Dave fiddles with a $19 Hameg HM205-3 combined Analog/Digital Oscilloscope
And yes, he's giving it away.
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Hi check out what I scored at auction for a whopping $19 It's a Haymaker 20 megahertz, digital storage, a scope or a combi scope actually. Yeah, it's a real analog scope with digital capability as well. Yeah, very low-end but hey it is a hey Meg good German quality scope for 19 bucks I Have no idea if it works at all. the auction didn't say so I got it from our graze it's not actually an eBay one.

They actually had three of these going and one of them went for 70 bucks and another one went for 40 I think but I picked this one up for 19, presumably because it's got a missing switch here, but not a big deal. Um, you know, really, that wasn't gonna stop me I Get in this thing. if anything, it will make an interesting teardown and hopefully it won't work so this can turn into a repair video. and I'm not exactly sure what vintage it is, but look, it comes from the University of Technology UTS haha One of my old stomping grounds here in Sydney One of the if not the ugliest building in all of the city.

CBD Absolutely horrible building the UTS building. Anyway, let's not go there I haven't powered it up yet Oh Cow this sucker on end. By the way, it looks like it's it's. got a label on the side called a ball and plate so I can only presume that maybe is being used by say you know, like the physics department or something like that.

maybe set up as a permanent demo I Don't know a ball and plate balancing demo or something. Came with a banana play guard. 2 B and C adapters are chained to the thing because students steal the bloody things. you know God I wouldn't even last a day.

And and of course that's how you know all. yeah, a lot of these at university. you know, classic experiments are set up. They all use big, you know, binding posts and banana plugs and you know, on a big base.

you know, a big A, wooden baseball or something like that, or just wired up. So it's probably my guess is what that means is that it's being used for some sort of a, you know, semi-permanent demo or something. and I don't know why they've got ridden it and rid of it. But anyway, let's power it up.

And yes, it was only 19 bucks. so if it does work, don't complain that you can't get in oscilloscope for under 50 bucks. Not a problem. So anyway, if it doesn't work, the good thing about this is that you can I checked before I actually got it.

You can get the full service manual with the schematics, just download it off the net for free. So if you are going to buy a second-hand scope like this, make sure you can at least get the service manual for it. and make sure it users have a look at the schematic and make sure it uses all off-the-shelf parts. I mean most ones like you know an old 20 megahertz scope like this is, you know, almost certainly going to use or offer you know, really available off-the-shelf parts.

but something like say you know 100 megahertz Tektronix or something is going to have some custom parts in it. So yeah, stay clear of them unless you know it's absolutely working. But I don't know, maybe we'll the magic scope smoke escape let's find out and controls intensity. Yeah, it's up near the top there.
Let's see if we get something anyway. Pairen ah helps them I plug it in dole. Oh and by the way, don't get too excited about the digital performance the storage performance of this thing. It is only 20 Meg samples per second with a 2k per channel sample memory.

So you know, pretty ordinary digital scope. But because this is a true analog scope as well, you just die. You know you don't turn your storage mode on, you just turn your storage mode off and it works as a regular analog scope. So and there's no sine x on X interpolation in this thing.

So don't go thinking that you can get maybe you know, five megahertz a usable storage bandwidth out of it. It's pretty crusty so yep. anyway here we go will a magic smoke escape. green light comes on.

That's good. Usually these things can take a second or two. Ah, it works. Ba ma Well it's you know we're getting traces up there, so there's our focus.

Yeah, yeah, this works. Unfortunately folks, this is not going to be a teardown. Oh well. I'll do it.

tear down on it, but it won't be a repair video on foot. Well I need to do a bit more testing on to feed some signals in, but that looks like it's a winner. Yep, times 10. Meg works.

Ah, we have a winner for 19 bucks so there you go. Don't complain that you can't get a decent scope in front of 50 bucks. I Scored this in Australia Where it's hard to get these things for $19 it does look like this is a winner. We've got our exposition there.

We've got our Y-position channel 1, Y position channel 2 dual sink all this chopped channel 1 channel the Trig channel 1 channel 2 So at times five vertical mag are usually going to get lesser bandwidth with your times five vertical magnifier in there. In the case of this scope, it's only three and a half megahertz. Oh I think so you don't get your full 20 megahertz analog bandwidth. this sucker will actually are trigger up to 40 megahertz so not that bad at all and external trigger and we've got our AC DC Hfl F line of there we go What? Lion Trigger It doesn't like that at all and we've got TV trigger.

If you're working on TV stuff of course then that might come in handy. although who repairs and works on TVs these days? But here we go. let's try storage mode. and hey, that looks like it works storage mode and you can tell because we're getting artifacts there Now let's when we chant yet look at that getting yet we're getting an artifact in there as we change.

