How to Troubleshoot Electronics Down to the Component Level Without Schematics

what's going on guys today I'm gonna talk to you guys about troubleshooting down to the component level without any schematic and I'll be showing you guys how to go through a power supply board without any schematics most of time when we get stuff in here we don't have any schematics so we follow a step-by-step procedure on how to troubleshoot it from the easiest all the way to the hardest the quickest to the slowest way of troubleshooting so follow along as I taking you guys step by step on how to troubleshoot down to the component level alright guys again today I'm gonna show you guys how to troubleshoot this power supply down to the component level without any schematic and as you guys know there's a there's power supplies all over the place but this particular power supply is from the poultry industry and it actually powers up basically a temp controller with alarms in there basically turning off fans and heaters if they need it to but let's take a quick look at this this is a linear power supply and as this is probably one of the most simplest power supply out there but I kind of go through and show you guys how to troubleshoot without any schematic so which will go down to the component level and I'll give you guys kind of my thought process over what I do so if you guys look at this right here first thing you want to do when you get something in you would want to do a visual first the first thing you always need to do is do visual because a lot of the time you'll get clues on what's going on right so when you do a visual you would look at it and see if there's any any common issue as far as like burnt component you can see here here's here's the board linear power supply kind of give you idea what's going on like there there's caps filter caps here here's a big old transformer here it looks like a bridge rectifier you guys could see that an LED of fuse a very very astir or mov again a big a little heavy transformer and here's my connector here's another fuse here and this looked like a choke coil with capacitors and a resistor here so very simple power supply then goes into the I think poultry industry so when you do a visual basically you will look at at the components and you'll see if there is any like burnt I burnt components or the board is burnt in any way sometimes you have some components that will heat up and it will burn up and doesn't just from doing the visual doesn't look like there's anything burnt on here and look for any components and may be burnt any capacitors and that might be bulging and just look for you any kind of clues may be missing components somewhere you could tell why maybe looking at at like any bare spot that you might see like I don't know if you guys could see it here but every one of these is labeled every one of these is labeled so if you see that there's a component missing somewhere then definitely chase it back but if you look see how big this transformer is is pretty heavy so what one thing you you will have to worry about is like coal solder joints and it looks like the transformer looks like it might or might even be soldered before but you will want to definitely want to see if there's any crack solder joints on here and sorry for the light there but you definitely want to see if there's anything any crack any traces that have it has been burnt and basically just want to see you see if if maybe even the board is crack four board with a transform of this heavy sometimes the customers would throw this around or lay it or drop it or something and then the board would be crack and it wouldn't be like broken all the way but if you do a very good visual on it you'll see that this crack on here and the traces would be completely open so you want to do those visual and like connectors like these you want to make sure all the pins are still there so first thing you want to do is you want to do a quick visual and in most cases you'll find like open traces burnt components board as getting heat up so again number one thing is do a visual second thing you want to do after you do a visual and if you can't find anything then you want to take your multimeter out and you want to make sure there's no short on your board from like VCC from your positive to your negative in this case right here if it's a if I see a transformer here and a bridge I know it's gonna take a sieve so I want to make sure that then one bridge rectifier my fuses are not open and then on my my DC side I want to make sure that it's not shorted from a positive to my ground so what I would do is I would take my meter right and you see there's the Dido setting here I would take it to my dial setting and my meter would come on and basically what I would do is do a component check so I'll be testing my discrete components and discrete components is nothing more than just individual components in their own packages so for example like a capacitor a transistor diode Zener fuse those are our packages that or components that are by themself so basically that's what I would want to do and if you have a meter that beeps if you touch it this is basically a short and it's telling me like this continuity short and is gonna beat and if it's open its gonna show oh L four I forgot what L stands for over limit so basically there there there is infinite reading so you can't read anything so that's the best place here and open and what you want to do is you want to test these components so if you you you definitely would have to understand electronics to kind of know how to test your or go through this like a fuse is pretty straightforward right so that would be I would start from the simplest easiest to the hardest so what I would do is I would look at okay