If you guys like this video and want to learn more on how to troubleshoot electronic circuits, then check out my online course. lue-yang.mykajabi.com/

Too many smart people here! This guy is trying his best to educate people who doesn’t really know much about electronics. Why for all you smart people out there, make an effort and create your own video! How about that!🤦🏻‍♂️

I just wanted to personally thank you for this vid, some of us really do appreciate people like you taking the time to run down things just like this and do find it hugely beneficial. Though a lot of us dont say thanks as often as we maybe should, but just know there are people out there even if they dont express it! Thanks!

Life long tech here: There was a period in my career where I had nightmares of little old ladies running around with Huntron Trackers fixing everything insight. I thought unemployment and hungar were in my future. Through my own use of a tracker, I learned it was just another tool siting on my bench. The greatest tool I ever used was an understanding of just how the damn thing worked. In todays electronics, components are very robust and far less apt to fail on their own. Everyone starts out thinking its going to be an electrolyte capacitor and in many cases it is. However, by far, the most common failure these days are cracked solder joints. Not from manufacturing faults , but from mechanical stress caused by different rates of thermo expansion and contraction between components and circuit boards. First thing to always do is a very very close visual inspection of solder joints. 50 years of experence working at a research University.

I just fixed my tv using your teaching. Thanks, saved me $5k

The best practical explanation of bridge rectifiers is included in this video. The diagram this guy uses to explain the bridge rectifier is much simpler and easier to read than the conventional drawings. I never had trouble in testing rectifiers after watching this video.

I’ve been troubleshooting circuit boards alarm circuits cameras, power supplies refrigerators for about 20 years and every now and then you just gotta go back to zero and see if you can pick something up. I’m gonna watch the video. I hope I learn anything. Thanks for putting up.

I've taken courses and learned the theory of components, even the theory of how to troubleshoot. Now I scored my first electronics repair job. Starting tomorrow, pretty nervous, and taking notes on this video - Thank you!

This guy is a good tech he knows his stuff by looking at how he goes through his trouble shooting step. Good job.

I liked the way you moved through the design and proved each stage/component. Good logic at work. Thanks very much.

I find this video very refreshing. Learning is a continuous process; one gets to learn, like my other boss would put it, some gimmicks.

I'm currently doing your course. Right now I'm about 80% done. I noticed three, extremely important points that I appreciate about course. 1) introducing most commonly used components in the right order 2) teaching how to use test instruments 3) analysis of some classical circuits. The course is most suitable for beginners who'd like to start from repairing through-hole component boards. The course is great for me. I recommend all beginners to check it out. Thanks.

Thanks for taking the time to break down your troubleshooting technique for a newbie (77 yrs old) that is trying to learn enough to troubleshoot a problem with a 46 year old High end Stereo Amp (NIKKO ALPHA 1) that has given me years of faithful service. I can't seem to find anyone local that is willing to even look at it. I have the schematic and found a rebuild kit on eBay and I am seriously considering doing the rebuild myself. I know my way around a multimeter but know that is not enough in the hands of a novice like myself. I deduce that the caps are most likely the main problems but I am trying to learn all I can from people like yourself. Thank you very much!!!

Grately Appreciate people like you that takes a common troubleshooting issue & breaks it down step by step to show the problem and solution hands on but also the explanation of how to get the answer solution. Great video and thanks for your time

Thank you for taking the time and effort to upload this video. It covers good basic electronic fault finding principles.

I worked in AIMD as an Avionics Technician working on ASW gear (technically my rate was Aviation Anti-Submarine Warfare Technician - AX - but they merged it to AT in the 90s). This is a great video to demonstrate RE techniques! Typically you'll want to have a schematic, but sometimes, especially with homebrew stuff, you might not have one. Being able to troubleshoot and experiment is important, but if you don't know what the circuit looks like you are basically in the dark.

Man, thank you Luke. I'm just like you. I've got my degree in Electronics Technology and received it in 1985 and I still don't understand a lot of stuff. I've been doing more of board level troubleshooting and Telecommunications (fiber Optics and networking). By watching your video I don't feel as dumb because I just realized that I'm not the only one with this same problem. I'm going to continue watching your videos and updates. Thanks again. You've been such a great help! I needed to hear your testimony.

Great video, I run into a lot of pcb’s without a schematic and have to figure things out as well, it’s good to see your thought process to troubleshoot. More videos please. Thanks!

Great video. Your understanding is so solid plus you make the application so practical and easy to grasp. Love the sketches!

