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 Back in October last year quite a while ago I showed the GSM mobile flone phone fluke video thing where if you put your GSM mobile phone next to a fluke 87 5 multimeter you could kill it. You could Breck the thing erase the firmware inside I wasn't able to do it, but it did happen to someone and fluke, uh said they'd look into it, take it seriously and fix it and I haven't really heard anything out of them for well basically since then uh and on just the other. Blog the other week I sort of said hey, fluke, what's happening They got back to me straight away and they said he don't worry, we have been working on it and we have fixed it.

In fact, not only have they fixed it, they've given me as a world exclusive basically. uh, they've given me a pre-production prototype unit that actually fixes the problem. Fantastic! I Can't believe a big company like Fluke would actually. uh, let me show and I'm going to take it apart and everything.

show a pre-production unit. Fantastic. It shows. they're serious.

You will actually be able to buy this uh, fixed fluke 875 in a couple of months time. I believe it is. Don't quote me on that, but um, yeah they will. It's not going to change.

it's going to be exactly the same fluk 875 except it's got a new revision PCB in here which fixes the GSM mobile phone issue. Fantastic! Let's take a look at it. and once I get them open. Here are the two units side by side.

On the right hand side here we've got the new Revision 11 unit and uh, the Prototype one and on the left we have my old Revision 9 unit I Know some people have the revision 10 PCB uh unit, but mine's up quite. You know, it's like five or 6 years old. at least this uh meter that I've got here, but um, yeah, they're identical. You can see a color difference in the LCD so they've obviously, uh, changed the type of LC Well, the they've changed the actual LCD they've used slightly.

As you'd expect. Um, you know the amount of time between these two units. They've probably refined quite a few things, but there really is essentially no difference at all. And if we take the top unit off like this I've already unscrewed SC it Then we can get straight down to the board and compare the differences.

We'll take a quick look at the backside here, and as you can see, the shielding is absolutely identical between the two units. No difference at all. The tracking seems to be exactly the same. how all the speaker and everything works is exactly the same.

and if we take off the shields which have little Clips on them, then we'll be able to see that there is no difference at all on the bottom of the boards. But the um, the actual type of mask solder mask used on this new revision PCB is actually different. It's uh, less. it's more, um, opaque.

You can't really, uh, see through it like the trucks really don't stand out like they do on the old one, but as you can see, it is actually an identical Uh layout. I Can see very few differences at all in the actual tracking. In fact. I I think there's I think there's essentially none.

actually. I think the uh top and bottom as we'll see on the top side. Uh, there's a couple of little extra vs up the top here. but um, really, the two boards are as identical as you can possibly get them as you can see on the new board.

here there it is Rev 11 down there and it's a it's got a a qualification sticker on it I'm not actually sure what that is, but this is a pre-production unit. hasn't actually gone into production yet. but I expect it will be absolutely identical to the one you'll be able to buy in a couple of months time. And my old board over here.

As you can see, it's a rev9. It's a REV 9 board. Um, so it's reasonbly old. As I said, there is a REV 10 out there.

Now let's take a look at the differences. Are there any effectively? Uh. B Basically nothing on the bottom side. I've taken a reasonably careful look at them and there really is nothing to speak of in the input circuitry.

In in that uh circuitry in the middle. There, it's only around the processor up the top as you'd expect, cuz that's where we had our RF sensitivity problem. I Forgot to mention one item here. This uh, Tanum cap here is actually been moved up on this new one as you can see and there's two unpopulated, new, unpopulated Footprints there.

So that is a minor change on the new board to that middle circuitry. But up here on the top as you'll see, there are quite a few uh differences. Let's play Spot The Difference Now I can see one extra capacitor there that's not over here like that. It's to do with that resistor there.

So maybe that's some sort of, uh, low pass, extra, uh, low pass filtering or uh, something like that. Perhaps I can see an extra resistor added here? That's not over here. Now they've changed this. the footprint of this device.

