on September 09, 2013, 10:43:46 pm
They were cheaper when I purchased, but apparently have reduced their prices since. In any case, they are based in Germany too so I don't see how it would make any difference.

I noted the differences in my previous post - which clearly show that, given equivalent prices, Batronix is a more consumer-friendly online site to buy via. But if you got a 'much, much cheaper' price from Zeitech, then it's understandable.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 10, 2013, 03:51:59 am
Thank you for the update mojo-chan,

it will take 1 or 2 weeks to get the board replaced

do you think they are referring TO the time that we should wait after sending the PSU to the service?

or maybe it's the time we all should wait to see the official recall announcement?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: etc6849 on September 10, 2013, 08:17:43 am
Any hints on how to uninstall the hacked DP832 options?

I tried using the following from Ultra Sigma under Windows 7 64-bit:

:SYSTem:OPTion:INSTall XXXXXXXXXXXXXXXXXXXXXXXXXXX
:SYSTem:OPTion:UNINSTall

where XXXXXXXXXXXXXXXXXXXXXXXXXXX is the license code without the dashes.

Also tried it without the first colon.  Nothing seemed to work...

The programming guide for the DP800 doesn't seem to list any commands for options (unlike the guide for the DS2000 series).  Maybe I'm SOL on clearing the options before sending the unit it?  Are the codes really unique to where Rigol will not know I hacked the power supply?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mickpah on September 10, 2013, 07:10:12 pm
Any hints on how to uninstall the hacked DP832 options?

I tried using the following from Ultra Sigma under Windows 7 64-bit:

:SYSTem:OPTion:INSTall XXXXXXXXXXXXXXXXXXXXXXXXXXX
:SYSTem:OPTion:UNINSTall

where XXXXXXXXXXXXXXXXXXXXXXXXXXX is the license code without the dashes.

Also tried it without the first colon.  Nothing seemed to work...

The programming guide for the DP800 doesn't seem to list any commands for options (unlike the guide for the DS2000 series).  Maybe I'm SOL on clearing the options before sending the unit it?  Are the codes really unique to where Rigol will not know I hacked the power supply?

I don't think :SYSTem:OPTion:INSTall is a supported command - have a look here  to check http://www.rigol.com/prodserv/DP832/document/?act=view&itemid=599 (http://www.rigol.com/prodserv/DP832/document/?act=view&itemid=599)
You need to enter it via the front panel
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Marc M. on September 10, 2013, 09:07:20 pm
According to TEquipment's website they have over 30 DP832's in stock so I requested a quote from them.  Here's part of the cover letter for the quote:
"....At this point we are waiting for a new shipment of DP832. The models we have in stock are going to be sent back to Rigol, as part of the recall, due to the heatsink issue.  The new shipment is going to be at least 3 weeks out.  Any orders placed now will be for the new ones. We are taking advance orders at this point. Credit Cards will not be charged...."


This was contained on the quote itself:
".....Thank you for your latest inquiry.
Please note that we are waiting for a new shipment of the DP832 to arrive from the factory. The models we
received are from the same batch written up on EEVBlog as being problematic.
As of now, lead time is a minimum of 3 weeks. Quite possibly longer.
We are currently taking pre-orders for a new batch...."

It appears that Rigol had intentions of selling off their remaining inventory of "heat challenged" supplies while quietly introducing the newest rev. of the board...  at least until that Crazy Aussie Bloke screwed everything up by publicly disclosing the issue on international video.  Due to the timing, I believe Dave's video and the backlash caused by it prompted Rigol to issue the recall 8).  It will be interesting to see Rigol's response to the hacked supplies if a method of uninstalling the keys isn't found.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: etc6849 on September 11, 2013, 12:08:47 am
I want to uninstall the options, not install them...  I don't think you can uninstall them from the front panel?

I don't think :SYSTem:OPTion:INSTall is a supported command - have a look here  to check http://www.rigol.com/prodserv/DP832/document/?act=view&itemid=599 (http://www.rigol.com/prodserv/DP832/document/?act=view&itemid=599)
You need to enter it via the front panel
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on September 11, 2013, 08:56:34 pm
Hi,
I have crack rigol 832 with r-78b5.0-1.5
work very well!!!!!!!!  , does not heat!!
Send the screen
(http://DSC00328.JPG)

(http://DSC00329.JPG)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mariush on September 11, 2013, 09:26:27 pm
That looks like a dc-dc converter , not a linear regulator.  Looks soldered properly albeit not so nice visually. 

Would it be possible to write down what says on that?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on September 11, 2013, 09:39:35 pm
Probably this one based on what he wrote:

http://no.mouser.com/ProductDetail/RECOM-Power/R-78B50-15/?qs=YWgezujkI1JgY7IeN1uB3w== (http://no.mouser.com/ProductDetail/RECOM-Power/R-78B50-15/?qs=YWgezujkI1JgY7IeN1uB3w==)

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on September 11, 2013, 09:45:57 pm
That looks like a dc-dc converter , not a linear regulator.  Looks soldered properly albeit not so nice visually. 

Would it be possible to write down what says on that?

Yes, is RECOM switching regulator 1.5Amp 5V out
work very well.
The resolution is bad of pic but work very well
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: salviador on September 11, 2013, 10:39:56 pm
yes, seems to go well.
but I need try approfondite test
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: riconette on September 11, 2013, 10:46:13 pm
Yes, is RECOM switching regulator 1.5Amp 5V out
work very well.
The resolution is bad of pic but work very well

i'd like to pay 5 bucks more for this kind of solution and, if needed, a low pass t-filter on the output-rail instead of the actual "miniature heating element".
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 12, 2013, 04:40:37 am
It was a revised board version already, heh...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Hydrawerk on September 12, 2013, 06:51:33 am
Hi,
I have crack rigol 832 with r-78b5.0-1.5
work very well!!!!!!!!  , does not heat!!
Send the screen

Oh, it looks so weird. Did this leave the Rigol factory?? But it is probably 100% functional and it can work for 20 years. No problem. Only it looks like home made repair...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on September 12, 2013, 07:07:07 am
Hi,
I have crack rigol 832 with r-78b5.0-1.5
work very well!!!!!!!!  , does not heat!!
Send the screen

Oh, it looks so weird. Did this leave the Rigol factory?? But it is probably 100% functional and it can work for 20 years. No problem. Only it looks like home made repair...

It is... ;)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: MasterOfNone on September 12, 2013, 07:11:23 am
Yep that PSU left the Rigol factory with a solution many of us would be very happy with, but it seems like their solution isn’t good enough for some. As stated by Zbig that PSU already had the revised board before it was improved(?)

Anyway I just had a reply from Rigol EU. Basically they stated that they are still setting up the procedure for the ‘Repair/Exchange’ and this might take till next week.
They’ll let me know ‘if’ things are settled and what to do next.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 12, 2013, 07:17:41 am
Hi,
I have crack rigol 832 with r-78b5.0-1.5
work very well!!!!!!!!  , does not heat!!
Send the screen

Oh, it looks so weird. Did this leave the Rigol factory?? But it is probably 100% functional and it can work for 20 years. No problem. Only it looks like home made repair...

That is NOT a Rigol fix. It's a mod made by the owner. Even though it might be functional, it is truly awful.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on September 12, 2013, 09:51:33 am
The salviador modify a board rev.03 ?

Tequipment.net recall  ;D

Hi Alexandre,

Thanks for reaching out to us in regard to your trouble. Please complete the form and email the completed form to RMA@tequipment.net. We will review and provide further instructions on how to proceed.

In the RMA # field of your form please put "DP832 Recall".

 
We apologize you're experiencing troubles but we will do our best to try and resolve this issue. If you are in need of a product immediately, we suggest placing a new order and we will credit accordingly once we receive the unit back.
 
Thanks so much for your patience and understanding during this process. If you require any additional assistance, please don't hesitate to contact me again.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on September 13, 2013, 09:47:04 am
Really, i don't know who is that will pay by the transport, but i think that i will pay.  |O

From brazil to Tequipment.net the cost is 177,00 u$, is better i purchase other dp832 (rev.3 now).


News of Tequipment,

Hello Alexandre,

We will gladly accept your return.  At this time, we are waiting on word from Rigol, as far as how to proceed with getting the units back to them for repair.  I will provide you with instructions soon to return your item.  Thank you for your patience and understanding as we work to complete this process.  I will be in touch with you soon.  In the meantime, if you have any questions, or require further assistance, please feel free to contact us.



Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on September 13, 2013, 10:59:02 am
Much will depend on how Rigol views a purchase....legit country agent or grey market.

I would expect a Recall to mean that Rigol picks up the transport costs to the 'in country' agent. Sadly if a unit is imported and no local dealer exists, Rigol may claim that it was not bought from an authorised local dealer and decline to pay shipping costs.

Good luck to all this affected by this recall. Rigol certainly appear to be doing the 'right thing'.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Tepe on September 18, 2013, 12:05:37 am
Well, the EEC is a single market so no excuses there.
It's called the EU these days and there are plenty of excuses  :-DD
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: MasterOfNone on September 18, 2013, 05:44:46 am
Update from Rigol EU:
Quote

We have ordered plenty of exchange boards/units from our fab to be able to
handle all requests.
But this may take a while till we will receive the parts here in Germany.
We will go ahead and try to speed it up, but the current time schedule is
roughly 6-7 weeks.

As soon as we have received everything we are initiating a board upgrade
procedure.
This will allow your instruments be updated to the newest firmware which
includes a calibration that will improve its low current
measurement capability as well as an upgrade to the latest hardware that
will maintain operating temperature even under
circumstances where supply voltage exceeds nominal values significantly.
Your instrument is eligible to have a firmware and hardware upgrade done at
our expense incl. shipping costs..

Note they are covering the repair and shipping cost of my unit, but I purchased mine directly from Rigol EU, so it might be a special case.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: thmjpr on September 18, 2013, 06:04:37 pm
Received a PDF:

Quote
Dear Rigol DP800 Series Power Supply Customer,
Thank you again for purchasing a Rigol power supply and trusting part of your bench to us. Recently, we became aware of a thermal management problem on a
previous revision of our power supply board that we have stopped manufacturing in July, 2013. Under certain circumstances and in some regions where higher than
nominal supply line voltage exists, it may cause overheating or instrument protective resetting. Even though this should be a rare occurrence under normal
circumstances in the U.S., we are initiating a board upgrade procedure that you are free to participate in. This will allow your instruments be updated to the newest
firmware which includes a calibration that will improve its low current measurement capability. We will also upgrade to the latest hardware that will maintain operating
temperature even under circumstances where supply voltage exceeds nominal values significantly.
Our records show that your instrument is eligible to have a firmware and hardware upgrade done at our expense. Please go here and fill out the information, call us at
877-4-RIGOL-1, or email us at dp8repairusa rigol.com and we will make arrangements to return your instrument to a service center.
For questions about this process and the issues with the earlier board revision please see our DP8 board version 2.0 FAQ.
Thank you again and please contact us if you have any other questions or concerns.

The underlined words are supposed to be links, but they don't seem to work. Going to send an email to find out.

edit: missing link 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)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on September 18, 2013, 06:48:32 pm
Interesting that RigolNA have not placed the recall on their product support page for the 832.

http://www.rigolna.com/applications/ (http://www.rigolna.com/applications/)

No mention of a fix for the switch-on transient either.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: twjtwj on September 19, 2013, 01:59:23 am
I just received that note today as well. That was fast! :)

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: manticore00 on September 19, 2013, 03:52:01 am
My account rep at TEQuipment sent me that note today but said that since Rigol USA doesn't have any of the new boards yet I should wait for a few weeks and contact Rigol directly to see if they have any of the boards in stock for fixes.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Marc M. on September 19, 2013, 10:33:34 am
I decided to pick up an 832 for the bench so I sent an RFQ into TEqupment on 9/10.  They responded on 9/11 and mentioned that a problem had been found with the 800 series of power supplies.  As a result of this issue, shipping would be delayed 3 weeks, possibly more.  At the time they were still showing 33 832's in stock.  I was happy to see that TE was upfront with the issues and were not going to ship anything until the problem was resolved.  I was surprised when a couple of days later I got a notice from TE that it had been shipped :-//.  It arrived on the 16th.  The first thing I did when I unpacked it was check the board.  Sure enough, it's got a V2.0 board with the cap heater :--.  Interestingly, it's less than 40 units away from the S/N that that Crazy Aussie Bloke tore down  :wtf:.  I immediately e-mailed TE asking why oh why would they ship out a unit that's known to be defective. 
Their response: an isolated clerical error |O. I'm curious if anybody else has ordered an 832 from TE in the past week or so and also been shipped a known defective unit.
 
My account rep at TEQuipment sent me that note today but said that since Rigol USA doesn't have any of the new boards yet I should wait for a few weeks and contact Rigol directly to see if they have any of the boards in stock for fixes.
According to the letter from Rigol, boards will be replaced as they become available and areas that are prone to overheating will have priority.  They downplay the issue in the United States basically putting us last in line but stated if you are experiencing the reset issue to contact Rigol or your distributor directly for an RMA.  I've had mine on for 12+ hours the past couple of days and haven't had any issues, nor do I expect any.  Of course I prefer my caps raw, not baked so I've already filled out the form for replacement.  They also mention that in addition to updating the hardware, they will update the firmware and recalibrate the unit which will "improve it's low current measurement capability".  So it sounds like they are also addressing the <10ma setting bug :-+. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 19, 2013, 11:21:51 am
Received a PDF:

Wow, they acknowledged the resetting issue  :-+
I've been told that I am the only one to ever see that and they had a real hard time reproducing it, but they eventually did right at the design extremes.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 19, 2013, 11:03:31 pm
240V is only 4.3% above 230V, hardly "significantly above nominal". I really doubt that the supply voltage being 4.3% higher would be the difference between the regulator reaching over 100C or not. Still, as long as they are fixing it that's fine.

On top of that you have normal production variations in the LM317 die, and with it being used above absolute maximum temp rating, anything goes.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Steffen on September 20, 2013, 05:28:56 am
I think cooling dimensioning issues are everywhere.
In the past i had to address a similar resetting problem with a Siemens ADSL router. The same LM317 issue: Siemens used one 317 as 5V regulator, didn't put any radiator. The router resetted spontaneously and lost all configuration data. Good that i had a backup file. I nealy burned my finger during checking of temperature issues.
Solution: I put a small clip-on finger radiator to the 317 and now all is fine. No reset anymore.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 20, 2013, 06:07:56 am
I think cooling dimensioning issues are everywhere.

Of course where QA is missing.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: hikariuk on September 20, 2013, 06:16:53 am
Quote
In situations where the supply line voltage is significantly above nominal values control components can overheat. For Instance, some countries have power line voltage that used to be 240V, but is now 230V +/- 10%. 240V is still a perfectly correct power line, but it can cause overheating on the DP8 board.  This can lead to a protective reset condition and/or performance outside of specifications.

240V is only 4.3% above 230V, hardly "significantly above nominal". I really doubt that the supply voltage being 4.3% higher would be the difference between the regulator reaching over 100C or not. Still, as long as they are fixing it that's fine.

I'm bemused as to how 240V could be "significantly above nominal" when the UK average voltage is still around 240V (I've seen up to 245V quoted).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: HackedFridgeMagnet on September 20, 2013, 09:07:53 am
It goes up to 253v in Australia and is still within spec.
I think it is quite common for the line voltage to go this high, as it can happen when your neighbour's solar panels are going full tilt. At this point they will cut out, so you shouldn't get higher voltages.
The fact that the unit was resetting makes it significant in my opinion, if the underlying cause was actually only the line voltage. Which is far from certain.

What about the display control circuitry, maybe that was drawing too much current. 700mA seems a lot.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on September 20, 2013, 07:32:51 pm
I couldn't wait. Found a nice heatsink I didn't use and inside it went. Mounted the TO220 lm317 isolated on the heatsink and it mates with the PCB using a small cable and pcbmount connector. Now at power on for about an hour the heatsink does barely even feel warm.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 20, 2013, 09:11:22 pm
I couldn't wait. Found a nice heatsink I didn't use and inside it went.

Nice, clean and excellent solution!  :-+ :-+
I love it!  :-+
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jsykes on September 21, 2013, 03:19:03 am
I couldn't wait. Found a nice heatsink I didn't use and inside it went. Mounted the TO220 lm317 isolated on the heatsink and it mates with the PCB using a small cable and pcbmount connector. Now at power on for about an hour the heatsink does barely even feel warm.

GREAT JOB!
That's exactly what I had in mind and the PC mount connector is a nice touch. Luckily I held off purchasing my PS until it was out there a while in case any hardware problems were discovered :phew:  I still may not be satisfied with Rigol's solution if it runs hotter than I'm comfortable with and in that case, will duplicate your method. It's good to see that there is room for that heat sink in the chassis and it looks like it's in the air flow too.
Thanks for passing this on.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on September 21, 2013, 07:11:17 am
Excellent solution nack.

Thanks for share.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on September 21, 2013, 07:53:30 am
Had I got a DP832, I'd definitely cut a circular hole in the top of the case, mount an aluminum plate in it and bolt the regulator on the underside. TADAAA! A coffee warmer!

I know, I know, thank you, you're welcome!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: John South on September 30, 2013, 12:52:35 pm
Hi - I have some pictures of the new boards.

For Australia and New Zealand customers we are expecting the new boards to be leaving China around October 17th. I'm not sure on the rest of the world.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mariush on September 30, 2013, 01:11:31 pm
Hmm... seems so weird of a fix to me. 

That heatsink is so large it looks like it blocks airflow...
It looks like there may be issues with the weight coupled with vibrations and shocks making solder joints weak...
Seems like there's enough room so they could have put there a regulator to get the voltage down to 6-7v, then use second regulator to get 5c and spread the heat on two heatsinks.
Title: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ddavidebor on September 30, 2013, 03:49:49 pm
Or design a little switching one on board.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on September 30, 2013, 04:40:42 pm
That heatsink is so large it looks like it blocks airflow...
It looks like there may be issues with the weight coupled with vibrations and shocks making solder joints weak...
Seems like there's enough room so they could have put there a regulator to get the voltage down to 6-7v, then use second regulator to get 5c and spread the heat on two heatsinks.

