How to spot a fault in a circuit, like a pro : hands on electronics [1]

[@AccidentalScience]

Wonder how to do this same thing BUT without schematic? Watch this video too: kzbin.info/www/bejne/r5vbpoCtgbNqsKs

[@thomastaylor2450]

I have never done this , I read several sites to find out how to do it, then I came here and learned 10x more than all the others in only 10 min so thank you!

[@will_doherty]

Very nice demonstration of fault finding using schematics. I find that schematics are mostly very difficult to find for anyone outside of the industry, so I have to use different methodology - firstly check all electrolytic capacitors for signs of leakage/doming and replace any that have failed, then have a close look at the board - particularly components and soldered joints for signs of failure (under a microscope) - the fault that you had I would have found readily, and maybe in less time too. Next, look at power supply circuits and check that they're functioning as they should, and check all discrete semiconductors Then locate blocks of circuit that I recognise and test the components in each block. By this time most problems have been fixed. Checking the datasheets of unknown multi-pin ICs often comes up with sample circuits, many of which have been utilised by circuit designers - that makes some fault finding very straightforward. If after all this the fault remains and a schematic is not available, it's probably time to invest in a replacement pcb...

[@AccidentalScience]

If you are interested on how to proceed without schematic I made this video: kzbin.info/www/bejne/r5vbpoCtgbNqsKs Hopefully it will be interesting for you. Greetings from the Alps.

[@d.e.c1609]

This is the very first step (in) troubleshooting. Great job! We don't have (time) to guess.....

[@jimmy_jamesjams_a_lot4171]

Very nice chuck fixture on that lathe. My main hobbies have migrated from EE over to Mechanics recently. I had never believed myself to be an innovator until I finally began with a few diy opportunities in recent times. I am saddened by the lack of instructions included with test equipments recently. So I am grateful for troubleshooting demonstrations such as yours. Accolades, and I wish you luck with your lathe!

[@AccidentalScience]

Thank you mate.

[@brettkaufman2299]

Thank you for the education. It is nice to see the trouble shooting approach. Nicely done.

[@theatremad9797]

Great video. Thanks for providing valuable information. This is worth much more than money. Knowledge is something you can’t put a price on. Thankyou

[@bobbauvian7700]

thank you that was very helpful. I have always wanted to see one follow signals and voltages on board to learn from. Could you please, please make some more videos on how to follow signals and voltages on a board. but with a bit more detail and perhaps a longer video please. if I may give a suggestions: when there is IC involve, perhaps explain the IC for a few seconds, have one IC showing in physical form at the same time showing it in the schematics and explain where the input, output and which pins to test at what state..... I would treat such a video like a treasure. thank you again.

[@AccidentalScience]

@@bobbauvian7700 thank you for the input, I'll take it into consideration. I will come back on this topic, though the next videos will be about building lab instruments, tools and doing some experiments. Cheers.

[@dporrasxtremeLS3]

Yes! This Takes the mystery out of the equation! Thanks!!!

[@AccidentalScience]

Thanks for commenting. Happy new year.

[@neodiy]

How do you always get access to the schematic diagram of the circuit...there is serious difficulty to find for certain specific devices

[@AccidentalScience]

For unknown circuits the only way is to reverse engineer. It takes time and sometimes it's really hard when BGA ICs are involved. With multilayer PCB very often the inner layers are just the GND and positive (and negative if the PCB has 3 inner layers).

[@abdelhamiedsarhan6308]

@@AccidentalScience good idea that I have from your video thank you

[@distort89]

I specialize with game consoles. The only thing I have difficulty finding is ps5. Most others have either been leaked or have been reverse engineered by someone. Most pcbs are multi layered and require an xray machine.

[@AccidentalScience]

Eventually I made a video about the case where no schematic is available. I thought to add a further reply to your comment with the hope it will be helpful for you, this is the link to the video: kzbin.info/www/bejne/r5vbpoCtgbNqsKs . Thanks for following my channel, greetings from the Alps.

[@andreaphillian3947]

Not hard to find if you have a phone, you can individually google the components parts number and see where they belong.

[@consolechips]

You missed another dry joint above the broken pad you found … look at 12:14 on the top right it has cracks all the way around the pad.

[@AccidentalScience]

Well spotted.

[@nevinkuser9892]

The whole thing looks a bit sloppy. The guy must have been making it right before lunch.

[@katiefinnegan4649]

I was so invested in this!!😆 well done

[@brianlittle717]

I like to use a plastic ink pen with the writing part of the pen retracted when I touch the board. The eraser part of a pencil also works. Never touch it with my fingers.

