EEVblog #511 - Rigol DP832 Power Supply Teardown

[Rexus]

Another great video Dave, keep them coming!

One of the questions I had was does the PS have to be so deep, couldn't they have made it shorter - well it does look like the toroidal and heat sinks pretty much determine the length, a problem for my bench sadly.

[warp_foo]

Is someone making a Dave English -> Amurrican English dictionary? I'm not quite sure what to make of "It's the duck's guts." Is that a good thing?

Dave has some int-teres-ting pronunciations, even to Australian ears. Perhaps he spent some time in the land of the long white cloud ... And expressions like "in like Flynn" (referring to the long dead actor Errol Flynn's love life) are not common currency, at least not when I drove a cab in Sydney when I was a EE student. But it breaks both ways, the first time I read "dove under the table" in Canada I thought about pigeons ...

I make do with an Agilent U8001A PS which is fine for my purposes, apart from a damn loud fan. It gets around power on voltage spikes by having an output relay that is disconnected at power up until an activate button is pressed on the front panel; and I can check the voltage and current settings before pressing the activate. Perhaps Dave could test the 832's constant current performance give that large capacitor across its output.


PS Flynn was born in Hobart, Tasmania so that is the Australian connection. He died in 1959 (before Dave was born?) after a Hollywood career more noted for its off-screen exploits.

I always thought he was trying to say In Like Flint, or an Aus variant...

http://en.wikipedia.org/wiki/In_Like_Flint

[Dread]

I think Citizen did have one valid point, the older videos are more educational (First 250) but they are also spaced much further apart, so basicaly Dave is making more video's but the educational one's come along at the same rate as before, with teardowns, mailbags and dumpster diving used inbetween to bring up the monthly total.   Fair enough deal for me, I would rather watch a mailbag episode than watch nothing at all. 

[senso]

I learned some thing new, like the routing around the voltage reference, never saw anything like that, so another thing to remenber/good to know, it seems a bit odd that it only uses one pass mosfet per rail.

[anotherlin]

I'm talking about the actual schematic for the series regulator, built with discrete components, not the overall method of building a linear PSU. Have a look at the schematic and PCB layout for, say, the triple rail Agilent E3631A.

For instance the Triacs are not used as pre-regulators, nor are using SCRs an option here. The Triacs are used as bipolar switches to select taps on the transformer secondaries, to limit power dissipation in the series pass device at low output voltages. In the E3631A they are triggered using optically coupled Diacs, which I suspect may be the SMDs close to the Triacs.

Ok, I've managed to find the schematic (p130 of service manual) of the E3631A. In this particular case, the transformer wiring is center tapped and the triacs seems to be some form of pre-regulator (feedback sensing voltage right after pass transistor). I wasn't able to find the schematic for the Rigol for comparison. Just because it uses LM393 and TL072 doesn't mean it's a "direct" copy of an Agilent schematic. Those are very common chips, TL072 are just found everywhere. Using a dual opamp (one for voltage feedback and one for current) is basically the usual way to design a pass transistor regulator.

On the contrary, I would rather think that the Agilent's and Rigol's share same ("classic") building method, but not schematic.

[EEVblog]

45min video of probing the DP832 coming up...
So much FAIL 

[jancumps]

yeah

[dr.diesel]

So much FAIL 

I'd like to hear Rigol's response, I'm sure this video won't make it on their webpage!

[Harvs]

- milled slot around the reference diode for temperature stabilisation(thermally induced mechanical stress)
-guarded trace from the opamp to the cpu, thats more than 16 bit there ...

As we don't have a proper part number for the reference (or at least I cant find what #R3A is.) What sort of class of reference and ADC would be required to build something with specs like this? E.g. could you point to an AD or LT device that might be similar league?

[ElectroIrradiator]

On the contrary, I would rather think that the Agilent's and Rigol's share same ("classic") building method, but not schematic.

From your last post I suspect we have a case of misunderstanding between us, rather than disagreeing as such. This may be due to my (ab)use of the Queen's English...?

45min video of probing the DP832 coming up...
So much FAIL 

Ouch.

