look there's some scope up a week or two ago surplus sale it although the nameplate says it's a 544 a it's actually a 744 a now these are pretty decent scopes and even now there's still decent scope they this model came out in 1995 or so and it was one of her scopes that had inst of you which is on the nameplate should be more similar to this nameplate the 754 see the top one it actually has 500 megahertz bandwidth and 2.5 gigas apples unlike here where it says it's 1 Giga sample two gigs yeah to get a sample sorta should have said so um Tech one of the first to come out with this and it was a pretty big deal at the time and its main selling point was full feature spell plus it could detect past glitches and it didn't even know anything about the fast glitch is all you needed to know is if there might be a glitch out there and it would do the rest and get this thing our on this thing actually cost me 75 bucks no one could get it to turn on and that's because someone I left the cowl switch in the back switched to the memory unprotected mode which won't allow these to boot up so we'll do all it would do is just sit there with all the LEDs on or not show anything and you can see that it's a 744 a it's not a math option what does that go back to that ship status counter here yeah so I think the 13 as a color display the 1f I can't me know if that's a floppy drive or about the math option and then the 2f is either the floppy drive or the math option or they the communication so I just don't remember anymore but anyway the 1m is the 1 Meg samples of a memory for a long acquisition so now shouldn't be this you put a probe on this these are a great starter scope I mean out to 500 megabytes of megahertz you can get rid of the get live without some of the decoding serial decoding this sculpt is as good as any and for the bench for the bench so what I've done is I've hooked up a QuickStart 8 board which is demo board for the 7000 series on PBS's and we'll do on auto set on it and we have a regular squirrel wave here it's looking to imagine on it let's see let's do frequency so you can see it's not a particularly fast measurement and you can see the waveforms wiggling there a little bit it's this class of scope any of them whether it's an Agilent scope or a Laphroaig or Tektronix of this era without fast acquisition mode is probably acquiring around 150 waveforms per second of course sure I can't perceive that your eye you know like we go to movies and watch 30 frames per second that kind of thing same things going on and still so they end up having to put waveforms on top of waveforms but typical sampling or update rate on the screen would be about 150 waveforms per second or the equivalent some scopes are far less and 100 others will be up to 200 but that that's about the limit of it and so you get a square wave like this it's on your screen it looks fantastic you think there's no issues with it the in tech came along and they said hey there's a lot of dead time you know I mean if we're only catching capturing this square wave 200 times times you know 200 times 2 times however many waveforms are on your screen you know say 3 and a half you're not seeing too many generations of 180,000 kilobits per second so they came out with the instant you which I just activated instead he turns on let's see if there's a problem i glitch thing doesn't always do this glitch in but we'll see try different village well no let's leave it there and then I happen to test the village before I get anything okay so we got glitching going on there so let me let me turn that off so the same spew again only this time you see all the way form of activity going on there 318 kilohertz yeah but the waveform itself looks okay and since we're only updating I'd say 200 times per second max right now 200 times the number of waveforms you see on the screen is about how many you're actually seeing per second out of 318,000 degenerations so we're missing a fantastic amount of the waveform that's occurring before our eyes right now we're hardly seeing anything that's going on but you might be thinking okay I'm gonna test my power supply here will it have you everything Lascaux sure okay let's go on to the next connection point to see why it is our system crashes crashes after 15 minutes then some guy from tech comes up with this scope and he says give this one a try and anything gonna happen catch any glitches oh crap there's something wrong with our circuit and so that was a big selling point of this and the other manufacturers would been in a real pickle liqueur at the quraían Agilent didn't have anything Lacroix immediately came out with something that kind of looked like it was doing this but you had to know what the glitch was to trader on and once you know what the glitches and then it's not really a problem anymore because if you know what the glitch is you can always trigger on it you can figure out what what you what your trigger parameters have to be to trigger on it so then it's not a mystery and these scopes are sampling fast enough for they can actually accurately draw whatever they see you know you know this isn't under sampling right now it's over sampling so it can see the waveform and what this is doing is Tek claimed 400,000 times per second it's updating a waveform database on screen and any anomalies that's captured in one of those 400,000 acquisitions just shows up on the screen as an infrequent event I'm so the scope is constantly acquiring waveforms constantly displaying them it's a circular database thing always writing always really never really stopping although there are holes in it I don't know if you can really believe tech with 400,000 waveforms per second I think it's a marketing thing by the by the much later 754 DS for example I think they were talking about 200 waveforms a second or 200,000 waveforms a second not 400,000 like this one so it's not likely that they went backwards in performance so I'm not sure where that came from there might be a some sort of reasonable explanation but that's one of the important things about comparing scopes that can do fast acquisition is you really have to sit them next to each other