In this bag is a piece of testing equipment so sophisticated and so
expensive that for its cost I could literally hire a full-time butler. It
has an arbitrary waveform generator,
power analysis options, automotive protocol. Okay, to explain what the crap
it is, we've got Lucas from the lab who's using it for our power supply
testing processes and who can hopefully explain a little bit of what we're about
to look at. All I know is that this is the Roden Schwarz MX058. 2 GHz, uh,
eight analog channels, uh, 16 digital channels, good oscilloscope. The funny
part is, if you break it down, an oscilloscope doesn't really do that
much. Just like your multimeter at home, it measures voltage using probes. But
what makes it special is the fact that it can show that voltage and changes in
voltage over time. With this particular one being able to handle, what is it?
4.5 million signals per second. That's a lot, right? That's a lot. Yeah.
Waveforms. First, I want to have a look at the accessories. Sure. Yeah. And I'll
try not to break anything. Okay. That's why he's here. Why don't you explain
some of these probes to us? Sure. Yeah. So, all it comes with eight analog
probes. These ones here like I believe they're 10 to one probes. Would you
abbreviate that like an AL for the
analog ones as opposed to like digi? You might say digi probes or like anal
probes? No.
So what do we use these ones for? So this will just be your like general
probes for viewing any any waveform really. Um right but it gets the full
you know bandwidth and we have digital probes as well but those will just be one or zero. This gets you know whatever
voltages. Now this is pretty overkill for what we use it for. Is that correct?
Yeah. Yeah. This is yeah is a lot for what we do. We just measure um the four
or five rails on a power supply um and some inputs to it. Conceivably. Could we
use this to look at something like memory signaling or is that too fast?
That's probably too fast. There's fancier oscilloscopes for that. But we have used this for some LT projects like
the Soviet keyboard. Um Oh, when we were trying to reverse engineer it. Yeah.
Yeah. Yeah. RL and I worked on that pretty uh closely and like worked to
Yeah. see what all the signals were saying and decode it. So that was pretty cool. That's super cool. There's a
little more to these than just the probes themselves. I noticed these little color coding rings and whatever
it is that you're putting back in that baggie. Yeah. Yeah. So, the color coding
is just, you know, helpful for color coding.
Um, this is a typical, you know, flying lead ground cable. So, obviously, you
need to complete the circuit. Yeah. Um, it's got a little, um, wrench in here
for controlling the capacitance of the cables. Why do I want to change the
capacitance of my probe? To compensate for the inductance of the probe. So,
because it's a wire, you know, all wires are have capacitance and inductance. Oh,
yeah. Yeah, it's hard to explain, but you know, square waveform, it's uh you
want to be exactly square, but any inductance or capacitance will skew
that. So, uh cuz it takes time for voltage to change and rise. Um so, you
can um compensate for that by adjusting the capacitance typically.
Is that it for the accessories? Basically, it's just got lots of probes
in it. It's got some vasa mounts, too. Oh, okay. So, you can mount it on a
monitor. Yeah, you can like you can get an arm for your rack, too, to hang it
off. Okay, cool. And then other than that, uh, manual, power cord. Let's have
a look at the scope itself. And maybe you can show us some of the wizardry you
do with it. Let's see how much of this I can figure out on my own. Oh, fuse,
power, on, off switch. I got that far.
Whoa. It has an SSD, I guess. I've never
opened that. Remove. I don't know.
What? What? What are you worried about? Never tried it. Well, it's first time
for everything. Oh, cool. It's just an M.2 drive. I want to open
it. What M.2 drive would Roden Schwarz
trust for their oscilloscope. Oh, look at that. It's our many times sponsor,
Kioxia. Nice. It's actually more important than you would think to choose
a high quality drive for an application like this cuz I would think it would just be constantly overwriting or I
guess a lot of it would actually go straight to RAM in memory probably.
Yeah. and then only be output to the SSD under Yeah, this is only 256 gigs. Yeah,
one of their advertising features is they have a ton of memory so they can store all those waveforms um for long
history and long sample rate or fast sample rate and we have extra options on
ours that expands the memory. Is that correct? Yeah. Yeah, I believe. Yeah. Uh
all right. So Oh, I forget how this goes
together now. H that may have been a
tactical error. There are way faster oscilloscopes. I was talking to the the
guy we know at Ro Sports. He's like, "Yeah, it's a good uh you know, standard
lab oscilloscope, but there's definitely faster ones and more expensive ones. You
know, they go into like like dozens of gigahertz and faster for communications
and all that stuff." And do we have any idea what something like that would cost? Uh hundreds of thousands probably.
