TEKTRONIX TYPE 503 Electrical Troubleshooting And Repair!

hi everyone welcome to another episode of Mr Carlson's lab today we're going to troubleshoot and repair a tectronics type 503 oscilloscope let's see what's wrong with it and let's get it working again let's get started here's the tech 503 oscilloscope fantastic little scope it's kind of the Mini version of the larger ones like the 547 and the 531 and 535 all of that particular 500 series this is like the the little squished down version of it it is really neat uh the 503 is a relatively low bandwidth scope I believe it tops at about 450 kilohertz but we might be able to stretch that with the sweep magnifier here just a little bit we might be able to see some faster signals we'll try that out here in just a little while so even though it is a little bandwidth it's excellent for XY display if you want an XY display scope that's very accurate you know accurate on the screen to the graticule you definitely want one of these things kicking around and you can find them for you know a pretty decent price nowadays so completely separate gain adjustments on both vertical and horizontal section both a positive and negative inputs on the vertical and horizontal section is everything an oscilloscope should have you know nice triggering section it'll internally trigger externally trigger trigger off the line uh you know you can light up the graticule on the front here intensity Focus you know all the stuff that you need to have an oscilloscope something like this honestly is uh great for a lot of troubleshooting even though it's a low bandwidth scope once you know how to use these things you can test a lot of higher frequency equipment with it it's all about the technique so I'll get into more of that on this channel here I've done some stuff on that in the past but I'll get a little bit more in depth in the future here and show how you can take an oscilloscope like this which you can probably pick up at most ham radio swap meets for 10 or 15 dollars no kidding and uh use it for Effective troubleshooting and not only that it's got lots of nice tubes in there it'll keep you warm in the wintertime so let's see what's on the side here it's in pretty good condition that you know it could use some touch up paint I've yet to get some tech touch-up paint I haven't done that I need to go get some a tin of the stuff mixed up and I can make these things look like brand new again it has the you know the usual abrasions from being slid in and out you know beside other equipment things like that and you can see here's a nice little abrasion on the side here so on the back side we have it has the newer handle too the older handles used to Decay and fall apart these ones here hold up over time very very well nice solid handle so when I have a really nice old Tech scope and I've got a bunch of old wrecked Tech scopes with nice handles I do a lot of handle swapping so I'll put these nice newer you know uh I guess you could say non-stitch type of handle onto them and these last the duration it's 117 volts line cord on the back a little nice line cord holder so you know what let's uh plug this thing into a variac put this over here and uh get this thing going all right it'll get the variac and everything all set up and I'll be right back I have the tech 503 plugged into the current limited isolation Transformer and variac Supply so what I'll do is I'll turn the scope on nothing's on over there yet and what I'll do is I'll move you in just a little bit here so you can see this just a little bit better the bulbs in the top maybe get it all in the in what's going on here pretty much there okay so now this is in current limit mode up here and down here I haven't turned anything on yet and the variac is right down so what I'll do is I'll turn this on so we really have nothing going into the scope so the bulbs are in line right now so what I'm going to do here is turn this up about three quarters of the way and this is very heavily current limited by these bulbs right now and they started out brightness you can see they're going down just a little bit which is a very good sign so what I need to do is watch those bulbs these are very dim at the top here so I'm going to turn this up just a little bit because there's really not a whole lot of brightness and the camera that might look a little brighter than it actually is so they're kind of a dim orange color over here I'll move that up so you can see that just a little bit better so they're kind of a dim orange color and I'm going to let this sit with the scope for about oh 10 or 15 minutes just to make the capacitors comfortable inside this scope I'll be right back about 20 minutes has passed at this point now what I'm going to do is turn this right up to the top which isn't much different so these Scopes they pull quite a bit of current so when I flip this through switch it's going to bypass everything and give the scope full line so what I'll do is I will move you down to the scope and I wouldn't want you to miss any action here so move this down here and I'll back this out just a touch all right so everything's on we're ready to go so what I'm going to do is I'm just going to flip that switch and see what happens on the screen here there we go see the Gratitude got nice and bright oh I do see a DOT and it's zipped off to one side or somewhat off to a good start look at that there's a trace on it that's actually looking pretty nice typical Tech scope type of Trace Pencil Thin so on this on the camera it's blowing out just a little bit so the cameras are very sensitive to this so this is very dim on my end