and see how they're doing because so much of it is marked me in terms I mean are they actually acquiring 400,000 waveforms or are they going or are they shooting each way from that they capture into a to a fast template to see if it matches the template if it doesn't and it gets stored and do they count all the misses as acquisitions I mean those are totally marketing things that are app happening under the hood and you really have no it knowing look that true acquisition rate is all you know is once people pick up the problem faster than the other but for the hobbyist this thing is as fast as anything you're gonna get on a hobby budget new it's you know it's probably much faster in fact so on this scope is definitely something to consider the 700s our derivative of the 500s it's a color screen this is a much different design from the earlier TDS 500s and the 500s the earlier scopes had a huge problem with their capacitors the electrolytic capacitors that all the boards were just terrible when they were put in they're all defective you're fool to even turn your scope on unless you verified that they've been replaced or you're in the process of replace them you never want to turn them on with the old caps but when the 700s came out and the 500 bees came out they were a new design they'd done away with the capacitors the electrolytic completely on the acquisition board and gradually later on they got rid of casters on the other scopes and thing is with the early skills in the capacitor problem it was leaking how electrolytic some things were shorting little you know data lines or even burnt-out and it's unpredictable you don't know where the failures gonna be you just have to troubleshoot the whole scope recently there's schematics of came out for the five hundreds and the five hundred is there on ebay RF media has them they want like twenty-five bucks there of course we've already hit the internet too as files that you could just simply download I don't know how that works and I'm sure tech never release that manual to the public domain but on but the copy my way may have ran out on it I'm not sure how those things work you know so I'm shark media doesn't want you to copy their work but it's not really their work so so on layer scopes like this one this scope would be equivalent to the acquisition board is the same one that's in a five forty be the this scope is pretty much the same as a 750 for a I'm not sure what the difference is the 754 C will transition from in stimu to non-interview faster than with this one well so you know we have that nice-looking square wave again if you had a 754 D you would the transition would be almost instantaneous and you'd be wondering what's wrong with the 744 a well that's really about the difference in what you're paying for now the 754 D for example probably had applications that you couldn't get on the 744 a I mean it did for sure and it has to in memory option same amount of memory I think on all the boards but that it had a 2m memory option all the leaderboards anyway so but aside from that most most of the like application software that you can get for these yeah I mean probably isn't it isn't some people want to use you just want to use the oscilloscope part as a hobbyist and these scopes are in that regard as far as an oscilloscope that goes out to 500 megahertz as an oscilloscope these rx scopes any of them things that go wrong with these the the earlier scopes the ones that aren't like this the older architecture with the crap your capacitors the attenuators almost never failed on those but on this family scope and later it's always the attenuator if there's an acquisition problem lesser than physical damage to the board it's always virtually always gonna be the attenuator if there's an acquisition issue the display will get tired it can get bubbling on on the screen that is the index matching gel back there is failing pretty much after to replace the display I've heard of people take them apart clean them but it's really hard to take those things apart I've done it before the drive very often if it's a dark it's probably the CRT but it can be the driver board that fails as well sometimes they'll start making a buzzing noise and that'll be an issue for you what else power supplies die on them sometimes sometimes you get lucky and the power supply died when the thing was young so you fix the power supplier swap out a new power supply and you're doing well I think that's 7:44 you should be able to get for you know well under 750 probably four or five hundred maybe as a fixer-upper if you find out the attenuator that's gone bad on these the attenuators look like that and there are a little there a little um ceramic PC board and they shatter if the smoke gets dropped hard enough the other thing that fails on them is is let's see if we can do this the solder at the feet will sometimes fail you can't see it you can't tell but you can um you can take a soldering iron and you just reheat it and it works fine let's see I have a print here somewhere that there's some ideas on the attenuators done a little research over the years so there's your attenuator that this is your cheat sheet that tell you how to kind of troubleshoot and zeroing on stuff if you want to know which is your your um 50 mega ohm 1 on 1 mega ohm attenuator thing you know relay for it rather distract us think about something I forgot to mention earlier so I mean you see at the very top on the left here I'm telling you that if you get an error log thing that says X failed at you know I forget you'll you'll recognize if you have the problem X feel that be oo 1 type errors the X is 0 is channel 1 1 is channel how's that work one is channel 2 and 3 and so forth and that can spate save you hours and trying to fix this thing you know so a little something that I'll help you figure out where your problem is on these things docile work that I will never have time to do this so so I worked on this little project kind I didn't didn't ever test it we get the photo tips that's ridiculous but anyway that the Oxford repair on a relay I took Tom this is a busted attenuator that I soldered just together so it was still