[JackOfVA]

As a general comment ... I've viewed every one of Dave's videos, going back into the archives to the  first ones, over the last months and have yet to find one that didn't hold my interest enough to watch it from start to finish.

And there's nothing like a good "Dave Rant" (Trade Mark registered with IP Australia?) to enliven a video. If something is a piece of crap, Dave will say so, and that honesty is a rare quality in today's "can't we all get along" environment.

[kony]

Voltage reference datasheet: http://www.analog.com/static/imported-files/data_sheets/ADR380_381.pdf.
I just wonder, if the routed slot around is meant to reduce mechanical stress or more likely to thermally insulate the reference as much as possible from surrounding PCB. This is common for temperature sensors in SMT packages (with routed slot or at least copper keepout and raster of holes for exactly same purpose as above) used for sensing ambient temperature, but I have never seen something like that done with voltage reference. But I must admit I rather like this idea.
FR-4 is a bad heat conductor, but not as bad as air is. Correct me, if I'm wrong.

[Blaffetuur]

The only thing some people want is Dave raging about some product, but if something is good people don't appreciate it.

[Harvs]

Voltage reference datasheet: http://www.analog.com/static/imported-files/data_sheets/ADR380_381.pdf.

Thanks!  Can I ask how you found it? I used every google trick I knew and it drew blank...

[EEVblog]

The only thing some people want is Dave raging about some product, but if something is good people don't appreciate it.

Yep, or worse, they accuse me of selling out, being bought off etc. 

[alm]

Clearly. Now you've finally been unmasked as mindlessly promoting a product with a flawed thermal design. Was the check from Rigol late that you had to resort to blackmail? Or did an Agilent power supply accompanied by an even bigger check just arrive?

[kizzap]

Clearly. Now you've finally been unmasked as mindlessly promoting a product with a flawed thermal design. Was the check from Rigol late that you had to resort to blackmail? Or did an Agilent power supply accompanied by an even bigger check just arrive?

  Really? do you have naught better to do then bring people down? If Dave was being paid off for product reviews, we wouldn't be seeing issues like this come up at all. Get a fucking grip.

The only thing some people want is Dave raging about some product, but if something is good people don't appreciate it.

I very much appreciate when Dave reviews something and finds it is really good. for my first 'scope I bought a Rigol DS2072, partially because of the work of cybernet on this forum, but more because Dave took the time to review it, and also reviewed some of the other 'scopes that I was looking at, and pointed out the pros and cons of all the products.

-kizzap

[marshallh]

I think he was using some heavy sarcasm there

[EEVblog]

Really? do you have naught better to do then bring people down? If Dave was being paid off for product reviews, we wouldn't be seeing issues like this come up at all. Get a fucking grip.

I think he was joking 

[kizzap]

I think he was using some heavy sarcasm there

I think he was joking 

If he was, he got me. 

[TerminalJack505]

I'm pretty sure he was just giving a sarcastic rejoinder for those that were arguing Dave went too easy on the Rigol PSU and that he was a corporate shill.

I know that when I saw Dave's rant I had to wonder what those people would say.

[EEVblog]

I'm pretty sure he was just giving a sarcastic rejoinder for those that were arguing Dave went too easy on the Rigol PSU and that he was a corporate shill.

Of course, the truth is it's been an elaborate paid setup all along 
I praise Rigol and appear like the shill, then I purposefully bag Rigol to recover my reputation and embarrass the conspiracy theory nutters. Then Rigol come to the rescue in record time with a pre-cooked solution with the worlds best customer service, and everyone praises Rigol as the best company ever and their stock soars.
You're all being played like a fiddle 

But the real masterminds are of course the New World Order run by the big mega banks who have infiltrated the entire youtube partner system.
Why do you think I'm in the garbage room so often, it's for those clandestine cash drops in the dumpster 

[Deepak]

...with the worlds best customer service

You know, you almost had me up until this point.

[riconette]

Of course, the truth is it's been an elaborate paid setup all along 

thats the answer you schould have given that… oh what was his name? twat. 

[alm]

Why do you think I'm in the garbage room so often, it's for those clandestine cash drops in the dumpster 

So what you said in this video was true all along? You were actually telling the thruth?