To learn more about electronics in a very different and effective way, and gain access to my circuit designs and inventions, click here: www.patreon.com/MrCarlsonsLab

The MOST overqualified refrigerator repair man in the world.

Mr. Carlson, your channel has the best audio quality. Hands down. Thank you!

Customer #1: “Yes Ma’am, your refrigerator requires a new control board”... Customer #2 (Mr. Carlson): I see that you’ve designed a custom solid state relay board with triacs and zero crossover opto isolators, I’d recommend re-capping the board and installing new relays... 🤣🤣🤣 As a commercial refrigeration mechanic, I can honestly say that this is the best video I’ve seen all year.

A good housewife opens the door at zero cross point of AC cycle.

After she passed and we inherited her stuff my aunts old school (non-electronic) side by side Frigidaire from the 70's wasnt built with all this failure prone B.S. and it lasted 40+ years without a single major repair, just coil cleanings and a door gasket. Same story with her '70's era GE washer and dryer, they lasted 40 odd years with one new hot/cold valve and a new heating element and belt in the dryer - the washer was one of the most durable ever made, the GE Filterflo, had the lint filter pan on top of the agitator. I was shocked when I went to buy a new washer and saw how badly they had been cheapened. I fixed the heating element in the dryer, installed a new belt just because and bought me a commercial duty Speed Queen washer thats old school on the inside and built really well---and it has an agitator-!! That thing washes clothes clean like an old Maytag and no stupid error codes or flying apart like the samsungs etc. have been doing. Nothing is built to last anymore, too much unnecessary electronics and too many gadgets and built to fail, lucky if you get five years out of many new appliances without trouble,

I was an MOS 1161 in the USMC for ten years. '81-'91, then had this bright idea to go teach English in Tokyo for five years. Lovely. Your channel is Sumo Uber Dupper. I'm fixing to enter into your patrion membership, have a ton of questions. I have learned so much from your videos, have always felt guilty receiving so much knowledge yet unable to afford the price of admission. Untill now. Living in low income housing waiting for the VA to fuse my ankles. Boo Hoo. You kick ass. You have kept me motivated and kept me going. I have hunted down a ton of kit on the cheap thanks to you. I can't say thank you enough. When a Marine sheds a tear. Does not happen often. Thanks for all you do. You are an inspiration to so many people. Unbelievable. Please keep doing what you are doing. Bless you. And thank you.

This is incredibly useful. Our refrigerator failed a year ago, shortly after warranty period was over. And repairman said we needed a new control board but that it would be easier and better just to get a new refrigerator. And recently, we have 2 friends whose refrigerators have failed, and they have to wait 6 weeks for a new one. DigiKey and soldering station much faster! Many thanks Mr. Carlson.

Brilliant! I bet thousands of fridges are dumped every year for small issues like this. So easy to fix with a bit of knowledge. Nice work Mr. C !

I simply replaced the incandescent bulbs with LED in my fridge. Saves relay contacts, and a few watts. And LEDs love the cold. Great video. I've been binge watching your latest videos. Thank you!

A few years ago, the bulb in my freezer burned out as I was opening it, and actually tripped the breaker. So I replaced the incandescent appliance bulbs with LED bulbs that I had removed the cover from, in order to fit them inside the fridge's lamp housing. It took care of the problem, and lit the inside of the fridge up brilliantly. I see they now actually sell LED appliance bulbs, and I think they're a really good idea for older fridges without built-in LED lighting.

I got a big fancy Samsung microwave a little while back for free because it was broken. Lights were on but nobody was home, the high voltage fuse was blown to supply the transformer and magnetron, so it wouldn’t actually heat anything. I put in a circuit breaker instead of the fuse temporarily, I realized the transformer was buzzing so it was always running (And so I guess dumping full power microwaves into the chamber too). When I poked around just a little, it dawned on me that there was probably a relay welded shut. Then today when I saw this video pop up in KZfaq, I realized why I figured out the shorted relay quickly. I had watched this video before and it’s almost the same problem! Thanks so much Mr. Carlson! I have the replacement relays but now I’m also thinking about putting in your zero crossing circuit instead for longevity.