Our verdict is the vertical there and you can see that you can see the sampling there. There you go, but it's a we haven't and we can of course hold that and it's got separate hold buttons for Channel 1 and Channel 2 that's really quite nice. I like that and then single shot mode be our single I reset. Ok, so you can get yeah, single shot mode and then you reset and oh no, it's sitting there waiting all right.
So because of course if there's no trigger coming in, so it's knob viously not working off the auto trigger there. So there we go and we've got joined mode as well. But as I said, that's a linear interpolation, not sine X on X Oh man, this sucker works really well. It could maybe do with a bit of slight bit of trace rotation there.

There's no I can't see any rotation control on the front here. Yeah, you can see that's slightly off on the rotation there, so they will no doubt be a control on the back. We can just tweak that a little bit. Got to be a bit of a perfectionist with these things.

Why not? Yeah, yeah. I've probably had a few people screaming at me. There it is. I missed it.

Trace rotation on the front panel. Not a problem. Let's just tweak that around and see. we can really give that a bit of a bill there, but well might hang up the right angle and that looks pretty good to me.

Sweet! Now here we go a little bit more. Here we go spot-on Let's feed in a 1 Kilohertz 5 volt peak-to-peak signaling I'll look at that in a beautiful analog display. you just don't get that on digital's I mean ah beard thing. a beauty joy forever.

Let's get rid of the dual channel mode there, shall we? Excellent got a trigger on this thing though. we might need our button. ah new. I Think we're gonna need our auto normal trigger button here obviously.

I'm not sure if I can reach through there and down I reach through their pocket I Reckon we open this sucker up and see what we can do with that button cuz most of the time you could just probably leave it on normal I mean I could you know you could? Maybe yeah. 3d print a little button to go in there or something like that I'm shy kid, you know, juryrigg something to go in there. let's try XY mode shall we? I'm feeding 2 separate 1 Kilohertz sine waves into this puppy and so that one here. We go there we go.

look at that. They're both the spot under 1 kilohertz. so we don't see our circle rotating at all. Change the frequency on our generator here by 1 Hertz Then we should be able to get it to rotate in one direction at a 1 Hertz Right here we go.

So it's a thousand and one Hertz One point, double O one kilohertz. And there we go. We got that sucker rotating at 1 Hertz Brilliant. And of course, if we stop that, the circle.

Whoop. Where we stop. That depends on where our circle is going to fix itself so we can rotate back in the other action. that's 999 Hertz and then stop up.

Stop. and then what? - that's 2 Hertz silly knob on this Rygar function. gin. And of course, if we up it, not by 1 Hertz but by 1 Kilohertz ie.

we double it up. But there we go. Bingo! And if we triple it, we get the famous ABC symbol. and then if we increase that by 1 killer her 1 Hertz Now we can get the ABC symbol to rotate.
Tada. Look at that. This is just figures. Love it.

On a real old school analog scope for 19 bucks. Brilliant! And this has got a nice bright trace on it - this sucker and there's no, it doesn't look like to be any screen burn. Looks really really nice. Condition their scope and if I have that to one-tenth of a hurt so I can get that to pretty much stop wherever I want nice I can't get this sucker to trigger so I have it.

Got the external trigger here and we'll there we go. We hit that. The external trigger works just fine and there's our horizontal vernier that's got a little indent there and I can hear that but click little indent. Not bad at all.

And yeah, like that. you know you'd expect the times 10 mag to be up here somewhere. or usually like, you know, a push of the Verdie or something like that. but your times ten Magaz actually down here.

but that seems to work just fine. Ah, now it's suddenly to a look. You saw it. Look, there's something wrong with the trigger in the auto.

I Assume it's in our auto mode because it it rolls so um, there's I then the the triggering could be could be a bit Dicky Here you saw it sort of just disappear there. All of a sudden it's decided it wants the trigger. so maybe there's something a little bit Dicky in the triggering circuitry. Perhaps that's the first time it's actually worked and triggered properly on that waveform.

Yeah, something going on there that's 50. that's may align triggering, but it seems to be working fine just now. I'm not exactly sure what that was might be a peb cap. Let's try Channel 2 here.

and how do we get Channel 2? That one? Yep, there we go. That's our channel - not a problem. And the other thing you want to check of course is the invert function. That works just fine.

Yeah, they're only going to have invert on Channel 2 because that's our subtract when you put add mode on there and you invert. Channel - that's actually subtraction and there are times five mag. So let's have a look at our noise floor there. turn our signal off, can totally disconnect that.

times five mag. There we go. It's pretty clean I Like that. Not a problem at all.

Of course you've always going to get a bit of dick eNOS in the switches like that, but that's not not really an issue unless the dark causes problems, right? You know, actually, when it's on the indent on the range itself. But this one's not bad. I Mean you know it's five volts per division, down to one milli volt per division. So very usable scope that's for sure.

and we can change the amplitude on that sucker to go all the way down. Let's go down on that. You can see it coming. it's on its way.

There you go. That's ten milli volts peak-to-peak Well, we've got some undulation there. Look at that? There we go. So switches might do with a bit of a clean maybe.
But anyway, I'm feeding in ten millivolts our peak to peak from my our generator and that one is. well, that you know. I mean you could tweak it a bit I mean it's a little bit off-putting in the center. I Mean it's a little bit under there, but geez, you know, um, you wouldn't.