Um, I Don't think that's of any significance. It's probably just that this one's more readily available or something, perhaps. But apart from that, if you're a member from the GSM video, this left hand side of the board here was the one that was sensitive. So uh, really, they've only added, um, the two extra components there.

All of the main differences I Don't see any differences around here at all. No differences there. but all of the difference. Um, the main difference seems to be over here.

They've got all these extra uh passives. There's a couple extra resistors and a couple of extra capacitors up here like this now. Um, whereas before, this is the previous board and it had some unpopulated uh pads there. so there were supposed to be components there, but they left them off for I don't know.

Whatever reason you can, uh, think of. it would require fluke to actually tell us that. but um, they've actually changed the layout slightly. and there's definitely, um, you know, four or five extra components there.

Now this is the JTAG uh interface for the processor and I think uh. back at the time of the GSM video, somebody guessed that it may have had something to do with uh, you know, locking up the J tag and reprogramming and re flashing the unit accidentally or something like that. and that's probably the most viable um. explanation or something like that.

but I can't see that there's any change to that. I Can't see that those components are actually related to the JTAG interface at all because the traces for these JTAG pins just go straight onto the processor. Um, so really, you know I I I Can't see any difference in the tracking there at all. They seem to have done all the tracking on the inner layers.

and um, if you have a look at the uh bottom, uh of the bottom side of the board as well. Um, the the tracking is pretty much identical on on the bottom sides of the board as well. They've just added in the extra components, so they've done well to keep the existing layout absolutely, um, spot on and just add the extra components in there and possibly Trace them on the internal layers. So there you go.

That's the difference. They've added a couple of extra parts. It's exactly the same. um MSP 430 processor.

There's no real difference there. Uh, and if you want to see the highres photos, I'll actually link those. They're up on my flicker account, so you can. Actually, if you're really Keen you can go in there and have a look at the highres photos yourself and see the differences.

But really, they've just added a few extra components and uh, that's about it. There's just a closeup view of the markings on the new Rev 11 board they still got copyright 2002 Fluke and my older board. As you can see, uh, there it is, the Red 9 and uh, really, there's Apart from that, there's very few differences on the top, um side here. here's the actual uh, new serial number sticker.

Now, curiously, they're actually calling it a REV X So you know, a REV 10, but the actual PCB is Rev 11. And if you're curious about what's under the raid switch, then, well, it hasn't changed at all. and that includes the two, um, uh, the actual contacts themselves. They're um, identical.

They haven't changed the build there at all. Have they taken the opportunity to uh, tweak the design in any other way? No. Well, inside is exactly the same. They still use the uh, you know the Crusty old 9volt battery snap which uh, the wiring actually goes under the under the main fuse like that and they haven't added a fuse compartment access.

You still have to undo the screws of the case to get it. The fuses those little Annoying uh quirks of the 8 s that, uh, if they fix those they would, you know it would be the perfect uh meter. almost. But um, they have change those things on the fluke 28 Series 2.

So which is basically a fluke 875 in a new ruggedized redesign package which uses Uh u a nice ablea battery compartment with fuse access. But yeah, they haven't really tweaked the design at all. Now they have actually changed the back uh tooling of the case here and they have actually taken off the TUV mark. This is the old my old meter and this is the new one.

There's now no TUV Mark uh there. I'm not sure what the deal is and now it says made in USA of us and non us Parts Ah, why did you have to put that to be politically correct just to meet the letter of the law? Crazy I Don't know it's made in the US it's made in the US Everyone knows all the parts come from Bloody China Jeez. and curiously, they've taken off the patents as well. What have the patents expired? I Don't know and it still has this ridiculous thing.

refer to manual for additional capabilities. Why don't you just print the capabilities on there for goodness sake. And there's absolutely no differences on the internal molding of the case or the piso transducer. There absolutely nothing identical and you can probably see the slightly Greener tinge here on the new uh display.