Cool. Very uh very specialized. So this is like really fancy to us. And then
we've got people who work at, you know, NASA or whatever that are like a Yeah.
Yeah. Cute. Okay, let's try and put this SSD back in.
Uh-oh. I know, Lucas. I'm trying to fix it. Okay, man. You seem stressed.
Hopefully, it works. It Look, it just says do not remove during operation.
Okay, it doesn't say don't. Did you think it just said do not remove? Did you not? I didn't read it. I didn't read
it. All right, cool. What else are we looking at here? Well, obviously we've
got rubber feet that allow it to be in I don't know, other orientations. They go
all the way back. We've got a couple of 120. Jeez, this thing needs a lot of
cooling. Is that just the processing needed for this level of sampling or
what? It's doing a lot of compute. Um, it does dissipate a little bit of power
inside as well, depending on what you're uh like probing. Oh, I see. Like not on
purpose. Obviously, they would love to not take any power, but you know, in measuring, you have to take in a little
bit of current or whatever. So, that makes sense. And then, oh, here we go.
So trigger in that'll be if you want to have an external trigger to capture
something specific like if you can't manage it in the software right and you
want to capture something or if it's like something that happens unpredictably or it's too fast for you
to like manually go oh yeah I want to capture now it's all too fast to manually capture now but you know it'll
happen automatically and then gen one and gen two never use those but I believe those are just from the function
generator the arbitrary waveform ref out 10 MHz that's also the function
generator this one probably calibrate off of I'm not sure out is for when you
trigger on something like one of the waveforms, then you can set a pulse up there. Got it. And a USB device. I'm not
sure what that one's for. Well, it's a target port, so I guess if we wanted to
hook it up to the computer via USB, that's possible. Meanwhile, on the other
side, we can connect USB devices to it. Do we connect it to the network? I guess
for Yeah, we do. Yeah. For all of our control and um for viewing. And then do
you use the HDMI and DisplayPort out or do you just use the built-in display? Uh
no, you can do it all over LAN uh like for the you can display from the
computer. So you use LAN both for remote control of the unit and to output to a
display. Uh yeah. Yeah, it's just for the same thing. But uh actually I was
looking on the website today and they have headless units of this as well. So
it's basically the exact same thing but without the screen. You can just use the
display out or the land. Okay. But this one has a screen. This one does have a
screen. Okay. Do you use the screen at all or is it just kind of superfluous?
Yeah, I mostly use the screen. Uh, use the LAN just for monitoring if I'm, you
know, at my other desk. Got it. So, there's your eight analogs and then I
guess each of these does eight digital channels. Yes, that's correct. Yeah. Oh
my god. Why does it have so many USB ports on it? We use it to save waveforms
uh to to USB if you want. Um, or you can use it for some power. Can you run us
through some of these controls here? Yeah, so a lot of them are multi-use and
they'll do different things depending on the screen. And it's a big touch screen, so you can do a lot with that. Um, but
you can control each of the eight channels plus any logic ones and math
ones. Control the vertical scale and position to move waveforms up and down.
Makes it a little easier to see what you're looking at, I guess. Yeah, I guess if you want to change view or see
a certain section of something. Um, you have horizontal controls for horizontal
scale or position. Why don't we plug it into something and then maybe you can
show us this in real time then? Yeah. Okay. Yeah, let's do that. When it comes
to this kind of stuff, they just kind of say, "Here's the one I want." And I go,
"Is it a good one?" and they say, "Yep.
Do you have like a power supply? Is that what we're going to look at or like what are we going to look at?" Oh, yeah.
Well, do you want to start the um screen recording? Oh, yeah. Um and tell you
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any discount they may already have. Hey, it's booted up. Now what? I had a little
demo prepared. Ooh, a demo. Demolition. Uh, no. Demonstration.