Uh, wouldn't complain about that at all. One thing that doesn't seem to work there. yeah, the Vernier there on the vertical. that's like I could feel the indent on that, but it feels a bit squishy.

Not sure what's going on there, but that doesn't seem to be working at all. and there's a ground. AC DC Coupling Hmm. Channel 2 There we go.

and that's yeah. Ah yeah. a little bit higher than the other. one.

gains slightly higher, but once again, that and that turns all the weight. Hey Whoop. Hang on. Oh hello, hello.

Look at that shaft going all the way through. which indicates that we're going to see some really nice switch stuff when we crack this sucker open. But yeah, whoops, that's a definite is not as something gone, something. God oh there we go.

Horribly wrong. That one doesn't really feel like it has an indent. Now we should be able to our single shot store this thing now that the triggers decided to work. So let's go into single mode set yet single mode and reset.

Boom-boom-boom-boom And of course if we take out the there's there's no trigger inside, it'll just sit there and wait so the LEDs will work. no problem. And there we go. plug in our signal bingo and with single shot captured that don't know how we zoom into it but there's our dot join mode off and on.

No, maybe that's only. well, there's 2k of our sample memory in there and everyone wants to see some good analog modulation. Of course, on analog scopes, I've got a 1 megahertz carrier with a 100 killer with a 1 kilohertz modulation at 110 percent and that was at the fastest time base we turned that up. We're not going to see that.

let's tweak our hold off here, see if we can get something nice with our hold off and sure we should be able to. There we go look at that beautiful dull I Didn't look at the sticker on the other side, it's the It is actually from the engineering facility. not from like our the physics facility or something like that, so obviously used probably for some sort of a semi-permanent demo in the engineering department. and there it is made in.

Germany I Know all my German viewers even tells you your x-ray dose. Fantastic! Takes a massive 46 watts and it looks like it's 1992 vintage, so 20 years old, but still works. A treat. Perfectly usable scope.

There's a rather unusual pin header on the back here I'd Normally see these are something like this on our scope, but because this is effectively a digital scope, is actually a 1, a Haymaker proprietary interface which can hook up to a GPIB or an external wire printer. Basically, it just allows you to get the data out. As it turns out, I Accidentally had the hold button on before, which was displaying a previous way a previously stored digital waveform that that's actually like a waveform save type function. So in digital mode here, I wasn't actually I was looking at an old stored waveform so to speak.
But yeah, this thing's going to be really rather crusty trying to measure this amplitude modulated that sine wave. It's got no hope. I'll try and give you a look at dot mode here, and its really is quite hard to see. I Mean that's dot mode and then we can.

If we maybe increase the get the focus just right, we can really make our waveform nice and fuzzy there. But yeah, there's no most difference between plugging like that's dot join mode. Off, that's dot you up I Hit the reset button. dot join mode on or off.

I You know? I don't even know why they have that button. Really, it's almost. It's almost pointless. Let's take this puppy apart.

There were two screws on the back which just held on the back plate and this thing just lifts straight off here. I Really should cut off that bloody chain? Really is a bit annoying. now. that should lift straight off.

No dead cockroaches? No, Are we going to get the good of a bit of a problem right? there we go, Tada and we're in like Flynn And if we have a look at the back here, there's our CRT driver board. Very nice. Our main power transformer here. all of our mains up here fused and all are protected around the top so you can't touch it.

But yeah. nice little cutout in the board going off to the main CRT board on the back. all looks in very good. Nick Everything in this is our socketed by the way.

so all the ICS are socketed. We've got a couple of pots here, only adjustable from inside. Another couple of pots over here, another one up here. pots everywhere, even the little transistors there a socketed.

Check that out and check out inside. there's our main processor board up the top here. We'll have a look at that. but the thing I'm interested in is, how do I fix that bloody button? Check this out.

We still got our button complete on the shaft there and we can just poke that back through the front. Brilliant. And it's just popped out. We've had some ham-fisted ever.

Well, probably deliberately because the idiots deliberately do this. I'll just Bend that back in place a bit. The switches a little bit a little bit out of sorts, but we can just push that. Should be able to push that back in there like that and look a little bit sticky.

Hang on. But we should be able to fix that. No drama. No, it doesn't want to spring back, but I could play around with that for a few minutes and I'm likely to get that there.

We go there. Perfect feel that fixed. not a problem. Beauty.
So that folks was the difference. Likely the difference between a $19.00 oscilloscope because in the picture it had the button missing. But you know, when you open up, the buttons still in there a couple of seconds. Bingo.

That should be fully fix. That's the difference between a $19.00 scope and somebody who paid $70 for another one. Identical. Anyway, there's our horizontal board on the bottom and you can see the lovely shafts going through that go through there like that.

I Love these old scopes that have the shafts going through them. Some of them have you know, bends in them and all sorts of stuff. and that. They really are quite nice.