there's a fuse here I could quickly test this fuse right so basically when I'm testing a fuse I'm just putting across it like this and as you see is there there's a basically a short so this fuse is good like zero votes right you can see here zero votes so that fuse is short is good here's the fees here also right I could I could take this fuse out or I could look in the back without taking it out and I could see that the basically come across these two points here so I could measure across here and is shorty also so this fuse is good too and as I as I go through there's there's a resistor here's a high wattage maybe a two watt resistor I don't I'm not gonna go through the value of it but it's not burnt most of the time if resistor is bad it's gonna be burnt and even sometimes when it is burnt if it's not open up the reading may still be right on point but it's just burnt so it doesn't mean that then you won't replace it you definitely want to replace it but I'm not going to worry about the e resistor but I'll check the fuse I check the fuse here capacitors right I can't check a capacitor with it if I have any diodes I can check a diode but in this case here I have a LED which is put which is like a diode and then I have a bridge rectifier which is here that's basically four diodes so I could check that right so the way the way you check a a bridge rectifier is let me grab a paper over here and I'll draw it out for you guys so in the bridge rectifier single-phase like this one right I'm gonna say I'm gonna draw this out right it's a four pin device and it's gonna be a notch here so you see here all right there's a this a notch here if I look closely on this even on the board down here I'll see this is a plus I call that squiggly lip line which is your AC sine wave and an AC sine wave and by- okay so negative positive and AC input it's AC input so that that's how a bridge rectifier or the package of this bridge rectifier so what does that really mean right if you know your electronics you know bridge rectifier bridge rectifier does nothing but rectifies your AC into DC so when I put my AC voltage into this board basically this bridge rectifier is gonna rectify or change my AC to DC and basically this is the how this basically has four diodes in there and this is how I like to draw on my bridge rectifiers so I have one diode two diode three do four diode this top bar right here is my positive this bottom here is my negative so my AC goes in between these two so I have a no Catto for this diode a no cathode anode cathode anode cathode so the part where the two diodes were the anode which is right here for this one and the cathode meets that's my AC input and again over here is the same thing AC input AC okay so so this point will be here and this point will be here and this point could be here and this point it could be here so basically this is the there's number of this one two three four so this could be one two sorry that would be this will be 3 2 right 3 to positive would be 4 1 will be a negative ok so that's my bridge rectifier I know what it does it rectifies AC goes in and then it's gonna change it into DC I'm gonna get too much into it but I'll do it I'll show you guys real quick since we're on this topic right on the side sine wave this is my positive side this is my negative AC it's gonna go in or I diet unless one only less current flow through the anode to the cathode which is for bias so when it's in the positive side it's gonna go through here through through this diode right it's gonna set up my positive there it's gonna back out and it's gonna go through I say just put a load here it's gonna go through this load back out to my negative which is to my negative and then it's gonna go through this diode right it won't go through this diode because at this point right here it's still positive so this point right here pretty much is not positive so my currents gonna go through here through this diode back out to my EC and then on my negative cycle which is here it's gonna go back this way now I was gonna get to this Junction to here and then it's gonna go through this diode on up here so this negative right here is get gets rectify and then now that that negative right here it's gonna get put here I'm not perfect but so and then is gonna go up here down here it's gonna skip this one because this is this point right here is positive it's gonna go over here through this diode and then on out to this side over here and then once it does that it's gonna change again back to positive and it's gonna keep on repeating and then I'm gonna get my AC output and then here I'm gonna get my face leave my DC out which I'm gonna get my RMS but basically that's how it works but back back to troubleshooting down to the component level I know how a bridge rectifier works I know there's four diodes in there so what am I gonna do I'm gonna since this is my meter is on diode the diode mode I'm looking for diode drops so for a diet when I test it it's gonna give me a voltage drop that means that a wing current flows through a put enough current to go through it's gonna be a voltage drop across there and then the die was gonna allow current to flow through and basically the meter is gonna tell me what voltage is gonna be across that diode so in here if I'm gonna test this bridge rectifier what I do right is I'm gonna put my red on the animal side of a diode and then my negative on the positive and I'm testing I'm basically testing this diode and then I'm gonna do the same thing on this one leave my my common or my black lead where is that on the positive and then I'm gonna touch the other AC side input and I'm gonna test this dial so basically I've tested these two and then when I get down to the bottom side of it the negative