The Art Of Methodical Fault Finding - A Practical Example

In this video we look at some Fault Finding Diagnosis methods, plus we have a practical example of how to diagnose and repair circuits when you have very little information about the circuit function and can't find any datasheets for the components

CHAPTERS
00:00:00 The Art Of Electronics Repair
00:10:35 The Victim
00:14:11 Preliminary Enquiries
00:16:44 Reverse Engineering
00:37:16 Forensics
00:37:19 Sherlock
01:00:42 Case Solved
01:07:41 Debriefing

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The Electronics Channel (live streams with Carlos and Detlef)

Gran Canaria Uncovered

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TEST METERS
ANENG AN8009 MULITIMETER
KAIWEETS HT118E MULTIMETER
VC480C+ MILLIOHM METER
MESR-100 ESR METER
XC6013L CAPACITOR METER

TM-902C TEMPERATURE METER
LCR-T4 COMPONENT ANALYZER
FNB58 USB ANALYZER
PCI POST ANALYZER
TL460S PLUS PCI_E ANALYZER
TOOLTOP ET120MC2 SCOPE
FNIRSI 1014D SCOPE
NPS3010W 30V 10A PSU
T12 STATION WITH M8 9501 HANDLE
M8 9501 HANDLE
YIHUA 982 Soldering Station C210/C245
FNIRSI HS-02 PORTABLE SOLDERING C210/C245
QUICK 861DW
PROS'KIT SS-331H

INFIRAY P2 PRO IR CAMERA + MACRO LENS
TOOLTOP ET13S THERMAL CAMERA METER
ET13S MACRO LENS
OPTICAL MICROSCOPE
TOMLOV TM4K AF FLEX
TL866 II+ PROGRAMMER
CH341 PROGRAMMER
NC-559-ASM FLUX

DESOLDER BRAID (I use size 8045)
HX-T100 SOLDER (0.6MM)
ESD-11 TWEEZERS

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Thank you
Richard

[LearnElectronicsRepair]

*IMPORTANT NOTE* At 51:12 I drew the collector of the transistor connecting to the wrong end of the 10K resistor.

[mattstroker]

If you're new here and interested in electronics repair, save this video to your playlist. Absolute gold!

[byroktheclock]

A note on the Intro. There is a book called a mind for numbers. It describes the 4 am solution process. For solving problems, your brain has 2 modes, focused and diffused. In short for math/logic problems you should spend 15 min at 100% focus trying to solve the problem. Then you should do some task that has a low mental effort e.g walk, sleep, bath. Your subconscious continues to work the problem. In this "diffused mode" some solution or progress will come to you. This harkens back to Archimedes and the Eureka moment if you read that story it will make sense. P.S great video!

[mrdarcy]

Fantastic vid. Problem solving is such a satisfying thing. It worked for me when I worked for Dyno Rod. It worked for me when I was a handyman. I am like you, 4am waking up with a solution to a problem that had bugged me the day before. I am not an electronics engineer, rather more an enthusiast. I have learned a huge amount of knowledge and have fixed endless items of electrical gear as well as a few electronic pieces. Hooray for guys like you who rather than keep your hard earned experience to yourself, choose to let us into the mystical world of mending electronic stuff via You Tube. . My appreciation and muchos gracias to you.

[zedcarr]

When I was an electronics engineer doing bench repair of industrial instrumentation and control electronics down to component level in the mid 1990s, I learned more about practical fault-finding and electronics in the first few months than I ever did in years as a hobbyist, student and engineer previously.
It was my personal ''Cambrian Explosion'' of my evolution as an electronics engineer that lasted about 18 months, but it advanced my knowledge and experience greatly.
This is why Dave @ EEVBlog says he hopes when you witch your electronics project on that nothing happens. 😊

[azurehydra]

This really is an art. It definitely takes time to develop it. Each and every video you're making is definitely developing the proper way to think. Thanks for the videos. 👍

[trippmoore]