It's got got that uh, more of that old school green LCD tinge to it and dare I say they've actually um, thickened up the digits possibly a tad. The these ones look a little bit thicker than my older ones here and the contrast um seems much better, especially um on the high angle like this is I Think that's a bit hard to get on camera there, but uh, they seem to improved the the contrast a bit which is great. One difference I did notice is the beep. The beep has actually changed.

Let's see if we can get it here. Listen, the new one is definitely softer and a slightly different pitch. The old one was much louder and they haven't fixed. Another annoying Quirk which I didn't like is that the backl comes on when you switch to 4 and a half digit mode.

Watch this and it still does it on the new one. Why? It just takes a gulp of battery current when you do that crazy just pissing away the current. And if you're interested in the back lights, there is a minor difference. I Probably prefer the old one, but oh, there's There's really nothing in it, but the contrast is much nicer.

I Think on the new one using the backlight, especially the high angle here where it starts to vanish, you'll notice that the other one is Vanishing whereas the new one stays much sharper. So the LCD is much improved. And now for the big test everyone wants to see. Here's my old one.

Here's the new one. Got my phone here. let's try it. Yep, the old one still plays up there.

it is, still goes burko a bit. and let's try the new one. Nope. Exactly the same thing seems.

not solid. No problem at all. The audio is probably horrible. It's uh, the phone is no doubt interfering with the audio that uh 218 HZ uh interference there from the GSM but uh, no, the meter works as you'd effect Fluka fixed it Beauty and Just for kicks.

I'll try my UHF uh walkie-talkie I've got here. This didn't actually caused the problem last time, but I'll actually key it and this is the old meter by the way and you can see the bar graph there go up as I as I actually uh, key the mic in like that and it it doesn't kill it. But uh, let's take a look at the new one and see if it does the same thing all well. let's switch it to molts like we had the other one on.

there we go. The bar graph goes up exactly the same. so uh, it's it's still. you know it's it's not going to be completely immune to all.

Um RF that's crazy. It do does actually have a spec for that, but um, yeah, it certainly doesn't crash with something like this. Um, half WT um uh. Walkie-talkie basically transmitting right on top and I thought I'd just show you the new fluke TL 175 probes that they're supplying with the meter.

Now they, uh, they aren't I don't believe they're supplying these old Tl75. it's been replaced by this TL 175 because of the new Uh regulations. the new Cat regulations. It's actually got a switchable see that it actually switches around and actually it's got a shroud which comes out and actually protects the uh exposed end like that.

because in I apparently um, you in to actually meet the cat uh 4 requirement. Um, you need to have that shroud on your meter. So this one in there it is in Cat three and Cat four position. It's got the Shroud in cat two position.

It doesn't have it, so that's just a a sort of a more of a legal requirement to actually meet the Uh requirements of of the cat or UL or who whoever actually um handles those sort of things. So they are new probes and if you compare it with the old one, it is much longer. um I I Much prefer the shorter Uh probes I much prefer the older one in terms of uh handling. but the Um the in in terms of the strain relief on the cable at the end is very nice indeed.

Um yeah, I'm not sure I'm a big fan of the Uh of the Shroud that comes out like that I don't know, it'll probably just wear out eventually, but uh yeah, there is um sharp as they always have been. really and uh, they differ on the me itself. as you can see they're got much longer uh uh. exit for the cable coming out of the right angle right angle connector there and as with the top end, they're very nicely.

The rubber on that is. it's beautiful. But once again, I don't know if I'm a big fan of having them actually stick out. uh, that far they're They're just not as nice and compact as the old style one.

So I don't know I'm in two mins. but there you go. that's a new fluke TL 175 Pro There you go. Fluke actually fixed it and they did it reasonably quickly in the schema.

things. Uh, for a huge company like that to spin a new revision PCB and test it for the world's pretty much the world's uh, leading multimeter? That's That's quite good work. And so thanks for Fluke for letting us actually show this! I'm not aware of another big company that would actually have the guts to show a pre-production prototype like that. It shows that they're damn serious.

I Love it! Thanks! Luke See you next time and remember if you got to try this at home, wear protection.