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  • EEVblog #164 – Agilent Fly To The Moon

    Posted on April 19th, 2011 EEVblog 35 comments

    Dave is a tad upset to find out how much standby power consumption the new Agilent Infiniviision oscilloscope draws.

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    35 responses to “EEVblog #164 – Agilent Fly To The Moon” RSS icon

    • I would like to see the response from Agilent, they better have a good reason. How can this equipment deals with power consumption legislations?

    • Hey Dave I agree that it is kind of strange to put in all that hardware and not put a hard power switch in the unit. The only reason I can think of is that the unit can be woke up remotely via the Ethernet or other type of communication port. You might look in the option menu to see if you can turn off any standby options. That might get the current consumption down to less than a 1 watt. Very common to have this in consumer products but usually the default is off rather than on.

      As a side note, I’m curious why you don’t use something like a Kill-A-Watt P4400 power meter (www.p3international.com). Very cheap, full feature, and they have a plug on the front instead of hardwiring. Seen them as low as $15 each. But maybe no one make a 240VAC model.

      • Probably the for the very same reason he doesn’t have a $3 multimeter – they’re both ridiculously unaccurate.

        • Actually it is fairly accurate. At least accurate enough for the type of measurements being made here. Just did a load test comparison a P4400 and my HP 3468A. P4400 read 0.53A and the HP read 0.53805A. Sure if you want 5 digit accuracy, use something else. But if you just trying to check load power consumption, its a great little tool.

      • For many years you have not been able to buy a low cost Kill-A-Watt type meter in Australia. Only recently have the come in, and most of them are shit at measuring <10W.
        I have a Silicon Chip meter kit too. Same result. The Gossen meter was just nicer to show on video.

    • If keeping the switcher warm to increase MTBF were an issue, I’d think a simple soft start circuit would suffice. “Energy Scar Certified”

    • I use Tektronix TDS3000 series scopes. They also have a mechanical switch that you would expect to isolate the instrument from the mains. Yet they also draw about 5 Watts in standby mode and feel warm to touch. I emailed Tek about it years ago – never got a response.

      • @Coder
        The secondary switch on the TDS3000 is a compromise.
        The scope can be operated by a battery pack which is being recharged even in “OFF” state.
        To be able to use both power sources, you would otherwise need to have two “switches” – a standby button and a power switch.
        (like on PC’s)
        I made myself a cable with a lamp switch to disconnect it from the mains.

    • This looks similar to how a standard pc works, on an atx power supply one of the pins is momentarily bridged to ground and the thing breaks into life. This generally uses a few watts when turned off but allows things like wake on lan to work it’s a bit of a waste for the majority of people.

      • Not as much of a waste as you’d think, unless you like replacing those coin cells that keep the BIOS settings and clock going. +5VSB is a handy feature of modern power supplies, they’re not terribly efficient because I think they’re usually linear regulators (like a 7805), but they’re not terrible.

        Shame the power factor is pretty poor on that pricey scope, though. You’d figure they could spare a little bit of room for a switching transistor/cap/diode for PFC, save a bit on the power bill in the end.

    • Looks like its main board does not turn off but rather goes into power-down mode to reduce start-up time. What are startup times of the scope (both cases, turned off by a switch and turned off by disconnecting mains) ?

      Another assumption is that they are having problems with physical turn-off, maybe filesystem gets corrupted or something like that, so they decided to put it into power-down instead so it can properly shut-down in the process. This whole thing looks like last-minute engineered to me. The board has a lot of space to accomodate large mechanical switch, yet they use only small logic-level one. If logic-level shutdown was designed in from the beginning, it would definitely go elsewhere, on the opposite end of the board, on the another board, etc.

    • Well, modern file systems use journaling techniques so that you won’t corrupt it by pulling the plug in the wrong moment, never. So since Agilent doesn’t use Windows 95 on this device, …

      But reducing the system startup time by putting the scope into standby sounds plausible.
      Or it is really some MTBF issue, which would be really shameful for Agilent.

      • > Well, modern file systems use journaling techniques

        Only if designers have decided to use it. A lot of Windows CE based platforms just use FAT over flash translation layer. I’m not sure if there is journaled file system for WinCE at all.

    • Nice one again! I am obsessed about standby power consumption and have a couple of Yokogawa WT210 power meters which I use to analyze appliances and such, which are very accurate down to the 5ma range. I have a Tektronix MSO4032 which has a big mechanical pushbutton switch on the front which I ASSUMED isolated the power supply circuit from the mains when off. After viewing your blog I hooked the MSO4032 up to the WT210 and here are my observations:
      MSO4032 on: 238V (UK Mains), .361A, 77.54W (Mode RMS)
      MSO4032 standby: 241.92V (UK Mains), 3.57ma, 0.0007W (Mode RMS)
      Sorry Dave, but I am not going to take my scope apart and look at the PSU circuitry!

      • …so what’s the point, comox?
        3.57mA and 700uW don’t match, so the current seems to be reactive.
        I ASSUME it’s the capacitors in the line filter which is located before the switch…

    • I think the speculation about the main board remaining in standby mode still needs to be proven. From what Dave said, the switch seems to cut the output from the SMPS, which I doubt leaves any other voltage supply for the board to remain in standby mode.
      Dave, could you investigate further to know if this is correct? If the switch simply cuts off power from the SMPS, then that would have been a really poor design decision.
      Cheers

      • I think Dave confirms in the latest amphour that the switch only kills the output from the psu, so yes a pretty piss poor design

      • I have mentioned this a few times now. Yes, the switch kills the output of the PSU. There is no voltage going to the main board.

