Kenmore LG Fridge Repair Process.

hi everyone and welcome to another episode of mr. Carlson's lab the refrigerator at her house ended up quitting I imagine sometime the evening before I ended up discovering it everything in the fridge was warm everything in the freezer was thawed a couple hundred dollars in groceries had to be thrown out at this point which is extremely unfortunate but this gives us something now to troubleshoot now here's the thing when I discovered that the fridge wasn't working I didn't have a camera on me at the time but here's the key thing I immediately started troubleshooting the refrigerator and the freezer without disturbing it at all and there's a few key things that I look for so I didn't want to unplug the fridge you don't want to touch any temperature controls or anything like that you do not want to disturb it these are the things you want to look for number one is the compressor running on the fridge when the fridge is warm number two when you open up the refrigerator do the lights come on when you open up the freezer do the lights come on number three do you hear any crackling in the freezer or the refrigerator so if you listen closely do you hear any like sizzling noise or crackling noise these are the three key things that you want to be listening for before you do anything if you unplug the fridge and plug it back in many times it will reset now most modern refrigerators are controlled by an IC so by unplugging it and plugging it back in if there's any relays in there it lets the tension off and then some of the relays will come back on sometimes it will reset the IC so that it'll run through a process again and this can really skew any troubleshooting for a few days so these are key things do not touch anything and do those things first compressor lights crackling remember those things we're gonna go take a look at that refrigerator now and we'll see if we can get this thing operating again Here I am behind my fridge and the controller board for this fridge is underneath this cap right here so in order to get to this board I need to remove these three screws right here now the fridge has been unplugged for quite some time and this is very important because there are capacitors underneath this cap that can hold a charge for quite some time so if you're following along you're doing so at your own risk so here we go these screws out of here and sometimes since I've been in here I will explain that very soon okay so here is the controller board for this fridge and in order to get this out I need to remove all of these wires now everything is the indexed and everything is a different size in here so what I need to do is remove all of these connectors so again I know that there is no charge on this board right now so I'll just unplug all of these like so they very easily come off and remove all of these from the top side so all you do is you pinch this little tab down and pull back and then these all come off so here's a little harder to get out because there's capacitors in the way and there's these little plastic tabs that just lock in place this isn't screwed in or anything like that so all you need to do is press this little tab in on the side and then pull forward and you can see it just comes loose so you look for the little tab that's protruding out of the side and you can just squeeze those little tabs together and then the board will just come out this one here is a little rougher to get just like so so let's head back to the lab and take a look at this on I'll explain what's going on here we are back in the lab with the controller board out of my fridge on the bench now I'm no stranger to the circuit board about seven years ago this board had a pretty bad failure point and a lot of other people suffered from this failure as well and I think you can see the solution right here that I designed for this board I designed another little circuit board to sit on top here and I'll explain a little bit about this in just a while so what happens with this board here and what's happened to a lot of people is when you close the door on your fridge the lights stay on and that's a big problem with these refrigerators especially way back when because they had incandescent bulbs inside incandescent bulb means that they have a filament inside them and they get really hot so when you shut the door on your fridge the bulbs don't go out and since the bulbs are on the upper portion of the fridge the top shelf is really close to that area gets really warm inside the fridge and food spoils it can cause a whole bunch of issues and a lot of people were dealing with this a lot of people had you know way more serious issues than I had with mine I caught mine pretty early so when you find that the freezer is still working very well but the refrigerator on the top is getting warm this is when you start to inspect things and of course I found that the lights were staying on even though the switch on the top was pushed in by the door so that the lights were just stuck on and this is a mistake that's made by young engineers well what happens with incandescent bulbs is when they're cold the filament inside is at really low resistance so it's closer to a short when the bulb gets warm so when the filament starts to glow the resistance climbs high so there is no problem see the you know draw their specified amount of current when they're nice and warm but when they're cold especially inside