There are plenty of vents before and aft of the heatsink, so airflow shouldn't be restricted.
A heaksink that size will be firmly soldered the board just like the other ones, so should be no vibration issues.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: unnecessarynitpicker on September 30, 2013, 11:09:27 pm
It looks like they replaced the coffee maker heat sink as well as another one of the small ones to a slightly thicker variety (the new heat sinks are silver and not black) but i guess that we are all wondering is what happens when you turn it on instead of taking it apart :P.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on October 01, 2013, 07:30:49 pm
LM317's (ST brand) I have bought recently also have the new thin-style tap design. Copper is expensive these days I presume...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 03, 2013, 09:26:19 am
Placed an order for a DP832 from TEquipment today. Thanks Dave for the EEVBLOG discount!  :-+ Waiting for the heatsink fixed ones to come in.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on October 03, 2013, 09:39:34 am
I wonder if they have switched to a different regulator as well? Even if it is still an LM317 the one they used seemed a bit odd, like the tab was unusually thin.

That's been covered already, the thin tab is pretty normal from ST.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 04, 2013, 07:53:06 am
Does anyone how to configure the DP832 to get +12v,-12v and 5v? I know how to configure it to get +12v and -12v since channel 1 is isolated. But is there a way to get channel 3 to output +5v at the same time (with all common grounds)? For example to power a op amp. Or can't it be done on the DP832?  :-//
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on October 04, 2013, 07:56:57 am
Outputs 2 and 3 share a common negative terminal, so setting output 1 to 12 V, output 2 to 12 V and output 3 to 5V and connecting the positive output of output 1 to the negative output of outputs 2 and 3 should give you -12 V from the negative output 1 terminal, +12 V from the positive output 2 terminal and +5 V from the positive output 3 terminal, referenced to the output 2/3 negative terminal.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 04, 2013, 10:12:50 am
Outputs 2 and 3 share a common negative terminal, so setting output 1 to 12 V, output 2 to 12 V and output 3 to 5V and connecting the positive output of output 1 to the negative output of outputs 2 and 3 should give you -12 V from the negative output 1 terminal, +12 V from the positive output 2 terminal and +5 V from the positive output 3 terminal, referenced to the output 2/3 negative terminal.

Got it. Thanks for clearing that up. :-+
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on October 04, 2013, 07:23:41 pm
Looks like the sense wiring in the unit isn't designed that thoughtful: http://www.youtube.com/watch?v=QPBXiH2AyNE (http://www.youtube.com/watch?v=QPBXiH2AyNE#)

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on October 04, 2013, 07:53:36 pm
Looks like the sense wiring in the unit isn't designed that thoughtful

Oops!  :-[
Issue reported.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: BravoV on October 04, 2013, 07:59:06 pm
So Rev 5  ?  ???
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: hikariuk on October 04, 2013, 09:07:05 pm
Looks like the sense wiring in the unit isn't designed that thoughtful...

I like his way of testing for >= 100C.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jancumps on October 04, 2013, 09:34:19 pm
Looks like the sense wiring in the unit isn't designed that thoughtful...

I like his way of testing for >= 100C.
i have 1 2n3055 lying here with my fingerprint on it forever from trying to check if it was getting hot with my index finger.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: grego on October 05, 2013, 12:14:53 am
Yeah Rigol needs to fix the sense wire issue.  However, at least this is something easily fixed "in the field".  That doesn't excuse it and I hope it's either already fixed on the new rev or fixed with another rev soon.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on October 05, 2013, 01:22:43 am
The faults being discovered in this unit are just so basic that I wonder what experience the design team had (students ?) and who they employed for product UAT. Whoever it was, they need to find a new person !

Rigol really are sullying this power supplies reputation....if not already, it will become infamous and the butt of jokes in the industry. A good example to show to EE Students at college ....... how NOT to design a precision power supply  :-BROKE
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: railman on October 07, 2013, 10:44:01 am
I wonder if all this PR has hurt or helped Rigol. Or has it made the DP832 the best power supply on the market for the money?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on October 07, 2013, 10:51:15 am
Rigol really are sullying this power supplies reputation....

Either that, or (once they fix everything) the best vetted supply in the industry?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndyC_772 on October 07, 2013, 05:45:40 pm
Maybe, but the more I hear about this unit, the more I like the HP 6632B's I picked up off Ebay.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on October 07, 2013, 08:33:02 pm
Dave,

A very good point. Rigol effectively have the largest UAT test that you could wish for. They are also having all the bugs pulled out by a group of very knowledgeable people FOR FREE !

That all sounds good but it is happening in public and you guys will not always be available to pull the bugs out of their products so doubt will exist when they release their next product ?

Now if Rigol had been smart, they would have done UAT and hardware testing in the same way as software is done. Alpha and Beta testers. An opportunity for paid consultancy Dave ? You know what the market needs and know how to test the product for performance. You are also independent of the companies design team.   
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on October 08, 2013, 02:10:33 am
Either that, or (once they fix everything) the best vetted supply in the industry?
Best vetted by a few dozen users? Compared something like the HP 6632B that was used in thousands of test setups across the world for many years?

But I would indeed prefer this power supply over the affordable competition from brands like Korad, Owon and Atten. At least the flaws in this power supply are well documented and for most of the part not deal killers. There's no guarantee that the competition won't have any issues. I wouldn't spec either for critical applications, though. Who knows what other problems might turn up, since the designers have clearly shown lack of attention to detail.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 11, 2013, 04:31:39 pm
Got an email from TEquipment today that my DP832 was shipped. The email was sent at 10:00am saying they shipped it today 10/10/2013. The damn thing was delivered to my door step by noon the same day. Wow their shipping is just as fast as email.. :wtf: They told me it will be the one with the fixed overheating issue.

Does anyone know how to tell without cracking it open?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on October 11, 2013, 05:28:56 pm
Does anyone know how to tell without cracking it open?

Well, see this post (http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/msg299111/#msg299111) from John South with images of the apparent fixed PCB with large heatsink.

 >> You should be able to see such a large heatsink through the side grill (where the carry strap is).

Also, see this post (http://www.eevblog.com/forum/testgear/new-rigol-dc-psu's/msg269988/#msg269988) by Uup for the info below on how to display the full system information:

To display the full details press the following soft buttons in sequence, when in the system info screen.
1 – 3 – 4 – 2  where the soft buttons (buttons under the LCD) are numbered from left to right.


 >> That might tell us what the latest versions of the firmware etc are for the new build, which would be helpful for those of us (including myself) who need to return DP832's to Rigol for repair.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on October 11, 2013, 05:36:20 pm
Best vetted by a few dozen users?

Don't underestimate a few dozen nerds  :P
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TooOldForThis on October 12, 2013, 12:24:51 am
I got an email from them on Wednesday saying they were delaying my DP832 shipment another 6 days.  Then I got an email on Thursday saying it had shipped.  UPS says it was shipped 13 hours before TE sent the first email. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 12, 2013, 01:40:54 am

I think it's more like their email system is really, really slow :-) They probably got an email from the courier saying "package out for delivery" and suddenly realized "oh crap, we didn't send the shipping mail!"

They informed me that they have a warehouse in my state when I asked about the tax charges. The warehouse if fairly close to me. :D So is guess the UPS guy was not on crack. >:D  The email did go out the same day. If only my ebay purchases from China came that fast  :-DD

I still give them 11 out of 10 for shipping for my order.... Only negative thing I can come up with is I was ticked for tax because they do business in my state. They have one of their warehouses in it.  |O My EEVblog discount was eaten up with by the tax. But the free shipping more than makes up for it.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: con-f-use on October 12, 2013, 03:17:15 am
There's an EEVBlog discount at TE? How do you get that and how much is it?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 12, 2013, 03:25:33 am
There's an EEVBlog discount at TE? How do you get that and how much is it?

5% Discount. just enter EEVBLOG6 (I think if my memory is correct) I called and asked them for the code. You will enter at checkout in the discount column.

Update: 6% Discount not 5%
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: con-f-use on October 12, 2013, 03:39:11 am
Thanks, should've written a PM. Sorry @all. But ontopic, I was actually thinking of buying a DP832 from them. Is there a hack to unlock the higher precision?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 12, 2013, 03:55:09 am
Thanks, should've written a PM. Sorry @all. But ontopic, I was actually thinking of buying a DP832 from them. Is there a hack to unlock the higher precision?

No, I don't think a PM would have been needed it is known that they have an EEVBLOG discount and they will tell you what it is if you ask. There is a hack that turns on all the options.

http://www.eevblog.com/forum/testgear/sniffing-the-rigol's-internal-i2c-bus/1170/ (http://www.eevblog.com/forum/testgear/sniffing-the-rigol's-internal-i2c-bus/1170/)  ;D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 12, 2013, 04:29:07 am
There's an EEVBlog discount at TE? How do you get that and how much is it?

5% Discount. just enter EEVBLOG6 (I think if my memory is correct) I called and asked them for the code. You will enter at checkout in the discount column.

Update: 6% Discount not 5%

I was wrong with the 5% discount. The correct discount is 6%
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: etc6849 on October 12, 2013, 04:52:28 am
The DP832 I ordered from TE came today.  It has the version of the board pictured below.  It came with firmware 1.06 and the serial number is DP8C153101xxx.

What's weird is it was definitely repackaged, presumably by Rigol NA?  For example, the sticker over the IEC connector telling you to check the main voltage setting had already been removed and the box was double taped, with clear packing tape over the original Rigol tape that had been previously cut.  Kind of cheesy of Rigol to charge full price for a repackaged unit (IMO).

Still this is a lot better than the first version of the unit I had.  Through the vent holes, temperatures on the side of the heatsink were 104*F and and 130*F on the backside where the fins are.  This is much cooler than my previous version which was always above 200*F and had the heatsink right beside the caps.

The fan sounds louder to me though.  It stays on at full speed.  It's just been too long since I had the first version so I can't remember if this is different or not?

I have confirmation that the issue has already been fixed in a new board revision.
They changed the board to fit a larger heatsink, but it's not a huge amount bigger. See photo.
They measured the temp at 76C in a 28C ambient , but I'm not sure if this is free standing out of the case, or in the case with airflow.
They will be replacing all Australian units, I don't know about other countries.

I would not call this a proper belt'n'braces fix, as I think the heatsink still isn't big enough, but it probably now puts it into the (just) acceptable category.
They have also apparently made a few other fixes.
(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=59166;image)


Do you know from what serial number done this new board revision?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on October 12, 2013, 04:58:26 am
The DP832 I ordered from TE came today.  It has the version of the board pictured below.  It came with firmware 1.06 and the serial number is DP8C153101xxx.

Interesting that the heatsink is not the full-height that John South posted as the new boards (http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/msg299111/#msg299111).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: os40la on October 12, 2013, 05:01:49 am
My DP832 came with firmware 1.06 as well.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on October 12, 2013, 05:59:17 am
Oh no, not the full speed fan 'Mod' that many feared might be introduced.  :--

Placing the small (inefficient) heat-sinks in a virtual wind tunnel may cure the heat issue but that is serious bodgery IMHO.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: etc6849 on October 12, 2013, 06:09:54 am
I really don't remember how loud the old one was since it's been almost a month...  I don't have a large load to see for sure if the fan gets even louder or not.  I measured about 58 dBA (SPL A weighted) 6" from the fan with no load.

Did the fan speed up and then slow down when you turned on the revision 1 DP832?  The fan speed on mine stays constant as it powers up.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Uup on October 12, 2013, 09:37:08 am
The fan on my DP832A briefly goes to high speed on power up then to an idle once the power up cycle is complete.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on October 15, 2013, 01:16:41 am
The DP832 I ordered from TE came today.  It has the version of the board pictured below.  It came with firmware 1.06 and the serial number is DP8C153101xxx.

What's weird is it was definitely repackaged, presumably by Rigol NA?  For example, the sticker over the IEC connector telling you to check the main voltage setting had already been removed and the box was double taped, with clear packing tape over the original Rigol tape that had been previously cut.  Kind of cheesy of Rigol to charge full price for a repackaged unit (IMO).
....

It sure repackaged, mine is came on 5 September and the serial number was DP8C153301XXX.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on October 15, 2013, 02:31:43 am
The power-on spike on the Rigol DP832 Lab Power Supply, hasn't any stable behavior or pattern.

At the following videos I demonstrate some of these on channel I & II simultaneously.
Sometimes nothing is going there, everything is OK, the worst pattern is at the 4rd video.
Sorry I haven't any HD camera, this are SD resolution short videos.
The scope was horizontal set at 5msec/div and vertical to 500mV/div.

PA149471 (http://www.youtube.com/watch?v=xMcqRWWfUEY#)
PA149473 (http://www.youtube.com/watch?v=MLvJ87-03vs#)
PA149474 (http://www.youtube.com/watch?v=gFgSWOTAu4A#)
PA149475 (http://www.youtube.com/watch?v=X3U5hRnIaD8#)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: olsenn on October 16, 2013, 12:47:29 am
How long do people here rekkon the rev. 2 board will hold up before overheating to death?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: etc6849 on October 16, 2013, 09:56:16 am
I was afraid of that.  My "new" version stays at full speed all the time.

The fan on my DP832A briefly goes to high speed on power up then to an idle once the power up cycle is complete.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on October 16, 2013, 07:18:56 pm
I agree, the same happens to mine scope with DP8C1533014XX serial number, digital version 00.01.06 and Cal Time 2013-8-17.

It is a little noiser in silent environment!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on October 16, 2013, 08:53:42 pm
I was afraid of that.  My "new" version stays at full speed all the time.

The fan on my DP832A briefly goes to high speed on power up then to an idle once the power up cycle is complete.

That's disappointing. What firmware version do you run on yours?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TooOldForThis on October 17, 2013, 09:47:20 am
I have a DP832, delivered two days ago, with FW rev 00.01.06.    The fan stays on 'medium' most of the time then switches to high if you give the supply a large load.   The sound of the DP832 on high is still slightly quieter that the sound of the fan in my DS4024 scope.  The fan in the DS4024 never slows down. :(

Anyway, the 'usually medium' fan in the DP832 keeps the problem heat sink at about 64C  (measured in the middle of the back of the heat sink in a cool room)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on October 18, 2013, 04:43:41 am
General, the Rigol has a issue with the louder fans to all models...

Your result is almost identical with mine, here (http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/msg287095/#msg287095). I had measured 48-68°C according to the heatshink measurement point.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TooOldForThis on October 18, 2013, 01:48:50 pm
Does anyone know if the DP832 can have its channels 1 & 2 wired in parallel to give 0-30v at up to 6 amps?  There is a tracking function that keeps the two channels at the same voltage but the user manual doesn't say anything for or against hooking the channels up in parallel. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on October 18, 2013, 02:06:01 pm
Does anyone know if the DP832 can have its channels 1 & 2 wired in parallel to give 0-30v at up to 6 amps?  There is a tracking function that keeps the two channels at the same voltage but the user manual doesn't say anything for or against hooking the channels up in parallel.

Yep, you can wire it up like that in tracking mode for 6A output.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on October 18, 2013, 10:43:05 pm
Does anyone know if the DP832 can have its channels 1 & 2 wired in parallel to give 0-30v at up to 6 amps?

Read the attachment to have confirmation from Rigol.



Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Zbig on October 19, 2013, 01:19:53 am
Does anyone know if the DP832 can have its channels 1 & 2 wired in parallel to give 0-30v at up to 6 amps?  There is a tracking function that keeps the two channels at the same voltage but the user manual doesn't say anything for or against hooking the channels up in parallel.

Well, as they're in parallel, the voltage is always going to be equal anyway, right? What I believe the tracking function does when in parallel mode is, it reads the master channel's current readout and applies it as current limit to the slave channel working in CC mode. It's the serial mode where the slave channel's voltage simply follows master channel's voltage.
Title: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on October 19, 2013, 03:35:18 am
As I l know the tracking is used to power up symmetrical devices like dual amplifiers
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ddavidebor on October 23, 2013, 01:40:20 am
or to use channel in parallel
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on October 30, 2013, 11:08:19 pm
nope...  :-//
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: con-f-use on October 30, 2013, 11:14:29 pm
Not a thing.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on November 01, 2013, 08:11:59 pm
Attached is the response from Rigol on the DP832 connection issue.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on November 01, 2013, 08:13:24 pm
Anyone heard anything about the recall yet? Particularly people in Europe. I have heard nothing.

Emona in Oz have received replacement boards and instructions, but still sorting out the recall/repair logistics.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on November 02, 2013, 01:26:21 am
Attached is the response from Rigol on the DP832 connection issue.
Translation: we have no intention of fixing this. The user should just refrain from connecting CH2 and CH3 as would be obvious from the front panel silkscreen. If you want the power supply to work within specs while treating CH2 and CH3 as having a common ground, please do our job and put the thick wire between the CH2 and CH3 negative terminal that should have been there in the first place.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on November 02, 2013, 01:36:09 am
Attached is the response from Rigol on the DP832 connection issue.

Shame they put less thought into the original power supply design than they put into that document.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: daveshah on November 02, 2013, 04:09:14 am
Attached is the response from Rigol on the DP832 connection issue.
Rigol are obviously using the state of the art in multimeter technology, as is evident on page 3!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on November 02, 2013, 05:21:43 am
Regarding the fix...

I tried to contact Rigol a few times by email and the contact form and never got any reply.

So I sent an email to TEquipment (where I bought it).  Jennifer there was very helpful and said she will get in touch with Rigol and figure out what is going on for replacing faulty DP832 units/boards for USA customers.

I haven't heard back yet, but I told her it was not a big rush, just wanted to make sure it doesn't get forgotten or swept under the rug.

So far I am less than impressed with Rigol, but very impressed with TEquipment.  Which is why I keep going back (Scope, FLIR camera, etc).