WHAT WE NEED IS MORE AND MORE COMPUTERS IN OUR APPLIANCES AND EVERYTHING ELSE WE USE, MY PARENTS HAD A 55 YR OLD GE FRIDGE/ICE BOX ( MADE IN USA-IMAGINE THAT ) AND IT RAN PERECT, NO COMPUTERS !! JUST COMMON SENSE WITHOUT THE GREED,......8 YRS FOR A 2K DOLLAR KENMORE WITH A NEW FANGLED (LG) INVERTER COMPRESSOR , NOW ITS BACK IN CHINA TO BE RECYCLED INTO MORE CARBAGE FOR USA CONSUMER....NICE GOING!! SO MUCH FOR ECONOMY AND SAVING THE PLANET !! MR. CARLSON YOUR A WONDERFULL, SMART PROFESSIONAL/PERSON,,,HOPE WE HAVE SOME KIDS LIKE YOURSELF COMING UP TODAY LIKE YOU .....BLESSINGS AND STAY SAFE PEOPLE ...TIME FOR A COFFEE...ON ME !!

Planned Obsolescence: 0 Mr Carlson's Lab: 2

MR. Carlson, u do it all. I'm a maintenance mechanic, and change relay contractors all the time, but never once gave it a thought that mechanical contractors can catch the voltage at its peaks, or as u said at worst time on top of the peaks.

Mr. Carlson i can't believe you were able to squeeze the mounting tabs for the pcb barehanded. you are amazing

Paul...Removed the Compressor from the Kenmore Elite/LG Refrigerator yesterday. What a job. After removing the Clips that hold down the unit you have to push the Rubber Vibration Dampeners down through the Mounting Plate. Then you can barely lift & wiggle the thing out. The worst part was getting the two Refrigerant Lines off! They are not Soldered nor are they Silver Soldered...they are Brazed! Had to purchase an Oxy-Acetylene Torch to get enough Heat to turn the Brazing Liquid. MAAP Gas nor Propane will do. Anyway, after I got the Compressor out, I discovered Sears sent the wrong replacement Compressor! The Compressor they sent was $200. The Compressor I need is $400 even though they assured me the first one was the right one! The thing that really gripes me is that the Compressor is still under the 10 year Warranty...but Sears will not Warranty it unless a Sears Technician comes out first to Diagnose it... for a $100 Fee, THEN AND ONLY THEN will he give me an Estimate for the Labor to Change the Part! So, essentially your Paying $100 for an Estimate! At that point you feel Obligated to go ahead with the Repair as now you have Money invested. I checked around with some Mom & Pop Shops and found out Sears Charges $600 to $700 Labor to Replace a Warranty Compressor plus the $100 Service Fee that probably takes someone with experience 2 hours to do! The Moral of this Story...Stay Away From Sears!

Peak Value = sqrt (2) x RMS value, so it is about 170 V for 120 Vac (RMS Value). - I enjoy your videos every time! - Cheers from Greece! :)

I have a GE that is stuck on defrost mode too. It was a 1500 dollar fridge that I am not willing to part with yet, so as it sits in the garage, I keep thinking I will "get to it". Now I am motivated after seeing this...thanks Mr. Carlson!

For four years I have been working as a repairer for electronic devices and with every new video from you I learn something new ... Thank you

Really nice job Paul. I think replacing those bulbs with LED bulbs would be even better for an older unit like this. I really love your approach to troubleshooting, appreciate it very much. Ron

Wow! I do part-time work with a friend and we recycle a lot of appliances with many of them being Kenmore brand refrigerators. Newer ones no less. And as we do the evacuation of the freon, we find that they were always fully charged. I wanted to troubleshoot them but my friend never wanted to bother. I am going to show him this video and maybe we might have some fridges to repair and resell. Surely we would get more for them than simply scrap prices. Thank you so much for sharing this information with us.