And the front pad. a lot of the the front panel switches down in here. Of course they have just, you know, right angle plastic arms on them in there. You probably can't see that, but there's some right angle plastic so the switches are actually below that board and then they just come up and pop those and then it looks like we've got the long shafts going all the way back here from the front panel.

What control is that? That's the x position and the XY mode. So the XY mode is going on. - yeah, the switches all the way back there for the XY mode. So justly, you know the have to design these things and like from a system point of view and actually get them working.

Absolutely, absolutely remarkable. And that's the main power switch. There's the rod for the power switch, which goes all the way back through and right right to the back over here. So that's fantastic.

So to actually get the design of these things right, and this isn't a terribly complicated one either. Hang on I'll show you this. these are the switches on the front. Check that out there.

It goes from a vertical switch like that and then converts that in horizontal regular move a regular PCB mount horizontal slide switch like that, multi position. Let's have a look at the processor board here. We've got two classic Motorola MC 103 one nine, 8-bit flash IDC's and this is obviously the input circuitry for each channel there. Man, I haven't used those in? Well, yeah, since the late 80s.

I Mean geez, you know I think the MC 103 one nine was old even when this scope was designed. So there you go. Absolute Classic. Next of that, we've got an AM 601, 212 bit multiplying DAC probably to generate the data I do store to display the waveform back on the screen converter back to analog.

Now the interesting thing about this storage scope. Oops. All the old labels are just peeling off. These are programmable, probably just a gate arrays I Have to scrape off the gunk on there and and have a look, but there's effectively no processor on this.

There's a couple of custom Jemez got branded chips up here and we'll take a closer look, but basically it's just like a state machine. You know, type thing is just hard logic because there's no on-screen you know, display readout. anything like that. It just stores the waveform, captures it in the ADC and then replays it back, converts a bank, holds it in memory, then converts it back into analog to actually display it on the screen.
Then you know it doesn't actually need a traditional processor as such. Even though up here, we've got ourselves A and while that's the clock for it looks like we've got ourselves a is that a 40 megahertz clock looks like a 40 minutes clock. I Think that's a 4-0 But yeah, you know they have that down. Of course for the 20, Meg's ample per second sample rate for the ADCs.

But ya know, traditional process like you know, in a sort of, you know, a sort of a vintage storage scope like this. Might not find a 68000 processor for example, because it's got to do on-screen readout and display the characters and all sorts of things on the screen. but this one doesn't have to do any of that, so it's much much simpler. So there you go.

This looks like a custom device I Don't know whose logo that is offhand, but it's got Tim Bass I Mean obviously you know our time base in HM oh five, that's you know. probably a custom, a chipper custom gate array or something like that. Arts specifically foot done for this Suss Cope for hey me And here we go. If you can call anything a processor, it's probably this.

There you go I'm humming branded. Obviously they didn't make it somebody else, but it's a yeah, it's got an ADR C CTR So you know analog to digital and what analog got controller basically. so that appears to be like the sort of you know state machine that type controller used in this Finn thing for handling all of the storage capability. If we get in there with one of these are medical swabs, just isopropanol alcohol wipes and you can clean all the gunk off those chitosan.

Yeah, it looks like we got that some power Lord gal in there. Let's take a closer look and look at that spot on There we go. Yeah, a Lattice I gal, sixteen v8 and then we've got some art Pal 16 V8 here. So um, for uh, you know programmable array logic there just to handle you know, all of the custom circuitry.

Otherwise it would have taken them a lot of us. Seven Four Series stuff. I mean one of these devices can replace, you know, a dozen or two seven Four series chips that's for sure. The funny thing is, after twenty years you kind of expect you know certain to some of the chips to you know wear loose from the Julian line sockets or me an don't get a Dicky contact or anything like that.

but this sucker just worked straight out of the box. you know, Unbelievable. So really, um, it's not surprising, but in one of these scopes you know a good thing to do is just go in and just you know, reseat any ICS that do look a bit, uh, you know do look a bit dodgy and sort of just hanging on by the last leg. And if we have a look at our horizontal boards you'll notice got a couple of transistors in here with a little metal ring around them like that that's actually effectively our what they're doing.
There is thermally bonding those two transistors so they're thermally matched so they're a matched pair so if there's any temperature drift it affects both of them at the same time. And there's our trace rotation pot. They're got a bit of a lien on that sucker, but you'll notice that this board is are all single sided very nicely. Our mark with all the silkscreen labels, jumper links.

Real easy to repair these boards. Fantastic! Now the only thing on this thing you might think is a bit how you're doing is the Y position board here. I mean that's all it's got is it's basically a PCB fixed at the back here mounted. It's got a a spacer in there mounted on top of the shielding can for the front end stuff here and it just contains the board.

and then they got ribbon cables going off through a slot cut out in the board here going down there so it's almost like they you know ran out of imagination there and they went oops Oh, we designed this thing and we we've got our y-position pots left over. I will just bugging the board at the back here and have it go down there. But and you might think all these boards are all our through-hole technology as well as we've seen mostly our single sided boards except for the main storage board which was a double sided board but all through holes so far and you'd be right if you flipped it over and had a look at the bottom side of the scope here. Check out all that.

we've got ourselves. the Main: There's some horizontal stuff going on here I think plus our component testers down here and things like that. Yeah, that's our X 10 mag switch there. that's our component test to switch.