Rigol could learn a thing or two about customer service. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on November 02, 2013, 09:20:28 am
Just to post an update to my post above - I have to soften my criticism for Rigol a bit.  I got a call from a guy there today - nice guy and he explained that the DP832 did have an issue and they were replacing boards on USA units.  Apparently they are waiting on a shipment of repair parts from the China factory.

I don't think anything they told me was a secret, but basically they are keeping a list of USA customers who need repairs on their units.  They will then be contacting us when it's time to send our units in.

More info here:

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)

There is a link on the above page to here;

http://beyondmeasure.rigoltech.com/acton/form/1579/0014:d-0001/1/index.htm (http://beyondmeasure.rigoltech.com/acton/form/1579/0014:d-0001/1/index.htm)

where you can fill out your info to get on their repair list (for USA customers only), and there is also a specific email address for USA customers inquiring about DP832 repair, that address is dp8repairusa@rigol.com

So if you are in the USA, fill out the form and then wait to hear back from Rigol.

I was told that my unit was the first one they have heard about having resetting issues (which only happens when I make it happen - i.e. put it in my rack, load it up and suck power from USB as well)... so to be fair, it's not like it resets all the time, but it does run hot as hell, measured way over 250F with my FLIR camera, so it definitely needs the upgraded board.

Just an FYI!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dave Turner on November 08, 2013, 07:52:03 am
I received my DP832 and DS1074Z-S today. Ordered from Rigol's UK distributor Telonic Instruments less than 48 hours after ordering. It does have to be said that they seem to be both helpful and efficient.

Having said that, even after discussing the issues reported in this forum, and in particular describing the larger un-anodised as opposed to the intermediate black heatsink, I have received the latter. I have mentioned this to Telonic and await a reply.

Unfortunately my temperature probe is too large to fit through the ventilation holes to measure the temperature. I await delivery of a new multimeter with a smaller probe.

Without anything to compare it to (and for many years having worked in a server room) I would not consider the fan noise excessive. Still I've not yet applied a serious load.

For interest the Serial number is DP8C15320xxxx and the firmware version 00.01.06.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TooOldForThis on November 08, 2013, 01:44:39 pm
Interesting (maybe) tidbit:  When the DP832 has channels 1 & 2 hooked in parallel, it will max out one channel before supplying any power from the 2nd channel.  If you pull 3.1 amps, ch1 supplies 3.0A and ch2 supplies 0.1A   On my older analog controlled supplies, both channels will split the load 50/50. 

Update: Different results reported 8 posts down.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: EEVblog on November 08, 2013, 08:09:32 pm
Here are photos of the replacement board:
http://www.flickr.com/photos/eevblog/sets/72157637434451504/ (http://www.flickr.com/photos/eevblog/sets/72157637434451504/)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on November 08, 2013, 09:47:22 pm
Here are photos of the replacement board:
http://www.flickr.com/photos/eevblog/sets/72157637434451504/ (http://www.flickr.com/photos/eevblog/sets/72157637434451504/)

lol, that's a hell of a heat sink for a TO-220!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Fraser on November 09, 2013, 12:29:35 am
Hmmmm...cheap and nasty fix  :--

Better regulator fitment would have been preferable but I suppose it all comes down to money when all is said and done.
Title: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ddavidebor on November 09, 2013, 01:09:43 am
If they had managed better those issue, i woukd have bought a rigol instead of a hameg
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: dr.diesel on November 09, 2013, 01:29:09 am
Hmmmm...cheap and nasty fix  :--

Agreed.  Although it screams poorly designed by an intern, it will allow the unit to live for years most likely.


If they had managed better those issue, i woukd have bought a rigol instead of a hameg

Which model, please do a mini-review/teardown for us!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Cdngreybeard on November 09, 2013, 02:15:50 am
For TooOldForThis:
The DP832 does load share when paralleling ch 1 and ch 2.  The load will split more or less equally based upon the lead resistances to the two supplies.  Cosequently, the higher the current draw, the greater the discrepancy. I have verified this with a 1 ohm load at 5 volts resulting in current draws of 2.6 A and 2.4 A respectively.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ElectroIrradiator on November 09, 2013, 03:16:09 am
lol, that's a hell of a heat sink for a TO-220!

Bonus silly points: The air cooling would have worked much better with a new profile, if they had just used a vertical metal plate parallel to the main heat sink, along the board. As it is, the new (huge) heat sink sits 'fins down' into the oncoming air stream, the worst possible option. Translation: Whomever devised this, didn't seem to understand the principles of forced air cooling. :palm:
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: TooOldForThis on November 09, 2013, 11:37:36 am
For TooOldForThis:
The DP832 does load share when paralleling ch 1 and ch 2.  The load will split more or less equally based upon the lead resistances to the two supplies.  Consequently, the higher the current draw, the greater the discrepancy. I have verified this with a 1 ohm load at 5 volts resulting in current draws of 2.6 A and 2.4 A respectively.

I was able to reproduce this result.  I had a 20mV loss on the banana jumpers connecting Ch1 to Ch2.  The channel with less loss to the load wound up driving the majority of the current.  When I connected both channels to the load symmetrically,  then both channels shared the load more or less evenly.   My older supplies have an internal relay for parallel mode that short the two channels together with low enough resistance that both channels supply the same current no matter how I hook it to the load.   
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: alm on November 09, 2013, 12:35:12 pm
Running one power supply in CV and the other in CC is a perfectly standard way of operating parallel power supplies, so I don't see the problem.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 13, 2013, 12:13:08 am
Just watched the video and short of replacing the LM317 with a bigger regulator and/or bigger heatsink the better solution would be to replace it with a switched supply (those 2$ ones on ebay should work well after a thorough check) as a preregulator to 6.5-7V and the heatsinked LM317 after it. It's a 15 mins and 3$ job compared to sending the unit over or causing it to fail and having to wait for another.
At least that's what I would do.
That's definitely not going to work.
LM317 has a 3 V drop-out voltage, which means you need > 8 V in (worst case scenario) to get a proper regulated 5 V out.
If you have anything < 8 V going in to a 5 V linear regulator you need to replace the LM317 with a pin-to-pin compatible adjustable LDO (Low Drop-Out) regulator like LD1086, LM1086-ADJ or LT1086 with a dropout voltage of max. 1.5 V.

Datasheets:
ST LM317 http://www.st.com/web/catalog/sense_power/FM142/CL1015/SC315/PF63704 (http://www.st.com/web/catalog/sense_power/FM142/CL1015/SC315/PF63704)
TI LM317 http://www.ti.com/product/LM317 (http://www.ti.com/product/LM317)
ST LD1086 http://www.st.com/web/catalog/sense_power/FM142/CL1015/SC312/PF259679 (http://www.st.com/web/catalog/sense_power/FM142/CL1015/SC312/PF259679)
TI LM1086 http://www.ti.com/product/LM1086 (http://www.ti.com/product/LM1086)
Linear LT1086 http://www.linear.com/product/LT1086 (http://www.linear.com/product/LT1086)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on November 14, 2013, 04:22:35 am
LM317 has a 3 V drop-out voltage

No, no it doesn't.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on November 14, 2013, 06:24:01 am
LM317 has a 3 V drop-out voltage

No, no it doesn't.

There are no specifications for operation with less than 3v  input to output. A datasheet might give you a plot of typical drop-out voltages against temperature and current which doesn't tell you how bad performance gets as you approach drop out or what maximums are. I wouldn't design a 317 into anything expecting less than 3v drop out.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on November 14, 2013, 06:43:13 am
LM317 has a 3 V drop-out voltage

No, no it doesn't.

There are no specifications for operation with less than 3v  input to output. A datasheet might give you a plot of typical drop-out voltages against temperature and current which doesn't tell you how bad performance gets as you approach drop out or what maximums are. I wouldn't design a 317 into anything expecting less than 3v drop out.

And the 3V figure isn't listed anywhere (the specifications are actually at Vin - Vout = 5V), nor is any fixed dropout voltage. The dropout voltage varies and how close you can get depends on how you're using the regulator.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 06:50:33 am
LM317 has a 3 V drop-out voltage
No, no it doesn't.

2.5 - 2.7 V @ full load (1.5 A) and max. junction temperature. Pretty close to 3 V.

But other specifications in the datasheets are often only specified at a range between 3.0 V <= VI-VO <= 40 V. Sometimes 2.5 V <= VI-VO <= 40 V.
Going under this regulation might get a lot worse than what's specified. Otherwise they would probably specify it down to a lower dropout voltage.
 
So you can tell what the specifications will be like below 3 V.

The dropout specs varies a bit depending on which manufactures datasheet you look in.

Also note Fairchild specs are only for a junction temperature between 0 and 125 deg C, while ST Micro is between -50 and 150 deg C.

(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=66996;image)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 07:37:07 am
And the 3V figure isn't listed anywhere...
It is at the top of page 3 in TI's LM317 datasheet: http://www.ti.com/lit/ds/symlink/lm317.pdf (http://www.ti.com/lit/ds/symlink/lm317.pdf)
Quote
Recommended Operating Conditions
VI – VO Input-to-output differential voltage: min. 3 V | max. 40 V
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on November 14, 2013, 07:56:17 am
And the 3V figure isn't listed anywhere...
It is at the top of page 3 in TI's LM317 datasheet: http://www.ti.com/lit/ds/symlink/lm317.pdf (http://www.ti.com/lit/ds/symlink/lm317.pdf)
Quote
Recommended Operating Conditions
VI – VO Input-to-output differential voltage: min. 3 V | max. 40 V

And yet, not the datasheet for the LM317T, which is the TI part I typically use in TO-220.

Can we just agree that rather than blindly following figures which vary wildly between manufacturers, across the same manufacturer, and with the phase of the moon, we should actually design and test things?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 07:57:35 am
LM317's (ST brand) I have bought recently also have the new thin-style tap design. Copper is expensive these days I presume...
Some LM317 TO-220 single gauge vs. dual gauge part numbers:

Fairchild www.fairchildsemi.com/ds/LM/LM317.pdf (http://www.fairchildsemi.com/ds/LM/LM317.pdf)
LM317T = Single Gauge
KA317TU = Dual Gauge

ST Micro www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00000455.pdf (http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00000455.pdf)
LM317T = Single Gauge
LM317T-DG = Dual Gauge

TI  www.ti.com/lit/ds/symlink/lm317.pdf (http://www.ti.com/lit/ds/symlink/lm317.pdf)
LM317KCT = Single Gauge
LM317KCS = Dual Gauge
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 08:01:57 am
And yet, not the datasheet for the LM317T, which is the TI part I typically use in TO-220.
Do you have a link for the TI LM317T datasheet? I can't find it at TI's website.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on November 14, 2013, 08:02:59 am
And yet, not the datasheet for the LM317T, which is the TI part I typically use in TO-220.
Do you have a link for the TI LM317T datasheet? I can't find it at TI's website.

It's under 117. http://www.ti.com/lit/ds/symlink/lm117.pdf (http://www.ti.com/lit/ds/symlink/lm117.pdf)

It does reference 3V for some of the specs, having looked closer, but not in relation to dropout.

Test it and see is the best solution. Or move to a more modern regulator.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rufus on November 14, 2013, 08:06:32 am
Also note Fairchild specs are only for a junction temperature between 0 and 125 deg C, while ST Micro is between -50 and 150 deg C.

They are not specifications they are typical characteristics giving guidance on what may happen if you operate outside the specifications.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 08:11:23 am
Also note Fairchild specs are only for a junction temperature between 0 and 125 deg C, while ST Micro is between -50 and 150 deg C.

They are not specifications they are typical characteristics giving guidance on what may happen if you operate outside the specifications.
Correct. Junction temperature isn't specified to more than 125 deg C even though the curve goes all the way up to 150 deg. C.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 08:14:14 am
And yet, not the datasheet for the LM317T, which is the TI part I typically use in TO-220.
Do you have a link for the TI LM317T datasheet? I can't find it at TI's website.

It's under 117. http://www.ti.com/lit/ds/symlink/lm117.pdf (http://www.ti.com/lit/ds/symlink/lm117.pdf)

It does reference 3V for some of the specs, having looked closer, but not in relation to dropout.

Test it and see is the best solution. Or move to a more modern regulator.
I haven't really looked into it, but what's the difference between LM317 and LM317T?

Is it a case of one being a design from the old National Semiconductor and the other being a design from the old TI?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on November 14, 2013, 08:22:54 am
And yet, not the datasheet for the LM317T, which is the TI part I typically use in TO-220.
Do you have a link for the TI LM317T datasheet? I can't find it at TI's website.

It's under 117. http://www.ti.com/lit/ds/symlink/lm117.pdf (http://www.ti.com/lit/ds/symlink/lm117.pdf)

It does reference 3V for some of the specs, having looked closer, but not in relation to dropout.

Test it and see is the best solution. Or move to a more modern regulator.
I haven't really looked into it, but what's the difference between LM317 and LM317T?

Is it a case of one being a design from the old National Semiconductor and the other being a design from the old TI?

Your guess is as good as mine. There are a lot of parts like that from TI, few have any difference in specification at all.

I've bought the T/AT because it often seems more readily available than the KCS, so I get a proper tab. I gave up on the lottery of ST parts from most distributers, and my experience with Fairchild has been popped parts and wild variation in specification compared to other manufacturers.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 08:26:46 am
In the LM117 datasheet there's one table for LM117 and another table for LM317A + LM317-N.

I guess LM317-N just a placeholder for all the LM317 versions in the datasheet other than LM317A? E.g. LM317T, LM 317H, LM317K LM317M etc.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on November 14, 2013, 08:30:15 am
In the LM117 datasheet there's one table for LM117 and another table for LM317A + LM317-N.

I guess LM317-N just a placeholder for all the LM317 versions in the datasheet other than LM317A? E.g. LM317T, LM 317H, LM317K LM317M etc.

I believe so. The A is specified down to -40C, the other versions are not.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 14, 2013, 09:23:18 am
Can we just agree that rather than blindly following figures which vary wildly between manufacturers, across the same manufacturer, and with the phase of the moon, we should actually design and test things?
Rigol strongly disagrees  >:D :-DD  :-BROKE

But I wouldn't run a part outside it's recommended operating range in a commercial product even if it tests fine there. You never know if it will be the same for the next batch. And you wouldn't be able make any kind of warranty claim against the manufacturer if you run them outside specs.

I know Rigol overclocked 40 MHz ADCs to 100 MHz with great success in the DS1xxxE scopes. They did so because there's 10 ADC in each device and lot of money to be saved for the 40 MHz vs. 100 MHz versions.
But they are from the same die as the 100 MHz parts. Not sure if Rigol tested and sorted each of them before use or if almost all or all of them worked overclocked and they just took the risk.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 22, 2013, 01:55:04 am
Hi - I have some pictures of the new boards.

For Australia and New Zealand customers we are expecting the new boards to be leaving China around October 17th. I'm not sure on the rest of the world.

(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=61842;image)

(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=61844;image)

(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=61846;image)
Looks like Rigol now use the same hug TO-220 heatsink as they use in the DS1000E series power supply (except for the missing black anodizing):

http://www.eevblog.com/forum/projects/rigol-1052e-fan-replacement/msg104898/#msg104898 (http://www.eevblog.com/forum/projects/rigol-1052e-fan-replacement/msg104898/#msg104898)
(http://i218.photobucket.com/albums/cc53/salas_043/RIGELID1.jpg)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 22, 2013, 02:01:15 am
EEVblog #549 – Rigol DP832 Lab Power Supply Followup http://www.eevblog.com/forum/blog/eevblog-549-rigol-dp832-lab-power-supply-followup/ (http://www.eevblog.com/forum/blog/eevblog-549-rigol-dp832-lab-power-supply-followup/)

EEVblog #549 - Rigol DP832 Lab Power Supply Followup (http://www.youtube.com/watch?v=6Kfp77-7VU8#ws)

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Skimask on November 26, 2013, 12:14:01 pm
Bought my DP832 direct from Rigol on Nov 7th.  Used it a dozen times or so.  Powered it up 2 days ago, Channel 1 failed.  Wouldn't source any current.  Channel 2 & 3 work just fine.  Just the way things go.  Either they fail right away or they last for decades, right?

Contacted Rigol this morning (~12 hours ago) via email, explained the issue, etc.  Within a few hours, got an RMA and shipping label.  Dropped it off for shipping a couple hours ago.  I've already got a tracking number for the new unit that's shipping back to me.

 :-+You can't beat that kind of service...Can you? :-+
Ok, sure, maybe it could NOT have failed within the first couple of weeks.  But other than a handful of minutes packing up the old unit, email'ing, dropping it off, etc., how much am I out?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: BravoV on November 26, 2013, 12:44:09 pm
:-+You can't beat that kind of service...Can you? :-+
Ok, sure, maybe it could NOT have failed within the first couple of weeks.  But other than a handful of minutes packing up the old unit, email'ing, dropping it off, etc., how much am I out?

Not if you purchased dozens or hundredths of these that you're going to use in an industrial/commercial usage or worst to be used in your production benches testing lines, imagine how many productivity hours lost because of that.

I think all these DP832 fuss summarized it self pretty well, its suitable only for personal or enthusiast/hobbyist grade usage only, and definitely should be avoided in pro/commercial environment that need a product that just work reliably out of the box when newly bought, not too demanding I guess.  ::)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 26, 2013, 08:10:41 pm
Still nothing for EU owners. I emailed them again, no response.
Who did you e-mail, http://eu.rigol.com (http://eu.rigol.com) or a European distibutor?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on November 26, 2013, 11:25:30 pm
Not if you purchased dozens or hundredths of these that you're going to use in an industrial/commercial usage or worst to be used in your production benches testing lines, imagine how many productivity hours lost because of that.

The same example is valid also for other manufacturers.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Skimask on November 27, 2013, 12:16:09 am
Not if you purchased dozens or hundredths of these that you're going to use in an industrial/commercial usage or worst to be used in your production benches testing lines, imagine how many productivity hours lost because of that.