Just wanted to thank you for this video. When I was a kid back in the 70's I became interested in electronics with a lot of inspiration from my grandfather. On Saturday's we would go to flea markets and find old tube-type radio's and take them home and repair them. Of course a lot has changed since then. Now most things are disposable and with the advent of s.m.d. technology rather difficult to repair, what a shame. Still, every now and then my electronic skills come in handy and I still enjoy building various electronic kits from Velleman etc. Thanks again.

Refreshing to watch as you move thru, pushing through wrong results with pose and grace. Very intelligent

Thanks. Very informative and helpful. What lured me in is your right. Textbooks only teach theory and fundamentals.

That was really good. Reminds me of my basic electronic technology classes years ago.

I wish something was actually broken. Let's get a patient in the E.R. with unknown issues and go start to finish.

Lue, I was totally blown away with your understanding of components and circuit boards without a schematic. I'm like you & most techs, I'd rather have the schematic than going through the process you go through. Even though it is time consuming and in my case a strain on my brain it makes perfect sense. Obviously, another person running a camera on the circuit board with HD quality & clarity would enhance the video, but you did well working solo. I wish I had had you as my teacher in tech school, I would have learned a whole lot more.

Dude, I am 70 and I can really relate to the memory issue. But I carry on regardless, passion for the work.

That was a very good troubleshooting exercise, looks forward to see more of those

What an amazing video. Thanks for sharing the info. I am trying to get back into electronics after 20 years nearly and this is a gem of a video.

Thank you so much for making this video! I'm a self-taught electronics hobbyist and I love learning about electronics, whether its on UKposts, some free resource, or a book. I think its great that you showed how to troubleshoot without schematics because sometimes, there isn't a model number you can visibly see on the component or maybe the datasheet isn't available online. My first instinct is always to look up datasheets for each component so I can know the pinout. Its easier to debug the issue when the components are by themselves but in a circuit, its more difficult because other components can affect your DMM measurements. For me, what I learned in this video was: 1) For visual inspection, check for burn marks on traces, cracks in the PCB (which could cause open circuit somewhere), and cold solder joints (e.g. look for cracking). Comments: I would also add to look for obvious things like a burnt component or possibly a capacitor is bulging. Maybe one of the leads of a component somehow snapped off. Poor solder connections (pretty rare). Liquid damage can also be an issue. 2) Go through and check for shorts and verify that certain components should be connected and/or have specific resistance/impedance. This is where datasheets can be very helpful, if available. Really know the components (this is something I need to improve on!) 3) Power on the circuit and verify that certain components are receiving their correct voltages/voltage drops or that LEDs are turning on/sequencing as they should be.

My main multimeter is a Fluke 77 II. 30 years old and STILL in calibration. Awesome piece of kit.

This guide is amazing for basic board troubleshooting. Very good troubleshooting tips to know.

i see a lot of bollywood video and click on thumb down (dislike) because uploader has made bare minimum effort to process raw input which is many times old films on celluloid ... no restoration no nothing and sometimes audio is not loud enough or too loud ... sometimes aspect ratio is out of whack making circle look ellipse ... so i have good reason to dislike ... but i fail to see why would anyone would thumb down an educational video like ... obviously the uploader creating an interest in a hobby or a future career ... youtube should let uploaders of educational videos to confront dislikers to give reason for dislike or just be disbarred from disliking ... you are doing great job by teaching your skill to complete stranger ... thank you

Excelente, se desarrolla la deducción y la intuición. gracias

Good stuff! To your visual inspection you might add these two: indication of prior repairs, which may or may not be correct, and may show points of failure. And look for components added to underside of board to correct design flaws. Maybe the patches didnt work as expected or lead to other problems or failures later.

You're a good teacher, combining theory and practice :)

Great vid! I learned a lot from you. O.L. means Open Loop in continuity testing. Of course, the opposite is Closed Loop, where the current can pass through. Looking forward to more tutorials from you, especially considering the actual experience that you have.

Thanks for sharing! More troubleshooting on PCB videos, please!

Great video thanks, especially the bridge rectifier explanation. I'd only seen it drawn like a "diamond" before.

great video. thank you Sir so much for your time, skill, effort to teach us. Much respect + appreciation.

Just found your channel. All I can say is Awesome.

Nice video. I have wondered how much you could do without a schematic all my life. I have always wanted to be an electronics guru I just never had the friends, mentoring, or time to raise my skill level (even though I have an EECS / mostly CS degree from MIT). Worked on a broken Heathkit oscilloscope and found the broken 7815 power regulator which was melted / crashed - after a FEW HOURS! Built my own bicycle-light charger starting with a 5vac adapter + full wave bridge for a do-it-yourself rechargeable wonder bicycle light. I think it helps that all power supplies (mostly) are pretty simple and pretty similar.