We've got a fuse on there that'll be part of the component testing circuitry around there I would imagine. And yeah, they've just got a body wire running off there to the component tester jack on the front there. That's really a bit rough and ready. So that's our component testing stuff.

We've got some more vertical mode stuff because that's our channel One channel to select things like that. So once again, we've got these lovely shafts coming back through the through the chassis here, back onto the board. I Just really love that. That is very, very nice indeed.

and few adjustment pots. But anyway, take a look here, you'll notice that they do actually have some surface mount on here. This is our vertical input amp and as you can see, yeah, they've got some mouths package resistors there. we've got some mouth diodes, and then we've got some chip surface mount caps in there.

So there you go. They just decided that you know, from a well, a high frequency point of view. In quote marks, you know this is the 20 megahertz. Our front end is not exactly screaming long, but they did decide to actually do the front end like that in combination.
but it's not all our surface mount. If you can see in there, there's tons of through-hole stuff on the top in there under that you can I Don't think this isn't going to be a fool teardown I Don't think I could be bothered to actually take that out because to get that out I'd have to get all of this top board I'd have to take you know everything out and really I just couldn't be bothered for this video. So I'm afraid you're going to have to go and have a look at the service manual which I'll link in down below if you're interested. It's got the full schematics for this thing.

really nice schematics real easy to read and the full PCB overlays and everything. And that's the beautiful thing about these scopes. They are easily repairable and if you are looking at buying one as I said, you know, having a shot for them on ebay then or some other options like Craigslist or whatever it is in your country, make sure you can get the service manual and the full schematics and the board overlay and everything else in there. You know the calibration and adjustment, nut procedures, and all that sort of stuff because if you can get that that, then it's really worthwhile getting.

If you can't get that, are you really taking your chances and they're not that easy to repair? or do a lot of that poking around if you want to fix the things. So yeah, just look out for that. but this one is quite a nice little up. My bodged switch there is not a hundred percent yet.

Yeah. I've got to I I'll lever that back into position. There we go. That's a little technical tweak.

there. There we go. Beautiful. Aha fixed.

Love it. For those who are interested in switch porn, here you go look at that thing of beauty and the joy forever. And yes, that is the horizontal time base. Fantastic.

You can see little marker in there going around in there wiping on those little wiper contacts. Ah Beautiful! Can play with that all day. really. I Don't think there's anything particularly you know, oddball or that custom apart from the gals and stuff and that custom processor type gate array on the main processor board.

But if you didn't want the storage function in terms of the analog part of this scope, I mean you could probably just rip out the storage board and this thing it you know still work perfectly fine as a dual-channel 20 megahertz, ax and log scope it, you know, here's a SL 304 6 and that's a an NPN transistor array. and well, you know that might be pretty tough to get for example if that failed, but hey, it's just a transistor array. it's just got like half a dozen transistors in there. If you really had to, you could get out, whip that sucker out and actually replace them with individual transistors and you know you can make up a little.
You know, a little vero board in there to actually replace that chip. You know there's some 7/4 Series stuff. and you know other things happen in discrete transistors which can all get a substitute for not a problem and various things even on the earth, even on the front end. I Don't think it's a huge deal, so these things are.

You know, very, very repairable. Not a problem at all. And as I said, real easy access mean you can access all these jumpers. Great test points.

You know things like every jump is a test point. Really, it's a you know, it's fantastic and full service, manual and theory of operation and everything else. Brilliant. Oops.

silly me. These two trim parts here I didn't hadn't looked at the bottom before but they they were. Of course there are I should have known they were these shafts coming out of course for your focus and your intensity knobs on the front so they go all the way back through to that back. CRT Driver board.

As you'd expect, and although this thing seems to work well, we're in here, we might as well measure some test points because, well, they're marked. look minus 12 plus 12 plus 5. What does that? 130 150 volts. So what we'll do is, we'll just have a look at those and see what we get.

Let's switch her on and you got to be careful when you're probing around these scopes. of course you're going to exactly what you're doing. The good thing about the design on this is that all the high voltage stuff is on the back here. so all this stuff on the underneath is that pretty or should be pretty darn safe to probe around.

So let's have a look here. Let's go ground and -12 shall we? - Twelve. Spot on, plus fifteen. Oh sorry.

plus five. Oh, four Point six, eight. Lights down a bit, but well, you know it's outside of that normal five percent tolerance, but obviously. um, it's still working and probably not gonna cry over that one.