I think all these DP832 fuss summarized it self pretty well, its suitable only for personal or enthusiast/hobbyist grade usage only, and definitely should be avoided in pro/commercial environment that need a product that just work reliably out of the box when newly bought, not too demanding I guess.  ::)
Well sure...can't argue that point.
But it wasn't and I'm happy...so...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on November 27, 2013, 12:33:21 am
Still nothing for EU owners. I emailed them again, no response.
Who did you e-mail, http://eu.rigol.com (http://eu.rigol.com) or a European distibutor?

Both.
What distributor is that?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: synapsis on November 30, 2013, 11:19:41 am
Order a DP832 from Rigol directly last week. Got this on the second powerup, I've never plugged anything into the outputs yet.

I can see the tall silver heatsink inside the unit.

*sigh*
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: synapsis on November 30, 2013, 11:35:22 am
Turned it on again and the now the contrast on the LCD flickers.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on November 30, 2013, 08:28:28 pm
Call distributor and get a RMA.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Skimask on December 03, 2013, 05:42:24 pm
Just got my new DP832 on my door step today.  (Backstory - Ordered one, got it early November, Channel 1 failed after a dozen or so uses, RMA'd for replacement last week)
Ordered direct from Rigol NA.

Old one firmware = 1.06, new one = 1.08

Old one had the "middle design", new has the new PCB with the large aluminum heat sink.

Beating it up a bit right now, trying (not too crazy hard anyways) to get it to fail now rather than later...  Gonna do this for a couple hours or so.
Got all 3 channels pushing 3 space heaters coils.  Ch1&2 @ 27v @ 2.7amps, Ch3 @ 5v @ 2.7amps.  About 160 watts.
Going over to the box every 10-15 minutes or so, switching it off, waiting a minute, switch it back on, and enable all 3 outputs at the same time (or as close to it as I can get).
Every 2nd or 3rd time, I'm waiting a minute after turning them on, switch all 3 outputs off, then right back on.
Got meters on the outputs watching volts/current.  DP832's LCD and the BK2709's match up pretty good.
So far, so good...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dave Turner on December 14, 2013, 06:15:35 am
Further to my previous post, Dave of Telonic Instruments Ltd the official Rigol distributor in the UK contacted me today to inform me that they are expecting the latest version of the DP832 in February. They have offered to swap out my DP832 for the latest model, including carriage both ways.

It should be pointed out that I had discussed and clearly pointed out the findings of this forum and my expectation to receive the latest version, the one with the overgrown silver heatsink, before I placed my order. (All by phone). Unfortunately that was not the model that I received; a fact that I immediately reported to Telonic.

I have offered to just swap out the board myself providing that they will accept my breaking the seal without affecting my warranty. This would be easier for me and might be cheaper for Telonic who seem to be amenable to this solution.

We have agreed to wait until February when the new versions are available before making a final decision on how to proceed.

Whilst nothing has been resolved yet, given the service I have received so far I wouldn't hesitate to recommend Telonic.

For the record I have no connection to Telonic and this is the first time I have purchased anything from them.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Timon on January 03, 2014, 04:22:41 am
Maybe someone has brought this up but why the heck didn't they use something like a OKI-78SR switching regulator? They are very inexpensive and they don't even need a heat sink to deliver 1.5A. In addition you can easily retrofit it.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mariush on January 03, 2014, 05:18:10 am
Adding a bit of copper wire on an already custom transformer is cheaper than one of those custom switching regulators.  They just screwed up by making that winding 10-12 v AC or whatever it was

Copper on transformer + bridge rectifier and capacitors and lm317 < 1$ ... that oki regulator, probably 2-3$.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on January 09, 2014, 01:27:54 pm
So here is my timeline...

Purchased DP832 in July of 2013.

Found out about the issue from Dave in late August 2013.

Contacted Rigol in September 2013 asking about a fix.  Contacted them several times and never got any reply.

In October, I contacted TEquipment asking for help.  They intervened and finally someone at Rigol got in touch and said they would fix my unit, and they had a sign-up list.  That was in late October 2013.

It is now January 2014 and still nothing has been done.  It's starting to piss me off that Rigol has been selling fixed units for months, but hasn't made things right with prior buyers.  Frankly, fixing existing units should have been the #1 priority, not selling new ones while they let the early adopters deal with dysfunctional supplies.


Has anyone in the USA had their DP832 fixed by sending it back to Rigol for repair?  I just tried emailing them again - we shall see what happens.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on January 09, 2014, 06:00:22 pm
Has anyone in the USA had their DP832 fixed by sending it back to Rigol for repair?  I just tried emailing them again - we shall see what happens.

I'm in similar situation --- I filled out the Rigol online form to get put on a list for the replacement board, but I haven't heard anything from them yet.

I'm using my unit frequently and without troubles at the moment so I'm not worrying much about it.  Also, I think I recall some photos of Oct/Nov DP832 units sold in the US having the "medium" sized heatsink, and not the extra large (silver) heatsink, installed...so I don't want to rush through an upgrade program only to have an incorrect replacement board fitted.  I don't know the potential of that happening...but just want to avoid it...

Would be nice to have some update from Rigol NA though --- if you do hear back, it'll be great to hear what you find out.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ivaylo on January 09, 2014, 07:47:31 pm
I told Tequipment I want to return mine. They defered to Rigol. I got a RMA and shipped it back yesterday. I had DP832A and the low current resolution was important to me (but broken). Got a refurbished Hameg instead from someone here on the forum.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on January 10, 2014, 03:55:46 am
I sent a polite email to "info@rigol.com" last night stating the timeline of my issue and asking for either a fix or at least information on when the fix would be offered.  I received an email back a few hours ago from a gentleman at Rigol who sent an RMA form and a pre-paid return shipping tag.  He mentioned they had been kept waiting for the repair parts, and that it was taking time to work through the backlog of units for repair. 

At least it appears they are now performing the fixes - hopefully the turnaround time won't be too bad.  I have other supplies I can use so I won't miss this one for a couple of weeks, but I hope it doesn't end up taking a couple months.  I don't think it will - they told me they should be able to turn it quick.

So for anyone still waiting, I guess you could either wait for contact knowing they are doing fixes, or you could email info@rigol.com and ask them to ensure you are on the list, at least.

Hope it helps.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: K1JOS on January 17, 2014, 01:00:18 pm
Is the heatsink design an issue only on the non-A832 or also the 832A?
jerry
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ivaylo on January 17, 2014, 04:55:48 pm
Both. It's supposed to be fixed in the new versions though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rasz on January 17, 2014, 09:42:37 pm
Adding a bit of copper wire on an already custom transformer is cheaper than one of those custom switching regulators.  They just screwed Copper on transformer + bridge rectifier and capacitors and lm317 < 1$ ... that oki regulator, probably 2-3$.

Because $2 of short term profit is better than good quality product, obviously :/
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on January 17, 2014, 11:44:55 pm
Just to inform all Italian customers that my local dealer, Batter Fly srl (www.batterfly.com (http://www.batterfly.com)), is ignoring my mails about the DP832 since december 2013. I am also unable to reach the CEO by phone.

I am seriously starting to concern about my Rigol instruments warranty. I was confident to have found a loyal distrubutor. At the moment I cannot think so.


EDIT: they finally reply to my mails, saying that the delay was because they're moving on another location and that the DP replacement will be made as soon new units will be available.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on January 18, 2014, 09:59:48 am
Adding a bit of copper wire on an already custom transformer is cheaper than one of those custom switching regulators.  They just screwed Copper on transformer + bridge rectifier and capacitors and lm317 < 1$ ... that oki regulator, probably 2-3$.

Because $2 of short term profit is better than good quality product, obviously :/

That's a foolish analysis.

If they were going for short term profit, they wouldn't be taking them back and replacing parts at no charge.  I bet the repair on my DP832 costs Rigol more than their profit on the unit amounted to. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 18, 2014, 10:30:21 am
Hello to all I play little with dp832, already have rev 2.10 fixed board but not with big heatsink and after some tests  I replaced the lm317 with home made L5972D 1.5A high efficency switching step-down,it  works fine I also removed smd resistor load 240ohm on 12v before lm317 , I used diagram from datasheet with 10uf ceramic cap on 12v 33uH smd inductor and tantalium cap on 5v out,temp on lm317 was 85c and about 5.14V , now I calibrated with 5.08V,the new temp stay at 36c on my little pcb.
 I replaced also fan with noctua, very quiet now but need also to decrease R50 from 2.4k down to 1.8-2.0k to avoid fan error, because noctua drain less current and trigger error when at idle,I tested with all 3 channel at max load and cooling is good we will see in the summer if go fire.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on January 18, 2014, 11:23:02 am
I replaced the lm317 with home made L5972D 1.5A high efficency switching step-down,it  works fine I also removed smd resistor load 240ohm on 12v before lm317 , I used diagram from datasheet with 10uf ceramic cap on 12v 33uH smd inductor and tantalium cap on 5v out
So this is the schematic you used I guess? Of course with the R1 and R2 resistor divider changed to get Vout = 5 V.

(http://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/?action=dlattach;attach=77259;image)
Image source: http://xinyeic.en.seekic.com/product/integrated_circuits_ics/L5972D.html (http://xinyeic.en.seekic.com/product/integrated_circuits_ics/L5972D.html)

ST L5972D datasheet: http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00002850.pdf (http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00002850.pdf)
ST Application Note AN1517 http://www.st.com/st-web-ui/static/active/cn/resource/technical/document/application_note/CD00043743.pdf (http://www.st.com/st-web-ui/static/active/cn/resource/technical/document/application_note/CD00043743.pdf)
There's very little documentation in the datasheet so check out AN1517 for the L5972D demo board. AN1517 contains a lot of info that usually belongs in datasheets.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 18, 2014, 11:28:58 am
yes changed resistor for 5.088V  I alredy have this pcb build for test this ic I used on other design you can also see mosfet sot23 to control on-off but tied 12v enable wire and not used
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rasz on January 18, 2014, 04:24:02 pm
Adding a bit of copper wire on an already custom transformer is cheaper than one of those custom switching regulators.  They just screwed Copper on transformer + bridge rectifier and capacitors and lm317 < 1$ ... that oki regulator, probably 2-3$.

Because $2 of short term profit is better than good quality product, obviously :/

That's a foolish analysis.

If they were going for short term profit, they wouldn't be taking them back and replacing parts at no charge.  I bet the repair on my DP832 costs Rigol more than their profit on the unit amounted to.

This is just post facto saving ones ass. They would made $2 more if not for those meddling kids (Dave)!
Do you really believe an engineer decide to use 317 there on purpose while listening to http://www.youtube.com/watch?v=GeZZr_p6vB8 (http://www.youtube.com/watch?v=GeZZr_p6vB8) ?Or that he was ordered to make it cheap?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ted572 on January 19, 2014, 02:19:54 am
Please, can someone tell me if upgrading the DP832 Firmware to 00.01.08.00.02 works OK without corrupting anything with one or more of Options activated.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 19, 2014, 02:21:30 am
I upgradet from 1.06 to 1.08 lost only advanced Trigger option also you need to do recalibration
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ted572 on January 19, 2014, 02:40:20 am
I upgraded from 1.06 to 1.08 lost only advanced Trigger option also you need to do recalibration
I was hopping that if the Rigol FW Upgrade Procedure was followed that Re-Cal would not be required.  This procedure is much more involved than the normal FW Upgrade, as it is applied to three (3) separate PCB assemblies is succession.

Note: I had not seen the DP832 FW Installation Procedure on the Rigol web site.  So I thought that there was a good possibility that other people doing the FW upgrade hadn't either, and that perhaps this was the reason that their upgrade to to FW 08 wasn't fully successful(?).

Did you know about this procedure (attached below)? 
Did you have to go through the complete Rigol Cal Procedure for the DP832?  And if so, about how long does it take?
Sorry for all the questions, and thank you very much for your assistance.   
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ted572 on January 19, 2014, 06:15:10 am
I upgradet from 1.06 to 1.08 lost only advanced Trigger option also you need to do recalibration
rsivan:  I didn't hear back from you with answers to my questions, so I went ahead and upgraded to FW 08.

I lost the 'Trigger' Option as you had, but Calibration was not affected.  So I'll call this a success, with the loss of Trigger as a secondary or worthy sacrifice for the other benefits.
I tried reinstalling Trigger, but I get an 'invalid key' response.  It worked in FW 06, so apparently there is an issue with the Trigger key, the Trigger option changing, or otherwise being disabled in FW 08.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 19, 2014, 06:30:50 am
Yes same mine upgraded and lost trigger but calibration I think not necessary I done because changed also lm317 now not 5.14v but 5.088v also to try fix ch2 which read 9mV up than real still now if you make calibration make sure wait 3,4 seconds before confirm insert value on adcv and adca calibration
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ted572 on January 19, 2014, 09:18:55 am
Yes same mine upgraded and lost trigger but calibration I think not necessary I done because changed also lm317 now not 5.14v but 5.088v also to try fix ch2 which read 9mV up than real still now if you make calibration make sure wait 3,4 seconds before confirm insert value on adcv and adca calibration
Thanks 'rsivan' for giving me the push I needed to install FW 08.  I was reluctant until now with the horror stories I read from a few, about the issues they had.
 
I also substituted a switching regulator for the LM317.  I used a DSN2596 which is an assembled PCB module that was very inexpensive at $1.44 with free shipping.  When I went looking for a regulator IC to make something up I found this, and it was ready to fit in, so I choose this rout.  If Rigol were to open up my DP832 they would have to think that they had installed it at the factory.  It looks that good.  Although not required, I pulled out the potentiometer and replaced it with two SMT resistors.  I don't recall now what values I used because that was a few months ago and everything worked great with it set at the original voltage I measured before pulling out the LM317.
Available at -> http://www.ebay.com/itm/380755874794?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648 (http://www.ebay.com/itm/380755874794?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 19, 2014, 10:17:43 am
This one also perfect  problem is only time ot get I already have mine assembled if I order this from China here in Italy I got in 20-30 days I don't like to wait better to build on proto board
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 20, 2014, 04:14:49 am
I done full calibration now works well very accurate Voltage and Current like 12.000v I read 12.000v with Agilent DMM no reset with switching mod my 5v board keep 35c max, is important you make erase calibration with command via  Ultra Sigma sw no matter if you don't get answer just send command like in calibration guide and after start calibration for each channel my fw is 1.08 lost only Trigger.
In picture an engineer from Rigol testing my work with 34461A :-)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on January 20, 2014, 11:07:02 am
Can you supply the calibration guide to us? Or show the location where to download?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on January 20, 2014, 11:30:19 am
Can you supply the calibration guide to us? Or show the location where to download?

See attachments in this post: http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg361709/#msg361709 (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg361709/#msg361709)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: nack on January 20, 2014, 12:10:04 pm
Great, thanks!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ted572 on January 21, 2014, 02:37:38 am
I done full calibration now works well very accurate Voltage and Current like 12.000v I read 12.000v with Agilent DMM no reset with switching mod my 5v board keep 35c max, is important you make erase calibration with command via  Ultra Sigma sw no matter if you don't get answer just send command like in calibration guide and after start calibration for each channel my fw is 1.08 lost only Trigger.
In picture an engineer from Rigol testing my work with 34461A :-)
Did you use Ultra Sigma 00.01.05.09 (the one we have been using) or 00.01.05.10 (latest version, ~530MB RAR file)?
BTW Ultra Sigma 00.01.05.10 is supplied with the DS1000Z Series Oscilloscope.
Perhaps the commands that haven't worked for the DP832 Calibration will work with the  00.01.05.10 version.
I understand that you have yours done, but perhaps you or someone else could check this out and let us know.

Download Link   ULtra Sigma 00.01.05.10:  www.batronix.com/exe/Rigol/VISA/Ultra%20Sigma(PC)Installer.rar (http://www.batronix.com/exe/Rigol/VISA/Ultra%20Sigma(PC)Installer.rar)
                          NI VISA Runtime for Ultra Sigma:  www.batronix.com/exe/Rigol/VISA/visa540_runtime.exe (http://www.batronix.com/exe/Rigol/VISA/visa540_runtime.exe)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 21, 2014, 03:26:28 am
checked now what installed on pc I is  00.01.05.10 I take from Rigol website when you have send both command listed on manual you see adc voltage feedback going out of spec and you can procede with manual calibration
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on January 21, 2014, 06:29:18 am
Rsivan, I appreciate your replies and thank you for sharing your experiences, but for the love of god, use some punctuation!  ;D
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 21, 2014, 06:37:18 am
Yes sorry I know...
I'm so excitated about this toy and I miss some punctuation
:-)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on January 21, 2014, 07:06:04 am
 ;D

me too, but unfortunately I've the REV. 2 board version; I'm still waiting for replacement and I'm not sure about the destiny of my official options installed (wich I've bought toghether with the PSU): will Rigol provide my another set of serial keys!?  :-//. We'll see.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jkw13 on January 21, 2014, 10:11:57 am
checked now what installed on pc I is  00.01.05.10 I take from Rigol website when you have send both command listed on manual you see adc voltage feedback going out of spec and you can procede with manual calibration

Do you mean the SCPI commands?

:Cal:Start 2012,CH1
:Cal:Clear CH1,ALL

If so, I cannot get those to work.
You mentioned "erase", what exact command did you send
and on which screen please?

Thankyou
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rsivan on January 22, 2014, 05:11:50 am
checked now what installed on pc I is  00.01.05.10 I take from Rigol website when you have send both command listed on manual you see adc voltage feedback going out of spec and you can procede with manual calibration

Do you mean the SCPI commands?

:Cal:Start 2012,CH1
:Cal:Clear CH1,ALL

If so, I cannot get those to work.
You mentioned "erase", what exact command did you send
and on which screen please?

Thankyou
Yes these are  commands I used,send both in sequence,after start manual calibration.
 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jkw13 on January 22, 2014, 09:38:33 am
Many thanks rsivan.

Calibrates fine now! :-+
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on January 28, 2014, 08:36:44 am
I sent a polite email to "info@rigol.com" last night stating the timeline of my issue and asking for either a fix or at least information on when the fix would be offered.  I received an email back a few hours ago from a gentleman at Rigol who sent an RMA form and a pre-paid return shipping tag.  He mentioned they had been kept waiting for the repair parts, and that it was taking time to work through the backlog of units for repair. 