Another wonderful video, easy to understand even for beginners as always.

Most of us would just have paid $80.00 for a new board and called it a day. Not Mr. Carlson. Love your passion, knowledge, skill and enthusiasm with what you do. I hope one day I can troubleshoot down to component level as easy as you can.

Some years ago, my wife was sitting in the kitchen near our new Maytag refrigerator at 11:30 PM. Suddenly I heard her scream, "Ted! the refrigerator is on fire! I was in bed, so I jumped out and ran to the kitchen and pushed the refrigerator out from the wall and unplugged it. It still smoked a little but the fire was out. Next day I took the door apart and found the circuit board had shorted to a 120 Volt wire that was bent behind the board so that the sharp wire ends could punch through the insulation. I called the Maytag repairman and he brought a new refrigerator and took the old one back. He could have just replaced the board, so this is an example of whole unit replacement instead of board level replacement.

THANK YOU Mr Carlson! This video specifically encouraged me that I could do this for my recently failed KitchenAid refrigerator. Fixed it for $9 in parts and $9 shipping. (I actually bought extra capacitors and will have them on-hand for “next time”, hopefully in 10 years or more.). All of your videos are instructional, and a BIG THANK YOU for sharing your knowledge here!

Old fridges operated by only one defrost timer and a thermal disc which are so simple and very durable.

A wonderful icing on a Sunday afternoon! So much useful information that helps everybody who loves repairing electronics stuff! Thank you Paul, for doing all the hard work over years and being an awesome teacher by sharing your unique experience with us for free!

In case you're wondering if you're a brand, yes, imo you are. I expect to hear your cheerful voice along with "Hi there, and welcome to another episode of Mr. Carlson's lab," at the begining of every video. It's your trademark.

Well done, Paul. It's nice to see someone who still troubleshoots down to the component level. It's becoming a lost art. And I second the vote for Digi-Key. They and Mouser are my go-to parts houses. BTW, one of the main reasons for heating the doors on a fridge is to prevent condensation.

It’s so great that you hacked your fridge board and built a board for the board!

wow, I am amazed with your detailed explanation you should get an award for sharing your profound insights on electronics, keep up with it. 👏👏👏👏👍👍👍💡💡💡💡

All my appliances had relay pin fails solder melts,no contact so I just jumped a small wire , nice to see how you rebuild the board ,mostly can’t find 10 year old boards so thank you !

What a wonderful channel. If Mr Carlson was a sugeon (of elecronics of course), I bet there would be many happy radios out there. Back when then of course.

Another *SUPER* job, Paul!

Paul, your level of detail and the way you strive for perfection and doing things slowly and thoroughly, completely aligns with the same character traits in me, which is why, yet again, I'd like to thank you for your time and effort in producing these videos. You REALLY stand out from the noise and the know-it-alls, your calm, thorough and slow-paced demeanor pays you, and us, dividends. God bless you, I hope you're all well, keep smiling my friend. Matthew, England 🙂❤️💜

Insightful explanation of the bulb relay fault. Great to see the master at work on every day problems. Very relatable video.

The cooling unit for the µ-processor on this board is enormous! :) Great assessment, repair and video.

Even more scary is when the contacts weld shut in the magnetron relay of a microwave oven. I had one that would energize the magnetron as soon as the door was closed, and without running the cooling fan or light! Luckily someone noticed the abnormal humming and unplugged it right away. Those Sam Young capacitors are not very good. I've seen lots of bad ones in TV's and monitors.

I'm reading Gordon West Amateur Radio Study book and he recommended your channel to learn from . I was already watching your videos ,it was kind of neat to see his recommendation . I've learned a lot just watching....Thank you

This video gives you the motivation to try to repair other stuff. I had a central heating wall control unit timing problem which turned out to be a faulty capacitor which saved me time and money for a new unit. Worth a go.