Plus twelve? No worries, and let's go + 1:30 There we go. under the thirty volts, not a problem and a hundred and fifty. Bingo. All spot-on except that five volt rail.

but the five volt rail probably has a decent load on it with all the 5 volt logic on the logic board and stuff. I'm not sure where the five volt is actually generated on here. if it is coming from the logic board then that could be loading it down. Plus you got drop coming through here, so I would expect the five volt to be heavily loaded on this thing anyway.

so not a big deal and I can confirm that let's measure a chip on the 5 volt digital board over here. There you go: Four Point Nine, seven. Not a problem. So I think by the time it gets to the other board through all the wire and everything else, it's probably got some drop on that need down.

I Don't know it could be a secondary supply on that board. I'd have to dig out the schematic, but I don't think it's a huge deal about only the major thing I Found wrong with this as we saw before, Just a little bit of Dick Enos on the on the vertical attenuator there. and of course the Vernier doesn't seem to work. There's a little bit of play in there I can feel the indent in that one I can't feel the indent in the other one so there's something wrong with that.
But look at the Dick Enos on that and that's not uncommon on these scopes. Given their age, the contacts do wear out. Um, well. you know they can get a bit flaky and get buildup on the contacts and stuff like that.

Usually no. Sometimes if you just operate them and I haven't been operating in years, you just operate them and I had ten or twenty times or something like that. Not then they can come good, but this one still still seems to have a bit of dick eNOS in there so it really needs a probably do with a good contact. clean.

Unfortunately, many of these wafer rotary switches used in these scopes are often not sealed like you know, press sealed or or medically sealed or something like that so you can't really. Well, they can be very difficult to take apart and actually clean. Some are almost impossible, so we'll have a look on the bottom of this see if we can get in there with the contact cleaner. It tests a second channel there.

yeah, that one's that one's got some Dickie this Happiny bit of a Dickie knee there so we'll be able to fix that. hopefully. let's flip it over and have a look now. unfortunately.

ah to get at this vertical board, the top side of this vertical ball which holds both vertical channels I'd have to take pretty much most of the scope apart I think which was really quite annoying. But anyway, through here we can see that there's three different way, four sections there, one two and another one tucked up right in there. Sorry, can't get a really good shot in there. It's really difficult but they look like the sealed type I can actually see it's a bit of a pin going through there.

yeah, won't show up on camera but looks like they're two sides of plastic and they looked a really sealed. but anyway I will try and get in there with some contact cleaner and see if I can at least spray it through the shaft and then rotate and hope that it sort of gets in there or something like that. so it's worth a go because it's not contact cleaner can't really harm anything else so just get in there and have a spray around. Now the stuff I'm going to use is this: Elektra Lube stuffs which cleaner lubricant SW see everyone's got their favourite type and there's pros and cons of the various art tights, but this one will work pretty darn good.

So I'm going to get in there and have a bit of a bit bit of a sky as I said it. Kurt can't do my charm really and I'll get in there on that pot as well that adjustment pot for that particular channel and probably want to rotate it when you spray it as well just to maybe make sure it I'll probably flip it up on its end so that it so that it sort of flows down in the shaft cuz at the moment it might be just a lot of it will be just dripping off the surface. And here's a better shot. actually.
from the other side, you can see the three wafers in there and then the pot is up there. You probably can't see that, but oh yeah, there we go. You can see the pot up the top. there There it is that's the one that that's sucker that's not turning there.

so you can see that pin of the shaft which I pulled out before that goes into this plastic gear thing at the back and it's supposed to lock in place and then turn the pot which is underneath that. but it's clearly not doing that because we're getting no vernier adjustment on the vertical. So yeah, bummer now. I'm adjusting that vernier pot for the vertical on the front or you can see it almost turn there.

There we go up and you can see it slide out of the shaft, but you see the shaft slide out. It almost like it screws in to that plastic block at the back. But then if I keep screwing. of course it just does nothing.

and then I can't I can see a little wiggle in there. A little wiggle wiggle wiggle. But yeah, we're not able to turn that. so unfortunately I don't think I'm going to be easy able to easily fix that.

I don't think it's worth my time to crack this whole thing open and see what's going on there. I think I'll just leave the Vernier nonfunctional on the vertical channel. It's not a huge deal and let's have a look at that. Hey look at that that looks that looks much better than before.

I think we fixed that. No worries whatsoever. unfortunately. I can't really get in there to spray this one this dinky one, but we certainly fixed that.

Not a problem whatsoever. By the way, this particular stuff is our non flammable and you can actually spray it on live circuitry. but just be careful. if you're doing that with some other brand, this one you definitely can.

Now this one here is really hard to reach unless I rip it all apart I don't see a way to do it. So I've taken out the Vernier nod there and that just came out and check this out. Look just the right I can slide that in just the right size. so maybe just maybe if that tube is open in there.