At least it appears they are now performing the fixes - hopefully the turnaround time won't be too bad.  I have other supplies I can use so I won't miss this one for a couple of weeks, but I hope it doesn't end up taking a couple months.  I don't think it will - they told me they should be able to turn it quick.

So for anyone still waiting, I guess you could either wait for contact knowing they are doing fixes, or you could email info@rigol.com and ask them to ensure you are on the list, at least.

Hope it helps.

Any update on this?  I wonder if you sent your DP832 back for the board replacement?  If so, have you got it back yet?  How has the correspondence been from Rigol NA about the process?

Thanks!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on January 28, 2014, 10:49:15 am
I sent a polite email to "info@rigol.com" last night stating the timeline of my issue and asking for either a fix or at least information on when the fix would be offered.  I received an email back a few hours ago from a gentleman at Rigol who sent an RMA form and a pre-paid return shipping tag.  He mentioned they had been kept waiting for the repair parts, and that it was taking time to work through the backlog of units for repair. 

At least it appears they are now performing the fixes - hopefully the turnaround time won't be too bad.  I have other supplies I can use so I won't miss this one for a couple of weeks, but I hope it doesn't end up taking a couple months.  I don't think it will - they told me they should be able to turn it quick.

So for anyone still waiting, I guess you could either wait for contact knowing they are doing fixes, or you could email info@rigol.com and ask them to ensure you are on the list, at least.

Hope it helps.

Any update on this?  I wonder if you sent your DP832 back for the board replacement?  If so, have you got it back yet?  How has the correspondence been from Rigol NA about the process?

Thanks!

Funny you mention that - I actually haven't sent it back yet, but I plan to this week.  Literally the day I got the shipping tag, a little emergency project fell into my lap using some white COB LED's that take over 30 volts.  I needed my DP832 to run these reliably so I figured I will send it when I am done.  I wrapped it up over the weekend and should get the unit out tomorrow. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on January 28, 2014, 11:10:26 am
Funny you mention that - I actually haven't sent it back yet, but I plan to this week.  Literally the day I got the shipping tag, a little emergency project fell into my lap using some white COB LED's that take over 30 volts.  I needed my DP832 to run these reliably so I figured I will send it when I am done.  I wrapped it up over the weekend and should get the unit out tomorrow.

Okay, thanks for letting us know!  Hope all goes well, and please update here as the process unfolds :)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on January 29, 2014, 07:12:30 pm
We make many threads for Rigol DP832 and I didn't know where to post it...

I had a contact with Rigol via local dealer where I am living, about Top Board Revision vs Thermal Behavior of LM317.

I sent them three photos, one with the first topology of LM317 with the two capacitors and LM to be very closed together (I call this "First Board Revision"), the second with the movement of capacitors and LM317 (I call this "Second Board Revision") and the last that we call Revision 2.1 with the big heatsink (I call this "Third Board Revision").

The answer of Rigol about this was : the first picture you send ("First Board Revision")are from the board Rev. V2.0, the others two are from the board Rev. 2.1, so no need to change ! On the old Rev ("First Board Revision") the heatsink is directly located next to 2 brown C’s.
Not the Size of the heatsink is important – the location is important – Also on the port is written which version it is.

From what I understand from this answer is that the last two versions that we have captured ("Second Board Revision", "Third Board Revision"), are from the same Top Board Revision (2.1) and the only Top Board that they change - under the warranty - is only the Revision 2.0 ("First Board Revision").

Have you any other information about this?

(Last Edit = with some syntax corrections)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on January 30, 2014, 04:56:01 am
I sent them three photos, one with the first topology of LM317 that the two capacitors and LM are very closely (I call this "First Board Revision"), the second with the movement of capacitors and LM317 (I call this "Second Board Revision") and the last that we call Revision 2.1 with the big heatshink (I call this "Third Board Revision").

The answer of Rigol about this was : the first picture you send ("First Board Revision")are from the board Rev. V2.0, the others two are from the board Rev. 2.1, so no need to change ! On the old Rev ("First Board Revision") the heatsink is directly located next to 2 brown C’s.
Not the Size of the heatsink is important – the location is important – Also on the port is written which version it is.


From what I understand from this answer is that the last two versions that we have captured ("Second Board Revision", "Third Board Revision"), are from the same Top Board Revision (2.1) and the only Top Board that they changed under the warranty is only the Revision 2.0 ("First Board Revision").

Have you any other information about this?

Thanks for this summary, and images of the different revisions all in one place. 

What you have shown is consistent with what I have read about --- there are only two different PCB revisions, with the placement of capacitors and LM317 being the major improvement.  The "Second Board Revision" and "Third Board Revision" both use the same (updated) PCB, with the only difference between them the size of the heatsink on the LM317.

I believe some people in the US got DP832 units from around Oct 2013 with the "Second Board Revision"; hopefully the "Third Board Revision" is shipping now.

From their comment, it seems Rigol considers only the location of the heatsink to be important, and not the size, and so they may decide to update units with "First Board Revision" only.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: lemon on January 30, 2014, 06:37:46 pm
Yes Sparky, you have completely right.

The information from Rigol to link: 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)
it seems that they refers only to Top Board Revision 2.0 (that I called First Revision Board) and not to Top Board with Revision 2.1 (with medium LM317 heatsink size).
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: primsam on February 03, 2014, 09:15:50 am
Hello,

So this is my first post here :-)
i am only a electronic hobbyist whit not a verry god understanding of all that what is happening in this magic :-))

so my question is
is it normal that i can measure some AC voltage between ground and CH1-2-3 of my DP832?
in Numbers:
CH1 to GND 5.8V (7,8uA shorted whit multimeter) with channel turned off and 9,8V(9,8uA) with cannel on
Ch2 to GND 16,9V (10uA) with channel turned off and 12,1V(17uA)
and channel 3 is depandent to CH2 and has the same readings.

the reason why i ask is that this behavior has probably blown some electronic under test because i thinked i was safe with a isolated power supply like this
:-S

so can somone tell me if this is ok and in spec of the supply?
or have i a faulty unit?

or im only to stupid for this

Thanks
Samuel

And sorry for my bad english
Title: Rigol DP832 Status Summary
Post by: Electro Fan on February 09, 2014, 12:28:28 pm
I know, "use the search".

Anyone here willing to summarize where the Rigol DP832 stands with respect to feature and performance issues? 

(Despite the issues I'd like to purchase a 832 but I'm not in a hurry and I'm inclined to hold off until these are sorted out - assuming Rigol will get around to them).

Any updates on the following? (have any of these been fixed in new shipping units?):

turn-on spike

overheating

intermittent restart

channel 2/3 cross connect

below 10mA software

any other notable issues

Thanks, EF
Title: Re: Rigol DP832 Status Summary
Post by: Sparky on February 09, 2014, 01:16:29 pm
I know, "use the search".

Anyone here willing to summarize where the Rigol DP832 stands with respect to feature and performance issues? 

(Despite the issues I'd like to purchase a 832 but I'm not in a hurry and I'm inclined to hold off until these are sorted out - assuming Rigol will get around to them).

Any updates on the following? (have any of these been fixed in new shipping units?):

turn-on spike

overheating

intermittent restart

channel 2/3 cross connect

below 10mA software

any other notable issues

Thanks, EF

turn-on spike: not fixed (I don't think anyone knows if this plans to be fixed or not)

overheating: "fixed" (larger heatsink on LM317 + some layout changes)

intermittent restart: this was due to LM317 over-heating, so this is resolved

channel 2/3 cross connect: design issue; not fixed in currently shipping units; probably not going to be fixed by Rigol because they have published their "heavy duty wire" workaround

below 10mA software: fixed in software update

You might want to follow this thread (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/).
Title: Re: Rigol DP832 Status Summary
Post by: Electro Fan on February 09, 2014, 02:09:19 pm
Sparky, thanks for the quick and concise answer.  Much appreciated!  EF

- PS, very nice "Marmad Formatted" DP832 - Firmware versions and bugs/issues (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/) thread you started.  I hadn't seen it but will definitely follow it now. Thx
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on February 20, 2014, 05:08:33 am
I sent a polite email to "info@rigol.com" last night stating the timeline of my issue and asking for either a fix or at least information on when the fix would be offered.  I received an email back a few hours ago from a gentleman at Rigol who sent an RMA form and a pre-paid return shipping tag.  He mentioned they had been kept waiting for the repair parts, and that it was taking time to work through the backlog of units for repair. 

At least it appears they are now performing the fixes - hopefully the turnaround time won't be too bad.  I have other supplies I can use so I won't miss this one for a couple of weeks, but I hope it doesn't end up taking a couple months.  I don't think it will - they told me they should be able to turn it quick.

So for anyone still waiting, I guess you could either wait for contact knowing they are doing fixes, or you could email info@rigol.com and ask them to ensure you are on the list, at least.

Hope it helps.

Any update on this?  I wonder if you sent your DP832 back for the board replacement?  If so, have you got it back yet?  How has the correspondence been from Rigol NA about the process?

Thanks!

Funny you mention that - I actually haven't sent it back yet, but I plan to this week.  Literally the day I got the shipping tag, a little emergency project fell into my lap using some white COB LED's that take over 30 volts.  I needed my DP832 to run these reliably so I figured I will send it when I am done.  I wrapped it up over the weekend and should get the unit out tomorrow.


I can update that I sent my DP832 for heatsink fix (Rigol RMA with shipping label) and the turn around was 4wks (plus additional 2wks for shipping there and back); it took longer than I expected.

The unit has the new (tall silver) heatsink in it, as expected.  It was also updated with firmwares (digital) 00.01.09, (analog) 01.02.00 and (boot) 01.06.

I have not tested it much since I got it back, but I note that it was (re)calibrated in Feb 2014.  Also, on the Test/Cal screen it shows the temperature is 11.82 (degC) --- it is not under load, but still that seems very low!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Galaxyrise on February 20, 2014, 05:25:24 am
I have not tested it much since I got it back, but I note that it was (re)calibrated in Feb 2014.  Also, on the Test/Cal screen it shows the temperature is 11.82 (degC) --- it is not under load, but still that seems very low!
Temperatures on cal screens are sometimes relative to the temperature the unit was calibrated at.  If that's the case, 11.82 seems high but not inconceivable (absent more data)... what is your ambient temperature?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on February 20, 2014, 05:36:03 am
I have not tested it much since I got it back, but I note that it was (re)calibrated in Feb 2014.  Also, on the Test/Cal screen it shows the temperature is 11.82 (degC) --- it is not under load, but still that seems very low!
Temperatures on cal screens are sometimes relative to the temperature the unit was calibrated at.  If that's the case, 11.82 seems high but not inconceivable (absent more data)... what is your ambient temperature?

Ambient temperature is 23.6 degC, while the temperature reading shown on the DP832 screen is now 12.11 degC. 

The temperature of the tall silver heatsink on the LM317 is now 54.7 degC.  I dunno where the sensor is that's giving 12.11 degC, but it just seems too low...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on February 20, 2014, 05:49:33 am
the turn around was 4wks (plus additional 2wks for shipping there and back)

SIX weeks?! more than a month?! :wtf: :rant: holy s**t...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on February 20, 2014, 02:06:23 pm
I have not tested it much since I got it back, but I note that it was (re)calibrated in Feb 2014.  Also, on the Test/Cal screen it shows the temperature is 11.82 (degC) --- it is not under load, but still that seems very low!
Temperatures on cal screens are sometimes relative to the temperature the unit was calibrated at.  If that's the case, 11.82 seems high but not inconceivable (absent more data)... what is your ambient temperature?

Ambient temperature is 23.6 degC, while the temperature reading shown on the DP832 screen is now 12.11 degC. 

The temperature of the tall silver heatsink on the LM317 is now 54.7 degC.  I dunno where the sensor is that's giving 12.11 degC, but it just seems too low...

And now it is confirmed as a bug in 01.09 (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg391168/#msg391168).


SIX weeks?! more than a month?! :wtf: :rant: holy s**t...

Yep!  You're not wrong!  Hopefully they'll speed it up, but people should be prepared to do without for a while.  For some, it might not even be worth the hassle...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Marc M. on February 26, 2014, 08:40:40 pm
I used a DSN2596 which is an assembled PCB module that was very inexpensive at $1.44 with free shipping.
Thanks Ted for the heads up on this inexpensive solution :-+.  I've had my RMA info. for my DP832 for a while now.  I was holding off on sending it in because they install .09 firmware which can't be downgraded.  Also, I didn't want to be without my PS for 6 weeks |O.  So I threw caution to the wind, tore off the warranty sticker and installed one of these modules.  The module has 2 isolated holes in the board for mounting.  On the Rigol board there's a board mounting screw in the area of the regulator so I mounted the replacement module in that position using a longer screw and few nylon washers.  It worked out very nicely.

...I pulled out the potentiometer and replaced it with two SMT resistors...
The pot on the board was wired as a variable resistor i.e. 2 legs were shorted together.  I set it for 5v, pulled out the pot and measured it right at 1k.  Conveniently, the manufacturer placed smd pads underneath the pot so it was simple to set it to a fixed voltage.  I soldered in a 1k smd resistor which yielded 4.96 vdc out.  Meh, close enough.  I put the power supply back together, fired it up and discovered it was in about a 5 second reset loop  :palm:.  I didn't want to mess around with swapping fixed resistors so I just re-installed the original pot.  I set it for a touch over 5 volts and put it back together.  It was good for about an hour then reset  :-/O.  This time around I got my tongue at the correct angle, set it to 5.125 volts and reassembled the unit.  I put it on an electronic load (Kikusui PLZ50-50A) and set CH1 to 30v@3A/90w.  It's been burning in for about 4 hours now without any problems. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Marc M. on February 27, 2014, 03:32:07 pm
An update from Zeitech. They are refusing to pay for return shipping, saying that Rigol will pay it. Has anyone had shipping costs paid by Rigol?
When I sent my scope in for repair to Rigol NA they wanted me to pay for the shipping to them and they would pay the return shipping.  I asked for them to pick it up both ways since the scope was only a few months old and I've purchased several pieces of their equipment. They went ahead and e-mailed a pre-paid FedEx label.  So I would suggest contacting Rigol directly to confirm that they will pick up the cost of return shipping as Zeitech is stating.  Even if Zeitech is FOS, Rigol may cover it anyway out of goodwill.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tequipment on March 09, 2014, 05:15:40 am
There's an EEVBlog discount at TE? How do you get that and how much is it?

5% Discount. just enter xxxxxxxxxxxxx (I think if my memory is correct) I called and asked them for the code. You will enter at checkout in the discount column.

Update: 6% Discount not 5%

Guys thanks for the business but can you remove the code.  We want it for eevblog members only and not posted publicly.. Thanks
Evan
TEquipment.NET
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tequipment on March 09, 2014, 05:17:13 am
There's an EEVBlog discount at TE? How do you get that and how much is it?

5% Discount. just enter xxxxxxxxxx (I think if my memory is correct) I called and asked them for the code. You will enter at checkout in the discount column.

Update: 6% Discount not 5%

Guys thanks for the business but can you remove the code.  We want it for eevblog members only and not posted publicly.. Thanks
Evan
TEquipment.NET

I was wrong with the 5% discount. The correct discount is 6%
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dave Turner on March 25, 2014, 10:40:54 pm
As reported previously in this thread Telonic Instruments Ltd, who manage www.rigol-uk.co.uk (http://www.rigol-uk.co.uk) as the UK official Rigol distributors, originally delivered a DP832 without the latest fix, but agreed to update my unit when the new boards were available.

I got the call yesterday and today a new unit and warranty card was delivered and exchanged for my old unit at no cost to myself.

My thanks to Dave & Karen at Telonics for their excellent service.

 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ivaylo on March 26, 2014, 05:27:49 pm
As I wrote before ordered mine from Tequipment about a year ago. Came a few months later with all reported here defects. Teuipment wouldn't help with the defective unit, sent me to Rigol, fine. Waited a few moths, got a decent Hameg PSU for the same price (from the forum here) and asked Rigol to return the DP832A. They agreed, shipped it two months ago, and they disappeared. Not replying to my emails, phone line always busy, etc. Not even sure if Tequipment is supposed to return my money (they got it initially) or Rigol. Not really impressed by the customer service of either company. It's a clear case of defective product line, solve it among yourselves, and don't make your customers do your work. Blah, rant over...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on March 26, 2014, 05:47:32 pm
...asked Rigol to return the DP832A. They agreed, shipped it two months ago, and they disappeared. Not replying to my emails, phone line always busy, etc. Not even sure if Tequipment is supposed to return my money (they got it initially) or Rigol...

If your intention was to return the DP832A for a refund (sounds that way since you bought a replacement), why did you send it to Rigol?  Rigol could perform repair under warranty, but you would need an RMA before sending it in, and presumably you got one which would have indicated if it was going to be repaired.

It seems logical to return the product to the place of purchase (TEquipment) if you want a refund...

In my case it took Rigol 4 weeks (+ one week shipping each way) for the LM317 heatsink fix, which was much longer than I expected, but it all worked out.

I hope you can get it all sorted out.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ivaylo on March 26, 2014, 06:37:59 pm
Quote
It seems logical to return the product to the place of purchase (TEquipment) if you want a refund...
It does seem logical. Tequipment played dumb, wouldn't take the unit back, sent me to Rigol. Rigol issued RMA and took it. Then disappeared.

Quote
In my case it took Rigol 4 weeks
From the moment you approached them (or did they approach you?) or from the moment you sent it?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on March 26, 2014, 06:56:44 pm
Quote
In my case it took Rigol 4 weeks
From the moment you approached them (or did they approach you?) or from the moment you sent it?