but it looks pretty bright on the scope I'm looking at it in the monitor I can I can't hardly even see that but on this camera it's pretty visible so as you can see at least I can see on the camera it's uh as you can see Pencil Thin right you can go up to Center Line adjust the focus you can see that's what mini Scopes look like or like that but as you can see with this I can almost disguise the trace behind one of the little etched lines here if I move this up or down you can actually see it passing the line at least I can on my end anyways so Pencil Thin Trace beautiful so so far so good give it just a bit more intensity so that's about standard brightness so I'll turn on one of my signal generators it's just an audio signal generator and now this scope here has got that earlier type of connector on it most modern Scopes have B and C's on the front this has got that BNC PL 259 kind of deal so I'll put the conversion on here or I should say a PL 259 so239 kind of deal so this converts that to a b and c standard fittings you find on the back of ham radios and CB radios and things like that right they're great connectors don't get me wrong I like these I like these a lot better than the other ones that they used way back in the day with that look like a relatively large BNC connector uh what are they called n connectors I believe if I remember correctly so anyways I'll plug this in put that on and we don't have anything now turn the brightness up oh we do so it's a little bit too much vertical gain fancy okay so let's adjust the time base here this is not in its on that would be calibrated yes yes but not kind of slow things down here and I can adjust the focus Just a Touch it's nice and sharp let's see if we can unlock this with a trigger we have no trigger it is on internal yes external in line so line external internal so so if I put that there and I move this around it should freeze this and lock this so that we can see this so if I move the trigger around it should lock that and it is not that's rerun there and this is should have found it should find it right around the center mark so it doesn't have any trigger so that could be kind of an issue if you want to lock onto signals so a lot of people have asked me in the past Paul can you explain the trigger system okay so here's a very easy way of explaining a trigger system in an oscilloscope you're standing on the side of a road and a car passes you 200 miles an hour so can you give me any details about that car that just passed and you're like well it went too fast I can't see it it just it was a blur same kind of thing with an oscilloscope now picture yourself in a car traveling at 200 miles an hour beside that car at 200 miles an hour you're moving at the same speed you can look over at the car you can see the driver you can see if he's shaved in the morning and you can tell if he's got a steering wheel cover on and you can you know you can tell all this kind of stuff right because you're you're right beside them but you can see you can see there still might be a bit of movement you might speed up or slow down you know so you're going to probably be doing this at 200 miles an hour until you have an arm that reaches over and clamps onto the other car now you're locked together so when it locks on to that it's like locking onto a signal so right now it's like this is a 200 mile an hour car right and we can't we can't really tell what this is doing we see a whole bunch of movement right so if I move the time base around I can kind of catch up all right I can make them kind of so you see that I'm kind of matching the speed so right now I'm kind of pacing the car you could look at it like that it's not really the same thing but you can kind of look at it like that okay so and then what happens is if you can have a triggering section it's like that arm reaching over and clamping on to the other car something metal arm clamp holding onto the other car now you're locked together now you can look at that waveform that's what a triggering section in an oscilloscope does it allows you to lock on to a very very fast signal so uh you can actually see it so that's kind of a different way of looking at the triggering section in an oscilloscope all right so we have no trigger so we got to find out what's going on with that everything else seems to be you know looking okay so we do have horizontal you know we can see that we move the horizontal around so and we do have horizontal gain so of course this is going to be for an external input right so and uh any sweet magnifier we can play with this later and see if we can look at some uh faster signals all right so what we need to do now is get into this thing here so I'll just unhook this and I'll turn it off so it's got a nice red gratitude on it see that graticule is nice and red most of them are white it's kind of neat so we'll turn this off and I will wait for this to just discharge for a few moments and I'll show you how to get inside this in just a moment getting into these Scopes is relatively easy as you can see it's unplugged right now so all you do is you stick a screwdriver in here and give it about a turn and the same thing with this and it releases the little lock and all you do after that is put your hands on it like so do that and you're inside so I'll just move this cover out of the way because chances are that will fall on the bench and make just a horrible racket and that's the construction inside a typical tektronics oscilloscope nothing but the best that is Top Notch and it's so nice and clean in here so obviously the previous owner of this took a lot of pride in the