EEVblog

[@redtails]

A discussion with an engineer is of a lot more value than lone rambling or talking with PR/CEO. That way you can get real insight and talk on the same level

[@Llirik13]

And this was king of video I watch EEVblog for.

[@Audio_Simon]

I do most of my electonics on audio equipment and I've yet to find a case where coupling grounds via any kind of resistance or filtering helps. You just need to optimise the connection orders to keep currents from flowing where they are unwanted while keeping ground resistance minimal. Seems like the same thing here.

[@bpa5721]

Love the sound the little spring makes. *plip*

[@WolfTronix]

looks like the beads got replaced with 0 ohm jumpers... the beads where isolating the grounds at high frequencies.

[@ChipGuy]

Yes, beads or capacitors, I can't tell. Most likely ferrite beads. These are next to the spring and the big diode. Edit: And yet again it should watch it 'til the end ;)

[@costyytsoc]

bingo, don't know why dave refered to the jumpers as beads

[@RWoody1995]

because thats what they were before the fix

[@stazeII]

Yeah. Those sure look like jumpers.

[@jamesharris5158]

Unfortunately that is often the case. If you put ferrite beads that far into a circuit you might be able to isolate the track from direct connection to the rest of your circuit at high frequencies, but that track will turn into an antenna inside your nicely screened box and then couple into absolutely everything else. Swapping the ferrites for 0 ohm links also makes a good connection between the external ground connection and the entire ground plane on the PCB. Before the modifications the problem would have been common mode RF currents flowing via leakage (capacitive coupling - hence the spooky effect of waving a hand nearby) through some sensitive part of the circuit and ultimately to ground, but afterwards those currents would flow through the 0 ohm links straight to the spring and onto the shielding foil at the back of the case without getting a chance to upset anything else. Even RF likes to take the easiest route to ground.

[@OneBiOzZ]

i love the spikes on the old meter when you plugged it in the the new one

[@voltlog]

the fix might involve some software changes plus some values changed on the passives, adjusting an input filter cutoff freq.. (it does make sense how they changed the ferrite beads and replaced them with 0ohm jumpers to avoid a resonant freq) but like you said Dave, this might be old stock that has been reworked.. the Agilent logo would certainly confirm that.. .anyway nice that they fixed the issue

[@TKomoski]

Track width on the fuse 15:54

[@ElmerFuddGun]

Yep. But why make the current track thinner?

[@kolby4078]

it's on the ma range

[@kolby4078]

might have just done it to save copper

[@sparkplug1018]

Noticed that too, maybe thats part of what was coupling the interference in? But seems like they did it just to save a bit of copper really.

[@jamesharris5158]

You don't save copper that way. The boards are made as a film across the entire surface, then the gaps are etched away in acidic etching fluid so by making the tracks smaller you just use up the etching fluid quicker and have more waste product to process.

[@symik3]

I would like to see it from the view of a Keysight engineer.

[@PlasmaHH]

What often happens is that the issue gets distributed to different teams, each does whatever they can on it, so software team says "yeah, what we could do is enable the filter per default" and the hardware team does some redesign and in the end both would have done the job, and now you have it extra good.

[@SylwerDragon]

Hi Dave. As i see it it looks that it was more changed than we ould see. I don't think it was only change. They changed revision on that board so it mean they changed much more ..maybe they changed something in inner layers as well but you can't see that ofc.

[@uN1Qu3DZ]

@ 10:45, also note the 8-pin SOIC package in the middle has flux residue on top of it. That looks like it has been changed too. And the 0 ohm resistors/jumpers... yeah. The trace on the mA range shouldn't have much influence except maybe for higher creepage distance, i think it's all in the replaced parts.

[@TheWP]

Looks like they replaced a few caps with a yellow tantalums. R2 value (bottom left of sideways image) also changed. L1 (near R2) also has a pad next to it. They widened the track by the silkscreen of the revision number. JP4 removed?

[@mikefinn2101]

I use keysight and seems that have improved over agilent. I am happy with Keysight.

[@ArumesYT]

Just tried it with a Voltcraft VC271. No issues at all. You can buy 7 of those Voltcrafts for the price of a single U1272.