I really appreciate the methodical way you went through and figured out how the circuit works. That's obviously something that takes time to become good at. I'm nowhere near that level yet, but at least I was able to follow along with you and it all made sense. I will have to troubleshoot a lot more circuits before I can sight read the values of resistors and know which pins are BCE for the transistors, but I'm sure I'll get there eventually. In a previous life I was a software engineer and so of course I took a good amount of EE classes including a couple upper division (it's been 25 years since I got my BS in CompSci). I always liked the EE classes and my favorite software classes were the ones where we coded in assembly. I much preferred managing the parameters in and out of a subroutine on the stack in 80x86 asm than I did designing data structures using virtual classes. Thinking about the latter still gives nightmares. It wasn't that i couldn't do it but it just didn't come to me as easily as the low level stuff. I worked with some brilliant software developers in my career that could design amazing objects that not only did the job but were so sophisticated with elegant interfaces. Whereas if I were to design the same thing it would probably get the job done (eventually) but it would look like a crazy person built it with scrap parts and things patched together in a convoluted way with some paths that lead nowhere. And my interfaces were clunky and incoherent so if you weren't careful you could easily break something. But those same class masters would be triggered even saying the word "opcode" or "register" and I could do some similarly sophisticated and elegant things in assembly. It's a shame that I went straight out of college to a 14 year career with a company that was mostly doing C++ programming. I did get to do some asm stuff early on but that's when our product only ran on PCs running DOS and the existing engine, although written mostly in C, had some asm subroutines and there were cases where we had to do new stuff in asm for speed reasons. But even in those early days the groundwork to move our code to a platform neutral model based in C++ and eventually ported to upwards of 13 different CPU/OSs, so we quickly abandoned writing any platform specific asm code. And don't even get my started on the nightmare that was to come of that "new" C++ code base. We really should have built the new system from the ground up but the paper pushers didn't want to give us the time and resources that would require. They reckoned that we already had something that worked (for the fading past) and we couldn't afford to just scrap it, so we had no choice but to use it as the base to build that scaffolding that was to support the next 20 years of who knows what. Supporting that code base on all those platforms was a nightmare. I've gotten way way off topic and I better stop before my blood pressure spikes.

Where was I now... Oh yes, looking back I wish I had gone the EE route and I probably would have enjoyed my professional life a lot more and not have burnt out so quickly. As it was I ran away from my well paying corporate software engineer job and had no idea what I wanted to do. I existed off my severance, which was quite generous, for a couple years living cheaply. But I had earned it after all the 60+ hour work weeks (salaried, of course) where it was always "not a good time to take a vacation right now". I had maxed out my PTO and was simply loosing it because my company was shitty like that. Had I been receiving cash payouts for those accumulated days off I might have stuck around longer. Anyway I eventually started an IT business and did that for about 11 years but I never really liked that either. I was always good at troubleshooting and fixing computers so it was a natural option. This is why I understand how you can't teach what you are doing. People would always ask me how to teach them and I would tell them I can't. I wouldn't even know where to begin, because I have no idea how I do it. I've just been hacking computers since I was 10 years old. I started on a TRS-80 with BASIC and a cassette drive, but we eventually got a low density 5.25" floppy. A couple years later the family upgraded to an 80x86 PC and a couple years after that I got my first 386! Every computer I got after that I built myself. When I am troubleshooting some sort of problem I just intuitively know where to start looking and even if I'm working with hardware or software or a system I've never used before I know the fundamentals and design commonalities that most of them follow that I can figure my way out and get up to speed relatively quickly. If they insist I tell them there's no way I can teach you to do what I do because it took me 40 years to learn it. It's just something that comes natural without thinking too much because I've done it my entire life, like waking or riding a bike.