one piece but I took one of the relays apart everything shakes this so and I figured out that if you stick a straight pin you know right there are on each of these relays you turn this one over right there if you take if you stick a straight pin that looks like this right there on the relay you know just you know what you used to put pictures on the wall or whatever you take the aux it this stuff squirt it in there and who knows if the relays fail and even like frequency especially in your Calabrian a lot of times you can see that you know it's failing at 500 megahertz that the 1 millivolt setting or something or color 10 milli will not not one but um you know you might be able to know if it works let me know I'll tell the world news that he'll be able to fix that problem but there the relays are the main problem on these stuff sometimes the power supplies die if you swap a new relay in I'm as a hobbyist you'll you probably can't tell even though your calibration is will no longer kosher the scope won't know that if the new relay you know passes spc which you know that's where you're failing where your problem is where you suspect you have a problem as your SPC's failing you can um you know if you swap a new relay and in it or not relay could swap a new attenuator and the scope you won't be able to tell if it passes SBC you want to be able to tell if there's a signal differential or you can calibrate I did a couple of videos on that you do and I think that software is kind of getting out there so anyway TDS 744 a pretty good scope the tech makes active probes for these of course they used to they're still widely available on ebay they're risky you want to have a right of return it'll pay too much for them but the same we'll use an active probe you can get decent active probe for under 150 bucks and if you need that out all hobbyists to you but if you need that that's pretty sweet you know I'm you can get one of the the newer agile types Phillips or tech type stilts or I should guess it's keysight scopes or or would be another Lacroix and I mean if yet buy an entry-level still from them the active probe might be as expensive as a scope if there's even one available for it so so this can be a a great low-cost machine out the 500 megahertz it has one mega ohm termination at the inputs it'll do on 50 ohm you know it's just an all-around you know this was a performance built back in 1995 but the design and many ways remained unchanged in 13 until 2000 when they start going to the windows-based scopes but I bet that you could take a TDS 3000 or no you can't can't and I bet you can take a DP or MSL 3000 or you know some of the keysight scopes even and this filled for the hobbyist is gonna capture those glitches as fast as the other guys are they might not this thing may not be literally as fast as little scopes but I'm for the hobbyist this thing will be just fine and if the 700 DS of this they um their displays are really fantastic I mean that way from activity really jumped up I don't know maybe a software think that on so we closed my book there's probably some other things show someone since I don't really work on these all that much anymore these scopes you can there's some information on the acquisition boards on these are reconfigurable I mean like I say this this scope will work just fine on a 540 B let's go the acquisition board will do just fine you took that acquisition board out of 540 B it stick it in here you change two resistors which dissipate this book just include you on then now the scope thinks it's a seven like on this one it be a 784 and a 784 you'll have a little more bandwidth in this scope currently house but once you get out past six hundred megahertz or probably five fifty megahertz you're probably going to have to calibrate the scope to 784 D and although your attenuators are all one gigahertz attenuators they're all identical these these will work on all the differences built so with the power supplies I'm talking about five hundred B's and later the 700 is the non 700 a all of those in later and the 600 B's and later the power supplies relays everything is all interchangeable you know so I don't think the black might display will work out too well but I think you'll get a trace I don't recall I did it once but I can't remember what the outcome was but um the issue you can run into into converting one of these to like a 784 that the even though all of the attenuators are one gigahertz rated not all of them can be calibrated out that far and it probably has to do with the age who knows maybe if you do the dioxide thing let me know if the diauxic thing works you know at least do me the honor of sticking it up posting a reply that it works out of curiosity for me so um so let's get back to my cheat sheet then that from seon go do that teenage these do have an app console port on them they keep there's information on the tech user forum about doing the console port thing actually how much I use it this is a genuine Tektronix console port right here genuine made by Tektronix for Tektronix scopes like replaced the capacitor that was the earlier type the pastor's that's how replace the capacitors by the way I don't use the SM DS and this worked great on the tech scopes this plugs into the console port on the board now the board is it's talking to you when you have this plugged in the scopes talk and here you're going when you're doing SPC and the channels failing at st. hate channel to isn't doing it the duty or something spc information keep in mind that the signal path compensation is affecting all channels at the same time so a bad attenuator can cause all of your all of your all or some of your different attenuators to appear to be bad but sometimes you replace it for example channel 2 and magically everything's all good so and a good attenuators probably worth 100 bucks on ebay i would think that if the trick is most solar don't have the slightest what they're selling till they don't really know adjusting your color display to get a more life a little bit of life out of it we got something like all interesting your color display posh in here you just that thing one time it just kill