Hi, let's take a look at the Fluke 88 42 a multimeter. It's a five and a half digit multimeter and it is probably one of the best secondhand meters you can pick up on. eBay You can pick these up working so like I've seen them go for as little as a hundred bucks, but you can't always get them for that price, but they need to go for around about that and this is a superb meter feature packed in its point double-o 3% basic DC Accuracy Class Instruments Practically like six-and-a-half digit class accuracy for a five and a half digit meter. Fantastic.

It's also got a 20 Ohm range as well and a 20 millivolt range as well. Handy for low level stuff, but this one, unfortunately is Folium. I Can't quite remember what the issue is event powers up I believe, but it's got some sort of issue so hopefully we can see if we can fix these things. But yeah, if you're looking for a cheap accurate I bench Me like used bench multimeter.

do yourself a favor. Now this one seems to be missing a few things. The GPIB of course is gone and we're whether or not it originally had it as a cable flapping around in the breeze in there, but no external trigger or sample complete. so I'm not sure if that was a option or not or whether or not they're They've ripped it out anyway.

Made in the U.s. of a USA and a good thing is about buying these internationally is it does have a switchable international voltage on this. Anyway, it's got the four wire sense on the back as well. You can switch between the front and the back terminals handy.

So let's power this up and see what we get, shall we? And one of the things we saw these unfortunately is the vacuum fluorescent display. They can actually dim with time. All right. So let's power this thing up.

Fingers crushed. Hey, we're in the displays. Not too shabby. I Do One thing I like about this display is that it is big.

Look at the size of the digits on these. It like it's larger than your usual one. So it really is quite nice. Okay, let's test the functionality, see what's broken.

Alright, although this is van. tests are 61 42 Voltage, current and generator reference is not good enough to calibrate this scene. It's good enough for doing some basic checks and it's let's a look point 5. Yeah, that's well.

okay, we need to. Could be a slug that's significantly out, so I'm not sure that is in percentage. But yeah, that's not terrific is it? But let's go up a range. Okay, not too shabby so we might have to get a better meter on there to do I Might have to hook up my MV 106 reference standard up there and I'm compare it with the seventh digit Mito to get our idea of its accuracy, but it's basic functionality on DC Volts seems to be there excellent, and the basic current functionality seems to be there as well.

It's got a slow updating there. Can we make that faster? Get our data? Oh I Doubt it. Right there we go. We can change that fast.

There you go. You trade-off accuracy versus let's drop down to 10 milliamps and let's just change that right again. Yeah, yet there we go. Yeah, no worries.

Beautiful. And the resistance seems to be bang on as well. So oh geez, look, it's so fast that it's a toggling between the two. You can barely make out those digits.

Oh yeah. well, yeah, they could like bang on on resistance. So DC volts current and resistance? It's yeah. I'm going to have to do a full calibration check.

That's basic functionalities there. Um-hmm Okay, I Just found the original listing and it said they've actually measured DC and volts and current fine. which it did, but it was out significantly out on resistance apparently, which we saw. it wasn't on one range.

so I have to recheck that but it didn't work on. AC So board over here to my Cal instruments without there fiddling around. Let's recheck the DC Volts there. Look at that.

10 volts. Absolutely bang-on and if we go down to 1, there we go. Look at that. no worries.

And 100 millivolts Wow can't get much better. And on the 20 millivolt range, it's not a problem. And I think I found the problem. Check this out.

Volts, Ac and A'right 30 I Love a meter that actually you know goes to the effort to you know they knew that this thing would have what they can report errors and it actually has a an icon on the screen for error. So error 30. Let's go to the manual and just some basic resistance checks outside. 10 Meg I Have compared it with my seventh digit meter, it's just fine.

We're good on all the ranges, so so much for significantly out. We've got test leads and all sorts of other crap on there. 13 Ohms. Okay, so now we're really starting to shouldn't be three Ohms out there.

1 Ohm and we're measuring for okay, so we might have an issue there. Let me actually plug that over into my seven and a half. and what do we got up door jump plug the wrong leads? Geez I mean idiot. There we go.