Neither.  I submitted an online form (on one of Rigol's websites) to get put in a queue and be notified of the board replacement process once it got started.  A few months after I submit the form, I got a surprise RMA via email to send in my DP832A unit for the board replacement.  I sent off my unit, and from when Rigol received it, it took them 4 weeks until I received notice of a return shipment to me.  So Rigol had my unit for 4 weeks, and it was one week each for ground shipping to them and back...so total I didn't have it for 6 weeks.  It was longer than I hoped, but all is good, and no cost to me.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dave Turner on March 29, 2014, 03:45:50 am
My replacement DP832 shipped with firmware v1.09.

On powering up with no load the temperature on the test-cal screen read 8.22. Note there are no units defined.
Ambient temperature was 17.5C.
After 15 minutes the temperature read 9.70 and 10.44 after a further 1 1/2 hours at which time the ambient temperature rose  to 18.7C.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on March 29, 2014, 05:04:40 am
My replacement DP832 shipped with firmware v1.09.

On powering up with no load the temperature on the test-cal screen read 8.22. Note there are no units defined.
Ambient temperature was 17.5C.
After 15 minutes the temperature read 9.70 and 10.44 after a further 1 1/2 hours at which time the ambient temperature rose  to 18.7C.

This odd temperature behavior has been noted previously in firmware 01.09, we believe it to be a bug.  See bug 5 (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg361709/#msg361709) in the list, and specifically the posts referred to therein.

>> 5. Temperature reading incorrect in 01.09

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dave Turner on March 29, 2014, 09:43:39 am
Sparky

Yup, I know it has been reported before. I was attempting to give a little more info in case it is of help to anyone gathering statistics.

 :)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on March 29, 2014, 10:02:15 am
I got my DP832 back from Rigol on Tuesday.  So it was just about 3-4 weeks from when I sent it back to when it was being delivered back.  It also was upgraded to firmware 1.09 which I was not too happy about.  Haven't noticed any extra fan noise - maybe even less, if anything.  Also haven't cracked it open to see what is new inside, but the unit seems to work great. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Sparky on March 29, 2014, 10:55:37 am
Sparky

Yup, I know it has been reported before. I was attempting to give a little more info in case it is of help to anyone gathering statistics.

 :)

Okay! No worries!  It never hurts to confirm that the issue is widespread, and not isolated to a few units.  Cheers!

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: thmjpr on April 21, 2014, 09:25:30 am
Went to perform mod mentioned by Marc M. and received a small surprise, the fuse on 8V AC input was replaced with a wire. Not a major safety issue, but I can't think of a good reason for doing this.

Replaced with 1.25A glass fuse + dc converter board, seems to be fine.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on April 22, 2014, 06:11:31 am
Is that corrosion on the screw on back of the heatsink?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: clivew on April 22, 2014, 09:22:20 am
I wonder what the white tubular component on the output (?) lead is? :-//
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on April 22, 2014, 12:13:02 pm
Ferrite? Shrink-wrapped by the look of it.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: thmjpr on April 22, 2014, 02:13:23 pm
Is that corrosion on the screw on back of the heatsink?
No, something waxy, probably flux. There is also a clear glue that was spilled on the top capacitor.

I wonder what the white tubular component on the output (?) lead is? :-//
Rigby is correct, a few small low frequency ferrites that I slid over the wire. Bit of paranoia from failed EMI tests in the past :).
Since the 5V is just for digital circuitry, I don't think the switcher will have any negative effect.

Similar part: http://www.digikey.com/product-detail/en/74270012/732-3987-ND/3316784 (http://www.digikey.com/product-detail/en/74270012/732-3987-ND/3316784)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bomber18 on May 27, 2014, 12:11:02 pm
The pot on the board was wired as a variable resistor i.e. 2 legs were shorted together.  I set it for 5v, pulled out the pot and measured it right at 1k.  Conveniently, the manufacturer placed smd pads underneath the pot so it was simple to set it to a fixed voltage.  I soldered in a 1k smd resistor which yielded 4.96 vdc out.  Meh, close enough.  I put the power supply back together, fired it up and discovered it was in about a 5 second reset loop  :palm:.  I didn't want to mess around with swapping fixed resistors so I just re-installed the original pot.  I set it for a touch over 5 volts and put it back together.  It was good for about an hour then reset  :-/O.  This time around I got my tongue at the correct angle, set it to 5.125 volts and reassembled the unit.  I put it on an electronic load (Kikusui PLZ50-50A) and set CH1 to 30v@3A/90w.  It's been burning in for about 4 hours now without any problems.
I finally broke down and decided i'd just do the step down repair myself after submitting the RMA repair form to Rigol in November and never hearing back from them and the stories of the 6 week turn around. I was hoping this would be a quick project for the long weekend but between the factory stripped hex screws I had to Dremel out and whatever wiring mistake i'm making it's been anything but.

I've got the points marked on the picture, 1 and 2 are the heat sink connections, 3 is the VAdj or pin 1 on the LM317, 4 is the Output or pin 2 on the LM317, 5 is the Input or pin 3 on the LM317, and 6 is a resistor point which I've seen some people connect to for different mods. I'm connecting In+ to point 5, In- to point 2, and Out+ to point 4.

I feel like an idiot as it seems many have had no issues with this but I'm looking for any advice on what i'm doing wrong here. I have my LM2596 adjusted to a 5.12V output but when I connect it in the power supply the output power at point 4, that is normally around 11V with the LM317, goes low to around 1V which renders the step down circuit useless.

If you noticed the alligator jumper that's from me managing to blow the fuse after I got frustrated and starting tinkering but any advice would be appreciated as I wait for my replacement fuses to arrive.

Step Down Converter http://www.ebay.com/itm/380755874794?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648 (http://www.ebay.com/itm/380755874794?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: madires on May 27, 2014, 10:17:04 pm
I've got the points marked on the picture, 1 and 2 are the heat sink connections, 3 is the VAdj or pin 1 on the LM317, 4 is the Output or pin 2 on the LM317, 5 is the Input or pin 3 on the LM317, and 6 is a resistor point which I've seen some people connect to for different mods. I'm connecting In+ to point 5, In- to point 2, and Out+ to point 4.

I feel like an idiot as it seems many have had no issues with this but I'm looking for any advice on what i'm doing wrong here. I have my LM2596 adjusted to a 5.12V output but when I connect it in the power supply the output power at point 4, that is normally around 11V with the LM317, goes low to around 1V which renders the step down circuit useless.

Have you checked if point 2 (for mounting the heatsink) is connected to ground and not something else or even floating?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on May 28, 2014, 03:25:20 am
My local dealer, BatterFly Italy, did NOT call me - like promised via email - for the RMA of my DP832. I was told that the return would be made on April.

Now it's almost June, and nothing happened. Even if this issue could be not directly in relation with BatterFly Italy (maybe it's Rigol Europe that is in fault), my dealer could at least inform me about the delay. Instead, I feel like I was abandoned. And probably is what I am.  :-//

This issue, if not solved from BatterFly Italy, make me understand that it's better to buy other T&M instruments brands than Rigol. And probably not from BatterFly: their customer support is - at the moment - very disappointing.  :--
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bomber18 on May 28, 2014, 09:18:05 pm
Have you checked if point 2 (for mounting the heatsink) is connected to ground and not something else or even floating?

I was able to probe those heatsink points last night and it does look like they are just floating.  My fault for making assumptions from the pictures posted and not checking myself. Thanks for the help!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on May 29, 2014, 03:27:45 am
Have you checked if point 2 (for mounting the heatsink) is connected to ground and not something else or even floating?

I was able to probe those heatsink points last night and it does look like they are just floating.  My fault for making assumptions from the pictures posted and not checking myself. Thanks for the help!
The housing on LM317 is connected to Vout (pin 2), so connecting the LM317's heatsink to GND would mean shorting Vout to GND.
The housing on TO-220 devices are always connected to one of the three pins, and there's no GND pin on LM317 since it's adjustable. So obviously the heatsink pads are not connected to GND as this would require unnecessary electrical (and somewhat thermal) insulation between the LM317 and the heatsink.

On fixed positive voltage regulators like LM78xx however, pin 2 is a GND pin, and the housing is connected to pin 2 on these devices too. But on adjustable voltage regulators there's no GND. And for negative fixed voltage regulators like LM79xx the housing is still connected to pin 2, but to make it more confusing, the pins are swapped compared to LM78xx, so pin 2 and the housing is Vin, with GND on pin 1 and Vout on pin 3.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on May 30, 2014, 05:04:50 am
As I wrote before ordered mine from Tequipment about a year ago. Came a few months later with all reported here defects. Teuipment wouldn't help with the defective unit, sent me to Rigol, fine. Waited a few moths, got a decent Hameg PSU for the same price (from the forum here) and asked Rigol to return the DP832A. They agreed, shipped it two months ago, and they disappeared. Not replying to my emails, phone line always busy, etc. Not even sure if Tequipment is supposed to return my money (they got it initially) or Rigol. Not really impressed by the customer service of either company. It's a clear case of defective product line, solve it among yourselves, and don't make your customers do your work. Blah, rant over...

Same problem here, Tequipment offers no guarantee about the problems with DP832. I'm fighting for six months and nothing happens.

And I thought this only happened in Brazil.

As they say here: is not easy for anyone.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on May 30, 2014, 06:10:02 am
Same problem here, Tequipment offers no guarantee about the problems with DP832. I'm fighting for six months and nothing happens.

As alternative, we can put a magnetron over the digital board and turn it on for 1 second just to fry some opamps: with a dead unit the warranty must be applied with no excuses.  :box:
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on May 30, 2014, 07:45:09 am
As alternative, we can put a magnetron over the digital board and turn it on for 1 second just to fry some opamps: with a dead unit the warranty must be applied with no excuses.  :box:

I lost this fight with Rigol/Tequipment.  :-[

The shipment cost is very expensive in my case, better i purchase other device.

Two months with my lab stoped.

Good luck for you too.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on May 30, 2014, 09:17:50 am
As I wrote before ordered mine from Tequipment about a year ago. Came a few months later with all reported here defects. Teuipment wouldn't help with the defective unit, sent me to Rigol, fine. Waited a few moths, got a decent Hameg PSU for the same price (from the forum here) and asked Rigol to return the DP832A. They agreed, shipped it two months ago, and they disappeared. Not replying to my emails, phone line always busy, etc. Not even sure if Tequipment is supposed to return my money (they got it initially) or Rigol. Not really impressed by the customer service of either company. It's a clear case of defective product line, solve it among yourselves, and don't make your customers do your work. Blah, rant over...

Same problem here, Tequipment offers no guarantee about the problems with DP832. I'm fighting for six months and nothing happens.

And I thought this only happened in Brazil.

As they say here: is not easy for anyone.

Didn't you hack your device?  (= Warranty void).  And Rigol sent you a replacement board due to the high cost of shipping to Brazil, right?

It is unfortunate that you are experiencing problems, but TEquipment has done nothing wrong, and Rigol has gone above and beyond for you on a unit that has no warranty because it was modified. 

Hacking equipment always runs the risk of bricking it or killing it in other ways.  When the potential negative outcome occurs, it's not the manufacturers fault, and certainly not the vendors fault to pay for shipping for manufacturer defects, whether hacked or not.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tsmith35 on May 30, 2014, 10:33:29 am
So, it appears that the Rigol 832 is a garbage power supply (http://www.rigolna.com/products/dc-power-supplies/dp800/dp832/) with a garbage warranty (http://www.rigolna.com/warranty/). Might as well buy something off of Aliexpress, save the money and take your chances. At least they don't mislead you into thinking you're buying a professionally-designed and supported piece of equipment.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bored@Work on May 30, 2014, 12:30:11 pm
It is unfortunate that you are experiencing problems, but TEquipment has done nothing wrong

A supplier going into hiding is a problem. Interestingly, we are talking about a supplier who is known for having issues with non-US customers in general.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ivaylo on May 30, 2014, 01:07:29 pm
Not without trouble (took me months) but I managed to get my money back. The way it worked was Rigol issued a RMA and I sent them the unit. Then they send Tequipment some sort of notification and Tequipment issued the refund. It's been nothing but waiting with buying Rigol through Tequipment:
 - order at Tequipment, and wait 4 months to get what you paid for (serious)
 - while I waited the news spread that the DP832 is a lemon
 - finally got it and confirmed that mine had all reported problems
 - immediately raised it with Tequipment but they just forwarded me to Rigol's recall page
 - waited 3-4 months, Rigol ignored my emails so I started bugging Tequipment again
 - they put me in touch with Jason Chonko at Rigol, after a few weeks of correspondence he issued a RMA
 - sent them the unit immediately and waited patiently
 - fast forward 2 more months, reminded them they told me 'accounting is slow'
 - another another month, turned out Rigol notified Tequipment but they didn't know  what that refund was for
 - then finally a very pleasant woman at Tequipment made sure I got my refund
 - phew...

Pretty much a whole year from the moment I ordered it to the moment I got refunded. Glad I had the extra funds to just buy a Hameg from Top Loser here on the forum so I can do whatever I wanted to do with a PSU like that. Anyways, the lesson(s) - the fact that Agilent used to outsource with Rigol doesn't mean that Rigol is Agilent, and the fact Tequipment have something listed on the website doesn't mean that they have it in stock or that they'll support you in any meaningful way...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on May 30, 2014, 02:21:48 pm
Didn't you hack your device?  (= Warranty void).  And Rigol sent you a replacement board due to the high cost of shipping to Brazil, right?

It is unfortunate that you are experiencing problems, but TEquipment has done nothing wrong, and Rigol has gone above and beyond for you on a unit that has no warranty because it was modified. 

Hacking equipment always runs the risk of bricking it or killing it in other ways.  When the potential negative outcome occurs, it's not the manufacturers fault, and certainly not the vendors fault to pay for shipping for manufacturer defects, whether hacked or not.

Yes, was hacked, but i never was asked about this.

I installed the new digital board and lost two channels (2 and 3 - firmware 1.03), looks that happens only with me, but I'll pay for the shipping cost.

The Tequipment said that will send at most in two weeks other device, because are waiting for a new batch to arrive, but already it passarm two months.

I'll wait another 15 days and buy another device, if necessary.

Not without trouble (took me months) but I managed to get my money back. The way it worked was Rigol issued a RMA and I sent them the unit. Then they send Tequipment some sort of notification and Tequipment issued the refund. It's been nothing but waiting with buying Rigol through Tequipment:
 - order at Tequipment, and wait 4 months to get what you paid for (serious)
 - while I waited the news spread that the DP832 is a lemon
 - finally got it and confirmed that mine had all reported problems
 - immediately raised it with Tequipment but they just forwarded me to Rigol's recall page
 - waited 3-4 months, Rigol ignored my emails so I started bugging Tequipment again
 - they put me in touch with Jason Chonko at Rigol, after a few weeks of correspondence he issued a RMA
 - sent them the unit immediately and waited patiently
 - fast forward 2 more months, reminded them they told me 'accounting is slow'
 - another another month, turned out Rigol notified Tequipment but they didn't know  what that refund was for
 - then finally a very pleasant woman at Tequipment made sure I got my refund
 - phew...

Pretty much a whole year from the moment I ordered it to the moment I got refunded. Glad I had the extra funds to just buy a Hameg from Top Loser here on the forum so I can do whatever I wanted to do with a PSU like that. Anyways, the lesson(s) - the fact that Agilent used to outsource with Rigol doesn't mean that Rigol is Agilent, and the fact Tequipment have something listed on the website doesn't mean that they have it in stock or that they'll support you in any meaningful way...

I have 4 months with Rigol (Jason Chonko) and 2 months with Tequipment.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bomber18 on May 31, 2014, 02:05:42 pm
I've got the points marked on the picture, 1 and 2 are the heat sink connections, 3 is the VAdj or pin 1 on the LM317, 4 is the Output or pin 2 on the LM317, 5 is the Input or pin 3 on the LM317, and 6 is a resistor point which I've seen some people connect to for different mods. I'm connecting In+ to point 5, In- to point 2, and Out+ to point 4.

A follow up for anyone else doing the step down mod. I got mine working with In+ to point 5, In- to point 6, and Out+ to point 4.

As far as the Rigol/Tequipment discussion goes i'd be lying if I said I wasn't jaded by the whole incident. I decided to buy new equipment when I was putting together a lab partly for the warranty and to see what that's worth now I don't know if i'll put the same value in it as I once did atleast not for the Rigol name.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rasz on May 31, 2014, 02:31:38 pm
As far as the Rigol/Tequipment discussion goes i'd be lying if I said I wasn't jaded

Just like in the case of rusting case of Siglent SDG5000 I actively discourage ANYONE who I hear is looking for new product to stay away from Rigol supply. I DONT CARE about excuses, or 3 shitty failed fix versions. There are no excuses for failing so hard.

So far I managed to steer two people clear of Rigol psu (actually one person and one repair shop). Not many people on the market for new  siggen in my circle of friends, but that doesnt stop me from mentioning effing RUST inside brand new equipment when we talk about shopping gear.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on May 31, 2014, 06:40:39 pm
Yeah, Rigol is making a very bad impression, I can't figure how a brand that effectively CAN produce good equipment could fail so miserably in helpdesk and in warranty.  :--

Their message to their customers is "Think twice before buying our products, because if you have some troubles with them, you'll be alone". And this could be only an epic fail strategy created by some meth/crack addicted sales manager.  :palm:

Honestly, I can't understand why they are so stupid. They are losing sales and, most of all, reputation for a so silly issue. :-//

All Chinese products always lack something in some way, and this is not racism, it's a fact:   |O
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tsmith35 on June 01, 2014, 03:51:26 am
Their message to their customers is "Think twice before buying our products, because if you have some troubles with them, you'll be alone". And this could be only an epic fail strategy created by some meth/crack addicted sales manager.  :palm:

It's "eBay" mentality: sold as-is. Perhaps they ran an eBay shop before they went big time.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on June 01, 2014, 04:05:30 am
It's "eBay" mentality: sold as-is.

There's nothing wrong with that if you warn me before the purchase.
Knowing that that is your marketing policy, if I decide to buy, I'll take my risks.