One of the best and most thorough videos I have ever watched on this topic! As someone trying to learn all of the basics on my own with no prior knowledge, you made this really easy for us to follow. Thank you!

*Wonderful. Great video. You have great experience. I'm also an engineering UKpostsr.*

Great video. I really appreciate you taking the time to do this.

The visual component inspection should also include the "SMELL" test. many times the tech can smell fried electronic materials when the device is opened up for the visual.

Thank you Mr. Electronic Tech. I am electronic tech myself retired, that was a perfect refresh for my mind. Appreciated Sir.

Bro as a fresh graduate, thank you. I wish I had a lab instructor that would’ve taught us in this format. Very practical knowledge.

Nice job of describing the proper steps of “Best Practices”. These boards are sprayed with like a clear lacquer that makes it harder to get readings. Scratching with a small flat blade, or other handy tool helps. Also, as you discussed having a heavy component like that transformer on the board, if it fell during the past, the printed circuit can crack. I would include that repair in a future video, if you haven’t already. ( Sorry, haven’t seen all the videos in your channel) If a broken circuit on the board, scrape gently to clean to the printed copper, then solder a wire across the fail point. I fixed the neighbor girls radio 35 years ago, after she dropped it. You guessed it if you said transformer end was the fail point. Same with “Cold” soldered joints. I’m sure you remember when tv’s took two men and a boy to move it. Mine wasn’t quite that big, but on day while watching it, the screen went black. So moved it away from the kids into another room, plugged in, turn on and wait for it to do that again...but only after your common sense step, visual, discrete component check, writing down voltages and making note ( Before digital cameras), it quit, I found it with my Fluke DMM, re-soldered it, let run to confirm, then placed it in service. 4 kids, wife and one income and one tv. The tv shop in a town that was the county seat, always or more often had a sign up that said; “ Gone Fishing, instead of watching your tv!” Thought that was funny. Very good information and clear to hear with my $3 dollar ears.

Very clear explanation and straight to the point.

Did electronics 20 years ago at collage and couldn't remember much of it, after watching its all coming flooding back thanks

just wanted to drop a thank you as well,, i watched the first 20 mins of this video,,, then resoldered in a capacitor, and now my lovely tech works again,, ive subscribed, and ill probably take your course when i have time, many thanks bro.

Good way of teaching newbies especially if there is no schematic. Been doing repair of electronic stuff for 20 years and still counting. I developed the skill of fixing things without schematic. I can even modify a circuit even if there is no diagram, I just have to make my own and get the the components ID and search in the web for the specs. For the power supply that you were checking, I guess the output is quite low. Assuming you are using the 115Vac input and the transformer’s expected output is 12Vac, then the turn ration has to be 9.5:1. The rectified output is supposed to be 12*1.414 = 16.9Vdc. Now adding the filter caps, C=I/2*F*Vpp. C=2/(2*120*2) C=418uF or the closest to that. With that filter capacitors the filtered DC out is ~14.9Vdc and that is at open load. What you were getting is quite low.

Thx! U have put in real efforts to make us understand the stuff-

Thank you for explaining things that newbies wouldn't know.

Thanks for your practical Hands-On, toubleshooting, without a schematic. Thanks for sharing.

A great illustration of bridge rectifier operation. Thank you

GREAT VIDEO!! I just wish you could show us different types of looks a fuse, a cap, or other components can have. Thank you big time!

I have been watching your videos for about a month now and I have learned quite a bit on how the SMPS PCB Inverter Board works. What I am presently working on is a power supply out of a Samsung RF 8000 refrigerator. I have meter to read voltage and continuity, amps. I followed your instructions on how to check the boards. I don't have a lot of electronic test equipment to test the circuit so I just use the connections on the refrigerator to power up the board . I am getting 115 AC in and it goes through the fuse through the bridge rectifier and using your formula , and it shows about 165 DC voltages through the capacitors , there are two that both measure 165 DC voltage . i follow the board down to what I think is an IC at the bottom and a smaller capacitor on the top side that looks like it is connected to a IC on the bottom that has no voltage where it is connected to the IC. I think this is the positive side of the DC voltage. On the other side of the DC voltage it goes up to what looks like a resistor to a bigger IC with a metal bridge screwed to the top of it to cool it down and that goes to the compressor to run the refrigerator, that is supposed to be getting at least 310 DC volts , but only getting 244 DC volts. I think the chopper CCt is keeping the the VCD/ PWM, from the feed back circuit to the main board that regulates the out that is 10 DC at the out put that should be 15 DC volts and 5 DC volts. My question to you is where is my problem? How do I find where the lost of voltage stopped. I know that the double wired coil is only hot on one side with voltage or has continuity on one side I can't remember which. Could this be my problem, I have tried everything else that I have learned from you guys . Is there any way that I can chat with you? or send you a picture of the SMPS PCB?