the display a lot right on the side will touch that one anymore brightness this is a brightness control the many of these controls you shouldn't really be adjusting all that much I mean your your risk your thing just simply dying on you you can look at that if you want I'm not sure that I really use that information sometimes I was just digging stuff out and then at future time I found a better way you know so it wasn't necessarily uh something that that you would want to do but you can try to read this on your screen I think this is gonna be filmed in fairly high resolution you might be able to read it couple years ago there's no way I was showing anyone of this stuff I've got like two cases of these displays similar I'll have to sell them they're kind of gold but all that much anymore stuff so when it all on its gulps like with this scope you're gonna find some of those electrolytic capacitors on some of the other boards you're on communications option in the back you can optionally replace them I haven't seen that there's a real problem with them but I used to always replace them as the guys posted actually on the tech forum that you could just simply wiggle the capacitor first mount capacitors off rather than to soldering them some boards of capacitors on the earlier scopes were really crappy board you know I mean what you saw on the pads of the surface-mount electrolytic capacitors could be anywhere from something look brand-new do black and crusty and the dirtier nastier the pads looked the more likely this the the trace the circuit trace on the board was gonna lift when removed the capacitor so I tried you know low-temperature disordering methods I tried hot air I tried tweezers hot tweezers and this is the way to do it is you you stick it down on the the capacitor and you go from pole to pole your roll pushing down pull the pole not this to pull the pole there's a guy Andy on not eBay on on YouTube that says to do it like this well I can say as I've done more than 2000 capacitors of this way so um and check this tool out I needed I had another I was using this but it just didn't do a very good job of grabbing the pastor so I needed to find something like this surplus from Tektronix yeah well you know so maybe I wasn't the first guy to figure that out after all it's not anyway I'm doing a lot of ohms so I think I'm coming to an end of this the scope itself does everything you would expect scope to do now we're just a regular oscilloscope I think in fast acquisition mode this is doing like 500 screenshots it says 500 points is what the screen is this thing let's see if I can how do I get acquire menus over here all it's still an instant so you know we can switch it to dots and I've seen actual actual samples it's an assistance you know if you've got a scope that isn't a fast acquisition this is what you're left with the fine glitches and on this particular glitch it's three to five minutes typical on this class with skull if you're if you got one of these things and you think the tech this thing could take an hour four hours to find glitch I'm not kidding it's really ridiculous so that thing's a big step back in technology as far as fast acquisition but it's a teaching scope you know give them that so um you know so much apparently ends to be right there - this thing has 500 megahertz bandwidth interleave so if you got one channel going you can have up to two Giga samples per second forget what it's saying up here this isn't the correct bezel on this thing so um let's see I don't think I'll apply a signal but on I'll transition out of it so we got one signal going here that's it so it does tell me sample right so sample rate is on the upper left of the screen so on to give you samples right now so that's how fast it's sampling out I'll change this down since infinite persistence so I'll start get it going again okay so um now if I turn on a second channel which I just did okay because it's doing that it's in the what they call that et thing it's um I've gotta do Repetto turn repetitive signal analysis off okay so now I'm actually let's just let's turn off that I do an infinite persistence get rid of it well anyway with two channels running you see that our sampling rate has changed to one taken samples per second now I'm not sure if three if it'll stay I'm not sure if with three channels will it stay out on one that goes to 500 so on this one one channel run you can have out to two Giga samples per second two channels running you have any two channels running you get one getting a sample percent second is your fastest sampling rate and then beyond that any three or more it's going to be 500 mega samples per second we have some so evenly else setup that's what I want we call a factory set up they do I don't work with this scope much anymore this thing's more nostalgia than anything come on didn't I tell it all sorry about that this thing again is a lot slower and screen transitions and what you would see in like a 754 D if you were gonna get one of those instead so so if I push a button it doesn't do anything and I just sit there it's because I'm not expecting that necessarily do anything so um so I can take this guy turn on a signal generator and a half of the drag the circle signal generator closer unfortunately so set I need to change the signal generator nothin oh I don't have it sent doing that signal thing try that it'll sit so there we are but I want to do acquire the one turn of repetitive off so okay so repetitive it's not done it's stuff on ship you know this this these are just samples so I think I can do single shot how do I do a single shot on this skull digested here so single shot to give you samples because it's using all of them what happens if I bubble signal up to two hundred megahertz and we spectra loose and bandwidth fast only but now if I turn repetitive signal back on see what happens there the time is on single shot soon our amplitude is this so you see it's kind of putting it back together pet it it off a little more real time because it's not doing as much it's not doing as much you know internal magic to these things to the signal figured ease and repetitive waveform with