To wrap this epic up, I have since closed the IT business recently to focus on fixing vintage HiFi equipment to make a living. It started out as hobby because 10 years ago I moved to Hawaii and I didn't bring anything with me. Eventually I got tired of using shitty Bluetooth speakers and since I couldn't afford to ship my beefy Cerwin Vega loudspeakers and Yamaha amp that I still had stored at my parents house (I kept a few of my nicer possessions stored there and sold the rest when I moved) I went to Craigslist to see what I could get cheaply. I picked up a simple vintage stack of Technics gear that came with a non-working tape deck. I hadn't listened to tapes in a long time but I thought I might as well see if I can fix it just so I can use it every once in a while. Having never repaired anything at the circuit board level (besides debugging my designs for EE classes on breadboards all those years ago) it was a bit daunting like going into the jungle for the first time, and the wiring being like vines completed the metaphor. lol. I had remembered the basics of electronic components from my college EE classes, like I knew what resistors, capacitors, diodes, transistors, and even logic gates and such did on their own, but I wouldn't say I had a great wealth of knowledge of circuit design. So I just jumped in with a cheap multi-meter and no other instruction (YouTube didn't have many channels like yours back then and I didn't really became a regular user of the platform for at least a few years after that point) and went at it the same way I would when I troubleshoot a PC. Magically I pretty quickly found some bad electrolytic caps on one of the boards (I had no idea that they were such a common fault in 20+ year old equipment at the time) and without trying to understand the circuit like you did in this video I swapped them out and it worked! I was so pleased with myself and my "new" cassette deck from the 80s that I bought a stack of old cassettes and sought out other old hifi gear to fix. It spiraled from there because I could fix something and then sell it to trade up for a better piece of kit for my system. When I got my first "audiophile" grade gear for almost nothing and was able to fix it I was totally hooked. I went from just wanting a decent stereo to acquiring, fixing, and selling as often as I could. There have been some failures and a lot more dead ends that I intend to go back to because my skills weren't as good at that time. Eventually I got people responding to my ads for sale asking if I could fix there stuff. I hadn't thought of doing that but I said sure I can give it a try...

So that's pretty much the story. I'm not making a ton of money, mostly because I keep too much of the gear, lol, but I'm in demand (and backed up) and I can work from home and people are so happy to have someone that can fix the old receiver that they got from their dad or granddad or they are an old guy that's had it since the 70s and it sat in the garage for the last 20 years. All this to say you got a new subscriber. I'm still learning and one day I hope to be as proficient as you. At one point I knew all the opcodes for the Motorola 68HC11 chip by heart and could read and write machine code in my head (that's a story for another time, but I'll just say RISC architecture is so much more simple so the instructions all follow a simple and well defined pattern) so I know I can eventually get to the point where I can sight read a resistor value! Cheers and Mahalo!

[markbaker]

Richard, I've watched electronc repair video's for the last 3 years, it's all voodo black magic!! However I am learning it in my head and fitng things together to make a picture. It's something I'll take up maybe or not at all when I retire. In the meantime what you said about assembly programming, yes, yes, yes you are spot on!! It is an Art, I've been telling people this for years! I only did it as a hobby, but spent 4 years doing it. I have only just gone back to programmming/Scripting in the last 2 years and what I learned all those years ago and my way of learning it helped me ick it back up really eaily!! It was nice to actully hear someone saying what I said; and prove to me mentally I was right! Thanks mate ;-)

[HsMalsn]

This guy ey!
Gold! YouTube has so many gems hidden

[paulc]

Oh goodness me, you've just described me, in when I did my apprenticeship In TV/Radio/Electronic repairs in the 70's very exciting times, College taught me the science of it, my allotted engineer taught me the how to do & expanded my mind to the voodoo of it, then one day it clicked, the voodoo was installed in my mind, that night I wrote down what I thought the problem on a TV we were working on, and showed it to Andy the engineer mentor in the morning, both our notes were the same, I was right YES, this week for instance I was given a lovely multifunction power supply, which the magic smoked from a regulator, so changed the reg, then I proceeded as to why the reg blew out, in my discovery I found 2 electrolytics with 4 & 6 ohm ESR plus a diode that went shorted a change instead of open, which I think was the problem along with the caps, May the Force stay with you.

[brackishwatersdesign]

I'm 46 and been in industrial manufacturing for 8 years doing electrical there and learned in the job. I left last year to go back to school to get the basics to better understand what to expect when I'm troubleshooting. I'm now going back to work but have finals next week first. It was really nice to watch this and understand everything you are saying as you go along this process. I wouldn't have been able to follow this a year ago.
You can learn to understand circuits and components but the discipline to find the root issues take practice and overcoming lots of failures or unknowns. Thank you for this video.