side of it what I want to do is put my positive here because positive I need to go Nina put it on the Anna side of the diode and then I'll go on each a C input and put my black or common lead on here and I'll test this diode and I'll leave the red here because this this is the same anode or same point and I'll put this on the AC input and then that way I basically went through and checked four of my diodes and within my bridge rectifier package so that's kind of how I do it so if we go back to the package what I would do is I would put I will put my positive on the negative and then I'll check pin two which is AC input and I should add I would drop and I should get a dye to drop and then here I should get like a one point something right depending I'm basing adding the two dollar drops together so I'll check that way I'm checking the bottom side and then if I'm and then I will put the black lead on the positive side and then I'll put it put my readily on my AC input pin 3 and 2 and they are I should get a voltage drop here or or that it would voltage drop and a diode voltage drop and if I do that and if I'm you know all my voters died a voltage drop then I know that my bridge rectifier is good and as long as I'm not seeing a short day and I'm sure I should be good right so what I'm looking for is no short so if I bring this back into the picture and again this this bridge rectifier is pretty much the pin out like here right so if I leave it here see if there's a better way of doing it what I'm gonna hang on to you it's no really good way of maybe doing it so just bear with me so what I'm gonna do is put my red lead here and test these I'm gonna get a voltage drop voltage drop and then like a 1 point something votes so my red lead is gonna go on the negative and then I'm gonna put my negative on the AC input and I'm not getting anything all right so must have pulled something there you go so I'm gonna get 2.7 0.47 voltage drop point four seven and I should get maybe 0.8 0.9 you see how is is changing basically is is on going through a cap and just charging it up and then you should get up to like maybe point like say 0.8 or something well I know I know I'm basically looking for is no short I like when there's a shortened bridge rectifier is bad so just keep that in mind cuz I'm keep on going he's gonna keep on going and eventually he's gonna stop but normally I always thought before then because I know it's just charging up and there's no short so I totally would have moved on already but as you see where I was like a point eight four it should be maxing out soon because we got it like a voltage drop like a point four or something in point four all right so it looks like it's slowing down so this this is pretty much a good okay so my bridge rectifier is good and so first step is do vigil second step is test my my like discrete components and those are basically all the discrete components I've got I I could I could I wouldn't initially go through and check the pastor's yet what I wouldn't normally do is once I power up then I'm gonna replace my capacitors anyways because these are electrolytic capacitors and they tend to dry up and they're one of the biggest issues so I would go ahead and replace them anyways so with that being said alright I've tested almost everything there is that I could test on here transformer I mean I can't really there's not really a good way of testing transformer in a circuit because of the windings I mean they're gonna read zero ohms but once I've done that verify that my positive and my negative is there's not a short on there and basically means that on my DC side there's no short and I should be get a power up right now step three right step three I got to figure out how to power up them so first thing again right I do visual didn't find anything step two I did my component check and there was no issue and I gotta move on to step three step three is to identify how to power up and basically I mean I'm using the clues here right so if I'm looking here let me move this out just by knowing he likes phonics remember I said you guys got no electronics so just buy no electronics I know that okay I've got a transformer here it's gonna take a seat I got a look from the primary side and a secondary side so when I look over here I'm gonna turn it around I'm gonna say okay here's two pins here and then here's two more here and two more here so this is the secondary just by looking at it and this is the primary side which I'm thinking it is and how do I verify that right basically bridge rectifier it takes AC input - and there's no give DC so if I have a transformer here more likely my secondary side of my transformer is gonna get stepped down and it's gonna feed right into my bridge rectifier so remember that drawing that I show you guys which is here AC input AC input so if I chase that back I should actually go to the secondary side of my transformer so if i if i flip it around in the two middle pin here right the two middle pin here is gonna go to my secondary side of my transformer so you guys noticed that it was beeping right acting like a short what is it's because it's right across the coil of the transformer and the cordial is nothing but in windings wires which is kinda like a fuse anyways it's gonna test short so if I go to this pin here I'm say oh right let's change it to ohms there's pretty much dead short the same thing here that's short let's go to this side nothing here nothing here nothing here nothing here so so I was wrong this side right here with the two pins is my my secondary side and the one with the four pin here is my primary side so primary sizing will go in and then it's gonna go out on my secondary side you always want to look at the transformer to to make sure that they that