"Spoiler" alert! Mr. Carlson fixes the 'fridge, and it's really "cool!" :D

"The more complicated the plumbing, the easier it is to stop up the drain" - Montgomery Scott

Awesome video, I enjoy seeing repairs on refrigerators and hearing your explanation on why components failed. Really great stuff!

Got to say Mr Carlson, a very professionally presented channel. Well done!

I was expecting something like a Supreme Fridgelizer refrigeration device from “way back when”. Nicely done and educational, as always :)

Digi-Key also has the best ziploc bags. I always save and reuse the bags from every order.

While watching this video, i thought of how many appliances and other devices are labeled "No user serviceable parts inside". Not counting there are people who know how to service the parts and are willing to do so. Very interesting video by the way.

What’s brilliant about your videos is the way you describe every detail precisely 😀

I was expecting Mr Carlson to growl "Focus you f*ck", when I remembered that that's someone else. This channel is chill.

Excellent vid once again Paul... 10/10 One suggestion though: Since you've replaced all the electro caps to ensure long term reliability, might I suggest you should replace the Varistor. I've found that Varistor's change their molecular structures over time. It becomes worse in very noisy AC mains area's and they will eventually crack or explode and can be flammable. It's also recommended to encapsulate the Varistor body with heat shrink tubing to prevent the expulsion of black gas that will spread all over the place, plus it prevents flame out. In rare cases, it can actually produce a flame. I was made aware of Varistor problems in the first produced Micro$oft X-Box's. The AC connector solder joints eventually crack and become dry joints. This condition caused major spikes within the PSU to which it eventually changed the molecular structure within the Varistor, and caused it to crack open or explode. I repaired many an X-Box due to this problem. Micro$oft were quite aware of this, and offered up replacement power cords with had anti-spike suppression to prevent the Varistors from flame out. It was a cheap and nasty way of them to avoid console call back. It saved MS as heap of money and it avoided any possible litigation, as some consoles actually caused fires... Once again, great diagnosis and repair...

All this, and refrigerator repair too! Man, Mr. C, I have to say I'm danged impressed! Good work!

Great I had the very same problem, wish I had seen this tutorial earlier, ended up buying a new fridge freezer!

Hi Paul, can you show us what the old parts look like on the curve tracer and the capacitor tester. am now building the third test device of your design. keep up the good work. am a patreon member

Suggest adding an external temp alarm set to give FUTURE "early warning" of out-of-range temperatures.

Very impressive. I love this kind of repair video for everyday appliances. Most people would have just bought a new refrigerator. Thank you for another great learning experience.

About the time your fridge failed, my microwave oven failed. (Mfg. in 2004.) I discovered that the control board was not delivering DC to the circuit board. Upon examination of the circuit board I discovered that there was a small resistor in the power supply section that had burnt out. Since the resistor was so badly burned, I couldn't read the color code so I put my resistance substitution box in place of the resistor and began cranking down the resistance until the board started working. It was a 100 ohm resistor. So I replaced the original 1/4 watt resistor with a 100 ohm 1 watt resistor and the microwave oven has worked ever since. I put my DVM across the 100 ohm resistor and discovered that the resistor was dissipating way more than a 1/4 watt ! I couldn't believe that manufacturer (KitchenAid) had deliberately planned for the failure. The board was made in China, so I assumed that they had planned for it to fail so most people would just buy another microwave oven... P.S. For those of you guys reading this, if you have a microwave oven failure, don't try to fix it yourself unless you really understand the workings of a microwave oven. There is Very High Voltage and a large capacitor in part of the oven, that will Kill...

I was going to give this one a pass. Glad I didn't. I love this channel, and the Patreon channel especially. You can't help but learn.