them this thing repetitive waveform it's not actually doing a sample but would it be if it's one getting sample of you know doing a sample every um nanosecond and if it's to be a half a nanosecond but um this thing it's doing random repetitive sampling so it you know so if using two clocks to the sample in between the spaces as well I told you give you samples so I'm on this sculpt if we go if I set the generator to ten megahertz and just back to ten just ten megahertz bring it back to ten okay so I'll measure let's do get it done rise time but let's do one of the RMS values are a mass and let's go back to the first page mystic frequency so we can see that I got a ten megahertz signal just think turn okay terminations wrong for the signal generator that's may have affected Phillip earlier in what 50 ohm okay so now we have a signal that is look good got a signal that's it's a little bit under this signal generators not heated up you had amplitude bump the amplitude up to show 100 millivolts right about there so our 3 DB cutoff point for bandwidth would be 70 point 7 so let's start start bumping our on frequency up let's go down 100 megahertz first so I'll change the scale just to keep it on-screen nice 70 80 90 100 megahertz now I'm gonna take steps and doing this with the control now I'm gonna take steps and I'm 100 megahertz and so we're watching for our 70 point 7 p.m. at 600 megahertz right now so this thing easily exceeds I'm stepping by tens well right there so that's pretty close to 610 is my fruit actual frequency that the generator is putting out so that's the bandwidth on this if I turn where things get a little funky on these is if I go back to the acquire menu say so real time only so now if I turn the second channel on it starts having some serious problems because it's not sampling as fast and it's having a little more difficulty it's having a little more difficulty picking it up let's look at I true - man you make sure that that's stolen channel one lets me set to 50% so that really screws things up so they're not completely infallible but again if I was to go back to my acquire menu I'm not really looking for glitches here I'm just looking at what's what's going on for the most part and so if I turn on enable so that our it's able to figure it out so real time it's you're taking a lot away a lot of the magic at the end interior the scope and it's just raw sampling power and it's not it's not giving things out so much but if you start adding channels to a channel 3 we've added to it it still is able to resolve what you know the frequency and you still have your bandwidth so these are pretty cool scopes actually they're good scope for the hobbyist you know prices on these things on eBay you know I mean it's always upside-down I mean you know I you know I I see what I would think our deals all the time for three four five six hundred dollars but you may have to replace an attenuator these attenuators are the Achilles heels of these you can get displays you can put else I've done plenty of LCD displays right 640 by 480 display in there and use the v-j connect from the back and route it inside to the display and use a buck converter 24 volts DC that the Spill passed to 12 volts DC if you roll your own it might be kinda noisy seem you want to buy one from China as much as I hate to buy stuff in China like that but um they're actually better than the homebrew ones I did where it's pretty minimal and effort into them but um so display issues can be a problem 10 you eight or you may have to swap out an attenuator you know you have to get the purse what you got to do with these to test them is is for example vertical menu when I have a 50-ohm signal coming in not working at all let me see this let me go back to ten megahertz so it's trying these other channels oops didn't do too well maybe I did just was slow so I go one mega ha meow that's telling you relay is working you know you're getting about twice the amplitude when you're in one mega ohm versus 50 ohm which was a lot more of a lot more current control through 50 ohms so what's going on there what about AAC while this this isn't a very good scope or signal try that on since it's an AC signal but um you know if you had a decent you know it's a signal generator so you know there's gonna be virtually no AC offset but if you had an S signal that was up like that you press the AC button you'd expect it with Center on the screen that's telling you I realize doing its duty and then ground that's what you kind of want to see so you want to do that with all the channels of a new scope that you get in you also want to run the SPC which I won't do now because that'll take a long time but um but it's shift utility and then you got your system controls and we go down here you compensate signal path it should pretty much compensate and pass short pass here every single time or block the screen there every single time you'll have also an error log you look in your error log and see how there's nothing in that black square I've had people accuse me that they I wasn't showing there that is the error log right there there's nothing written in there saying blah blah blah blah blah floppy drive fails no big deal you get a disk cleaner kit that's a disappointing kit just stick this in there put some that juice on the disk itself run it a few times and magically a floppy drive starts working but if there's mass storage errors that's your floppy drive that's all who cares if you're plugging in an act of probing you're kind of screwing with it and you're just not getting it right you'll get some error pearl bearers who cares you know you just flew there our log was playing information out there about the other log or how to deal with it so you'll send the air you're a lot clearer if you man it's something like that air log there I think with your Jeep head and then of course the scope should be able to get through all of the diag arrows in that there it should be able to get through all of the self tests you just don't like that but I won't waste your time with that so anyway you check your your chin or attenuators on each channel make sure that you have a ground you