there's markings on there and as you can see on here I can read this so I'm gonna put a sticker says 230 volts ac on there so more likely it's gonna be taking it to in a 30 volts AC but even on this transformer if you see the markings on here you see I can make it focus for you guys come on let's focus here you I think is ringing my meter take my meter wait come on focus on it okay there you go oh I lost it okay my camera is not wanted to cooperate to thee come on pick it up okay oh come on alright you see there 115 volts or 230 volts you see that 115 or 230 so this could be a dual input and output output should be 12 volts right here and it sorry about that but they'll give me my pin out so if I if I'm gonna do a a 230 I'm gonna have to short pin three and six and for 115 I'm using each each one of the windings by itself okay say one or six or three and eight and in this case it if I'll flip it over you see how how the board's made they pretty much tie the two pins together so that's why it's taking a 230 so 230 is gonna go here and then I'm gonna get I don't forgot 12 volts so he's getting 12 volts out and then 12 volts gonna go to my bridge rectifier and in my bridge rectifier again it's gonna rectify my AC into DC so here is my input and I'm gonna have to follow this back so let's bring by meter back into play I'm gonna I like I like the beat so I'm gonna chase it back and I'm I could do a visual on it it's gonna go here through here to over here right and then from there I'm gonna look it's gonna go through this coil so quarter was nothing about a piece of wire so if I did it again it's going to go here all right so on the other side I'm not sure where the other side goes but here's my connector see here see that's my connector if you really wanna cheat right you can look here and you can see oh there's my ground and oh here's my l1 and l2 and these are my input so if you wanted to cheat and which is I say those are bonuses you could you could cheat so basically that's my two input and then my ground is there and if I omit out right here's my connector again if I oh man out see he goes there about zero ohms I could do the same thing over here because this is a coil but you see that there's a little bit of resistance there so if I move it to this side over here which is the other side look winding it's gonna be short so just for grins and giggles let's put it homes alright it's gonna be like that short if I put it over here I got about 41 ohms so my winding is 41 ohms okay so this I goes to here so that's my AC input so AC is gonna go in through here it's gonna go through a fuse you see a fuses here see input goes here and then you can see you can see the trace going over here to this fuse which is here then go back out the other leg it's gonna go out through here through my coil here down the other side and then to the other winding so that's my my input so I can put AC here and then I'm gonna and then I could put it my dinners gonna go through my my primary side and then it's gonna get my secondary side if I put 220 in there right I'm gonna get 12 volts out because of what the transformer said and then I'm gonna have my my DC out and when I get my DC out more likely my LED is gonna come on excuse me and obviously is a red LED so the red how these gonna come on sometimes the meter could is enough to turn on the LED but I'm not sure if this led is enough to turn it on so let's just hold up this way see you guys could see that no is not it's not enough basically if you have a capacitor check it you could put it across there from the positive put it on the animals Kathu capacitor checker puts out a whole lot more voltage or if you have a curve tracer like a hunch wrong and you can put it on there it gives out an AC signal and it has enough voltage to turn on your LEDs but in this case here right I'm not too worried about it I'm gonna power it up so once I identify that I'm gonna power up and when I power up what what would I want to do right I will I would want to make sure there's any sequence when I power up I'm thinking an LED is gonna come on I gotta make sure that LED comes on if there's a green LED on there I want to make sure there's a that it comes on or if there's a sequence that I want to make sure it comes on and most of the time I would record it so so if I were working on a more complicated power supply or a printed circuit board with relays and and bunch of LEDs well when I first power up I'm gonna record it so that I know the sequence like Oh LED the green LED came on first and then it started blinking and then here's a red to other red LEDs and once they on solid and one is blinking on and off so if I have recorded that and then at least I'll know what happens just in case I blow something up I don't want to make sure that I fixed everything or if I fix something and then the the power of sequence is different then at least I have documentation of what's going on so you always want to make sure you know all that and if you guys are like me my memory is not so good anymore so it's always good to have technology on your side and use it so now I'm gonna try to power up but I'm also what I what I'm gonna do is that I know DC is gonna come out but where's it gonna go right because there's no other connectors out there besides this one so I need to figure out I need to figure out where my DC is going and remember the two inside isn't my EC so again this pin right here is gonna be positive this panel right here is gonna be negative and let's find out where it goes you can see these caps all these caps over here right these are all my filter caps and it's gonna go over there I was into one pin see how it goes there this is my negative and if I look over here I can see my negative of my filter caps and more