of a refrigerator depending on where in the AC cycle you open the door the contacts in one of these relays will close and if those two incandescent bulbs have cold filaments inside them it can draw a lot of current for a very short period of time until that filament warms up that excessive current drop will weld contacts inside of a relay so when the relay closes it goes spark and then they can't release because they've welded together and that's what happened on this board here so I designed this little solid-state relay board here for both the refrigerator and the freezer lights and this isn't just a standard type of solid-state relay these optos here are known as zero-crossing opto isolator z' and they're special because they turn these Triax here on when the cycle is very close to zero cross and in order to explain how that works I need a piece of paper that'll help you greatly understand how relay contacts weld together and how something like this is a very decent solution I've had absolutely no problem with this circuit here and I've gone through you know light bulbs in the refrigerator since then and the circuit still remains nice and strong so I'm not worried about this it's the rest of the board in this video that needs to get fixed at this point so I'll get a piece of paper and I'll explain what this little board is doing in order to understand why the relay contacts are welding together we need to take a look at what's actually going on so first of all in the wall outlet of your house you have 120 volts AC 60 cycles per second so that is one whole cycle this is known as zero cross right here right here right here and so on as we go along this is zero volts right here now oscilloscopes show peak values in order to make this a little bit easier to understand we'll just use the RMS value what your standard DMM will read all right so we'll go positive 120 volts ac here right at the top and we'll go 1 negative 120 volts ac right there so what's happening is this is changing continually in your wall outlet so we have it going to positive 120 volts AC and then it comes back down to zero again zero volts and then it changes polarity angles negative 120 volts ac so the polarity in your wall outlet is continually switching back and forth like this that's why it's called alternating current now this is one whole cycle right here and there's 60 of these in one second so that's what it is 60 cycles per second is how many times this is moving right so it goes positive and negative in one cycle and then so that would be one cycle and then another cycle and another cycle we have 60 of these in one second one easy way to remember AC is if you have an AC signal that looks like this right if you join your fingers like this you get a circle right way I'm twisting my hand here on camera it's not looking quite like a circle but you know you get a circle one complete cycle one circle alright now when you're opening the door on your refrigerator this is moving you're not in sync with this alright so this could be anywhere in the cycle when you're opening that refrigerator door so this is starting at zero volts and it climbs up to 120 volts AC and then it goes right back down to zero and then it changes polarity and it's going to 1 negative 120 volts ac coming back up to zero and it's just doing this now you can open the refrigerator door anywhere within the cycle because you're not in sync with this so if you could be very very fast and you knew the times you could open the door when this is at zero cross right here so it's at zero volts so just say that relay closed to turn on the lights in your fridge at zero across well there's no voltage there so and there's no current being supplied to those bulbs so what happens is is when the contacts closed there's no spark right now just the light bulb would turn on with the cycle right now what happens is since it's random you can open the fridge door at any time you could open it when it's here on the cycle so you know the voltage might be climbing right to 120 volts AC or you could open the fridge door right there alright that would be the worst place to open the fridge door because what's happening now is the contacts in the relay will go click and close at this point well this is supplying maximum current at this point right hundred twenty volts AC at maximum current is going BAM like this so you're gonna get a spark in there when these spark like this it's they spot weld together now this doesn't happen with any relay or with just any relay if you have a big enough relay they can deal with this they can close and spark and be just fine but these relays here cannot deal with that load especially with these two incandescent bulbs in parallel in the fridge so what's happening is is just say throughout the entire life of your fridge you're lucky it's like winning the lottery every time you open the door you opened it at zero across here so what would end up happening is the switch contact that relay contacts would close and it would climb with the cycle and it would be absolutely fine the contacts would never weld well the chances of that are very very slim there's a really good chance that your opening and closing the door all over the AC cycle and of course if it's anywhere on the AC cycle like this you're gonna get a spark and since the filaments are cold the resistance is very low so it's closer to a short and this has to supply maximum current as soon as those