I had a fridge fail once. I went over the board 100x's, checking caps, relays, soldier joints, etc. Also checked the compressor. Everything checked out good. It turned out to be a bad fan in the freezer (responsible for blowing cold air in to the fridge portion). I unplugged it and the fridge kicked on. $10 later (for a new fan) and everything was right in the world.

Just retired two years ago from a local county Sheriff's Office detention facility, after 30 years, where I was, in reality, the 'maintenance electronics geek'. Almost all of the equipment that I repaired was commercial grade stuff. Financially it was a boon to be able to repair most of the board level failures as the prices for the replacement/repair of the boards were hideous in comparison. When I started for the county, 1987, they did NOT do their own repair work and I had to convince them to get troubleshooting equipment. I specified about $7K in equipment to get all I needed at the time. Thank God that my new boss believed in me. The first year I posted about $17K in avoided repair costs in just the PLC input and output boards. I also did the refrigeration control boards and the kitchen equipment. Not nearly the volume of repair, but expensive as all get out from the manufacturers. Getting schematics for the boards was more than problematic as the manufactures did NOT want anyone to bypass their cash cows. Some smoke had to be released while 'researching' the correct parts for a few of the boards. Digi-Key and Newark were my main sources of parts. National Semiconductor and International Rectifier were instrumental in 'helping' me find industry standard part numbers for some of the supposedly custom parts with mfr's unique part numbers on them. Many of the standard parts were curiously more robust than the parts originally used. HMmmm... Lol, imagine that! Thank You for another great video, we are a vanishing breed, I am afraid. The fiscal pressure that the mfrs are facing make the equipment prices so low as to make them harder to repair as their modularity is being lessened to make the machine one big module with a lesser degree of sustainable repair. For a while we in maintenance were allowed to help specify the new equipment to insure it's service availability. Alas, when the head of maintenance retired and was replaced with a talking head with a business degree, the procurement process was turned over 100% to county purchasing which operates on a bottom dollar process. I always took pride in my repairs of the older equipment, keeping them head and shoulders above the newer stuff in their available service hours per year. The new boss was totally surprised that I did board level repair, even after seeing the $ense of the economics of it, he just said "That is way too granular." he really said it! After I left, no one took over my job in the depth that I did it, even though they hired someone to replace me about a year and a half before I left, they did not allow me to train them how to troubleshoot & repair at board level. The new man is a 'black boxer', similar to the guy that I replaced because it was an expensive practice... Bureaucracy & History a tangled web.. Again great videos, I learn something(s) from every one of yours that I watch. Michael in Colorado

Thanks Mr Carlson , I learned a lot In under an hour , I won’t shy away from considering working on my fridge .

Awesome and informative! Your broad knowledge of electronics never ceases to amaze me. I love how Digi-Key packs things. They're top notch. Mouser is alright too. And don't be fooled by those "young engineers" Paul, it is the bean counters that restrict what they can do. I was in appliance repair for years and saw the trend of cheaper and cheaper. They're all down to a 1 year warranty, but used to be 10 years at one point (Remember Maytag?) Relay failures became commonplace, especially in electric ranges, and fan motors quit for no reason other than cheapness. Components teetering on the edge of failure from the start so they will fail once out of warranty. I got out of that business a few years ago when replacement parts costs skyrocketed, and the companies made me, the service guy, foot the bill, then they "reimburse" me. You have one of the good refrigerators from a good time period before the "ultra cheapness" really set in. When your compressor finally gives up, you would be miles ahead replacing it, if done properly by an expert, and it will last longer than anything "new" out there today for way less money.

Only one embedded controller? A real fridge runs on 7 ARM5 controllers with embedded windows.

I started laughing out loud when I saw a Carlson custom board on the thing.. this guy!

You've supplied the inspiration I needed to take another look at the fridge I have in storage. People who gave it to me said "it works great." Didn't work when I plugged it in.