I Can maybe get some switches if I'm lucky and perhaps we'll find out and check it out. Feel that now that we fixed it. Beauty. What a Bobby Dazzler Like a bought one.

ha ha. Sometimes you get lucky Murphy must be sleeping today I Guess so. Yeah, just happen to be the right size. although we probably could have just sprayed it in the top and let it flow down out.

all the jet just would have got in there. but yeah ah love it when a plan comes together and next cab off the rank is this component tester. We use these two banana plugs here is positive one here and there's the ground reference and just some alligator clips and well, we've got our dot up there, but we should be. Oh, if we shot those out, no, it should have got our line and it's not working.
I'll get a decade resistance box and hook that up and 1k. No, no, that's not working. Our exposition works the only control so they're going to work here. I Mean it.

Basically, it bypasses your attenuators. Don't do anything here. bypasses all of those bypasses your horizontal time base. absolutely everything it bypasses and then, no, it's not working my decade resistance box.

No note: we should be getting a yeah, we should be getting a line there at least for a resistor so that the component tester doesn't appear to be working. Let's have a prod around. I Mean here's our output. That's our output wire, go into the positive terminal on the front and the negative terminal of course is just connected through to the chassis.

So you know it's going to be this circuitry around here. possibly some of this, but most likely it looks like it's just a simple op-amp There is not, doesn't appear to be a huge amount er to that. So but look, we have a fuse. So although I did see I thought I saw the waveform shift a bit when I shorted it so that fuse there.

it looks like it's possibly protecting the output. Of course that's the component tester switch, so that just that switches that and somehow bypasses all the rest of the circuitry. So I don't see any visible signs of any anything blown up or anything like that. But I'm definitely going to check that fuse.

I can't see it right here. I can't see the filament. hang on mm I'll just check that out. Oh 2.4 Meg knew she's blowing ha ha.

So I've popped a new one in there. It was a 50-million fuse I'm all out of em 2:05 low-value fuses. so I had to use a half amp one or yeah, whatever. Um, it'll at least allow us to wear tests to see if the component test is working.

Let's give it a go. Tada, that is more like it. That's what we expect on a component tester. So oh by the way, the horizontal here.

if you turn it to farther to higher settings. two seconds per division and five. they're only for the storage mode, it tells you there. so if you go in here, it actually flashes.

It says all we need to turn on storage mode So all that sort of jazz works. But anyway, that's what we expect. If we shorted out, we expect the line to go completely vertical. And it does.

And of course, if it's a resistance value, we will get a different slope of line so we can hook that up to our decade the resistance box and we can have fun. There we go. You can have some fun now playing around with that so we can go for five. There we go down to 100.

Ohms. There we go. 100, 200, 300 Boom Nice. That works a treat.
And if we hook on a capacitor, we expect a circle. So I Got a 22 mic here so let's give that a go. And there we go. Haha.

Beautiful feel. that and a 4148 silicon diode. Let's give that a bill and we expect a right angle. or it depends on we know which are quadrants is in.

Gun depends on which polarity we have it. There we go. Bingo! and if we reverse our polarity of that diode. Aha fantastic.

And if we use a silicon diode with two series connected 10 might caps to give us a total of five mic, Let's have a look what happens. I Think we'll get ourselves a letter. the letter: P for Platypus Beauty So that folks is a perfectly fine 20 megahertz dual channel analog scope analog CRO Everyone wonders what CRO means Cathode Ray Oscilloscope that's what we call these things here in Australia that's strong for a yeah, a classic. got CRT Oscilloscope Crowe No worries and that looks like it works.

a treat. Haven't fully tested every single function, but you know it's pretty darn good. I Like it. Perfectly usable scope for a beginner.

And speaking of which, if anyone wants this thing, please leave a comment in the forum the forum thread which will be post below the video you must post in the forum thread if you want to give me your bleeding-heart story about how you don't have a scope and this and make a wonderful first beginner scope for you and I'll send it to you, but only for Australian residents only. sorry these things are expensive are they are heavy and expensive to work ship overseas so only for the Aussies out there. Sorry about that. I'll get lots of complaints no doubt, but I'll give this sucker away once again.

sorry this didn't turn into a repair video. I was hoping that the damn thing would not work that. I when I got it so that I can do it video fixing the stupid thing but unfortunately not. Maybe I should have like a I should actually whack on a blindfold and then just you know, randomly pull out a component or you know, short something out or you know, maybe spill some drink inside or do something horrible like that and make it fail.

But and I can't do that to the poor thing. So yeah, I got no like at all. it works. So anyway I will give this away it to where somebody in need of a good and long scope because like all those people out there complain, you can't get one.

Well I'm giving one away. So there you go. Fantastic! Um I The only thing which didn't seem to work at first was the auto trigger functionality of this thing. It seemed to you know take some time to warm up but I haven't hit that again.

I've turned the thing off, left it off and turned it back on and it seems fine so maybe there is. You know, some sort of you dried-up electro or something in there is not that great. Although to be able to track it down um, you know I've got a I've got to make it fail I can go in there and have guesses and things like that, but that's no good. That doesn't make for a good good repair video at all.
You really need a solid fail fail condition really to actually do that And the trigger comes. You know, auto trigger comes straight back on. and of course the normal works just fine. Check that out.

