How to Think like a Repair Pro - Learn to Fix Random Electronic Devices, No Schematic or Datasheet
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- Опубліковано 3 лип 2023
- Here is a good example of how to complete a repair on some random electronic device you never saw before. It's all about the method of thinking it through to work out what is wrong and what caused the fault. Learn to think in this methodical way and you will be able to tackle most repairs
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Thank you
Richard
Keep doing what you are doing Richard. I changed careers at age 56 because fixing electronic things is quite fun.
all fun as a hoby but not when it becomes your job
Thank you for posting this!!!!! Please more vids like this. You get a faulty piece and just troubleshoot. Great for us novices.
Agreed.
Will do 😉
Agreed!
Electronic component shops. I live in Tasmania, an Island State of Australia, we have a population of 510000. We have 1 small component shop and they carry the very, very basics. Components like the relay in this video, I would need to order from the mainland of Australia, Melbourne, Victoria, pay ridiculous postage and it will take a week to get here. It wasn't that long ago we had electronic shops in every main suburb, including Dick Smith and Tandy but now there all gone. As a matter of fact, the reason could be is that there are no electronic repair shops in Tassie anymore, none that i know of... that's why i love videos like Richards,learning so much for a great opportunity for a small business here, repairing electronics.
You're a great teacher, thank you for all you do. I'm 67, and just started in electronics, so thank you.
Hi - I'm always impressed by your logical approach, your enthusiasm and your respect for learners. Messing around with vintage electronics has been a hobby of mine for over 40 years and I never fail to learn something new from LER. Great work! (Any chance of something on valve/tube amp faults..?)
I work on CRT monitors for old arcade games and I use devices like the IEC device to connect to CRT boards all the time. Perfectly fine if your smart and take precautions!!
Excellent, thanks. Like to educate myself more for electronics repair. Your videos are a great resource for me to learn.
I am still catching up on the videos from the past ... This is another great one and that last lesson about testing the diode out of circuit... Vs. being in circuit and what has to be considered, This is a very useful lesson. And I would assume the same concept of considering what's in a circuit for testing any component must be taken into account. Though we have seen a lot of testing in circuit with demonstrations of the validity of doing that. Anyways great reminders and examples in this video, it takes time to gain experience to make judgment calls 🙂
Hi Dicky, I hope there’s a part 2 to this fix, great job as always. 🤙🏼🇦🇺
Joe from Australia 🤙🏼🇦🇺
Fantastic! Youre teaching me what my father couldn't. Thank you
Thanks for sharing your knowledge. It's made it easier for me to have a go at things ☺
Richard you are a gem, keep up the good work kind regards from Cheshire
Keep on, keeping on. We in the U.S. are lacking the next generation of "Fixers". You have inspired me to continue and teach. I love your channel!
Hi from Spain, these videos are very entertaining.
I Like This Tutorial. Thank you for making me more enthusiastic
Love your videos awesome learning material right here
😁 just about my level. loved this vid to bits.
Great video thank you😊
Nice Video a simple repair !
IMO you have 2 electronic stores is because it's an island so probably more tend to fix their stuff because I'm guessing the prices for new electronic stuff are higher for you than on the mainland.
Nice job.
You were right about the local parts suppliers in the states... It's very hard to find any.
I guess they can't compete with the online suppliers.
I expect there are higher import duties where you live so buying individual parts from the manufacturer is to expensive for most people.
The parts suppliers where you live probably buy in bulk and make a little profit selling the individual parts to the public.
Thanks for demo on heat plate for Screen Repair...