[@WilliamSiansala-k7t]

Is there any way to test signal without oscilloscope and a multimeter

[@paulf1071]

Thanks for putting this video together 💯 Did you have much trouble sourcing the schematic diagram of the ESC circuit?

[@AccidentalScience]

Well, no ...it's my own design :)

[@paulf1071]

@@AccidentalScience Wow, nice work!

[@AccidentalScience]

@@paulf1071 thanks. If you are interested, in a previous video the circuit has been described. It should be available even on my website.

[@AccidentalScience]

If you'd like to know how to proceed without schematic watch this video: kzbin.info/www/bejne/r5vbpoCtgbNqsKs

[@onegenius6390]

YOU SHOULD LOOK CLOSE AT THE BOARD. THEN USE AN STICK CHECK WHAT IS LOOSE.

[@DJAPPOL]

Bro you are a BOSS

[@dashley2525]

My 10.2 PowMr will harvest so Load is being met but battery is not being charge till about 1800 w. The PV input readout is an arbitrary .5 kw till about 1800 w PV input. No one has had a clue why so far. A replacement 6.2 kW PowMr works perfectly. So the issue is surely in the 10.2 unit. Issue existed at initial startup.

[@nevinkuser9892]

This is exactly how you would systematically work through a car's schematics.

[@hobonickel840]

I've been trying to learn about using dmm because recently had a bad hexfet on tennisball machine PCB.. that's how I found your awesome video. However, now I'm more interested in that spindle head on the lathe.. Is that a Taig 5c or did you diy the the spindle, bearings and housing? I'll have to look through your channel and see if there's more vids about the lathe. I'm trying also to decide which route to go with a home hobby lathe and the Taig 5c spindle head is $600 ...that's a nice looking spindle/head and perfect for what I'm looking toward for making pool cues update: ok nvrm, I found your video regarding the lathe ... luv it

[@AccidentalScience]

I wanted to try the route of making a lathe from the perspective of J. de Vacaunson in 1700s, and studying the Whitworth method for achieving flat surfaces. I was wondering how they do reach precision from scratch. So it was a long and insightful journey. I ended up having a quite precise and very strong bed and carriage (with no compound on purpose). But I also experienced a lot of setbacks. If you want to build your lathe, be aware that if it shall be a decently high precision machine then it will be a long and steep journey. The setbacks I experienced were not strictly related to the lathe, but the complexity of the job took its toll. Hope to be helpful, and good luck.

[@hobonickel840]

@@AccidentalScience Let me ask ya ... I have steel track rails from old Belsaw sawmill ... they look like railroad rails .. do you think these could be machined down for carriage rails?

[@AccidentalScience]

@@hobonickel840 hard to say, I don't know that sawmill. Generally steel is a good material even though it sports a higher coefficient of friction than cast iron. Cold rolled steel is prone to deformation if, let's say, you make a hole in it. Once made flat the rail should not be worked further: no machining, no welding.

[@hobonickel840]

@@AccidentalScience so it's better to not to flatten and use the steel rails for precision rails??

[@AccidentalScience]

Not necessarily if you plan your work well. For example if you need to weld the rails do it before flattening them. Also consider annealing the part in an oven once it is welded, and only then go for the flattening job. Another option is to do all the required holes, then flatten the rails and finally bolt and glue together using locating pins and strong epoxy resin. p.s we are off topic under this video.

[@lennym1273]

Good advice just one problem, most of us don't have a scope lol...

[@AccidentalScience]

Yep that could be actually a problem. However because in this case we mostly have continuous signal in many points we could have been able to find *this* partcular fault even using a voltmeter. Though for a more general methodology even a simpler scope is a must. Thanks for commenting, have a nice year.

[@rabarebra]

You could actually just use you eyes looking for bad soldering joints first. Problem solved. No need for $20000 scope equipment, just some solder.

[@NoSpam1891]

I just got a good little scope on eBay for less than $25 shipped. Not a huge bandwidth but you rarely need that and I have a 100 Mhz scope if I need it. The new one slips in my pocket.

[@juliantambwe8551]

That was on point, thanks.

[@RobertsTube99]

12:05 Is there another loose solder contact slightly above it? It seems like it

[@jluke6861]

Thank you for the great video.

[@AccidentalScience]

Thank you for commenting. Have a happy new year.

[@sloopycat1954]

Hi Accidental science & everyone I have washing machine with faded and disappeared lettering on the digital display control board PCB I think it's called, some letters are visible but not all, i think it has ribbon connectors, please can you help me so all the letters are visible again, thankyou in advance. Great video thankyou.

[@AccidentalScience]

@@sloopycat1954 it can be a lot of things: defective ribbon cable, bad connection, LCD failed, broken resistors, broken driver... The only help I can give is to tell you to check following the path backwards from display to microcontroller with a voltmeter, and check from solder pad to solder pad for continuity (with device off of course). Good luck.