As Mr. Scott said, "The more they overthink the plumbing, the easier it is to stop up the drain". Jeez ... never a truer sentiment.

i bought my mum a fridge for christmas, you should of seen her face light up when she opened it

This video has it all! In situ removal; board layout review; hacking improvement ideas, dignostics for various problems; un-wrapping of new stuff (a Carlson un-boxing video! Never thought I'd see that); and repair! Wow!

Fascinating bit of education. I can't believe how much I learn from each of your videos!

Good Video! I replaced my incandescent's with LED's a couple of years ago and no more bulb heat plus brighter light. It's worth doing.

I just peeked in my fridge to check if the lights still go out... they do! :-)

Excellent! Love watching you work on anything electronic!

Had a Kenmore fridge a long while back with a very similar board. My house was old, had poor or maybe even no real ground on many outlets, even three prong outlets. That board had a resistor that would blow every time there was a nearby thunderstorm. All this did was prevent the fan from blowing the cold air from the freezer into the fridge. Everything else looked right. I had bought the extended warranty. They replaced it three times before I (not the repairmen) finally examined the board they pulled out, saw the resistor, remembered the storm a few days before, and put a surge protector on the outlet. Never happened again. Much newer house now, probably fine grounds, but all my 120V appliance outlets get those single outlet surge protectors on them because even the washing machine has a complicated, expensive pcb in it now.

Mrs. Carlson: "dammit Paul, just fix the damned fridge and stop with the videos!" ;)

My first 1994 fridge lasted 24 years, my second 2018 fridge lasted 1 year

As one of the TV commercials used to proclaim; "Simply amazing." A great video and the fix for the refrigerator seems so simple. Thank you, Mr. Carlson. Several years ago we had an upright freezer die. So, we threw that out and replaced it with "new." If that happens again we may , "buy new." However, I will tear into the old device and see what I can find and perhaps sell the old one at a yard sale to recover the cost of parts or maybe Mrs. Bob theGrape will want to keep it. Thanks for this enlightening video.

Paul, Another great troubleshooting video! I enjoy the modern troubleshoot/repair videos as much as the antique ones you share. Unfortunately, for us the appliance repair techs are board replacers and can't take things to the component level as you do. I had a similar problem, caused at times when I experienced an AC glitch at the line voltage level whenever the utility company performed switching. FYI, I agree with your comment regarding Digi-key. Great folks there that deserve a shout out. Again, many thanks for another fine video.

The back of that fridge was way too clean. No dust bunnies? I'm afraid to look behind mine. 😄

The other good point is the triacs don't open until zero cross also.

I really enjoy watching your videos. You explain in great detail , clear voice and precise. You are a master electronics technician indeed. Keep up your very interesting videos.

Can you imagine Mr C Appliance Repair coming to your house! Awesome channel, great info and interesting!

It would have been nice to see how bad the ESR's where on those old capacitors???

His wife must be mad, Honey lets get a new fridge...oh no I can fix it ;)

Well now we are branching off in a new direction here ! A lot more like you’re first or one of your first videos about an emissions gizmo on your T/A. Infact I think I’d like to watch that again after this. Cheers from S Ontario Paul.

That is one appliance I hate working on. I just repaired mine a few weeks back, Would not auto defrost. A friend that is a fridge tech came out and replaced the thermostat. Did not fix the problem. I found that the heating element was open. Great repair Paul, thanks for sharing.

Maybe you could replace the incandescent bulbs with LEDs to avoid replacing them in future.

I experienced a similar failure of my 'fridge but on the worst possible day...Thanksgiving! It was not discovered until the following day and all the holiday leftovers had to be trashed! In my case, the defrost relay stuck on causing the refrigerator and freezer to heat up! The odor the next day told the tale... Clever mod, on your part! Thank you for the full explanation of your modification as well as taking us along on your refrigerator repair!

Thanks as always for sharing. Also great video quality and most of all sound quality! From a long time patreon-member!