[@williamsquires3070]

Look at the middle left on the PCB - there appears to be some sort of red goop or epoxy resin right above the screw-hole. Also (@ 7:10) follow the screw hole dead North and you'll see a black/dk. gray thing on the original, and on the new one it's silvery. There's also an orange tantalum cap just to the right of it that was black on the old one (rev. 4). Finally, in between those two and lower on the board, there appear to be two SMD inductors that are noticeably bigger on the rev 4 board right near the left edge and NW of the red goop.

[@jabelsjabels]

Dang, I'd love to hear how the engineers arrived to that solution!

[@RabbitHoleLabs]

Have to be careful with the ferrite bead's intrinsic inductance. Sure, they may act resistive at some frequency, but they behave like inductors at DC, which can add all kinds of surprises if not taken into full consideration at a ground plane connection. Used some on an RF transmitter design once to help isolate induction into the SMPS; ended up causing problems even with careful design. NP0 filtering proved more effective with less surprises. Bottom line is, ferrite beads are on-par with RF design - pure black magic. :)

[@shaman_-1089]

Another bead or a resistor is now populated near U17.

[@xZise]

Is it possible in the future to add a note somewhere (for example in the description) what changed when you change a video? It doesn't need to be super precise but at least like "added a manual fix at the end". Because I personally don't want to watch the complete video again if it is mostly the same. I mean I wouldn't have looked closer if I didn't looked in the comments, because I couldn't find an indicator that it wasn't the video I already watched.

[@williamsquires3070]

Never mind the comment about the red goop; it was just a reflection off the bare copper ant the right angle of lighting. Also, the larger thingy was a zener diode, not an SMD inductor after all. Interesting about the 2.4 kilohm resistor they changed out; maybe it has something to do with the LPF being enabled?

[@bernhardroth8034]

BTW: Replacing the ferrite beads will affect calibration. Check your ohms range :) In my meters I replaced them by 0.2 ohms resistors. Calibration on ohms was still off by some percent but this was fine for me.

[@mickleman52]

it would be cool to see a follow u p video on this if you find anymore fixes.

[@LeonidKorobeynikov]

I think that were not inductors but RF supressors. They're likely the same but supressors don't have inductance at high freq, they just convert them to heat in magnetic core.

[@GadgetReviewVideos]

How about C126, can you take a closer look at that and see if that's the same value in both also?

[@Panhead49EL]

Is that the one that went from black to yellow?

[@GadgetReviewVideos]

Yup, but I wasn't able to find the HiRes photos to see the writing close enough to confirm if the value changed or not.

[@bernhardroth8034]

Firmware version on my meters "fixed" and "affected" was both 3.03. @Dave: Are your meters using the same version as well? I remember there was a change in 2.04 to 3.03 (if memory serves me correctly) to enable the LPF by default.

[@dergrunepunkt]

I'm waiting for you to change those surface components and confirm that's the fix!!! :-)

[@d3xdrive]

Does Dave not see the giant track which is changed, which is right under the REV004 / REV006 which he mentioned?

[@EEVblog]

That trace doesn't matter.

[@d3xdrive]

You're the expert. I was thinking it looks suspiciously like it's the same width as the pair of RF beads which they eliminated.

[@bzim]

It's not only the track, on the REV006 board there is also JP4 which can't be seen on the old one. Wondering whether there are other changes under the second board.

[@johnfrancisdoe1563]

Brad Crowley Maybe the rev 4 to rev 6 change was before the EMI issue was spotted, way back in the Agilent days. So the entire fix was done as mods to existing stock and returned devices. Dave spotted 2 component replacement mods and one firmware mod. Maybe they also used firmware changes to firmware controlled electrical values, such as ADC clocking or the state of seemingly unrelated FET signal switches.

[@treadmillrepair754]

The solution is to buy a Fluke 289.

[@OneBiOzZ]

also aside from some stop around one of the leads of the inductor, i see no other board changes that hints to me there was 2 revisions of that PCB ...

