Hi welcome to the Eev blog an Electronics Engineering Video blog of interest to anyone involved in electronics design. I'm your host Dave Jones Hi you remember a couple of months back I reviewed these new agilant Scopes and how groovy I thought they were now a couple of days ago. uh, a person by the name of Rufus on the Eev blog Forum noticed that his one when it was turned off was still a little bit warm and he measured the standby power consumption and to his surprise and to mine it wasn't zero. He measured about 6 wats or something like that standby power consumption.

Now this thing has is supposed to have listen to it clunk a big real Main's power switch. it's got the mechanical Rod which goes all the way back to the Main's power board at the back and well I was as shocked as anyone. so let's investigate it. so let's measure the power consumption of this thing.

I've got the new Adelin Infin Vision 2000 series scope here I've got my Gosen Metr hit Energy Multimeter. Now you've seen this in a previous blog. It's really cool. It allows me to uh, measure uh Power and apparent power and a whole bunch of other stuff and log uh Power not only for the mains, but for other stuff.

So I've actually got the uh Mains uh, the mains cord here which goes to the oscilloscope I've broken it out and it goes into the multimeter so we can measure P and as you can see here, it's actually acquiring data. There's nothing connected, but it's it's working away there and it's drawing about 54.3 wats and that's at 247 volts which is the Australian Main's voltage. At least it here is at least that's what it is at my place here in Sydney at about 256 odd milliamps. Not a problem.

And if we go over here, we can also measure the Uh apparent power as well, which is about 63.3 Now the power factor is about 86 on that, so let's see if it draws anything. when you switch it off t Look at it. There it is. it's still drawing 6.5 watts.

Are you kidding me? God You fly to the damn moon on 6.5 Watts Unbelievable. And the apparent power? Because the Uh power factor is much lower. Now it's 0.32 The apparent power's gone up to 20.5 but un un believable. 6.5 wats.

Shame Agilant Shame Okay, now here's the board. I've taken it apart and as you can see, it's got this long Uh mechanical, very traditional mechanical lever arm. Going back here to the Main's input power supply. there's the I input connector.

there's the input choke and it goes through to the Um Lineage Power brand. uh, switch mode power supply which looks like a really high quality one, but apart from the standby power consumption apparently. Um, now when I did the review of this thing I Very. I I Just looked at that curs, you know I just gave that a cursory glance I hadn't taken the board out and I thought great.

It looks like a, you know, a proper Main's mechanical switch. it's over here. On the Main's isolated side, you can see the uh ground plane starts from here, uh, backwards and this side here doesn't have the ground plane on it so it's totally separate and as you can see on the back here, it's um, totally isolated. So I thought Beauty: it's on that side of the board so normally if that you know you would think Common Sense would tell you that is switching the Main's input but it's not I Thought this was a little bit wimpy at the time, but I you know I didn't really give it a second thought I Thought: Beauty: a proper Main's power switch.

But look, it's if you actually take a look at uh, the board here, you'll notice that the input tracks for the line and neutral go straight through to the choke and then they go straight through to the Um to the input connector of the switch mode power supply. It doesn't go to that switch at all and if you look on the back, you can confirm that. in fact, take a look at that solder and it's not the world's uh, best. They haven't uh cleaned that at all.

but as you can see, it does not connect through at all now. Unfortunately I can't see where those tracks go because it's a four layer board and if I hold it up to the light I Can't actually see the traces going off. so they've got to go around there somewhere. But thankfully you can use your meter here and you can actually measure it.

so let's try that. I've discovered that the center of this goes to this pin over here like this. As you can see, it's connected straight through. so the center of that main switch is connected through to this pin here and there's that wire there that uh, pin number one or whatever it is and as you can see, it goes straight through to this separate connector.

I'm not sure what this one is, it's probably some sort of monitoring output or something or monitoring input, but Uh goes through to the control side and this connector over here is all the output voltages. So there you go. What do you know? The new Agilant Infin Vision scopes have a 6 and 1/2 watt standby power consumption. You can fly to the moon on that.

It's incredible. What is this? The 1970s? that's you know. 6 and 1/2 watt figure is something that you'd expect from a VCR straight out of the 70s or the 80s. It's incredible.

Not in a modern, properly designed bit of instrumentation like this. I Certainly don't ex expect 6 and 1/2 watts and it's not acceptable 65 Watts Maybe not a problem. Okay, now they've gone to all the trouble to engineer this properly. for a Mains a proper Mains input switch, they've got the isolated Mains section.

They've got the um, the traditional mechanical arm going back. Beautiful. Lovely. But then they put it into a logic level switch and they decided to switch the output off and on logic level on the switch mode power supply.

Why? What's the advantage of it? Does it increase the meantime between fire of the power supply because it's already warmed up and you stop those huge inrush currents when you switch them off and on? I don't know I can guess at it it adelent what's going on here. let us know because this is just unacceptable. Really? Yeah.