scope it's uh spotless on this side now another reason that this could be spotless too is that there is no it's not forced air like a lot of them are so many of the text Scopes have forced air they have a fan in the back and they're just you know continually you know blowing air through the scope right so this is pretty good even though they have filters they still get you know fine dust and stuff inside them so this is looking spotless so actually kind of surprised looks like there's paint over spray on the top though on the cover so somebody did get some white paint on it you can see that here see this some white over spray on this it's obviously been sitting in somebody's garage or something and they've been doing some painting so so I'll move this and this one here and we're on the tube side now look at that everything likes it looks like it rolled out the factory floor here let's move this out of the way again when those things fall they make an incredible racket those lids yeah look at this it looks just absolutely fantastic in here obviously the previous owner so clean this thing over with a toothbrush or something wow transistors under here some tubes in here and lots of tubes all over the place here so you can see this tubes all over the top here and in the back typical television horizontal deflection tube back there so not a whole lot of tubes but enough that's for sure the filter caps down here power transformer and yeah very nicely laid out lots of six dj8s by the looks of it on the top here you can see that all the audio guys are going I want to go buy one of these things for 60 g8s please don't do that it's a fantastic fantastic piece of History these things and there's such a nice piece of test equipment when they work they're so beautiful you know they're so it's a wonderful piece of equipment to use right so all of these Tech Scopes are so anyways what I need to do now is get a manual and locate the triggering section in this so I'll locate the triggering section and we'll test that out and see why we don't have trigger over here so we need to match the speed of those two cars here's the instruction manual for this Tech type 503 this really is an everything manual it has schematics in here it has a calibration procedure in here it has everything this is designed to help you get your scope working if something is wrong and of course calibrate it if it's not up to spec and that's the way they did things way back when oh I forgot to show you this so if that's not neat check this out for all of you that are new to Tech equipment see this right here down in here that's a roll of solder that's how they encourage you to fix your equipment way back when they include a roll of solder in your equipment so you can get it going again granted this is a special solder because of these little ceramic tie points here these ceramic tie points have these little horseshoes in them and if you don't use the correct solder these little horseshoes will let go due to migration so they provide a little roll of solder to make sure that you take proper care of your oscilloscope it's better for them to include just a little bit of this solder than for you to hurt your own equipment right that's a company that cares about its customers right there so do you think if you bought a brand new computer today they would include a roll of solder with your switch mode power supply maybe a couple of caps that don't develop ESR overnight so anyways how far we've come right or maybe How Far We've gone so anyways what we need to do here is see how it has little tabs here assist sweep trigger so you want to open it to this page and immediately we come to the triggering section and it looks like somebody's already written in here now this isn't the book for that particular scope I have quite a library of these books so somebody has obviously worked on the triggering section in one of these Scopes and they've written out a whole bunch of things it looks like it's a 70 volts Peak to Peak here and they've looks like they've got plate voltages and cathode voltages and so on and so forth so this is how we set everything up to test the trigger section here so I'll just set that up as a bunch of flicking some switches here Okay so let's move this up here so you can see what I'm doing okay so we did have the source on internal so it says here you can see this here sweep normal it says horizontal position centered trigger Source One or a trigger Source line here this is a sweep time one millisecond uh trigger coupling AC and slope positive so we have the sweep here one millisecond we need to put the source at line all right so basically it's going to be triggering on an AC signal from inside uh horizontal position is pretty much centered and the magnifier is not on what else we have these set in the right position I think we're ready to go yeah we're pretty much ready to go Okay so you can see in the triggering section here we have a bunch of 6dj8s so I think this is going to be very easy to find so the audio tube of choice zoom on into this here again you can see six dj8 v24 and it says here uh v45a v45b so yeah it looks like we're probably going to be on that row it's right behind the triggering section so call me crazy but I think that's probably the triggering section so in order to start troubleshooting this in order to uh troubleshoot this uh with style what we need to do is use another piece of tech gear to do that so see the light stem draws a little bit of current might possibly heat the house during the winter so what I need to do is let this warm up we'll use this plug-in here one of my favorite