But you CAN NOT declare "3 years warranty" and then do the exact opposite, forgetting the customers. F**k that. If I knew this s*it, I would have bought Siglent, Uni-T or Atten.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jimjam on June 03, 2014, 02:39:50 am
It's a pity. Feature wise it seems good. I am looking for a Power supply right now. I guess I'll get a Siglent.

Dave mentioned in his blog that Siglent had far worse rust issues than Rigol but I can't find the video on him doing a siglent power supply review
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on June 03, 2014, 05:08:51 am
It is unfortunate that you are experiencing problems, but TEquipment has done nothing wrong

A supplier going into hiding is a problem. Interestingly, we are talking about a supplier who is known for having issues with non-US customers in general.

TEquipment isn't hiding at all - you are believing one side of the story, and I am very sure TEquipment has a very different view, that they won't be posting here because there are plenty of bored people waiting to pounce on them for being fatcats taking advantage of engineers.

I bought all my Rigol stuff from TE.  When the DP832 issue came to light, I contacted Rigol with no luck (by email).  I then contacted TE - months after I bought the unit and my return window was up (and TE's responsibility to me was ended), and they got in touch with Rigol and made sure I was taken care of.

The "issues with non US customers" is a bullshit criticism.  They have well defined payment processes that people complain about... well, don't buy from them then.  The fact is that people are like kids - they want their cake and to eat it too.   They don't want to buy locally because local suppliers are more expensive, but they don't want to take on any additional work to buy overseas.  In this case, why should TE pay $170 to ship back a unit from Brazil?  They shouldn't.  Frankly, Rigol shouldn't either... shipping costs are consequential damages and every company is going to disclaim consequential damages.  I hear that shit all the time from customers... will Sony pay your catering bill because the big screen TV you bought for your superbowl party died in the first quarter?  Will Chevy pay the bills for your missed holiday because your car wouldn't start and you missed your flight to Europe?  Of course not.  That's just the risk you take buying internationally... the reward is you save money, if things work out.  If people don't want to take on that risk, then buying a brand new design of a product isn't the best idea.  Not to mention, it's not like the PSU's were non-functional.  They were running at a temperature most engineers would agree was too high - it's not like they were bricks.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on June 03, 2014, 12:03:42 pm
TE and Rigol is a good store and nothing more, but six months to solve this problem is a very bad situation.

My inbox was updated today with a email of UPS@29Lbs.

Thanks god !   |O
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on June 03, 2014, 09:38:07 pm
Not to mention, it's not like the PSU's were non-functional.  They were running at a temperature most engineers would agree was too high - it's not like they were bricks.

Sure. So now the problem doesn't even exist! Who cares about the catastrophic failure to the digital board that that regulator will cause when it will blow like a firework in the next 2 years?

I've not paid for a time bomb.I've paid for a PSU that should last for some years.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rasz on June 03, 2014, 09:47:51 pm
Not to mention, it's not like the PSU's were non-functional.

yes, psu didnt reset or anything , right?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on June 04, 2014, 03:53:58 am
In this case, why should TE pay $170 to ship back a unit from Brazil?  They shouldn't.
If any company won't/can't manage international issues, why the hell they choose to sell internationally? Oh, yes... maybe because profit. We're all great merchants when all goes fine. It's when you must manage troubles that you show your company reliability.

You don't want the international customers to bother you? Stop selling internationally. Period.

shipping costs are consequential damages
Probably in your country. Not in EU for a thing like this one (bad engineering).

will Sony pay your catering bill because the big screen TV you bought for your superbowl party died in the first quarter?
These are of course examples of "consequential damages", even if they are bizarre (I would have choose "burnt or damaged circuits powered to the PSU, profit loss etcetera). No sane person would ask to the manufacturer to pay the catering bill if the TV died during supebowl. Seriously.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on June 04, 2014, 02:15:09 pm
Sure. So now the problem doesn't even exist! Who cares about the catastrophic failure to the digital board that that regulator will cause when it will blow like a firework in the next 2 years?

I've not paid for a time bomb.I've paid for a PSU that should last for some years.

Come on - I'm laughing here.  So now you've determined the whole logic board will fail within 2 years based on.... what exactly?  I am not aware of any failures - are you?  And... Rigol offered to fix the problem.  I think some folks are only happy when they're unhappy.

Shit happens.  And when it does, you hope the perpetrator of that shit fixes it.  In this case, that's exactly what happened.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on June 04, 2014, 02:16:50 pm
Not to mention, it's not like the PSU's were non-functional.

yes, psu didnt reset or anything , right?

Did they reset?  I believe Dave got his to reset with the case off (= no airflow).  When I talked to the guys at Rigol, they were well aware of Dave's video, but not aware of any 832's which were actually resetting in normal use.  I tried to get mine to reset, but it didn't.  As I said, some folks are blowing this way out of proportion (look at the above post about exploding regulators within 2 years causing catastrophic damage).  Fact is, there was a part running too hot, so they fixed it.  Next.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Corporate666 on June 04, 2014, 02:21:50 pm
If any company won't/can't manage international issues, why the hell they choose to sell internationally? Oh, yes... maybe because profit. We're all great merchants when all goes fine. It's when you must manage troubles that you show your company reliability.

...and the terms are clearly spelled out when you make a purchase.  If someone chooses to buy internationally to save money, they take on the liability of dealing with those ToS.  That means if the shit hits the fan, you might have to pay return shipping.  It is the vendor who sets the ToS, and it is the customer who chooses to shop there or not.  If you are selling your car and I buy it and ship it to the USA and then have a problem, is it now your responsibility to ship it back to your home country to be fixed at your cost?  Of course not. 

Quote
You don't want the international customers to bother you? Stop selling internationally. Period.

Probably in your country. Not in EU for a thing like this one (bad engineering).

You have no experience running a business.  If you buy something from another country, you don't have the benefit of whatever local laws and regulations govern transactions.  Like I said above - if you want those protections, then buy locally.  If you buy from another country to save money, you take a risk.  When things go wrong, that's just the price of taking that risk.  Sometimes shit happens. 

We all have to put our big boy pants on at some point in our lives and take personal responsibility for our actions - including accepting the ToS of stores we choose to shop in. 

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Bomber18 on June 04, 2014, 02:52:22 pm
So now you've determined the whole logic board will fail within 2 years based on.... what exactly?  I am not aware of any failures - are you?  And... Rigol offered to fix the problem.

Well what do you think will happen when you expose those two capacitors millimeters away from a part that hot over time? Not to mention that the part itself is operating at the tipping point of it's thermal limit  I don't think calling the thing a time bomb is too far off myself.

Yes Rigol "offered" to fix the problem by posting a website for RMA requests. Unfortunately I submitted my information and heard nothing for 6 months and it doesn't sound like I was an isolated incident. Also a 6 week turn around time is pretty absurd for those that were able to get RMAs fulfilled.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: ivaylo on June 04, 2014, 04:18:42 pm
Corporate, for whatever reason you are taking this too personally. If you are so happy with Rigol & Tequipment just say so and let's move on. I am in the states, not international or anything, I still spent a year in limbo plus probably 20 to 30 hours of my time dealing with this. Then I got my money back. Now let's hear what experiences others had...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on June 04, 2014, 09:56:13 pm
So now you've determined the whole logic board will fail within 2 years based on.... what exactly?
Well, a regulator can't live for many hours at that temp. An of course the caps near him have a limited life. It's not rocket science.

Quote
I am not aware of any failures - are you?  And... Rigol offered to fix the problem.
Oh, yes. It's only that they doesn't reply to me and my local distributor just ignores me.

Probably in your country. Not in EU for a thing like this one (bad engineering).
You have no experience running a business.
And you think you know everything about the others just reading two lines.

I was referring to EU purchases. I live in EU, and I've bought in EU.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rasz on June 05, 2014, 12:28:51 am
Fact is, there was a part running too hot, so they fixed it.  Next.

and it only took them few months of shipping back and forth

Did they by any chance fix channel two turning on output by itself? and bad readings?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: tequipment on June 08, 2014, 02:25:40 am
Hello.  Just to be clear.  If anyone has had an issue with any item contact me and we will take care of it.  We have a staff and they have procedures.  After 30 days the issue is a warranty issue with the manufacture.  This is the policy BUT that dosent mean we cannot help.

Send me a message and I will have someone follow up on it.  We stand behind what we do.  I have owned this company for 12 years since I got out of college as an EE.  We have the integrity and we stand behind our customers.  After all our rep is everything. 

I am out next week but will forward anything I get.

Have a good weekend.  Off to clean the yard and go to the kids soccer games. 
Thanks
Evan Cirelli

Vice President and Co-Founder
TEquipment.NET
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on June 08, 2014, 03:03:42 am
If anyone owns a DP832, can they test the parallel configuration of this PSU and report back?

Are both channels stable when they are connected in parallel?  What happens if you make one channel differ by 1 V?  In theory, the channel with the lesser voltage setting becomes the output voltage of both channels, and the channel with the higher voltage setting will match that voltage setting and go into constant current mode.  This is a stress test, but any linear CVCC supply can perform that test without instability [ albeit not advised in the long term as one channel is 'overworked', ideally each channel shares the work equally.]

The Rigol application note:

http://www.batronix.com/pdf/Rigol/DP8_DP1_ActiveLoads.pdf (http://www.batronix.com/pdf/Rigol/DP8_DP1_ActiveLoads.pdf)

States no 'active loads' should be applied to any channels as it could damage the 'powered device.'  It implies its not advised to parallel even its own other powered channel.

But what I think Rigol means is you cannot connect a fixed voltage source to any channels such as a fixed voltage wall wart supply, a battery or a solar cell.  A CVCC device adapts dynamically until an equilibrium is reached, and both devices are in a steady state.

Finally, an 'active load' means something like an electronic load, which clearly can be used on the DP832 so I think the wording they chose is not ideal.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on June 08, 2014, 03:33:43 am
The first page of that document explains what they mean when they say "active load" - any device that can source power into the supply.

When running channels 1 & 2 in parallel, I've always had them "ganged" so that controlling one controls both simultaneously.  I've not had an issue with that.  That doesn't answer your question, I know, but it might help knowing that you can set up a master/slave channel arrangement so that you don't need to worry about setting the channels independently.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on June 10, 2014, 12:37:27 am
Much thanks Rigby.

Since you got it working with the Rigol's track function [ which 'gangs' the channels] I take it the parallel setting works ok but one should test it for stability to make a claim it supports parallel mode. 

When you set it to track and parallel the outputs do both channels stay in CV mode?  That would be excellent. 

It should not switch between CV and CC mode alternatively under load as it would cause DC regulation problems.  To stabilize it one channel is set 0.25-0.5V higher than the other and permanently sets one channel as CV and another as CC.
 
Most CVCC supplies allow any other CVCC supply to be paralleled into its ports so you can take 'N' linear supplies and output 'N' current.  The difference in voltage between either channel can be ~1 V without damage so one can adjust the channels to balance them manually. 

The first page of that document explains what they mean when they say "active load" - any device that can source power into the supply.

When running channels 1 & 2 in parallel, I've always had them "ganged" so that controlling one controls both simultaneously.  I've not had an issue with that.  That doesn't answer your question, I know, but it might help knowing that you can set up a master/slave channel arrangement so that you don't need to worry about setting the channels independently.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on June 10, 2014, 03:24:30 am
The user's guide for that power supply specifically mentions parallel connections between channels 1 & 2, and I've done it myself.  I've not gone through the motions, I just expected the PS to behave, and it did.

I've also used the track function to supply an adjustable positive and negative voltage from channels 1 & 2.  that worked great, also.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: thmjpr on June 12, 2014, 06:10:47 pm
If anyone owns a DP832, can they test the parallel configuration of this PSU and report back?

Are both channels stable when they are connected in parallel?  What happens if you make one channel differ by 1 V?  In theory, the channel with the lesser voltage setting becomes the output voltage of both channels, and the channel with the higher voltage setting will match that voltage setting and go into constant current mode.  This is a stress test, but any linear CVCC supply can perform that test without instability [ albeit not advised in the long term as one channel is 'overworked', ideally each channel shares the work equally.]

I don't see how what you are describing is possible unless the supply is four quadrant (or has a crowbar circuit?). What I expect to happen is the voltage output will be whatever channel has the higher voltage, as it boosts the lower channel up. But I will describe what I noticed.

As soon as I connect CH1 to CH2 there is a 40mA current that passes between channels. Presumably this is a constant current load activated when O/P voltage exceeds set voltage, to drain the caps. I can set CH1 to say 10V, and CH2 can be set from 0-10V with the same 40mA draw (and both displays read 10V as its o/p is boosted by the other channel). However, the opposite is not true, if I set CH2 to 10V and CH1 to 0V, the display reads 0.3A on CH1 and 40mA CH2. I'm not sure if this is a software bug (from reverse current flow), as the external current flowing is still 40mA. Or maybe circuit architecture.

One thing I thought though, if you do a lot of paralleling it would be nice to have the supply auto-add the two channels together on the display.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on June 16, 2014, 07:47:16 am
Thanks thmjpr for the detailed reply.  The basic response of a CVCC supply in parallel is well described; here's a good reference for the details:

http://www.home.agilent.com/agilent/editorial.jspx?ckey=520808&id=520808&nid=-11143.0.00&lc=eng&cc=US (http://www.home.agilent.com/agilent/editorial.jspx?ckey=520808&id=520808&nid=-11143.0.00&lc=eng&cc=US)

http://powersupplyblog.tm.agilent.com/2012/11/how-can-i-get-more-power-from-my-power.html (http://powersupplyblog.tm.agilent.com/2012/11/how-can-i-get-more-power-from-my-power.html)

When you adjust one channel's voltage higher than the lower voltage set channel do you notice it switch from CV to CC annunciator on the LCD screen?

The response you write off for the PSU is a bit odd, I'm analyzing it now and will report back.


If anyone owns a DP832, can they test the parallel configuration of this PSU and report back?

Are both channels stable when they are connected in parallel?  What happens if you make one channel differ by 1 V?  In theory, the channel with the lesser voltage setting becomes the output voltage of both channels, and the channel with the higher voltage setting will match that voltage setting and go into constant current mode.  This is a stress test, but any linear CVCC supply can perform that test without instability [ albeit not advised in the long term as one channel is 'overworked', ideally each channel shares the work equally.]

I don't see how what you are describing is possible unless the supply is four quadrant (or has a crowbar circuit?). What I expect to happen is the voltage output will be whatever channel has the higher voltage, as it boosts the lower channel up. But I will describe what I noticed.

As soon as I connect CH1 to CH2 there is a 40mA current that passes between channels. Presumably this is a constant current load activated when O/P voltage exceeds set voltage, to drain the caps. I can set CH1 to say 10V, and CH2 can be set from 0-10V with the same 40mA draw (and both displays read 10V as its o/p is boosted by the other channel). However, the opposite is not true, if I set CH2 to 10V and CH1 to 0V, the display reads 0.3A on CH1 and 40mA CH2. I'm not sure if this is a software bug (from reverse current flow), as the external current flowing is still 40mA. Or maybe circuit architecture.

One thing I thought though, if you do a lot of paralleling it would be nice to have the supply auto-add the two channels together on the display.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on June 16, 2014, 10:15:09 pm
Here's the typical response of a behaved linear supply.  Forgive the appearance of the pic as it was quickly done.  The test load is the Array 3710a, and the PSUs are a $20 Radio Shack Micronta that has CV adjusts only and a Mastech 3030D, $70.

Array shows 1.50 A draw and 4.89V at the terminals.  The difference in voltage from the PSU are due to V drop on the cables.

The Micronta is set to 5.081V as shown on the Fluke and supplies 0.5A shown on its paltry analog meter  :-\.  How much current it provides in the share can be adjusted by setting the Mastech output voltage, in this case the Mastech supply's 1.0A.

The Mastech supply shows 1.04A at 6.0V and, set higher than the Micronta, provides most of the current.  To share the current equally between 2 supplies, adjust the higher voltage set supply lower, until the desired value.

You may not be able to set the supplies exactly the same by their onboard readouts unless you use remote sensing, because the V drop on the cables are also taken into account by the circuitry.  As cables and units heat up, the setting may drift slightly, so in the end, a stable balance can be had for something like 55:45 once your PSU are warmed up and in a stable state.

Finally, in balance both units are in CV.  When one PSU provides most of the current and the other PSU providing only excess to the load, the unit providing most of the current goes into CC mode.

The image is huge is show the readouts as true.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: thmjpr on June 17, 2014, 03:22:19 pm
Thanks thmjpr for the detailed reply.  The basic response of a CVCC supply in parallel is well described; here's a good reference for the details:

http://www.home.agilent.com/agilent/editorial.jspx?ckey=520808&id=520808&nid=-11143.0.00&lc=eng&cc=US (http://www.home.agilent.com/agilent/editorial.jspx?ckey=520808&id=520808&nid=-11143.0.00&lc=eng&cc=US)

http://powersupplyblog.tm.agilent.com/2012/11/how-can-i-get-more-power-from-my-power.html (http://powersupplyblog.tm.agilent.com/2012/11/how-can-i-get-more-power-from-my-power.html)

When you adjust one channel's voltage higher than the lower voltage set channel do you notice it switch from CV to CC annunciator on the LCD screen?

Ok the link/pics helps me understand better what you were previously describing.
When I adjust the voltage higher than the lower voltage channel, it switches from CV to UR to CC over about 6mV range. Basically as you expected (with the added UR state).

Description of UR:
Quote
DP800A series power supply provides three output modes: constant voltage output (CV), constant current output (CC) and critical mode (UR). In CV mode, the output voltage equals the voltage setting value and the output current is determined by the load; in CC mode, the output current equals the current setting value and the output voltage is determined by the load; UR is the critical mode between CV and CC.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on June 21, 2014, 11:31:06 pm
My unit has been replaced last week after more than 8 months of requests.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on June 27, 2014, 04:30:56 am
I receive yesterday my second unit of dp832, with the same problem of my first device.

Channel 2 and 3 locked on UR mode (critical mode). Or I'm a noob that not know adjust voltage on a power supply ?  :palm:


How to do for change the operation mode of channels from UR to CV/CC mode ?