contacts close again you get the spark and they weld together all right now what's happening with this little circuit that I've designed here these are known as Triax so basically AC switches okay these two little white blocks that you see here are known as zero crossing opto Isolators so what happens is just say the switch on your door say you were to open the door on your fridge and the switch was to supply current so this little processor right here little microcontroller here is now telling this opto to turn on at this portion of the cycle well this little block says no wait a minute so what it does is it waits until it gets very close to zero across and then it turns on the triac so these things wait until it's at a point very close to zero across to turn it on that's much easier on the switch and it's much easier even on the bulb when I discovered that both the freezer and the refrigerator were warm I immediately started the troubleshooting procedure I was very careful while doing this not to disturb the original failure point this is absolutely crucial in finding a problem especially a problem like this so I listened for the compressor the compressor was off when I open the freezer door the freezer light did not come on when I opened the refrigerator doors the refrigerator lights did not come on so at this point I'm thinking that there may be a problem in the power supply here because nothing is happening now in the back side of the freezer I hear a crackling and a hissing noise to me that sounds like the defrost heater so I put my hand on the plastic on the backside of the freezer and it's nice and warm so everything is off except the defrost heater well immediately that tells me that this relay here has most likely stuck this is the relay that controls that what's happened is the processor most likely told this entire board basically just a shot down told the fridge to shut down because the fridge won't come to temperature within a certain time period so it's just shutting the thing off so it's it's run and run and run and run and it just won't come down in temperature because it's fighting this heater there's a heater on the defrost heater rightness basically trying to melt things and it's creating heat in the backside of the freezer it can't fight that so it just shot down so my first thing that I'm going to be doing is I'm going to be replacing this relay in fact I'm going to replace all the relays in here because this thing has been in service since 2007 now that's when this fridge was built and put into service now these capacitors have also been working 24 hours a day 7 days a week since 2007 what does that mean this thing needs to be recapped this thing isn't cycled it's not something that's steam turning on and off these things are on 24 hours a day so what I'm going to do now is order up brand-new relays I'm not concerned about the value of this particular relay because this has been in service again since 2007 and chances are the contacts in here have just you know from sparking on and off chances are that the plating is worn off and they're sticking so something is light is tapping a relay like that a lot of the times will free it up and it's the same thing with these original relays the ones that I replaced for the lamps all I had to do was just tap them and they would let go and they would work again just that easy so again anything can disturb a failure point in something like this so that diagnosis procedure allowed me to find that this here is sticking on and the fridge is just you know it can't fight that amount of heat it just won't come to temperature so just the whole thing has shut down so that's my next line of repair here is what I'm going to do is just replace all these relays I'll leave this solid-state board in because you know for the lights that's a really great you know it's a great feature in this fridge because you don't have any contacts moving it's all solid-state right and if anything's being cycled it's those lamps every time you open the door those lights are coming on and off so I'm going to replace this relay this relay this relay this one this is the compressor relay right here I'll replace that as well and all of these electrolytic capacitors every single one of them I'm going to replace with a brand new high quality device hi our capacitors some ones that will last a very very long time now they were nice enough to put a legend on here so you can follow this right to the relay you can follow the wiring you know defrost heater is here you know we have freezer lamp which is this right here refrigerator lamp which is this we have valve 2 and valve 1 so if we look on the back side they've even marked it on the back side they were really nice when they built this board a lot of companies don't do this so you can see valve to involve one or just one relay they're hooked together and then we have a front door heater which is this rate so it heats the the actual seals of the door so that way then the air heats the actual door so that when the door is closed they don't you know stick especially the freezer you know because if there's any moisture in there and it gets really cold you don't want it to stick so they have heaters in there as well and of course you know that also helps I felt around the actual door and the doors are nice and warm themselves so I guess it stops the refrigerator from also you know cooling your host down that's well you know but