plugins the 1a2 aside from my very favorite is plug in the 1870 and uh we'll start troubleshooting this scope over here so I just need to let this warm up for about five minutes uh it'll take about a minute and a bit for the trace to come on the screen just alone so hold everything stabilize and I'll be right back okay so here we are ready to go so what we need to do is look for this and that is here and that is attached to pin six of the vacuum tube so we should get this on the scope screen all right so off the plate of v24 pin six so this here is v24 so we look a little closer so if I move myself over here we have nine eight seven and six so that's this wire right here so I need to clip the scope probe onto this okay so I'll clip the ground here and I will clip the scope probe onto this and take a look at this that looks pretty close and the amplitude is pretty close as well all right so we're doing pretty good there all right so remove the scope probe you can see here it goes away right so nicely that locks onto that that's how this scope should work all right so we know that's working so now remove this and I'll move this actually I'll just remove that completely for a moment so it doesn't unclip and fly into the circuitry because it probably would so the next thing we need to look at is this here we want to see if we have a square wave over here so we should see a line a line a line and a line because you won't see this is you know pretty fast wave so we'll just see top and bottom lines when we look at it so we want to look at pin number one of v45b and that's the next tube over so that's this tube right here so if we look here this is the index is that the index where is the index let me see where the index is this is the index right here and this line right here is pin one this one right here so this I will attach probe again here and we will clip on to one let's take a look at what we have on the scope and it looks like our triggering section is working all right so right now we're at assist two volts but we have a times 10 probe so that's 20 volts per division and so we're roughly about 30 volts and it looks like what they have written down here is from 240 to 264. so we're just about 25 volts right so it's very close see that well you can see that from 240 to 264 right so we're just about 25 volts there so we're very close and we have our Square all right so it looks like the triggering section is working on this so what we should do is check the power supply and see how that is happening so I'll just move some stuff around here move this off to the side I'll get this open to the power supply and we'll start checking that all right you're in for a special treat with this this is the power supply here this is a vacuum tube switch mode power supply ever seen one of those before so in a large switch mode power supply say for your computer you have a fat which drives the switching Transformer well in this case that's this very large tube in here and it drives this Transformer so we have an oscillator in the bottom and this is our feedback right here which sets the 100 the negative 100 volt Supply it's right off the right off the negative 100 volt line so that's a very important Supply to have working we have another regulator up here which is a shunt regulator and this makes no sense because there is no lead off there should be an arrow pointing out from here because this is a shunt regulator now I don't know if this is an earlier or a later schematic I'll have to go and see if I can dig up another schematic and see if they've amended that because you see how we have arrows coming off here we should have 85 volts at this point here that's the reason they have this resistor here and we should have you know a line with an arrow that says 85 here so yeah that's kind of odd because this wouldn't do anything just the way this is right you know the only thing it could possibly ever do is load this down just a little bit but that makes no sense to have a regulator to do that so uh interesting possibly uh Monday morning no coffee with the engineer and then somebody overlooked this obviously the person that double checks everything hadn't had their coffee either so we have a negative 3 000 volt Supply here and so just so you know you know these Scopes have got lots of voltage in them so that's for the CRT so we need to check all of this stuff not really this we don't really need to worry about that because the CRT is glowing if the CRT is glowing chances are we're doing good there so let's check this Supply rate here it says positive 250 so we need to get to the top of our 659 and the easiest way to do that is to spot the tube look for pin one or five and then follow the resistor back so you want to read on each side of this resistor so this side of the resistor we should have about 85 volts what it's doing here is it's not shown and at the top here we should have about 250 okay and usually they're they're pretty accurate that just says 297. so uh interesting all right so very very interesting so what we'll do is we'll take a look here inside the scope so this here on the other side is the 100 volt adjust right here and if we look down we can see you can see just the camera angle right there it is uh the 50 or is it 5651 see that right there and you can see they got pin one and five joined all right and that travels up through this right up to this resistor here and this is a different valued resistor so there must be a multiple schematic for this so at this point we should have about 85 volts about and then we should have our 250 at this side right that would make sense right