The Rigol and Tequipment doing me paid again all taxes and shipment cost to brazil.

I spending 550,00 dolars yesterday just to received my "new" unit.

 |O





Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on June 28, 2014, 06:25:23 am
I do not own this unit.

I think UR stands for "unregulated", that is the third state of most any CV-CC type power supply.  Its often not mentioned because its "critical" that the supply not stay in this mode for long, or it will damage itself or the device its powering.

With the current at maximum, the leads open circuit, the channel must be in CV mode.  If you short circuit the outputs, it should jump to constant current mode.  It should not be in UR for any length of time.  PSU may go into UR mode when you turn the volt or amp adjust knobs for the most briefest of instances.  UR can also appear for a indefinite period once you sink current into a PSU that was not designed to sink current.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: centon1 on June 28, 2014, 09:11:36 am
How to do for change the operation mode of channels from UR to CV/CC mode ?

When all else fails, read the directions.

DP832 User guide dated Mar. 2013 covers it in section 2-1 'Front Panel Operations'
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: geekGee on July 26, 2014, 02:05:51 pm
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.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: AndersAnd on August 01, 2014, 08:27:20 am
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.
Have the replied yet?
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: geekGee on August 04, 2014, 01:33:19 am
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.
Have the replied yet?

Yes… the supplier contacted Rigol then responded that the bad board was replaced earlier this year.  As I was almost 100% positive that was incorrect, I then contacted Rigol Tech Support directly.  Based on my description of the board from looking through the cooling holes, the engineer confirmed it was the bad board and has issued an RMA on the unit.

Rigol feel that it was likely their mistake.  As they are taking ownership of the issue, I am optimistic that I will have a positive outcome.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: stormbr on August 07, 2014, 01:13:07 am
Rigol is not serious company, low quality products and have no warranty.

3 years of warranty is a lie.  :--


I spending 4k $ with this company, but this was last time.


Rigol and Tequipment never more to me !

Two DP832 and one DG4062 damaged here.  |O


I thinking that happens only in Brazil ! Is not easy for anyone.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: f1rmb on August 28, 2014, 04:13:05 am
Hi,

    This afternoon I was using my brand new DP832, powering a device under 24V (on channel 1), current was sets to 2A (but the device needs < 200mA).
Then, I had to leave the bench, so I turned off the channel (1), but when I came back, turning the channel back to ON, the power supply switched to 'UR', with few mV output.

I tried almost everything, turning off OCP and OVP, reboot, without any effect.

If I turn the channel ON, with few mV sets, then slowly increase voltage (using knob), the channel turns to 'UR' for a sec or so, then switch back to Constant Voltage. But if I increase too fast, it sticks to 'UR'.
Also, setting output voltage to ~1V, then turning channel output ON seems to almost work (voltage slowly increase, but doesn't reach 'UR' state).

Does anyone experienced the same problem, or have any clue or fix ?

The firmware version is 1.10, all options "turned" ON.

Cheers.
---
Daniel.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on August 28, 2014, 10:50:21 pm
TFM (that I guess you have read  :P) says:

"In CV mode, the output voltage equals the voltage setting value and the output current is determined by the load; in CC mode, the output current equals the current setting value and the output voltage is determined by the load; UR is the critical mode between CV and CC."

I think this behaviour is caused by the load. You should try to power another device to see if it behaves the same.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: f1rmb on August 29, 2014, 03:22:20 am
Hi,

    Okay, problem found and fixed.
My reseller asked me to ship back to him the device. Noooo way I spend half the price of this baby in UPS/DHL/whatever shipment.

The positive terminal on the top board has so badly soldered that I pulled it out when I tried to remove the wires.

Also, one of the soldered fuse (5A) on the same board was almost dead (this explains why the voltage was increasing so slowly.

For test purpose, I temporary straped the fuse, and the channel is working again. Now I need to find a replacement.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on August 29, 2014, 04:47:11 am
oh wow. 

nicely done spotting those and fixing them.  replace that single-use fuse with a polyfuse.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: f1rmb on August 29, 2014, 06:20:48 am
Thanks  :D


Yes, polyfuse sounds good. Lets check Farnell and RS.


Cheers.
---
Daniel
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on August 29, 2014, 06:54:04 am
Great find  :phew:, and good job  :clap:.  Naturally, it makes one now wonder about Rigol's quality control.  What does this fuse protect?  Is it to power the main board(s)?


Hi,

    Okay, problem found and fixed.
For test purpose, I temporary straped the fuse, and the channel is working again. Now I need to find a replacement.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: f1rmb on August 29, 2014, 08:39:31 am
Great find  :phew:, and good job  :clap:.  Naturally, it makes one now wonder about Rigol's quality control.  What does this fuse protect?  Is it to power the main board(s)?

Thanks. Lead free solder is really a PITA. Otherwise the build quality is nice, IMHO (except the LM317 stuff, even with larger heat sink).

This fuse is in the channel 1 AC input line.

Cheers.
---
Daniel
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on August 29, 2014, 09:08:28 am
That LM317 should have been a switching regulator from the beginning. 

Leaded solder isn't too bad once you get used to it. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on August 29, 2014, 10:56:36 pm
Naturally, it makes one now wonder about Rigol's quality control.

EVERY product can have a trouble like that.
Do you think RIGOL checks every-single-PSU? At that price? You're kidding...

They probably calibrate the boards by using pogopins and not the completed PSUs, so this can explain the issue.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: saturation on August 30, 2014, 12:57:30 am
Yes they should.  Proper QC can be fully automated.   The market for T&M is small, so reputation particularly among people who can examine the interiors and truly appreciate poor design or workmanship, makes it even more important they are strict with QC.  Burn testing this PSU then scanning the PCB with a thermal camera could have revealed the fuse was about to blow.

The fault mentioned here looks like either the one part was faulty and is an easy fix, or there is another fault downstream that blew the fuse,  so one has to check for it after the fuse repair.


EVERY product can have a trouble like that.
Do you think RIGOL checks every-single-PSU? At that price? You're kidding...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on August 30, 2014, 01:12:04 am
Yes they should.

I agree, but at that price you get a TRIPLE OUTPUT, very accurate, low ripple programmable PSU that costs much, much less than any other PSU... There is no comparison with other PSUs on the market at the moment.

I think it's a compromise.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: f1rmb on September 23, 2014, 07:20:34 pm
Hi,

    Since I don't want to crosspost, here http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg518001/#msg518001 (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg518001/#msg518001) is the first informations of the new top board I just received (pictures to come).

BTW, if you want to see the pictures here instead, just let me know.

Cheers.
---
Daniel.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: f1rmb on September 24, 2014, 01:24:43 am
Hi,

    Here are the topboard v02.20 pictures: http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg518139/#msg518139 (http://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/msg518139/#msg518139)


Cheers.
---
Daniel.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: pascal_sweden on October 22, 2014, 04:41:24 am
Are all the issues fixed now on the Rigol DP832? Or which issues are still present in the last revision?

Do the units still suffer from overshoot? Or can I leave the PSU connected to my target board without risking my design to get destroyed?

When will Rigol make a version where all (-) are isolated and not two common?
Do they actually have this in higher-end models or do they always share two (-) in common?

The Rigol DP832 would be a nice replacement to Philips PE1542, if it does not have the overshoot, and if it would have 3 completely isolated outputs.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: akkarin on December 02, 2014, 10:37:11 pm
I would also be interested which issues are still present in the latest revision.
Foremost I would like to know if the fan is still that noisy.


I am currently in the market for a new and better PSU and the DP832 could be "the one". But I hate noisy equipment I like it almost silence on my bench. Does not have to be super silent whatsoever but I once heard the DP832 and thats too loud for my ears. ;)

Anyway some update would be nice if someone has some news.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on December 02, 2014, 11:25:56 pm
Do the units still suffer from overshoot? Or can I leave the PSU connected to my target board without risking my design to get destroyed?

It's not a Rigol's PSU issue. Most PSUs has overshoot at power on. I have a TTi and it behave almost identical. IMO you should never leave your circuit connected (without a properly designed input) when powering on a bench PSU.

Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on December 03, 2014, 02:31:00 pm
So I think one could pretty easily mod the 832 to use a quieter fan, though mine does drive the fan according to load just fine.

If you were to use a couple temp sensors you could keep it to a very quiet idle until something heated up, and let a PID loop handle the fan for ya.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Gallymimus on December 05, 2014, 07:53:37 am
That LM317 should have been a switching regulator from the beginning. 

Leaded solder isn't too bad once you get used to it.

That would be incorrect.  It is foolish to use a switching regulator for control circuitry IF you want low noise.  A linear regulator was likely the right choice (again assuming it is powering the DACs ADCs and signal amps)
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Monkeh on December 05, 2014, 07:55:28 am
That LM317 should have been a switching regulator from the beginning. 

Leaded solder isn't too bad once you get used to it.

That would be incorrect.  It is foolish to use a switching regulator for control circuitry IF you want low noise.  A linear regulator was likely the right choice (again assuming it is powering the DACs ADCs and signal amps)

I strongly doubt it's powering anything of the sort.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Rigby on December 05, 2014, 07:56:23 am
As do I.  Looks to me like it's driving the front panel only.  I haven't opened it up and looked in a while, though.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: MattFL on November 07, 2015, 06:18:58 am
Not to druge up an old topic, but I'm shopping one of these and would love to hear from anyone who has purchased one recently if there are any issues with the revision that is currently for sale? 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Howardlong on November 07, 2015, 07:08:45 am
Not to druge up an old topic, but I'm shopping one of these and would love to hear from anyone who has purchased one recently if there are any issues with the revision that is currently for sale?

As far as I am aware, all outstanding bugs I'm aware of were resolved at firmware release 1.14. Happy to be corrected of course, Rigol has a reputation for having several different hardware versions of boards, and the regression testing matrix doesn't always seem to be completed across all combinations.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on November 07, 2015, 10:20:47 am
anyone know information about serialnumbers and when they are produced?
I got my 832A unit today with serialnumber DP8B17***
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Teneyes on November 07, 2015, 03:11:37 pm
anyone know information about serialnumbers and when they are produced?
I got my 832A unit today with serialnumber DP8B17***
rigol uses the 1st 2 digit after model "DP8B" as the year of production since 1998 . So the 17 is 2015. The next 2 digits is the week in the year of production 01-52 then serial number , I think last 5 are sequential for the model
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on November 07, 2015, 06:46:01 pm

Ah, so week six then, second week of february?
DP8B1706xxxxx
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: rs20 on November 07, 2015, 06:57:24 pm
rigol uses the 1st 2 digit after model "DP8B" as the year of production since 1998 . So the 17 is 2015. The next 2 digits is the week in the year of production 01-52 then serial number , I think last 5 are sequential for the model

Wat.. mine is DP8C1524xxxxx. I wonder what the C means? Can't be a newer revision, mine is dated 2013, which sounds about right.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on November 07, 2015, 07:52:29 pm
The dp831a that I got sent wrong instead of the dp832a had DP8A1520xxxxx
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stupid Beard on November 07, 2015, 08:13:36 pm
rigol uses the 1st 2 digit after model "DP8B" as the year of production since 1998 . So the 17 is 2015. The next 2 digits is the week in the year of production 01-52 then serial number , I think last 5 are sequential for the model

Wat.. mine is DP8C1524xxxxx. I wonder what the C means? Can't be a newer revision, mine is dated 2013, which sounds about right.

Mine is DP8C as well (from end of 2014) and is a plain non-A unit. neslekkim's is a DP832A, hence the different serial number prefix.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dino KL0S on November 08, 2015, 11:38:46 am
I went ahead when updating my bench suite with Rigol gear and got the DP832A which has the multi-color channel display. Even at full brightness the third channel which is colored some kind of magenta is very difficult to see.  I've asked the Rigol guys several times to consider adding an option to the 832A firmware that allows you to select the same green color as you get with the DP832 be applied to the three channels on the A model as that color is easier to see. In retrospect I often think buying the 832 with the resolution upgrade would actually have been better! Seems like a simple option to create but things work slowly.

I do have to say that they do listen and make changes albeit slowly. For example, my DSA1030A-TG did not have the VSWR software included in the firmware much to my chagrin after purchase forcing me to make and record manual measurements with the directional coupler.  |O Rigol's latest spectrum analyzer firmware added that capability!
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: neslekkim on November 08, 2015, 08:33:50 pm
what if you change contrast and brightness a bit?
I also was considering the 832 and getting the options separately, but it would be more expensive than the 832a (unless I hacked it ofcourse)

But one thing they didn't fix after all this years.. the fan.. very very noisy even when the unit is idle...
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Dino KL0S on November 09, 2015, 02:01:36 am
I've tried all the different combinations of brightness and contrast and the purple channel simply isn't very readable, at least to me. Maybe it's a hardware thing.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Stupid Beard on November 09, 2015, 02:55:03 am
But one thing they didn't fix after all this years.. the fan.. very very noisy even when the unit is idle...

The fan drives me nuts. I haven't replaced it because I didn't want to void my warranty, but I'm starting to change my mind on that.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation FIX?
Post by: tkarlmann on January 08, 2016, 02:32:47 pm
I am hoping to purchase a DP832 in the next couple of months.  Dave's reply stated that Rigol's "fix" for this problem was to increase the size of the heat sink on that crusty 5v regulator.  Ok.  My Question:  Has anyone measured the Input Voltage to that 5v regulator AFTER Rigol's "fix"?  When Dave stated that the input voltage on the unit he tested was 12v DC, I thought that sounded high for a 5v output @ 700mA.  I would think 8-9v DC would be sufficient for the 5v regulator (need to check the data sheet for input/output required differential).  ANY reduction in that "12v" input would, of course. dramatically reduce the power dissipation in that 5v regulator.  Does anyone have a "Fixed" DP832 they could check the level of the input voltage to that 5v Regulator?  My suspicion is that Rigol may have lowered that voltage. 
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation FIX?
Post by: Sparky on January 08, 2016, 05:19:02 pm
I am hoping to purchase a DP832 in the next couple of months.  Dave's reply stated that Rigol's "fix" for this problem was to increase the size of the heat sink on that crusty 5v regulator.  Ok.  My Question:  Has anyone measured the Input Voltage to that 5v regulator AFTER Rigol's "fix"?  When Dave stated that the input voltage on the unit he tested was 12v DC, I thought that sounded high for a 5v output @ 700mA.  I would think 8-9v DC would be sufficient for the 5v regulator (need to check the data sheet for input/output required differential).  ANY reduction in that "12v" input would, of course. dramatically reduce the power dissipation in that 5v regulator.  Does anyone have a "Fixed" DP832 they could check the level of the input voltage to that 5v Regulator?  My suspicion is that Rigol may have lowered that voltage.

Rigol implemented a hardware fix for this long ago...before Nov 2013!  If you're buying a new unit and not second-hand I don't think you need to worry about this issue.  Read the whole thread if you want to know exactly what went down and various fixes proposed by individuals, or start around page 30 of this thread to see pictures of updated PCBs...  Rigol probably have even more recent hardware revision by now...

Sparky
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mij59 on March 21, 2016, 11:52:12 pm
Wondering if there's a thermal issue with the secondary triac switch at 3A output current.

At 3A output current the triac  RMS current will be something like 5A, giving a power dissipation of 5 to 6W.
Seems to me the triac is mounted on the same kind of heat sink as the  LM317.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: Kleinstein on March 22, 2016, 03:50:08 am
For the loss of the triac it is more the average current that is relevant, not so much RMS. So 3 A average current is more like 3.5 - 4.5 W loss.  Still this could be a problem, but the triacs might be more tolerant to high temperatures than the LM317.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mij59 on March 22, 2016, 04:16:42 am
For the loss of the triac it is more the average current that is relevant, not so much RMS. So 3 A average current is more like 3.5 - 4.5 W loss.  Still this could be a problem, but the triacs might be more tolerant to high temperatures than the LM317.

I tested triac switching a few weeks ago and concluded that the power loss is fairly high, take a look at the attachment AN10384.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sdouble on November 16, 2016, 03:02:40 am
A newbie question here.
I have several DP832 at the lab.
Some of them work great.
I have some troubles with 2 units.
I use the 2 30V-channels. They do work constantly. +6V on 1 channel, 1.5 V on the other one. Far from the max current sucked. 200 mA on 1 channel, 100mA on the other one.
After some hours of use, they erratically switch off. They I can switch them on again. But that's pretty annoying.
Any idea about where that problem could come from ?
Cheers
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: thm_w on November 16, 2016, 09:31:20 am
A newbie question here.
I have several DP832 at the lab.
Some of them work great.
I have some troubles with 2 units.
I use the 2 30V-channels. They do work constantly. +6V on 1 channel, 1.5 V on the other one. Far from the max current sucked. 200 mA on 1 channel, 100mA on the other one.
After some hours of use, they erratically switch off. They I can switch them on again. But that's pretty annoying.
Any idea about where that problem could come from ?
Cheers

Did you look inside to see if it has the old smaller heatsink or the newer bigger heatsink?
Is firmware recent?

Take them back if still under warranty.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: sdouble on November 16, 2016, 10:57:41 pm
Yes, the firmware is recent. But I did not dismount the units yet. I should do that ASAP I guess.
unfortunately, I stored those units in the lab for more than 1 year before I used them for the 1st time.
In addition, I bought them from TEquipment ,meaning that I would have to send them back to the US... I am in France !
Shipping cost is just prohibitive.
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: jficara on September 19, 2017, 12:43:56 am
Hi,

Does anyone know if there is there any way, without opening up the DP832, to see if you have a unit that has the larger heat sink fix?  A greater than serial # or something that indicates a version that has the fix.

I am still under warrantee and didn't want to risk voiding the warrantee by opening it up to check.

Best,

Joe
Title: Re: EEVblog #512 - Rigol DP832 Bad Design Investigation
Post by: mcinque on September 19, 2017, 06:33:34 am
You can see it thru the vent holes on the right side of the unit. Use a flashlight and if you have the "bigger" silver heatsink, you will easily see it.