[@megadjc192]

From what I see there was a trace shape change on the amps input terminal to the current fuse. so with that change the capacitance of the trace has gone way down. So it looks like the beads with trace shape changes are what fixed it.

[@EEVblog]

I'm pretty sure that trace would not make any difference.

[@Graham_Langley]

+eEEVblog A true engineer would ask why the change instead of dismissing it like that. It also looks like there's some others on the sub-board that's always annoyingly just out of shot.

[@therealjammit]

-I think they replaced the inductors with zero ohm resistors (jumpers).- Edit: I really REALLY need to watch the entire video before posting.

[@DerAlbi]

No its impossible to watch until the end without screaming :-D Not recognizing 0Ohm-resistors was quite a bit to much for my nerves too... I think he was so fixated on finding added beads and stuff that he didnt want to see removing them could help.. I am not sure why they are in there in the first place. Disconnecting a ground like that doesnt seem a good idea.. if you want ground isolation you would need coupled inductors. The fault here seems to be that the shield is not referenced to the input jack but the shield is connected to the (high frequency wise) floating ground of the meter. So any coupling to the shield will throw off your measurement.

[@Mr.Laidukas]

I also for all those long minutes screamed "Dave can't you see those are 0 ohm resistors? Stop calling them as different type beads :) "

[@lasersbee]

Yeah... saw the 0 Ohm resistors that replaced the inductors right away as well.. Dave did originally believe they were another value inductor. Just removed my comment.

[@dangerousdave5076]

Looks like there is also flux residue on those through board joints on the left side (at 18:30)which isn't apparent on the older board. Maybe they replaced those components as well?

[@hakemon]

It looks like U2 has some flux on the new part, maybe that one was replaced with something else, or even a different brand if one brand was found defective?

[@svenk.5308]

What is the reason for the fertit beads in between the grounds anyway? I See that a lot in datasheets, but from my experience this does more harm than good. What is your opinion?

[@mikeissweet]

Sven Kolberg You want to prevent the high frequency switching noise of your digital components from getting on your analog ground. But in this case it appears they created a ground loop (which acts like an antenna) by not providing the noise a short, low impedance path to ground

[@tomshirvo1]

The board looks like a different material maybe. Where the Gold pad on the left next to the screw post. You can see the colour of the board is different. Also the trace to the vertical HRC fuse is smaller.

[@davidwilson3524]

At 6:34 (and 7:50) you can see that there are two jumpers instead of one (JP1 -> JP1/JP4).

[@darrenjacobson7456]

So, you would say you fixed the old meter then? Like, you'd be happy with it as a commercial product kind of fixed?

[@Kosmicray]

Love your channel man!

[@ossiebird0]

I would imagine along with the change of components the new revision has also had a firmware upgrade hence the low pass filter default and other compensating changes, which is also possibly why the old meter did not respond to the new components to the same extent.

[@gblargg]

That microscope displays the zoom level in hex. LOL.

[@KasLewis]

If I may ask then, for all the meters already out in the wild, how will Keysight address those. I ask because I registered my product but never got any info on this, as for firmware updates I don't see any of those either...

[@OneBiOzZ]

One one last thing, on your fix test you were using a square wave where on the test of the new one you were using a sine wave, that might be causing the difference

[@EEVblog]

The square wave is worse.

[@SidneyCritic]

3 black parts got changed with orange parts, 1 on one side 2 on the other. I wonder why the vid was taken down yesterday. EDIT - Dave added a section at the end where he changed some parts.

[@wenjayshieh2244]

Put the new meter component which is taken off into the old one, this can show out which problem did there fix?

[@gatoalfa7]

And possibly a firmware change? Can you update the FW on the old one?

[@markwebcraft]

German Alvarez definitely a firmware change since the LPF is force on in DC amps now

[@GeekIWG]

I was thinking the same.

[@nihonam]

Are there on channel any videos on DMM basics? I still don't understand how autorange function is implemented.