so I'll probe the uh this side right here first all right so focusing in on the meter at the top here off to an angle just a little bit here with the camera over just to make that a little easier to see of course now we have a shadow in there of some sort okay so this is the 85 volt side and we have 84.1.2 that's close enough and on the other side we have 275 volts well 276 roughly all right okay so we know that that's somewhat within spec right so we know just by the fact that we have this the scope screen is glowing so we know that this is obviously working if this t620 wasn't oscillating we wouldn't have anything on the scope screen so this should oscillate around 25 kilohertz something like that so in fact we can probably see that on the scope here let's attach the scope so what we can do is that signal the drive signal would be available at Pin 4 which is the control grid right is that the control grid there no it's not this is the control grid here pin five so we should have a signal available there so that would be yeah pin five okay so if I clip this on here I'm gonna go to and where are we here one two three four five and we take a look at the scope screen Just Adjust this get rid of this light on the top there we have it that's our relatively fast oscillation right there so it is oscillating right that should be around 25 to 30 kilohertz in that area somewhere without any doing really precise math on that so not bad so it is working we obviously know that because the CRT screen is glowing right if it wasn't glowing then we would know that we wouldn't have anything there Okay so we know that that's happening let's see what else have we got we've got the positive 100 volt Supply and the negative 100 volt Supply so the negative 100 volts is what controls all of this so why don't we just check that out all right I found another schematic and look positive 85 volts so somebody didn't have their morning coffee in this manual here surprised that slipped by oh well it happens to all of us so there we go they caught it [Music] so this is 51k and that makes sense to what's in this so obviously this schematic is more relevant for this scope here because that was the resistor that we read across here was 51k right this one right here let's move this out of the way this one right here grab my pointer this one here this is 51k so five one and then three zeros 51k right there so I guess that is more relevant so this must be a very early book or something like that so we need to test the negative 100 volt Supply and that's what this adjustment here is for again that's the negative 100 volt Supply there and if I zoom on in we can test that right at this point right here okay my finger's a long ways away from that believe me I'm nowhere near close to this this right here high voltage rectifier on the bottom so I'm very far away from that so this right here is our negative 100 volt Supply so what I will do is I will touch my probe to this and I'll move you up to the voltmeter right here so you see that off to the side all right there we go it's negative 79 volts so that's low that has to be right at 100. so that's what sets everything in here kind of like the uh the master Supply so this voltage has to be spot on so that tells us that we have an issue so maybe the 100 Supply is just low wouldn't that be something so let's take a look back down here at the scope so that is the adjustment right there let me turn you around here disconnect that clip from the meter turn this all around and see what's going on in the back side here so that's the uh that's the really big fat if this was a switch mode power supply that is the that's what's oscillating there the uh that Transformer and you can see negative 100 volt adjust right there see that written right down in there so I will put a screwdriver in this and turn this as we take a look at the at the meter so we'll move this around here all right proper clip found and I'm about to adjust this right here so move this around just a little bit so see what we get on the meter so this should very easily come to 100 volts if everything is working okay because that's how these Scopes work so I'll move this one way nothing's happening oh there's absolutely nothing happening there yeah absolutely nothing happening right that was moved from side to side completely so if I can get this all in you see this here put this in here again all right so we definitely have a problem in that Supply something is going on in there so the very first thing that I would suspect would be capacitors I would suspect that at first so I'll Zoom you into this here so I can get too Incredibly Close so what we want to do on the negative 100 volt Supply is probe that and we should have nice clean DC at this point so let's check that out see if these are okay we can very quickly check to see if these are okay just by doing that right so easier than unhooking everything right I'll move this back around again and I'll get rid of the volt meter so I will attach the probe into the supply down at the bottom there okay so I'll just ground this to the case like so and we'll go right here this is where that cap is where the supply is anyways take a look at the skill screen whoa okay well what does this tell us easiest way to check a cap look at that so I'll zoom on into this here move this forward so you don't have to see the glare of this lamp so there we go you definitely have an issue there look at that give it a bit more intensity what does that mean well that means we have no filtering so that's what's wrong with the negative 100 volt Supply let me get a capacitor and just clip it