Very good video. Thank you for taking the time to share your knowledge.

All your videos are GREAT! Encourage you to grow your youtube and online class!!!

Good video. I will have to say it's better to check a fuse by testing output voltage. I have seen many partially blown fuses causing a voltage drop and not an open circuit.

Well done! Thank you! I have grown some more as a result of your knowledge and thoroughness.

Great job explaining your thought process

Im getting an electronics kit and when it arrives Im coming straight back to this channel, took me 0s to make that decision see ya then

I was hoping for something simple but, I know, electronics is crazy with math & flow charting. But, you are reminding me of all my electronics classes 25 years ago.

Thank you friend for the great video . I've worked for several years diagnosing automotive electrical and electronics. Testing sensors, actuators and wiring but never really understood circuit boards . Subscribing :-) Thanks

very informative, I learnt some nice stuff thank you

Good job, power supplies are one of the most mystic and difficult to understand sections of a (PCB) printed circuit board. Mainly because they convert AC to DC and the components don't like giving up their secrets with a simple good or bad answer. For instance the capacitor and transformer may test okay but under a power load they break down. Let's see more videos!

This knowledge I've shared is from my 2 yrs College EET, 1986 - 1988.

Oh man why did you stop uploading? I'm starting to learn some basic board repair. Thanks for the video! 👍Helps explain a lot to someone who doesn't know all that much about electronics 🙏

Thank you for the video. I learned a lot. I learned things that I did not learned from a 4 years college on electrical things. Thank you.

Thanks! I'm about to watch this whole video. I've a broken Roland TR707 from the 80's, hoping i can diagnose!

Thank you. And I’m gonna use that grins and giggles line lol. Would love to see more from you, thanks again

thanks for sharing the know how, you kick ass man

sir your effort is very nice to educate others we are also trying the same plz keep it up

Awsome video! You present your process very clearly, I followed along easily!

I really needed this, thank you, as I am learning I think about making my own I got caught up in programming hardware software, but not able to organize it all together all books I read not quite understanding them fully trying to memorize them all only to forget a few months down the road I get flash backs of what I have read. I do get flash backs of what I read though, this video is amazing what I was looking for thank you (gush shu bay ) meaning thanks

Something else to look for in visual inspection. If there is vibration, sometimes heavy parts will lift the traces off of the PCB and break them or break the solder connections.

The world's best teacher thanks

thank you for this informative video keep sharing

You are an excellent teacher. Thank you

Great explanation. 👍 A thermal camera is the best investment you will ever make to shorten a troubleshooting session from hours to under a minute!

Thank you sir I really enjoy your vvideo.

Thank you, much appreciate your patience.

33:40 "I done did a visual"...love it!

Hey, Thank you my friend. You should get some sort of Patron. I would donate in a heart beat! I can't thank you enough. Ive been repairing AV equipment for 10 yrs and i'm really good! But not at the component level. Thank you for adding value to my performance and my ability. Now excuse while i watch and like EVERY VIDEO YOU'VE POSTED! What a good man you are THANK YOU!

THANKS DAMN GOOD VIDEO LESSON REALLY HELPS BEGINNERS 5 STARS!!!

thanks sir.. really easiest way explained in the youtube till today

i have an old amplifier i believe has a bad diode in the rectifier...maybe...it was intermitant and then it just quit....i love so i ant to get it going....it is a tube preamp, MOSFET power stage hybrid style, and not many techs know where to begin, but after watching this i am ready to give it another shot....thank you very much.

Please i want you to go more further on electronic. I like your explanation.

Great video. Hope you have one on ic chips. Especially with processors, ram, eproms!

Great video! Thank you!

Thank you for you time in sharing your knowledge.

Thank you for all you great work. Is it possible for you to show how you get the AC from the Variac Transformer to the power supply and maybe a quick tour of your lab. Thanks again

Thanks for sharing your knowledge

Great job and informative explanation thanx for sharing your experience

great work!!!!!, inspiring!!!!!!!! 💜💜💜from Bangladesh 🇧🇩

Thank you for the AC X 1.414 formula, never knew that, any more tips would be great in a video about troubleshooting. Thanks for the great video.

This was just what I was looking for thank you for your wisdom and information

This is a great lesson man. I learned how the rectification works in bridge rectifier clear as day, Thanks! you are awesome, SUBSCRIBED! Hope your other videos are this great!