[@sloopycat1954]

@Accidentalscience thankyou so much for your kind advice.

[@UdayKumar-xl5gp]

Good explanation with ckt diagram , but what about without ckt disgram

[@AccidentalScience]

Thank you. You made a good question. I'll try to address it in a video.

[@MECANICA_NA_GARAGEM]

Hello. the electrical circuit you are using, in addition to the motors (why two?), is it from a washing machine? What changes did you make? From the schematic drawing shown in the video, were the changes in the handwriting? can help? I'm also building a mini lathe and wanted to use a similar motor. but I'm having trouble controlling the rotation of it. Thank you for your attention . Cheers I forgot.... congratulations one more subscribed

[@AccidentalScience]

Thanks. The circuit is my own design. Look at previous videos where it is described as a driver for washing machine /universal motors. I used two motors to get more power.

[@reylambarte5615]

During the visual i noticed that lots of components were desoldered. If i am to start with signal checking after verfying the power supply i will start at the output and go backward checking the inputs. Desoldering should not be performed until the faulty component is positively identified.

[@AccidentalScience]

There were no desoldered components! This is a configurable board and what you think is a desoldered component is actually a config or modification component.

[@reylambarte5615]

@@AccidentalScience okay, but the work is dirty. What do you think?

[@AccidentalScience]

I had to give a look again at the board and at the video to get what you mean, since this stuff is 2 yrs old. The board has some significant modifications on top of its configuration setup. So, again: no desoldered components for the purpose of finding the fault. Indeed one of the points of the video was to follow the signal path (look at 3:16) . Yes I convene that the modifications are not aesthetically tidy, but they are firmly secured and functional.

[@reylambarte5615]

@@AccidentalScience yap, thank you, i have a long experience on manufactured controls for the manufacturing equipment and had worked on poorly designed circuits that need some modifications, but the circuits that came direct from the manufacturer, modified or not it should be soldered clean.

[@timwhite7127]

You took the words right out of my keyboard. I would at least start midway to eliminate half the circuit from the git-go.

[@plis6516]

is it possible to do the same thing but with an analogic tester?

[@AccidentalScience]

It's much harder.

[@MartinLDeLoach903]

Those that don't know that triangle thing on diagram is called a op Amp, operation amplifier..

[@ronbianca1975]

Very good my friend! What is your native language? Stay healthy.

[@AccidentalScience]

Ohh it's complicated, it's a dialect with some inflections went from an almost dead language. I even mostly forgot it.

[@kolbakolba]

2021 problem 2022 no problem

[@Necrozene]

Huh? You missed that on initial visual inspection? Oh dear. Great fun though, following your subsequent logic!

[@ebenezeradentwi9062]

How do you get the schematics Sir?

[@AccidentalScience]

It's my own design.

[@LookOutForNumberOne]

Hi, are you in the UK??

[@AccidentalScience]

No longer.

[@LookOutForNumberOne]

@@AccidentalScience All good, np

[@laidman2007]

Thank you.

[@HereOnYouTubeCommenting]

1:00 Broken solder joint .... or cracked circuit board.

[@AnuroopMusic]

Nice 👍

[@EvgeniX.]

well what if you're trying to fix a random board with no schematic where you don't know the expected values? the video tells nothing about that 😐

[@AccidentalScience]

Next video.

[@OMNI_INFINITY]

Appropriately named channel for somebody that didn't discharge a large capacitor after unplugging board from wall outlet

[@geoff4009]

You mean that 16 volt capacitor connected to +/- 6 volt supply? Yeah big danger mate, watch out!

[@brianredmond4919]

Shocking

[@giacomomarchioro3455]

Non c'è una versione in italiano?

[@AccidentalScience]

Sorry at the moment it's not available. Maybe I'll do something sooner or later. Mi dispiace al momento non disponibile. Forse fraro' qualche cosa presto o tardi.

[@johnsmith-tr3dh]

I think this guy went to the Italian university "Wossamotta U"

[@chrisleech1565]

Aha

[@bk201xe]

cancelled. just tell us what the title says this video is about. don't tell us your life story. a-hol.

[@alexlukwago3070]

in africa we replace the board at once

[@YesSekupang]

Its not a pro by using schematic🤷

[@AccidentalScience]

@@YesSekupang there's a pinned comment, give it a look. BTW, professionals *do* use schematics.

[@viking1ur]

Like most youtube video U talk about everything that do not matter.......did u forget to tell about your cat and your grandmother

[@amadoujallow429]

What is you contact

[@bussi7859]

I spotted you, ,,