    • What’s the model number of the main’s power meter?

      Can you explain how the power factor thing works? i.e. what 86% @6W vs 3% @20W??

      • Do you want Dave to do a video on the power factor or do you want a short answer ?

        Answer
        Power Factor is the solution of

        cos(phi) = PowerFactor

        So with the PowerFactor and a Pocket calculator your result is an angle, this Factor is important in AC applications (but also HF) as in an AC circuit current and voltage can go out of phase to each other, and this is what that factor describes.

        They can go out of phase because many wound power lines with magnetic fields crossing each other are a coil, even if you call it an electrical motor.

        The background can be understood via Wikipedia:
        http://en.wikipedia.org/wiki/Phasor

    • Madness! I say modify that switch to bring in the mains, then use a micro or a 555 to make a 1 – 2 sec delay to activate the start up.

      It may be worth seeing if the function of that switch is firmware configurable. I’m sure Agilent did that to allow for some kind of LAN wakeup feature or something like that, I wouldn’t be surprised to see a simple option that allowed for the main controller to turn off such peripherals.

      I’m sure Agilent will explain themselves anyway.

    • what version of ce is it using 6.0 use exFAT which is not a journaling file system.

      my guess is the wake up lan too

      remind me of freeviewbox box i came across that uses the same amount of on and in standby.

    • This is hilarious… You should put a lamp switch on it! Hahaha..

    • That’s crazy. This joke would cost me about $20 US dollars a year at $0,36/kwh here.

    • If you pause at 5:08, A picture is worth a million words;

      http://www.lineagepower.com/oem/pdf/cch125.pdf

      :)

      – Matt

    • Mike in Alaska

      Maybe its for some sort of remote operation capability with the LAN connector? Being awakened to take measurements?

    • Good find Dave. In CA that scope would cost about $7.50 a year just to have it off. …The scope you never stop paying for. Inexcusable.

    • The power supply CCH125 has a remote on/off control
      (a low signal turns the power supply off) and has
      a single 12V DC output. If in the “Off” state there is
      no 12V voltage on the power supply output, then it is
      clear that the oscilloscope is completely off and
      doesn’t have a Wake-up on LAN function.

      CCH125 power supply datasheet:
      http://www.lineagepower.com/oem/pdf/cch125.pdf

      See the page 96 of the 2000/3000 X-Series Oscilloscopes
      Service Guide “To check the power supply DC output”.

      http://cp.literature.agilent.com/litweb/pdf/75019-97012.pdf

      * * *

      I’m quite sure that Agilent has evaluated many brands of
      power supply during the development of the oscilloscope.

    • (Sorry it’s me again from Italy).

      Measurement of Standby Power & its Implications
      http://www.energyrating.gov.au/pubs/2002sbws3-spooner.pdf

      * * *

      Are we sure that the used Gossen Metrawatt multimeter is capable
      of an accurate measurement of the no load power consumption of
      an SMPS? See page 79 and 80 of its manual.
      http://www.gossenmetrawatt.com/resources/tt/metrahit_energy/ba_gb.pdf

      What about repeating the measurement with something like that
      or something more accurate?
      http://www.hameg.de/downloads/man/HM8115-2_D_E.pdf

      Or simpler, ask the manufacturer of the power supply for the
      no load power consumption of this SMPS? (Power consumption
      when the SMPS is turned off via its remote control feature).

    • I don’t know about your particular dso, Dave, but I’ve been told before (at shows, no less) that people prefer chunky power buttons and thats why they use them (and from your first video review, that seems true for you too). They don’t however like the ability to cut off the mains power supply feed at any given moment. This gives them the opportunity to do things like save settings when you switch the dso off, rather than everytime you make a change.

      It would be interesting to see if the infinivision is the same. Quick check: Change some of the settings and then exit and pull out the power cord. See if the settings remain after you plug it back in :)

    • @Dave:

      (I saw your message posted on April 23rd, 2011 at 18:10, thank you).

      I still think that the values you get are not accurate because
      the multimeter is unable to measure the power consumption of this
      SMPS with the output turned off via its own remote control pin.
      From the datasheet of the SMPS and from the model number
      visible on your video (time 5:06), I understand that this power
      supply has active power factor correction which improves the
      system efficiency. (Regulations in Europe require PFC for SMPS
      with more than 75W). This is a modern power supply so why have
      an active power factor correction when the power consumption
      with the output turned off via its own remote control is so bad?

      It would be good if you could perform the following test:
      Connect a 100W incandescent light bulb to the Gossen Metrawatt
      multimeter and measure its power consumption and write it down
      on paper. (The measurement of this resistive load will be
      very precise, and the multimeter can certainly handle that).
      Now, in addition to the load of the light bulb, add the load of
      the oscilloscope powered off and measure the power consumption
      of the two loads together and see if what you get matches what
      you get when you add together on paper the individual power
      measurements of the light bulb and the oscilloscope. If you get
      a discrepancy that is significant enough, then it is most likely
      that Gossen Metrawatt multimeter is not suitable to measure the
      power consumption of this SMPS while its output is turned off
      via its own remote control pin.

    • Everaldo Luiz Grothe

      Hi, my contribution to the topic.
      I performed a measurement in Agilent DSO-X 2012A that I have with my Fluke 43B.
      I hope I helped.
      hugs

    • Everaldo Luiz Grothe

      Hi, my contribution to the topic.
      I performed a measurement in Agilent DSO-X 2012A that I have with my Fluke 43B.
      I hope I helped.
      Please note at the beginning I inform Power x 10 so the power is 5.2 W in Stand by mode.

      hugs

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