Okay, so we got a little SBC of some sort. What's that? Like an ESP32 I set
up here and I've just programmed it to uh send a little command here. Okay. So,
one of the neat things about this oscilloscope is that um it can do a lot
of decoding of digital signals. Oh, so we tell it which pins to monitor out of
our eight channels here. Uh yes. Yeah. Sorry. So, I plugged in the digital.
This is again this is the thing about engineering people. They just start doing stuff assuming that everyone
around them is like following along. Yes. Carry on. So, I've plugged in the
digital probe here. Uh channel zero and one. Um, and I can go in here and go
into the apps and protocol and to SPI.
So, I'm comm communicating over SPI. Okay. And set this S clock on channel
one, I believe. So, this is the kind of thing where if you didn't know how this
was outputting, it would be a bunch of trial and error to figure out how to
even monitor it like if you trying to reverse engineer something. Yeah. So, a
lot of this like a lot of the setup it's done while you're testing. You know,
some of these parameters, but you also have to just kind of find some of this.
I have to also change the trigger so that it triggers onto that one. So,
there's plenty of nice triggers in here, but we're just triggering off of a digital signal. Okay. And the edge. So,
whenever it rises, then it will capture a waveform. And that's how we can see
this here. Okay. And what are we looking at here? So, here it's got automatic
decoding of this. So, we just capture a single waveform. You can just capture a
single one instead of run stop as it was before capturing all the latest ones.
Mhm. Um, you can see and it's just automatically decoding the message I was
sending. Oh. Oh, Leila. Oh, look at that. It says PSU circuit. Yes. Which is
the channel where you guys can see all of the power supply testing that Lucas
does. What are the chances? A more practical case would be you have your
PCB or some other device. Um, did you
just make this be a keyboard essentially? I guess in a really slow
way, yes, we can make this a pre keyboard. Yeah. Could Could you just
type into Could it could it detect that as well if you set up your triggers so
that it Yeah. And like decoding of whatever um communication standard
you're using. Yeah. It's got a lot of different ones you can do like canvas and other things for more like
automotive. Yeah. Exactly. Okay. That's and more complicated stuff. So this is
like a really simple example, but if you want to see if your sensor was actually giving back the proper values, there's
maybe a breakdown in your lines somewhere, you could monitor that and
see, oh yeah, it is sending everything back correctly, just we're losing it or
we're decoding it incorrectly on our own. Oh, that's super cool for
diagnostics then. Yeah, exactly. And this is only using two of the 16
channels. So if you had like a hugely parallel bus, then you can decode them
all. So like this would be awful to, you know, count on your own and see one 0 01
kind of thing. Right. Right. Right. Right. Cuz this is each of our characters here. Yeah. Yeah. It's also a
touch screen. Right. Yep. You mentioned that. So we're back to our first signal
here. This is a capital P. On the bottom, we have just our our clock that
tells us when to sample a zero or one. And then on the top, we've got our
signal. So, what we're looking at here then is our first clock telling us to
sample. That's a zero. Then on our second sampling point, that's a one. On
our third, it's a zero. On our fourth, it's a one. And for the last four, it's
all zeros. So, this one would be 0 1 0 1
0 0 0. And that's a capital P and ASKI then. Yep. So, then this would be how
you guys reverse engineered that keyboard then. Yeah. A lot of that you have hook it up and see like when things
are high and low. um and trying to figure out what all those random pins
were cuz there were a couple we weren't even sure what they were. And I think that's how we found out that one of the
decoding um like uh chips was broken and
it was just sending all zeros like so it's sending the same kind of bits but
then the second four bits was always zero for all of them right that I
remember that the first half of each bite was working and then the second
half of each bite was broken all zero because the chip was dead and so we
could see that. All right, enough of the high school electronics class demo. Let's get this hooked up to a power
supply and show you guys how we actually use it. So, these probes are all just
like wired into our testing equipment. Yeah. Sorry, it's not uh you can't see
it, but these run into the test chamber. Okay. Um connected to connection board,
which is connected to the power supply here. I can show you guys what he's got
in there. Here's our second
one. So, all his probes are going into
this and monitoring our various voltages
from the power supply. And what's really cool is Lucas painstakingly soldered our
measuring points to the bottom of our PCB so that we don't have to worry about
this cable length affecting our measurements. What are we looking at?