1.4 So yeah, we obviously have a problem there on the low ohms. but geez I'm not too fussed about that yet. What we really need to look at is that AC Volts RMS is that's what we want to fix. and I do like faults like this.

Not only do we get narrow message so we'll be able to go to the service manual for this thing. Even if the service service menu doesn't have the schematics, it should list all the error codes for us. so you know having something that we can, you know a fault that we can, narrow down and fix like this. This is really what you want.

So if you see an eBay listing for something like this and it even tells you that it gives you an error 30 or something, then hey, you can go to it. You can download the manual before you buy it. Check it out and you know least you've got something to work from. unlike getting some meter that just doesn't power up.

Although that could be good as well cuz it could just be a power supply issue or something like that, but something that just goes completely haywire. It could be. you know, like who knows. It's nice to have something narrowly focused like this.

Let's go and just my luck. you read the manual and error 30 is actually not a hardware fault. It's not part of the power on or automatic self testing inside this thing. It's simply the lack of a true Rms option for this at saying you can't Jacque Volts AC This meter is not has not had that option installed I didn't even know that was an option.

It's like I haven't used my these are decades. So yeah, so there's nothing wrong with the Volts Ac. It doesn't even contain a physical module to do that or may I Don't think it's a software option, it's probably some like hardware and in daughterboard. So anyway, I'm only one thing left to do tear this thing down.

So it turns out that yep, that's actually option. oh nine. So if you're buying one of these things there, it is there. The AC a nine.

If you can get a photo of the back of the thing, make sure it has that ticked. Otherwise I Feel like they put a marker pen or something there at the factory? Make sure though, stick. Otherwise you're not going to be actually able to measure. It's not just true.

RS you're not going to have any AC voltage or current measurement at all. So yeah, a bit of a showstopper. Anyway, let's open it. Ah-hoo The first thing I notice is the red silk screen.

Check this out. Ah ah, that. leave the red silk screen markers. Ah, sex on a stick.

Look at that. I Tell you what. This is just a beautiful meter inside. Whatever.

A closer look, but look at the ceramic resistor divider networks. one two, three, four, five, six, seven, eight is there I That's just that's just crazy. Aha. Anyway, yes and they are all laughs.

Look custom because fluke actually of course. I Famously make their own no resistor hybrids I have I done a video on that? I think I may have. Hmm. Anyway, one of the first things and interesting things I noticed.

Look at this. They've completely potted that transformer Look at that. It's like it's in one big potted monolithic block. I Have never seen anything like that that is absolutely amazing.

Anyway, it's very, very neat and tidy. Got ourselves a big-ass Hrc fuse over there. Very nice to see. Got ourselves a common mode toroid there for the input terminals.

one on the front, one on the black and back. Isn't it? just beautiful and colorful I Love it anyway. Zai Logue Zilog Go crazies I Love Fanboys. but I don't think no, it's not as its as that Eight so logs at Eight processor Wow Anyway, we have our date code on this puppy 1994 there abouts I'm not sure when they stopped making this like if the manual says like you know 2000 copyright 2000 I'll show how long after that they kept up making it but it had a long life.

This puppy because it was a really quite a nice bitter. And the good part about this meter when it comes to our service in the manual for just the regular manual has the full schematics in there. Absolutely fantastic. If you want to repair it should be, you know, eminently repairable.

Of course it's all laughs through-hole makes it very nice. very easy to get in there and don't measure stuff and replace stuff. of course users you know like it's going to have some custom II flute type stuff and it looks like there there are the odd Luka branded chips down there. They could be just off-the-shelf ones, but actually rebates with the fluke part number.

So maybe the service manual might shed some light on that, But you know it should be fairly repairable in that respect. So yeah, and it's just a nice layout, easier access, and you know, I'm a big rod fan, Boy, look at that and that's the power rod going through. Interesting that they've got that PCB on the bottom there that's actually quite thin. That's like naught point, eight millimeter or something like that.

