EEVblog #502 - $19 Hameg Analog Oscilloscope

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

Channel: EEVblog

Views: 282,489

Rating: 4.916584 out of 5

Keywords: hameg, oscilloscope, hameg oscilloscope, hm205, hm205-3, analog, combiscope, tektronix, review, teardown, repair, how to, component tester, horizontal, verstical, power supply, measurement, multimeter, troubleshooting

Id: ghQYRv68qrU

Length: 51min 41sec (3101 seconds)

Published: Fri Aug 02 2013