[@OsmosisHD]

All the capacitors seem to be from a different manufacturer. And one SMD Cap and/or ferrit bead? look like a different value and color. near C126 (original black, rev 6 it's yellow) Diode D16&14 seem to be a different size/manufacturer as well Also the ground plain near C35 seems smaller on the new version

[@EEVblog]

My old model is like 5 years old or something. BOM's and suppliers change.

[@OsmosisHD]

Nowhere near skilled as you, rather a rookie. I kinda made a assumption that it could have been noisy/Intermitting caps causing the problem partially

[@randomnight935]

I've contacted Keysight about having the same problem last week but they haven't bothered to respond to email.

[@emmettturner9452]

If that's all there is to it, why did they update the board revision?

[@Graham_Wideman]

Have they replaced BD4 and 5 with plain 0-ohm jumpers? They look very like R88.

[@Graham_Wideman]

Hahaha, looks like Dave spotted the same thing at 17:40.

[@soothcoder]

Probably irrelevant but did you see R2 (top left near electro) is a different value? Doesn't look like re-work.

[@nychendavid]

Dave ,, ,,comparing the two meter at 15:52 ...Just below the fuse. It look like that there is a different at Ampere input. What is that ?

[@Thomas3DG]

Hi I have an ETEK 10709 multimeter that's not working right. I tried to measure ac voltage of a transformer and did something wrong because now the meter shows inaccurate readings. Any guess of what could it be?

[@iexec182]

on the Inputjacks givs a "JP4" link on the new Model, but i don't see any trace on it. is a change on the frontside of the Board?

[@cookzeng6441]

perhaps they replaced some OPAMPs with EMI REJECTION input like OPA2188... ?

[@mxskelly]

There's quite probably some sort of software change too, right?

[@randomnight935]

I think the fault came under this category : literature.cdn.keysight.com/litweb/pdf/U1272A-07A.pdf - The Problem -Interference observed in the DC current measurement below 80MHz environment

[@ZomB1986]

What happened to your previous #987 video? It was suddenly gondor.

[@tusisima]

Dave you should have made some measurements With the beads in place and looked for the resonant frequency. Do you have a network analyzer for characterise the beads?

[@EEVblog]

No I don't. The resonant frequency is not just the bead, it's the whole system at some point(s) in the measurement chain.

[@CoRDSau]

The track under the revision number is vastly different on both of those boards

[@Graham_Langley]

+CoRDS And must have been changed for a good reason. But Dave knows better...

[@onlyrgu]

At 21:00 Multi-meter was tested with the back cover open....that can also decrease EMI Immunity right?

[@ziginox]

I think that was the back half of the case from the newer meter.

[@LycanWitch]

Actually that's the backcover of the newer multimeter, because if you notice, the tested one at 21:00 is propped up on it's tiltstand, something that wouldn't be there without the backcover. Also if you look at 6:00 when we see the new and old backplates side-by-side, the old on left, new on right, if you notice the foil shielding, the older one's foil is quite knackered while the new is smooth as a baby's behind (the one we see at 21:00). I guess you must have really believed Dave and thought the old multimeter is truly spooky, because it's now tilted and floating without a backplate stand.

[@onlyrgu]

correct, without the back cover MM wont stand by it self

[@williamsquires3070]

Yeah, but I don't think Dave is going to get any entanglement... unless he trips over the test lead set! :)

[@jam99]

Dave, everyone knows that red herring live in the sea, not in warrens.

[@1337Shockwav3]

So ... where do I send mine to get a hand soldered fix?

[@Firecul]

A pad added near L1 on the top left of the board also?

[@God-CDXX]

What is the difference between a jumper and a 0 ohm resistor I have seen these in threw hole as well

[@cmssniper]

Well there are three components that changed (other manufacturer? Other value)?

Any plans for free replacements of old, flawed generation, Keysight? :-)

[@robin4670]

How about peeling that foil of the screen of that signal generator xD

[@lasersbee]

What happened to the same video that was posted yesterday and disappeared ??

[@Kilohercas]

took me 10s to spot difference, capacitor added in one spot, like 0603 or 0805 near SOIC chip

[@EEVblog]

There are many SOIC chips, be more specific. If you mean the tantalums, that's likely a normal BOM change.