likely the positive is gonna be on the positive which is all here all right so those are my filter caps so where I'm power up they should go maybe here yep so this pin is negative negative don't know that pin is don't know that pin is negative negative nothing nothing so it looks like this side over here is my negative nothing positive positive positive positive so it looks like the the two middle pin is does it go anywhere and this size my negative and this size my positive okay so just by looking at I have no schematic have a little bit idea of how power supply works and know my components and there you go i'm i dont went through and have idea what to a spike right i've done i did a visual did a component check identify how to power up with the markings on the transformer at least have idea of you know the voltage that i'm gonna get out and how much voltage am i gonna get on my AC or my DC side well there's also a formula i can give that to you guys - you guys have filter caps on there bassy your formula is gonna be easy right input times 1 point 4 1 4 equals sorry I'm ran out of rooms room equals my votes DC ok so let's let's do the math on that since I'm not good with math all right here's my calculator if my power supply only goes up to 150 volts ac so let's just say I put 150 votes in times 1 point 4 1 4 I should get about 200 or 12 volts ok so let's put this here and let's power up all right so hold on a minute I'm gonna grab my connectors and find my screwdriver and we're gonna hook it up and power up okay so break time okay I'm back so as you guys can see I don't put my AC input into here which is my input and then I'm looking for a DC out on my bridge rectifier so I'm gonna turn this to AC I wanna monitor this just for a little bit right I guess zero volts now I'm gonna turn on my power supply and I'm going to increase my voltage I want to make sure that there's no nothing else it's gonna blow some more slowly increase it and as I'm doing that too right here you guys can see this is my connector from from the backside see that remember the connector from the backside now tells you the two outside pins is my DC so I know my my power supply my variable or very active it's not gonna go up to 230 volts AC so I could turn it up to max which is gonna be about 150 somewhere around there so what I'm gonna do is I'm gonna monitor my DC vote out so I'm gonna put it here and here I don't care if it's if I got it on the right polarity or not let me find a better place here this is when when it's good to have four hands or three hands all right let's do that all right switch over to DC I'm gonna keep on going keep on going looks like my DC out is fine I'm gonna keep on going all the way onto like I get to 150 which is I'm maxed out on my AC power supply all right so let's check my input again hey about 144 DC oh I didn't look see my LED is on now see so power is on check my DC again all right let's make connections I get about 10.5 this is positive besides negative so 10.5 hey let's let's just for a group grins and giggles let's do let's do my my math again right so I actually did my math wrong because I did in my 150 is not 150 memory on my secondary site is really what my voltage is so on my secondary side we can measure my secondary side just be careful these things don't touch secondary side is on here I'm gonna go back AC I get about 8.4 right so now that now that I power up right the next step will be to do my voltage measurement make sure there's no short make sure nothing's heating up and 8.4 right going back to just for grins and giggles remember AC input times one point four one four and I think I was rounding out to like nine votes so nine votes AC 9 plus AC times one point four one four he had 12 points seven two six and how much did I say we have over here ten point five one so we're off by and I don't know maybe two votes so it still do well it's not off it's not bad so powerful pasta flies coming on this is a power supply vultures is coming on and there's no bridge rectifier or anything so there's not really a good good regulation going on besides the filter caps and I should get my voltage on my caps on this side too because there's a same point right so if probably got my capacitor here I should get that ten votes something on there so I know my fuse is good my fuse is good bridge rectifier is good transformer is good because I'm getting the correct voltages all right I've done all my measurements on it so measurement measurement on my AC input and it's going through my my primary site and then it's getting on my secondary site which is stuffed it down just from 150 volts AC it stepped it down in to the 12 volts AC and then from there 12 volts goes into my bridge rectifier and it rectifies it over to 10 volt something and that 10 volt is crossed my capacitors and pretty much that is going out to this connector here and this pond supply is doing what it's supposed to do right so let's power down make sure I don't get shocked or you know have it touch something you always want to make sure that you you stay safe so if you guys look my LED is still on I have no load and there's no discharging going on so if I measure it I see I could take steel that way I could take my Lee's out or better yet I got a meter right I could just measure it I have no voltage gonna see the waters going in and my LED is still on I gotta make sure that I discharge it again safety first if you look here I still have about six volts so we could let it just discharge if you have a capacitor handy right don't use your screwdriver or something like that but you have a capacitor only a resistor as handy with a high wattage or something just touch it across there and you would use it as a load and it would discharge so that's basically