So, another great part about this oscilloscope is the um the
automatability of it. So, we're able to do a lot of our tests um without, you
know, actually touching a lot of it. We just have to set up all the programming
beforehand and then as it's testing it'll send all the commands to properly
configure it um and test without us
having to stand here. But we really like standing here, don't we? We love it.
Yeah. And hopefully this will work. I
don't know. Somebody removed the SSD. So
what what it's probably fine. Oh, should
we talk about some of the things that ours is optioned with? Oh, sure. Yeah.
It has a one gigabit GPTS memory extension. Uh yeah.
So that's one gigap points memory extension. So that's another one that's
lets you capture a lot more waveforms and it's a lot of memory like we said
before. Oh, for longer waveforms. Yeah. Okay. And more of the same. So if you're
measuring a really like we're measuring that thing of saying PSU circuit that
was repeating like once a second or whatever, right? And so that allows to
capture like multiple samples of it and you could average them or see if there's
any like aberrations, right? So for diagnosis of say for example like like
an an erratic error that only shows up once in a while that could be really
useful then. Yeah, exactly. This is great for that and a lot of oscilloscope is used for that where um like 99% of
your signals will be exact right waveform but you want to capture the one
or two that is that isn't the intermittent problem. They call them
like runs or whatever. Yeah. or it's like maybe it stayed high for too long
or there's some kind of glitch. You know, there's a lot of people that find
that word pretty offensive, right?
This is our brown out test that we do for PSU circuits. Um, we basically just
turn off the input power to the power supply for a very short period and see
if the power supply survives. So, we can see here it's doing a lot of stuff on
its own. It basically just configured itself so that it's got all the right
measurements set up and it'll capture this waveform afterwards. So, okay,
there we see here. So, what we're looking at here then is AC power going
doing its thing, right? And then we're looking at Whoopsy Doodles. No AC power,
but our 12vt on the power supply was
uninterrupted. And what's our purple one here? Uh, yes, 3.3 volt. 3.3 volt.
There's 5 volt and the power good signal. So that's the one from the power
supply that's telling the motherboard and the computer like power is still
good. I can still guarantee that we have the right output voltages. What if we
gave it a longer brown out then? Exactly. We'll proceed through this.
It'll go through and it saves the waveforms. This is how we save them back
to a file and we can later graph those and create large graphics from them. And
eventually that power good signal is going to be like no. Yes. Yeah.
Hopefully we'll capture this. You know, it's always a lottery. We're doing it live. So we can see here it's in blue so
it's hard but you see it cut it cut out here and went low for a while and came
back up. So for that short period the power supply was saying you know I can't
guarantee 12 volts output and if we have a good motherboard that behaves the way
that it should it should say hey I don't have good power that'll shut down the
computer. Yeah. So at that point it's like it's nice that it's kept the other
voltages high but it's already turning off your computer because presumably
that's enough for it to and this is exactly the behavior we'd want. We would
want it to say, "Hey, the power's not good." before there's a major
interruption to the voltage it's delivering to our components because
otherwise, I mean, this is a very very small surge, but if we had a bigger
surge, that could be an issue, right? Surge and just reliable things. So, it
may be trying to save memory to uh like to, you know, storage or something and
it might corrupt that or have some unpredictable effects. We'll see if
we'll get one where it just fully drops out. We can see there's already little
dips in the voltage, right? Oh, okay.
So, it really didn't like 25 milliseconds of power being gone. About
22 milliseconds or 24. I'm not sure exactly which one, but yeah, you can see
it blips in the 12 volts and it just completely drops out, but the power good
line dropped before that. Now, a lot of our testing is focused on the ATX
specification and making sure that power supplies adhere to it. Have you
encountered any that do not meet the ATX specification? Yeah, a lot of the power
supplies will not quite meet in some places like oh maybe it's in the dynamic
tests it doesn't quite meet the voltage regulations or one of the timings off.
Um but a lot of them it's not a huge deal and it could be a part of our how
our setup test setup is different from the ATX. Got it. So is that why we don't
necessarily publish every result that we record right now cuz we're kind of
waiting to make sure that it's on the up and up that we're in we're confident in
it and we don't make any claims of like full ATX certification with that. So um
yeah it's just you know indicative and one of the things that we really care
about a lot though and that we are publishing now is any failures in safety
mechanisms that are built into power supplies because you know I don't think
that most people are going to look at a slight blip in the 12vt rail when they
have a 15 millisecond power outage and go I'm not going to buy that power
supply but we've had some that will just outright fail under an overcurren
scenario where we are drawing more power than the power supply expects. Yeah.