in there so obviously that Cap's open or they're both open one of the other the place I was probing is right here on the diode which is right here so we should have 20 microfarad right about at this point right here so what I'm going to do is just for the test I'm going to bridge in a capacitor here you can see how the the positive portion of the calf goes to the chassis because this is a negative Supply all right so what I'm going to do is take a 22 mic 450 volt cap right here I'll take the positive which will make the red lead of this cap here and just attach it to the chassis any old place for now is fine it's crude but you know it'll work and then we'll take the negative cap and clip it to this diode okay the scope is off right now just so you know so I don't want to be clipping anything in while it's on right because it would instantly try to charge that cap and it could damage some circuitry in here so everything is off so I got the cap attached here see that where are they okay so we'll set this off to the side so that it doesn't get in the way of anything I'll turn the scope back on here we go let that warm up for just a moment and let's see if I can get some stuff ready here while we're waiting so I still have the ground attached here from the from the meter and we'll turn some stuff up notice the screen is moved a little bit all right so let's measure the voltage at the same spot again so it's right at the uh initial voltage that we could read would be here that's on the other side but let's just read this we should have a nice clean 100 volt negative Supply if it's working somewhere around that oh look at this we got negative 94 volts now I think we're on to something huh all right negative 94 volts that is a good sign all right I'll move this around very carefully because that cap is just Loosely clipped in there and I got ground leads and everything all over the place turn this around okay I'll put my screwdriver back in here again see if I keep moving this without anything bad happening I think I'm getting to my limit to where I'm going to start pulling leads off all right poke the screwdriver into the negative 100 volt Supply and move it around look at that we've got a negative 100 volt Supply leave it right there it's about as close as we need to be right so it's definitely a cap so what I need to do now is I'll just shut this all off move this back around over here again so I can do this safely without having wires short out and create more problems so obviously the cap under here is bad so there's a cap under here that has gone bad [Music] so I will desolder that capacitor and we'll check its rating and then we'll look at the other one as well because there's two of them here so there's there is this one here 2 times 10 and 2 times 40 so we should have 20 mics and 80 mics right about here so this is the one that was bad right after the diode that's where we checked and we had that incredible amount of of uh Ripple there so what I will do is yeah I'll just disconnect those capacitors and I'll be right back we'll take some readings both the capacitors are now disconnected both c684 and 6082 right here and here so you can see I've opened this one lead right down here again everything is safely discharged so I've opened this lead down here and that attaches to the case of the capacitor but the case is isolated which allows me to use this as its own standoff which will be really nice for a capacitor replacement so this is isolated right now and c684 up here is also open you can see this down in here I've opened this up down here so that we can test both of these capacitors without the circuit loading them down so capacitor meter right over here I will attach because the positive of the cap down here is attached to the chassis we'll attach the positive to the chassis and we will go to the case here with a negative five six Nano for red I'd say that capacitor is open yep very bad the capacitor is supposed to be 20 microfarad that's really bad okay so now over here same deal so what I'll do is I will attach the positive to this here right this is open from here so I'll attach the positive here and I will attach the negative to the negative of the cap and what do we have here 95 96 and that should be about 80. now these caps are very good capacitors very rarely do I ever see these fail at Tech so these might actually be overachievers we might actually have a little bit more than 40 microfarad per side so there's quite a tolerance for these caps one way to tell if it's leaking or not is to take the leakage tester will I trust this capacitor here still even though it reads 96 let's find out I grab the leakage tester here and attach this into circuit here and here okay so there we go all right you ready let's go shut this light off so you can actually see what's going on so we're on the red scale right now seen it should move down quickly if it's good it is look at that will I trust this capacitor after it's been tested with this absolutely this is a very stingy tester if this tells you your caps are good and there's no leakage there really is none so that's doing very good so no leakage in this so this can be left alone so what I'm going to do is replace this capacitor down here and after that's replaced I will show you how I've installed a brand new capacitor and we'll try out the scope and see what it looks like see if we can get the thing to uh it'll basically lock onto a signal see if the triggering section works the new capacitor is installed right here so the old capacitor is out of circuit it's still in the chassis and it has a ground connection to it which I'm