They're just using that as a big shield, so that's quite neat. Copyright 1983 and Chum Fluke Manufacturing Co. There you go. So it probably went for like a rev F in 88 1988.

Is that I mean that's how long this sucker it sold until at least 2000? So I think according to the manual. But anyway, yes, they've got another rod down here. Now that's actually for the calibration too. Like, you just stick a screwdriver through and you can push that and that engages the calibration mode over there.

The good thing is, check it out. So we've got a psych or a squared prom down in there. You'll notice the lack of a battery in this thing, so none of that pain in the arse. Battery backup calibration values Eva So a squared problem all the way with LBJ No prizes for guessing that custom fluke chip is the ADC the dual slope or a multi slope integrator.

and is that our voltage reference down there? I Get my macro lens out for Ult fanboys, Ha. We don't have an LM 399, we have an LT FL You which is our LT manufactured by Linear Technology. It was a custom job for fluke and it's not the LT LT said 1000 easier. It's a different variant that doesn't have a built-in heater, but it's used in some of the it's using the Fluke 732 voltage reference standard.

That's why this meter is so darn good at you know point double O 3 percent class meter because the reference in it the LT FL you is brilliant. So that is massive overkill. For a five and a half digit meter, it would be overkill for a six and a half digit multimeter which would use the classic you know, LM 399 for example which is not as good as this. This is like almost a transfer standard class reference and they've got it in this 5 and a 52 meter.

So if you buy one of these, you know you can buy one of these. I paid 60 bucks for this, you know, broken in quote marks I'm you know, solders not working and some people would say it's worth it just for the reference alone. All the vault nuts out there anyway. I'm sure check out down on the PCB copyright 1983 so this one was manufactured in that 94 and as I said so, it probably had.

you know getting on to a 20-year lifespan I would suspect. Awesome! Now if you're wondering, where does the AC oh no and true RMS option go? Well, it actually goes into this big-ass header here, and I'll include a photo of that. It's actually a separate board, separate whole separate module that actually plugs into that. So obviously the software are detects.

It's got a pin on there that detects whether or not its installed and it's not error 30 when you press. AC Of course they didn't even bother. take the button out of the front panel because that would be a user installable option. Just you know, opening this thing up, plugging the board in.

yeah, you'd void your calibration if there's a cow sticker on it, etc. but still. you know it's not something that has to be done at the factory, that's for sure. Now if you are working on these, it should be pretty safe.

You know all the Transformers potted everything else. All the mains Warren's are nice and neat and tidy, but the range switch on the back of the X the rear side of the board there is exposed, so just be careful that you don't. you know, accidentally. just go.

Oh yeah, I'll just move it and grab good that thing like that. Just be careful. Better puffs and that should be pretty safe to work on. I Love how that poor power resistor there is been I Almost Boys din.

Although it does show, the silkscreen does imply that it sort of supposed to be mounted vertically, but he need and more bad news. it works. dull the eevblog repair cause it's just hopeless I Buy it. You know, a faulty bit of gear and there was nothing wrong with that Ohm's range.

What it was, it was most likely just the input input selection or well, the front and rear selection switch here. probably just had a Dickey contact. it just needed to be cycled a couple of times and then go like what? 1.4 That's the leads in the box and everything else. That's what my other seven half digit meter measures with this box on that rein so that is okay, it's fine.

everything's practically going on with this meter like it's okay I need to have been probably a bit more exhaustive calibration checking which is you know it can be really tedious but it spot check on each range so far is well within spec. so yeah I like unbelievable Unbelievabl. Anyway, very useful our 20 ohm range. that for right you know one milli ohm resolution.

Very nice for tracking down shorts and stuff like that. Very handy as is the 20 millivolt mode as well. that's that's a pretty jazzy 1 microvolt resolution. and given that this is a point double O 3 percent class basic instrument I'm quick.

If you can pick one of these up for a you know 100 bucks, definitely do yourself a favor and get one. Awesome! So it's that switch down there. that's the culprit there. and they're going to be like a self effectively self wiping self cleaning contacts in there.