[@Kilohercas]

near comunication led on the right

[@tomvleeuwen]

Maybe there is some soft?are change as well? Is it possible to view the software version in a service menu of some kind?

[@sepertude]

THey could fix that beeper sound at the same time to be faster as well as fix capacitance mode so that its more accurate for uF.

[@steveone]

Didnt Keysight take the old meters back ?

[@mortensentim511]

Has C125 on the front of the board changed value?

[@alphanimal]

I would guess a low pass filter is always a good thing when you try to measure DC, as 0 Hz is is a pretty low frequency :)

[@RussTanner]

The track width on the fuse looks a lot wider on the new board.

[@guser436]

Weird trick.. I cross my eyes until the two objects align and then the differences just pop out and "shimmer". I ace those spot the difference games :) Only problem with this was the resistor colours were different so it caused a bit of shimmer.

[@guser436]

"a complex system thing" ;) Nice one

[@dipi71]

I wonder how high Dave's midichlorian count is.

[@ncrdisabled]

I was in the NAVY for 7 years on submarines and noise is a very bad thing it can get the sub sunk. We used only top end meters like fluke . This was back in the late 80s. Now the weird part back then when we ordered a meter we got a few radio shack meters . For some reason they did not pick up interference like the fluke. So the radio shack meters we dispersing more than the fluke . And yes I have both meters. Hell the NAVY can afford a few thousand meters as the probably get then taken on all the subs.. As long as you take care of the battery the meters still work better than some of the fluke meters today. Oh by the way the fluke cost 15739.00 and the radio shack 14277.00 Why so high they have to be certified to go on a submarine's hell a ball valve cost 10k

[@krishna1408]

Why do the two meters show such different temperatures?

[@babuvio]

21:18 whuuu, use the force Luke! :))

[@DAVIDGREGORYKERR]

That might be using LASER soldering for very accurate soldering.

[@georgegherghinescu]

What the heck does beulah mean? I hear Dave using it from time to time.

[@819jt]

Ferris Bueller's Day Off. A teacher calls for Ferris during roll call.

[@timoliver2211]

lets see if this one gets taken down...

[@jjoster]

I wondered what happened to this video. It disappeared for awhile.

[@simmydsimmyd]

craftycoder well, dave probably took down the previous video. This one is quite a bit different, for example he correctly identifies the BD4/5 parts as being resistors instead of ferrite beads.

[@Greeegification]

The original didn't have the part at the end, where dave attempts to 'fix' the original.

[@balaclava351]

What happened to your Orange Pi cluster project?

[@briantech4037]

What study program did you follow?

[@ottoreuter6279]

So Dave is the last Jedi then?

[@FLyyyT_]

when you stop to ask us if we see anything, it sorta feels like a kids show like Dora the explorer

[@wolfgangbeginners-mind2853]

Holly crap Bat Man Counterfeit Ferrite's!

[@tomshirvo1]

The temperatures are different between the two

[@tomshirvo1]

Maybe they put another ground plain in?

[@crocellian2972]

And the predictable response. No problem. At this point we know you are a fanboy. No one cares. Just keep quality content coming and we can understand why you protect your gravy train. Seriously, just keep it coming.

[@lillydoye7418]

Thicker trace from 440ma fuse.

[@ahmetmetinuzun]

It's "Bueller" not "Beulah" :)

[@EEVblog]

That's what she said.

[@martinda7446]

Agilent is a much nicer name than Keysight.

[@jmcorp8021]

Watching on a phone so can't see to well. But it looks to me like they also switched to tantalum caps in a couple places

[@EEVblog]

Standard practice to mix caps in a BOM across different builds.

[@jmcorp8021]

I thought I read that tantalum caps can help reduce stray inductance at high frequency or something.

[@RandyLott]

Jesse Motes The tan colored caps and black caps are both tantalum. Probably a vendor change.

[@angusdorbie1693]

C126 changed.

[@shakaibsafvi97]

pretty sure they also tweaked the software.... I see the programming connector also added....

[@joechurchill8055]

Shakaib Safvi removed it

[@shakaibsafvi97]

yup... my bad... removed....