There we go. And the time bases are spot on. By the way, for those wondering there it is. 10 divisions at one microsecond per division and times 10 mag.

That even works a treat as well. Where's the horizontal position? there? It is. every scar. It's different.

and there we go. it spot-on no worries. But anyway, if you want to discuss it, the Forum is the best place to do it. And well, yeah, there you go.

None And and in it. I Got it for 19 bucks that's in Australia and they're impossible to get here apparently. Catch you next time you, you.

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By YTB

20 thoughts on “Eevblog #502 – $19 hameg analog oscilloscope”
  1. Avataaar/Circle Created with python_avatars ahmadamir says:

    Hi how to measure the high voltages with oscilloscope but not damage the oscilloscope? For analogue oscilloscopes

  2. Avataaar/Circle Created with python_avatars Mosaic 2008 says:

    Do oscilloscopes have screen burn-in?

  3. Avataaar/Circle Created with python_avatars caspar valentine says:

    the uts building is not ugly! i like it! it looks functional

  4. Avataaar/Circle Created with python_avatars Coptertim says:

    I like the Hameg scopes because most models have built in component testers. Not a bad inexpensive starter.

  5. Avataaar/Circle Created with python_avatars John Mullee says:

    92 is ahem cough uh 31 years back now

  6. Avataaar/Circle Created with python_avatars A Aa says:

    Can you use it to turn your voice down a few octaves please?!?! 🙉

  7. Avataaar/Circle Created with python_avatars rene0 says:

    This is very similar to the scope i bought last week, a HM 203, and i'm very happy with it although the x-axis looks slightly off calibration, which i'm not gonna bother. Last service sticker only a few years back. Been watching Dave for years, then suddenly youtube is clearvoyant and pops up an oldy 🙂 (that, or google knows all including passing my search for a manual to yt) edit btw, payed way more for it, a whopping 35 minus 5 bargain skills = 30 euro's, without any probes so add another $13,95 from amazon. Still so worth it, it goes way over this 20MHz. (-edit2 didn't want to borrow probes from work as before you know borrowing becomes permanent.. will be fun to match this one vs the digital '200MHz' i got over there. This scope goes like 'well, it's only 20MHz – the trigger only goes to 20Mhz and it's over 6dB less signal over 25, but you might see a 30MHz or more). Vs the 200Mhz that apparently has a 50MHz analog limit or so. Anyways, happy either way my hobby equipment has been upgraded.

  8. Avataaar/Circle Created with python_avatars max wang says:

    Bob’s your uncle!

  9. Avataaar/Circle Created with python_avatars Shaun Tremayne says:

    My hm605 is still using it today from when I purchased it in 1988 and the HN205-3 which I bought 20 years ago is also still working.
    I love the component tester.
    I do have a rigol digital

  10. Avataaar/Circle Created with python_avatars robert steentjes says:

    Hallo EEVBlog do you also buty on Ebay?

  11. Avataaar/Circle Created with python_avatars K.D Electronics says:

    Excellent video!
    For the red cal button on the volts knob you should use a tiny allen key to screw the allen bolt that hold the shaft . It was loosen. Thats why it wasnt able to rotate the potentiometer.

  12. Avataaar/Circle Created with python_avatars Khyle Atkinson says:

    Just scored a fully working HM305 from the Uni skip bin where I live in Newy. Just starting to learn how to use one.

  13. Avataaar/Circle Created with python_avatars IndianTechSupport says:

    you couldve connected ch1 via bnc splitter to external splitter

    edit: yeeeeh, i watched it to the end

  14. Avataaar/Circle Created with python_avatars IndianTechSupport says:

    19$ ? mine was analog and 90$ in germany

  15. Avataaar/Circle Created with python_avatars NH3 says:

    I bought a 30V 10A lab power supply and i got this scope thrown in with it. Payed a total of 35 euros

  16. Avataaar/Circle Created with python_avatars TechDoc.Repair says:

    Hey I saw on your forum you restored an HP 4328A milliohmmeter . I just got one with a bunch of old miscellaneous equipment. Is it worth checking out and restoring?

  17. Avataaar/Circle Created with python_avatars john amptech says:

    If the wafer switch has a clear plastic cover like the switch porn wafer and the bugger is hard to remove whatever,maybe a hot probe could melt a small switch cleaner injection port,maybe perhaps.

  18. Avataaar/Circle Created with python_avatars Keri Szafir says:

    Got an earlier model (HM204), been using it for over 10 years I think and gotta agree that they're lovely analog scopes. Joy for ever indeed. I'd still love to get a Tek, preferably tube one.
    The component tester works similar to Mr Carlson's Lab curve/signature tracer, drawing the I=f(V) characteristic for the part. "P for platypus" LOL.

  19. Avataaar/Circle Created with python_avatars Garry Chauvin says:

    Best of others

  20. Avataaar/Circle Created with python_avatars zvotaï svfi says:

    "joy forever"

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