So unless it proves to be an intermittent issue, it will require more use and more playing around to determine that. But it seems rock-solid now. So I think it just had a bit of crud in there and just needed to be cycled once and Bingo! So I wouldn't be going spraying contact cleaner in there willy-nilly You know there's people who say oh yeah, the first thing I do is contact cleaner right throughout the switch and yeah, you can just do it on this squirted on the top and it get down the individual pins down in there. So if you've got your favorite contact cleaner then by all means go for it.

But I don't think I'd bother on this one because it hasn't caused me an issue apart from that one time, you know it's probably been sitting in storage for 15 years. And by the way, if you're worried about, you know the annoying part about having to take off the cover to replace the fuse down there? Don't really worry about it because it's actually just a backup fuse. The primary one is on the front non Hrc of course, but that puppy is going to. you know, just in general use is going to blow first.

You typically wouldn't be using these on high power and main stuff. They're like more for bench measurement use and stuff. like that, so that's all fine and dandy. Shouldn't have to open the case, especially if you've got one with a recent cowl sticker.

Then yeah, you can just replace the fuse on the front. Oh worries. And here's an old friend: I haven't Dre down in the world The Fluke 54:58 resistance calibrator. I've been meaning to do a calibration of this, a calibration of the calibrator using my weak armor resistance our standard which I've got which is actually better than this and you can use the one single 10k transfer standard to actually calibrate all the ranges on this.

There's a sneaky procedure that allows you to do that I've been meaning to do a video on that for a long time. some I get around to it one day. Anyway, this allows us this is a reference resist standard. I've done a teardown of this I'll link it in down at the end.

It's beautiful inside. Oh Check out that video, trust me. It's fantastic. It's almost pornographic and this allows me to generate a low value resistances.

I'm on the 10k stand at the moment, but I haven't verified the calibration of this right down. so it claims to be 10 point, triple, oh, one, two. Anyway, more than good enough for this. There we go.

We're in a last couple of last least significant digits there. Of course, if we switch over to the two wire mode, you see ten Point Three because it includes all the lead resistance and their contacts. and every you know the contacts inside, the switching in there, and everything else. But on four wire mode.

of course, there you go. It's basically being on and we can actually use the 1k at the one own standard down here. Ah, you got to see it. That's Nine, Nine, Nine, Six or so.

It's once again, a couple of least significant digits out that's got to be well within our spec, so no worries whatsoever. And yeah, we could do this until the cows come home. I Know everyone wants to see every range, don't they? Yes. All right.

All right. I haven't tried this. I Can ask? Well, most bang on. Ah, Ah, and you know that's all.

These are going to be well within spec. well within spec. So this meter is a winner. Winner? What? Yep, that's good enough.

we know. Winner Chicken dinner. Oh look at that and a hundred mega. Don't think it does.

Hundred? Meg No I think it only goes up to 20 Cal Remember how many counts this is? The twenty two hundred thousand count something like that. Anyway, there you go, being on. So once again, sorry I was hoping to bring you a repair video by these repair things occasionally and you know to hope in crossing my fingers that there'll be an interesting repair, not just a simple blown fuse or not beyond economical. Repair is quite a few of my repairs that turned out to be so yeah.

I'm not even going to title this repair video because it's not, it's just a look at the fluke 8840 to a multimeter with like almost a transfer class reference standard in there that FL you one reference stand if you like like it for a hundred bucks you can get these that are working. you wouldn't get one that's you know, recently calibrated for that. if you can then an absolute bargain. But yeah by all means put a search term on eBay I know that if I mention something's good and available on eBay they you know double in price instantly.

So sorry you know, but these things have gone for as little as like a hundred bucks. But yeah, it's like fantastic meter if you can still pick it up with a decent display because these vacuum fluorescents do fade over time I think someone might have even done like a replacement to slide project for it or something like that. but yeah, really nice old-school meter. The 88 42 a if you can pick one up, do yourself a favor anyway to like the video.

Please give it a big thumbs up. As always discussed down below, catch you next time you.