Regarding diodes, back in '67, I was working on a piece of equipment having 232 diodes, and 84 relays. working with Texas Instruments engineers, we found most of the diodes had been installed backwards, and many of the relays had incorrect voltage going to the contacts. It took us about two months to find those problems and rewire all those "black boxes" for their original purposes.
another great example
I just recently had a customer come in with a defy microwave oven which started but no heat and no fan or platter rotating. The problem was a relay on the PC board with the buttons. It was making a click but no continuity on the switch side. Dumb fault caused a ZAR 2500 microwave oven to be a paper weight. Thanks for showing this.
thx for that - i never would have thought the heating plate is ran through those flimsy wires ? i expected something like 16-12AWG at least
- please tell the owner that the blue film on top of the plate is a protective film that should be removed _before_ first use. the same kind is used for stainless and chrome
Two brick and mortar stores, Nice. There are some in the states but they are few and far between. I’m in the Midwest and the closest store to me is a couple hours drive. Most everything is online but luckily the shipping isn’t two horrible and typically have the parts in a few days to a week depending on their warehouse location.
Great Troubleshooting,
if you have worked on cars at all, this is really common with wiring and relays on cars that carbon dust from sparking builds up and generates high resistance and heat . this in turn kills components and the relays it self and some cases blows the fuses due to the higher draw of current
Hi Richard, don't forget to tighten the loose fuse holder 🔥😁
We don’t have electronics components shops anymore. Have to order online quick and easy in canada
Love the sense of humour with the chinese watts lol and hey nice carbonised contacts sets up a nice arc welding circuit inside the relay and about 10,000 chinese watts of heat :D Richard is isopropyl cheap there? Coz it ain't here, it's like $27au for a litre! Obviously you go thru it like tea, hence the question ;)
The last time I purchased 5 litres of the stuff for around AU$30 in 2019 delivered to a residential address (Melbourne).
Bear in mind it is Hazardous Goods and can't be sent in postal system.
Buy it from a chemical supply Co., not some small bottle seller like Jaycar or 'hardware' shop.
Hi Richard , what’s the make/model no of that clever little desolder tool you used in this video to remove the solder on that relay ?
Did Handy Andy forget to remove the plastic protector and it forever and ever stayed there? I hope I am wrong, LOL!
Thanks
What was the amperage of the fuse that was in the loosey goosey fuse holder?
Can you do a follow up video Richard, would be nice if you can identify why it's tripping the rcd?
Looks like there was something else connected to the power supply previously. 22:10 in the video. Possibly a power on LED?
Hello,
At 1:25 when you perform an input-resistance test, is the device’s ON switch, on? Or is it off? Please let me know - I want to learn. Thank you kindly
With regards to the relay, I think we need to determine whether it is the coil that went or the contacts. The coil will burn out if there is overcurrent/heat but the contacts will burn because of arcing caused by ultra fast switching especially if it has a good sized load on it. I think it would be nice if you could do an autopsy on the relay to see what actually happened. From the pics I found online (hg t78l relay) you can see that the area where the contacts are is the part that's burnt, I would surmise they are what caused the failure instead of the coil. It's also listed as an automotive 120v relay so I don't know if it's meant to be used in ultrafast switching applications. I would also like to see what that fuse is rated at. It really is strange that it reportedly trips the mains but the fuse doesn't blow.
Looks like contacts failed.
My initial thoughts were excessive high switching rate, in which case a solid state relay would be a better replacement than another relay. Not hard to rig up MOSFET to do that high speed switch duty.... if it actually does so, in which case it's faulty design using a mechanical relay.
Deeper investigation as to how this monitors heat of the plate and any form of PID control would be interesting, but I doubt it is sophisticated and use high speed switching to keep the plate at an accurate temp range.
Hi Richard, can I modify simple home steam iron?
sure you can.
Does the thermo couple actually creates voltage with temp difference or does it only change its resistance with temp and we put it in a voltage divider circuit to measure what its reading
there are both styles available
A thermocouple generates a voltage due to a temperature difference, see the thermoelectric effect. A thermistor changes resistance as a function of temperature.
thermocouples generate voltage. Thermisters change resistance.
French plug/sockets are polarised, when using earthed equipment you can only plug it in one way round. They use two pin plugs on double insulated equipment.
Have you ever done an endoscope with faulty camera issues?
look at the pads on the two red wires at 22:28 on the video - or are my eyes playing tricks on me
Its not your eyes, I see it too
You mean the remnants of black and black/white wires where they obviously cut that pcb out of a 12V power pack? 🤣
@@LearnElectronicsRepair oh, to the untrained eye it looked like the pads had lifted off the board where the red wires are coming in. But I see the left one is black - I just had a man's look as the wife tells me.