[reacey]

I agree, electronics repair is something best learnt actually trying to repair things, im 33, ive been mending things since i was a little kid, i buy anything faulty, it doesnt matter what it is, if its got no power im interested .i think the thing about the 4 am ideas is exactly what makes me able to repair things(i see you make revisit videos on things you couldnt repair, i see how you dont like being beaten either), i dont have an in depth knowledge of circuits and what exactly is going on, but my mind relentlesly searches for the answer when i cant repair something and i process different possibilities and outcomes in my mind, and 9 times out of 10, ill find the problem, and im slowly learning alot, i watch all your videos, i try to absorb as much as i possibly can and try to piece together the puzzle of electronics . Also i think i have the intuition you talk about, over time you get much faster at homing in on the fault. Also making less mistakes ang going down unnesessery rabbit holes happens less the more you practice

[timflynn]

I have found that one of the best ways to learn trouble-shooting skills is to breadboard circuits - you are sure to make mistakes along the way. Finding those faults helps me understand the circuits in a hands-on manner rather that just a cerebral way. That is a big difference for me in terms of my learning. I'm a hobbyist, not a pro, but the trouble-shooting skills carry over to my day job as well. Getting hands-on at the component level, is really the only way to learn it. Like the alphabet, you have to learn the letters, then put them together, then you can read and write and take your skill further for years to come. Thanks for your postings, I love seeing the steps you take, the mistakes you make, and the corrections to get things resolved.

[romancharak]

Only trying to repair broken products on your own will teach you how to fault-find. Watching videos like this can help you get ideas of what to look for. But in the end, practice, practice, practice, will get you ahead.

[peternotpeter]

I've been watching your repair videos to inspire me to repair a transistor guitar amp that keeps blowing fuses, I haven't found the issue yet, but you're inspiring me to continue. thank you so much for all your analogies and troubleshooting techniques.

[pauldery]

WOW, I love how you stuck with it and figured it out, great video, Paul USA.

[jeanjacques]

Thank you for sharing your knowledge on CCA repair

[chrissvgri]

You are a LEGEND of a hands-on teacher!!! Thank you for all your lessons & tips!!!

[gordthor]

Intuition is often referred to as a "gut feeling", but really it is our subconscious mind piecing together the puzzles (of which we are consciously focused on) in the background (unconsciously). The processing power of our conscious mind pales in comparison to our million times faster subconscious processor. Everyone has an intuitive cognitive function, but the degree of strength in intuition varies due to personality type, because the our cognitive function order (strongest to weakest) is what discerns the differences in personality type.

For instance; a person with a dominant cognitive function in intuition and secondary function in thinking, will have much more than a "gut feeling" (more like a knowing) compared to a personality type with dominant feeling and secondary sensing. Every type has their cognitive strengths and weaknesses, but when it comes to pattern seeking, deep analysis, seeing how things are interconnected, nuances, coming up with novel ideas, problem solving, can understand complex dominant intuition and thinking (either order) are by far the best at these tasks.

I'm pretty sure Richard is an INTP personality type (same as Einstein) with dominant introvert thinking and secondary extroverted intuition. I'm not surprised why he is so good at the art of electronics.

[MaverickM]

Big big thumbs up for the assembly comparison. As a former c64/amiga asm coder really can understand it. Assembly programming -just as electronic repairs- needs much more than knowing the basic rules and elements. While trying to resolve a problem in asm we sometimes deleted all our work just at the finish to start over again to try out another solution found while writing the last one. Asm coding was a kinda trial and error method in term of logic of the solution. It was never a problem to write the code for a new logic, the real deal was to always find a better logic/way. That’s how all those audiovisual demo programs were made on computers with several mhz. Now as a game developer (using high lever languages) I feel the need for turn my old amiga on and do some asm coding just for fun. It was the golden age for sure…