what I would do if if if I didn't find anything I would in most cases we don't find anything but if we do find something it will be in the bridge rectifier side and fuse will be open and sometimes transformers do open up and if it does open up we won't get any voltage to the secondary side so if the voltage AC voltage is on the secondary side then it definitely won't make it to the bridge rectifier right we didn't test the LED because I knew we was gonna power up the LEDs you can come on anyways so I didn't check that but caps seem to be holding up fine because it's definitely when I took the power off these four caps is still holding its charge so the caps seem falling so this board looks like it's working fine but as I mentioned earlier I would definitely still go through and change out these caps anyways and just to make sure because let's you let the caps there they're full of electrolyte which is a liquid chemical and over time with liquid right when you add Heat capacitors get hot you know what happens to liquid alright has to change state and into gas and then from there right over time is not gonna be able to hold as charge when there's no to none less she was left in your electrolytic capacitors so that's why capacitors go bad and that's why we replaced them and even if they're sitting on my shelf these capacitors have a life or what they call shelf life and fish sitting on shelf for a couple years you definitely want to replace it anyways but if this board had I seized and and like Moss Fez and transistors and things like that I would I would go through and check those two I can easily check those out I could turn them on and check those and see if they're actually turning on and off there's there's off those but if I if I had ICS which is some of the hardest thing to test and it's more time consuming I would pull a datasheet on those and when I pull datasheet on it I could I could use my oscilloscope and I could check my output if it's like a flip-flop or something I I found and with without having a schematic I'm just looking for any kind of output is it right is it wrong I don't know but if it's dead it won't give you any output so if you pull data sheet on your your digital ICS I mean there's only if it's a simple one you could inject the signal in using a function generator and you can scope your output and you can see it change and more likely as good same thing with your analog your op amps op amps are really difficult to check well the reason why is with you not having any schematic you won't know how the circuit is like so you don't know what the game is what what the op amp is designed for there is a comparator is it like a ten thousand gain 1100 game you don't know so for what for or what we do here is we basically just and check the signal in and see if we get any kind of change on the output and that's basically what we do and whenever it is there's any question we replace it because they're fairly fairly cheap so that's kind of the step that we go through to troubleshoot bores without any schematic and again this is very simple over you know I mean very simple and you know I know there's not a lot to show you guys but you guys can see if you guys know your electronics and you guys are familiar with it you guys know how test your component just kind of go through those steps then you should be able to find a problem before then so again right you first thing you want to do is you want to do like a visual second thing you want to do is do your discrete component shake third thing you want to do is you want to identify how to power up is the AC input it is a DC input right AC again you're looking for transformer bridge rectifier right those are given for your AC and if it's DC you would be looking for like voltage regulators and you would also be looking for your high C's right your VCC and your ground and you can pull data C on it is it gonna take a 3.3 volts it's gonna take a 5 if you have op amps and it's gonna take 12 or I mean positive 12 positive 15 or negative 12 negative 15 right so as long as you know your eye sees you need to power up from there so those will be your indications for DC voltage so once I identify how to power up then I power up make sure there's no short and I power up and see if any of my components heat up and if anything blows up and I'll basically do my voters check and make sure I get all my Craig voltages out and again if I have any if I don't find the problems then I want to go to my my high seas of high vices and I would check my I Caesar and I can't find problems then I'll send it back to the customer with no problems found but more likely if they sent in for an issue then you would have found it first and high-seas is not normally things that we find wrong here is more of your discrete components semiconductors excluding your ICS but that's basically what we do to go through and troubleshoot without any schematic hopefully it has been a help to you guys and you guys should be able to go through and do that if you guys have any questions on how to take it further or deeper then leave a comment and I would jump on and answer any kind of questions you guys have I know this was really brief and I've already spent a lot of time on this video already so if you have you guys have any questions just leave a comment and I appreciate you guys watching

Channel: Electronic Tech

Views: 436,425

Rating: 4.7065883 out of 5

Keywords: power supply, diode, bridge rectifier, electronics, how to troubleshoot electronics, how to test a power supply, how to troubleshoot a power supply, how to test a bridge rectifier, how to test a diode, how to fix electronics, how to troubleshoot a printed circuit board

Id: QFAWb1F_EpE

Length: 49min 24sec (2964 seconds)

Published: Fri Jun 28 2019