Why did you not change for leds, does it have adaptive defrost?

would love to see the circuit for your relay replacement please

Great video and explanation. I have 2 Sub Zeros, a refrigerator and a freezer and both have caused troubles in the last almost 20 years. The first was a leaking condenser which I had to have replaced (under 5 year warranty). The second issue, the freezer compressor would not turn off rendering -15° freezer temp. Guess what-a frozen, welded relay. I banged on the control box unfortunately located inside the freezer and the problem went away...for awhile. I replaced the relay but did not replace anything else-my mistake. Now it's almost 20 years and the freezer icemaker doesn't work but leaks water into the freezer causing a big ice pileup. The solution here was a water valve leaking at a very low rate but enough to cause a complete freeze up of the drain system. Being a semiconductor design engineer, I cannot believe that they use these small relays for a product that should last 20 years...at least. My parents GE lasted as long as I can remember-but it was not frost free. (at least 30 years). Relays in appliances should be a thing of the past. I have had relay problems in all of our top-of-the-line products: Fisher Paykel dish drawer, Thermador 48" range, Sub Zero refrigeration and also microswitches in our GE microwave. Next time I will take your advice and replace all mechanical relays and electrolytic capacitors on the boards. The Themador range had a "hot wire" relay failure in the first few years of operation. The replacement has lasted 15 years or so.

More repairs of modern electronics, please. Thank you for the video!

Is the 'preserve the crimescene' mentality in electronics a highly used tool in the diagnostic process? Normally by the time i arrive to fix something the kit has been cleaned, the floor swept, coffee made, and the employee using it when it broke sent home!

2:30 Or they can become a Patreon and get your great capacitor discharger:-)

There are thousands of kenmore elite owners that are tossing those refrigerators because of the board and compressor failure rates - I replaced the compressor on ours and run it with an external relay using the fan (hick style) Great channel been watching for a while.

Nice repair. good things to know about semi-newer fridges. I agree 100% with the digi-key statements too. they do a fantastic job with packaging.

Ah, damn you, Carlson... Thanks to you, I'm going to spend 1/2 hour watching a fridges circuit board... 🧐

I don't get why the switch doesn't switch the Bulbs directly, why use a relais?? That seems to overcomplicate things and add another point of failure for no reason... Well, good question is if my Liebherr Fridge does have electronics or not...

Great to see how a little effort and a $3 part can prevent an otherwise perfectly good appliance from ending in landfill. But that prevents a $1500 sale of a new 'Fridge. The Manufacturer and the Stores don't want that, so its designed to have failure points. I've gone from the consumer repair field to industrial controls and its nice to see most industrial stuff is far better designed. Well done as usual Paul, a fix, plus an excellent explanation of the how and why. the troubleshooting knowledge you share is pure gold.

My relatively new LG refrigerator failed. LG authorized service company replaced whole circuit board. Like you said, after a day or so same failure code appeared. I found on-line actual service manual with actual service notes. It diagnosed and gave test points for checking continuity of defrost circuit and fusible links. I did not trouble shoot further as I did not want give the service tech an excuse to blame me for getting in there. The service techs, after I showed them the service notes, then replaced the defrost heaters and fuse links and problem went away. Got reimbursed for the unneeded circuit board. Second comment: Many years ago in the Air Force I worked on hospital General Electric x-ray machines. We had 3 phase power and the main contactors had a vacuum tube sensors for zero crossing (of kilovolts) on main contactors. Try as we and local GE service techs could we could not get the circuit to work consistently. Finally called in GE engineers from the home factory to trouble shoot. After extensive trouble shooting they found the Air Force base supplied three phase transformers were slightly out of sync so that occasionally the the phases were not consistent. The transformer had been struck by lightning years before and replaced (by GE coincidently). What was interesting was that this base did a lot of nuclear system design and testing and had never noticed the transformer wiring 3 phase discrepancy.