Which we don't expect it to be able to provide more power than it's rated for,
but we do expect it not to catastrophically die. And we have had a
couple die during this test where we're just shutting it off for brief periods
of time. Can't explain those ones, but cuz it's not super ownorous, but uh
yeah, like this is something that a power supply should be able to handle.
Yeah, we do it a lot of times and we do it at 0 degrees, 20°, and 40°, but it
should be, you know, fairly fairly survivable, I think. Do you have any
more tests for us to look at? Yeah, we also have the timing test that we use the oscilloscope for. And I think
that's, you know, more interesting than the brown one. When you say timing, what
what do we want to know? What how does the timing matter of a power supply? I
mean, it's DC. There's no signaling. There's no waveforms even. There is
signaling. So, there's a couple signal channels on that like the power good and
the power on, but there's specific time they have for how long it takes for the
voltage to rise to a certain level or to drop or delays between those. So this
configures the oscilloscope for a turn on waveform which we get here. So do we
want to go from 0 to 12 volts really quickly or do we want it to be slow?
What do we want? I believe there is a maximum time I can I don't know the exact timing now but the maximum time
for 0 to 90% of the voltage spec. So of
12 volts 5 volts and 3.3 volts. Got it. And then there is also a spec for the
delay between them going high and the um power good signal going high. it'll save
this waveform and then reconfigure so that it can um save the turn off
waveform which is also important in for like brownout and stuff. So this one the
first one will be basically just flat lines once it's saved because there's
very little load on the power supply. Yeah. Um but future ones um do actually
drop and you can see them there. It takes about two days to fully test a
power supply. And if we have a failure, we always obtain another unit and fully
test that additional unit to see if it was just a one-off bad unit. What's
interesting to me though is so far we haven't had a lot of bad units that
weren't just a bad power supply. All but I believe one of the ones that have
failed, the second unit has failed as well. Yeah, there's one or two that the
first one failed and the second one survived, but so far it's been Yeah, they both die and often run on similar
tests. So, here's another one. So, this is trying to turn on with a load and
obviously it failed that. Um, a lot of power supplies do even though I think
it's in the spec, the ATX spec that have to be able to turn on with a load. Um,
they just can't because you know it's not typical. I guess your GPU isn't
pulling power before it has, you know, a voltage. We can also use this for ripple
testing of a power supply. Is that correct? Yes. Yeah, we do that same. Can
you explain like on five why ripple matters? Because a perfect DC voltage
output like 12 volts, it'll be perfectly flat, but because we're in the real
world, there's capacitance, inductance, lows, everything else, it's not going to
be flat. Um, there's some ripple to that. We can see that. We can see it.
Little little bit of noise in there in the line there. Why does excessive ripple matter? because the components
later in your like in your computer are expecting a really constant um supply
and something they can predict and you know operate um consistently on and they
further regulated down to other voltages like CPU like 1.2 volts and stuff but
even those regulators want a really consistent input voltage. Got it. So it
just helps with general stability and reliability. Could it improve longevity
to have low ripple? Uh yeah it'll put less load on the capacitors over time.
Put less energy in and out of them. Here I have another way from where this one actually went down. So this is another
one. So during the timing test, we can measure how long it is between the power
like it turning off and the um power supply shutting down and how long it
takes for each of the voltages to drop. This one's at like a 10% or 20% load. So
this is the whole thing where you hit the power switch on something and it takes a minute for it to like for the
LEDs to you know Yeah, exactly. So that' be like for a small load and you'll see
with like even larger loads, it's almost instantaneous the the voltage drops. Oh,
one more thing. Actually, we've alluded to it, but I don't think we've explicitly said what one of these
run-of-the-mill benchtop oscilloscopes is worth. It's a bit of a range
depending on options, but it's about 20K to 50K US,
right? Yeah. Go and buy one now. Yeah.
Use our affiliate code. Lucas from the
lab, everyone. And the Roden Sports MX05
series. Subscribe to ShortCircuit.
and power supply circuit.