down at any rate right around the seals is where it's always nice and warm so you can see on the back side it's you know really straightforward single sided board you know it's just everything is really you know really well laid out this looks like a from a uln 2004 2003 or something like that I can't really see that here so just a relay driver there using this as a relay driver so the outputs from the processor right here drive this I see and then this I see is what you know drives all the relays to keep the load of the relays off the processor so for some reason all the relays are one of the relays was not to work at all this is the first thing this actually protects this IC from this side which is kind of nice so nice little bit of isolation between the processor and the coils of the relay so just pretty straightforward stuff you can see up here everything is all labeled at the top as well so you can see here so freezer sensor refrigerator sensor door sensor front door switch stepper motor and then the display this runs up to the little LED display with all the selections on the front so you can adjust the freezer and the refrigerator temperatures so and it has everything you know pumps and doors and fans all that kind of stuff just you know everything is very well laid out so they did a nice job putting this thing together the board itself it's just too bad they didn't design this little area a little bit better so I'll get that underway we'll get the board back in the fridge we'll see what happens okay parts are in let's take a look in here brand new really right there so that is that any thing about digi keys they do such a nice job packaging this stuff no I'm not sponsored by digi-key but they do is just everything is just packaged so incredibly nice I ordered a bunch of other supplies as well and everything is you know just wrapped so nice the heavy stuff is at the bottom of the box and the light stuff is at the top just you know good planning at any rate new replacement cap right there very high quality capacitor and I ordered some extras ordered a few more like this so thorough person that did this was very thorough taped to spots told this relays in place see okay so they're all brand new relays so I replace these ones I'll have two as spares just to put in the box because these are nice little relays nice relays to have around maybe for another project or something like that cuz at this point I doubt that I'll be replacing these again so again these will just stay in the solid states which works very very well so getting this out looks to be relatively easy and just like that it's out and ready to be replaced so I'll end up doing that with all the rest of the components replace them all I'll try this thing out all the relays and electrolytic capacitors have been replaced so at this point it's pretty much ready to try out I've cleaned off all the flux residue on the backside of the circuit board and on the bench here you can see all the components that have been removed from this board that have been replaced so time to put this thing back in and see if the fridge works okay let's see if this thing comes to life so I'll put the circuit board back in [Music] and here you so there it is here's the line cord let's see what happens here we go that is a really good sign so the compressor started up and I hear the PWM of this little IC for the fans inside so all is looking good the fridge has been on for a short period of time now as you can see the display is working let's take a look at the temperature so I'll zoom on in I just put this little thermometer at the backside of the fridge focus in on that and as you can see it's very comfortable within the Green Zone which makes me extremely happy and if i zoom back out here you can see their fridge light turning on and off and you're the fan starting up here the PWM there so everything is working great the fridge is back in working condition which makes me extremely happy I hope you enjoyed troubleshooting and repairing this refrigerator with me today if you are enjoying my videos you can let me know by giving me a big thumbs up and hang around there'll be many more videos like this coming in the near future we'll be repairing troubleshooting and even reverse engineering modern in antique electronic devices alike so if you haven't subscribed now would be a good time to do that as well if you want to be notified as soon as I post a new video don't forget to tap the bell symbol if you're interested in taking your electronics knowledge to the next level and learning electronics in a very different and effective way you're going to want to check out my ongoing electronics course I'll put the link just below the video description and it'll also pin the link right at the top of the comment section I'm also sharing many of my personal electronic circuit designs there for customized test gear to make your troubleshooting procedures all that much more easy so there's a lot of really interesting things going on definitely check it out all right until next time take care bye for now

Channel: Mr Carlson's Lab

Views: 155,171

Rating: 4.9493017 out of 5

Keywords: Fridge repair, kenmore repair, LG repair, circuit board modification, fix a fridge, refrigerator repair, LG refrigerator, Kenmore refrigerator, Kenmore circuit board repair, LG circuit board repair, fix electronics

Id: ABK-BndqGz8

Length: 27min 59sec (1679 seconds)

Published: Sun Sep 15 2019