using so it's actually acting as a standoff for this capacitor and this one is tied into circuit so it's tied to this point right here and to ground so that worked out really nice so it's a must whenever you're replacing these old capacitors to completely remove them if they've failed because it may be open now but it could short later on so we were testing the voltage at this point earlier to see if we could get any change so now that everything is all done we want to get really accurate and make sure that we definitely have the 100 volts so we're going to tie in at this point right here right because it's going to obviously be just a little bit of change across this so we're going to tie in right here for the final adjustment and we should get around negative 100 volts that will be right at this point right here so if I point to it it's right here is where I'm tying in all right so I'll tie this in right here and get a good connection with this let's try this again all right so we have negative 99.5 volts that's pretty close so what I'm going to do is carefully turn this and put the screwdriver back into over here see where the adjustment is down in here and I will adjust that for negative 100 volts right there there it is so now it'll be interesting to see how close the other voltages are so I'll disconnect this out of here get rid of this probe something a little bit more Pokey in here like this probe Master probe my by the way absolutely fantastic probes so I've had these for so many years and they just pulled up wires never break nothing ever happens oh I should mention by the way this tester that you saw is on patreon I designed and created this if you want to build this it's up there with all the plans this leakage tester all right okay so let's take a look at the 250 volts again so let's take a look at this and see how accurate we are 250 at this point right here so that if I remember correctly that was right here see look at how much closer that is right so we're only within four volts there and on the other side and let's see what this is at 84 again no problems so you can see that went way down so you know 254 is absolutely fine for there so this sets everything right or this uh sorry this right here this negative 100 volt Supply can't see what I'm doing one negative 100 volt Supply here is setting everything and that's this adjustment here is what we're adjusting so that's what it needed looks like that cap is Happy look at that solid negative 100.0 just doesn't move old tectronics regulated supplies they're fantastic probably stay like that throughout its entire temperature range as well oh and if you want to take a look and see what this looks like on this scope now remember where we tied in we had that horrible looking wave there because of that cap move you down here pardon the camera movement lots of movement here get rid of that I'll tie in you'll see a jump on the screen here because this is AC coupled okay and I'll tie right into that point that's what you see that's what it should look like that's DC so if I move that over here again you can see I'm tied right in the same point right off that diode so you can see how much Ripple there is with just that cap open that would obviously affect a lot this cap is really good and to be honest with you most of these old Tech scopes I have so many of these as you know and so rarely do these electrolytics fail really they hardly fail I'm gonna say out of all the Scopes I've seen all the tech Scopes I've seen that might be the second one that I've ever seen that's gone bad all the rest of them they just hold up all the ones in the 555 Scopes the 547s 535s 545s I've never seen one open or even short they always just keep going and going and going so very very good capacitors in these again tektronics only bought the absolute best way back when and put them in these scopes and of course knowing where most of the other Scopes went like the 555 that I have is an old sculpt from Boeing and I have some that were used in some pretty interesting places let's put it that way they came from some very interesting places so hey let's see if we can get a lock on this this down here story for that camera movement here it's just this tripod is rather rigid in case we have this now let's see if we can get a lock I'll put that same signal in here the signal generator still on all my cables are all tied up here and it's got so many wears on this bench right now back this out you can see what I'm doing turn this down this in here turn the intensity up we'll put this on internal and look at that walks like a champ isn't that nice don't even have to touch the control at all just like the other scope that's the nice thing about these Tech Scopes right because they're just uh they just work like a champ s out of here get a little bit of glare off the screen this up maybe very bright so there we have it no problems there whatsoever very impressive I wonder how well this is in alignment I wonder how well it does so look at we can magnify this so for the fun of it you know what let's uh put a 450 actually let's put a one megahertz signal into this here it is displaying one megahertz of course we have it at times two sweep time maxed out that's it times five you really expand upon that we're also at maximum intensity to do that so let's go 1.5 megahertz let's have some fun here 1.5 megahertz is it still going to show us anything 1.5 let's try two megahertz two megahertz I'm turning the gain up as you see here so it'll trigger it too very touchy trigger a little bit more gain just the more gain we have the easier it's going to trigger right so it's seeing too of course it's having an issue here and two megahertz so this is with no magnifier it still shows us a wave but it's getting pretty tight so it's times two and see if I can adjust the trigger here to steady that up a little and it's looking like two megahertz pushing pushing like it was supposed to top it at 450 right so we're really pushing this here and that's that maximum sensitivity so two megahertz so the 503 will see two megahertz just like that let's go 2.5 megahertz wishful thinking so if we go back to 450 450 kilohertz there we go now the scope is happy and there we go your position up and now the vertical section can deal with it and everything let's get rid of the magnifier not bad not bad at all what we can do is we can test this and see how accurate it still is time based wise so let's just do that so I don't know if I'm going to get into checking the you know the vertical sensitivity and the gain and all that stuff but let's just for the fun of it let's see if uh if the time base is on it should be kind of interesting I'll set that up and I'll be right back all right place your bets how accurate do you think this is going to be so I've got the level set to Auto right now and if we take a look up top I have the tu50 test unit this is a unit designed to calibrate tectronics oscilloscopes this is on and warmed up at the top so I'll click on 1000 microseconds which is one millisecond what do you think the scope is going to display do you think it's going to be accurate look at that 503 is spot on now if this was decalibrated or something like that say it was screwdriver you might have something like this so the comb should be perfectly in line with the graticule right and if we click to the calibrated mode that's calibrated right where it's supposed to be pretty amazing let's go here and we'll go here and make sure everything is aligned look at that this is just spot on the scope is doing just fine no problems at all let's go to here look at this right down into here right down into the microseconds right five microseconds right now no problems it's right on the line try to make it look as aligned on the camera as possible it depends on what angle you look at the graticule from so if the camera is kind of off to the side a bit so you know to my eye I need to move this over just a little bit but you can see it perfectly aligns with a graticule so the comb is right there this is time bases in perfect alignment in this and there's a lot of things that can throw that off so this scope is doing very very well so it looks really like just the the 100 volt Supply the negative 100 volt Supply failed inside this I'm pretty sure probably all the rest of it is spot on as well and of course you know I'll end up off camera going through the entire thing and making sure that you know the vertical sensitivity is right and all of that so everything matches up but there you have it school prepared and time based accurate and it will see about two megahertz before it really starts to uh to not see anything anymore of course it's well out of its calibrated Zone but you know it still sees it could be used very comfortably for servicing am radios and all that kind of stuff so there you go little Tech 503 lives again seems like a happy little oscilloscope thanks for stopping by the lab today hope you enjoyed this video involving the tech 503 sure was a lot of fun getting it working again and I really hope you enjoyed the process as much as I did if you are enjoying these videos you can let me know by giving me a big thumbs up and hang around there'll be more videos like this coming in the very near future we'll be taking a look at modern electronic devices and older electronic devices alike so this channel is all about Electronics so we're going to be doing a lot of troubleshooting a lot of repairs a lot of circuitry design Restorations teardowns all of that stuff surrounding Electronics so if you're all about Electronics like I'm all about Electronics you're definitely going to want to subscribe and tap the Bell symbol that way you'll be notified as soon as I post a brand new video if you're interested in taking your electronics knowledge to the next level and learning electronics in a very different and effective way and gaining access to many of my personal electronic inventions and Designs you're definitely going to want to check out my ongoing Electronics course on patreon there's something there for everybody if you're into modern Electronics or antique electronics I try to teach everything up there and try to convey as much information as I can the goal of this whole thing is to take what I know and hand it over to you that's why I'm doing this and that's why I have that Electronics course there definitely check it out you'll enjoy it I'll put the link just below the video's description under the show more Tab and I'll pin the link at the top of the comments section so if you click the link it'll take you right there all right until next time take care bye for now

Channel: Mr Carlson's Lab

Views: 38,419

Keywords: Mr Carlson's videos, New Mr Carlson's videos, Tektronix, oscilloscope repair, learn electronics, electrical engineering, electronic engineering, electronic troubleshooting, electrical troubleshooting, fix electronics, testing electronics, electronic repair, electronic laboratory, best electronics teacher, radio repair, radio restoration, electronic restorations, electrical restoration, HAM radio repair, valve amplifiers, tube electronics, teach electronics, electronic guru

Id: GDZS1yEVqko

Length: 58min 12sec (3492 seconds)

Published: Sat Aug 05 2023