I learnt this since the age of six. Interesting, that A+ students in top school couldn’t find the fuse on a tape recorder deck.
Could it be the contacts in the relay just burnt together because of burnt contacts?
Talk about beating around the bush!
The heating element shows an abnormal value (about 34W @230V). It may have short-circuited, causing the destruction of the relay contacts, then evolved towards the too high resistance value measured. The mechanical stress caused by heating can lead to this type of defect.
I have a Sony XBR 55X850D and i changed theT-con board because the tv would go blank just after the boot up screen comes on and then have 6 red flashes
how to use oscilloscope for fault finding? can you make a video about that?
I can't possibly think why you would need or want to use an oscilloscope for this kind of job / repair!
I'm guessing the reason you have 2 component shops is you don't get same day, or next day delivery. Also small islands around the world often have a culture of self reliance, so they actually fix things to component level.
Funny how the unconnected normally closed relay pin in the most burn one on the board - I guess it just because it had no heatsink(pcb trace) like the others
Maybe the resistance reading of the heating element isn't that wrong. 1570 Ohm would result in 34W @230V. Looking on the dim bulb tester which goes dim also points to
Oh, "chinesium watts", that makes sense. Darn chinee, tricked us again.
The heating element circuit appears to be run in parallel to the 12V power supply circuit, so that would Reduce the resistance/increase the current and power when both loads are active.
Good analyses, except the fact it's drawing current tells me that that resistance I am reading on it is nothing particularly sensible (ho, ho). Probably needs a transil or similar across the relay contacts, but beggars can't be choosers. Personally, I think electronics shops mostly died out because they tried to diversify into selling trashy toys and other junk. I remember Maplin from days of old. Presumably there's no real competition (from the likes of Farnell, RS etc) on the islands.
Happy 4th from America....
Cheers!
Hmmm....it's a day of mourning for the English ;-)
Comes with plenty of storage space, that's value.
I still don't understand why the mains tripped and the fuse didn't blow. How do you determine the correct rating for the fuse?
RCD will likely have tripped at around 30mA of fault current to earth, preventing the fault current getting high enough for the fuse to act. The fuse would be more likely to act in a Live-Neutral short circuit, where fault current can get upto thousands of amps without locally going to earth and thus not triggering the RCD.
Current rating of the fuse would be done by calculating the power of the device. Power = Voltage x Current. This device states it is 450W so 450W / 230V = 1.95A. So you would select the next appropriate fuse size up from that to provide overcurrent protection.
That power supply already came out of something else, you can see it had black wires and they were fut off.
Step by step repair
still unclear why it would trip the mains but not the fuse?
The fact that it is tripping anything is confusing me. Perhaps the circuit had some sort of short due to the melted relay. Otherwise, it would just seem to be a relay stuck open to me, and generally resistance increases with temperature, meaning that the current should actually drop as it runs. Perhaps they have a material that decreases in resistance with temperature, causing increased current flow, and perhaps the first person's house is quicker to flick the circuit breaker than the Chinese fuse is to blow.
I only have the owners word for the fact it was tripping the mains, but no reason to doubt him either. The most likely reason would be earth leakage but I don't quite see how. The controller board with the burnt relay only has incoming live + switched live out. There is no connection to neutral or earth from there - apart from the potentiometer shaft is bolted to the front panel and the case is grounded
Perhaps it's a timing thing? It is my understanding as a layperson that mains breakers usually have both thermal (for long-term low overcurrent) and magnetic protection (short high current spikes, usually associated with direct shorts). Maybe the magnetic portion of the mains breaker trips before the thermal fuse in the device has a chance to melt.
Doesn't say much for Handy Andy that he had to send it to you Richard... :-) Just saying like..
Does one else want too see the new relay go in any it working as it should or is that just me!!!!
OK if you like, Handy Andy will be in Las Palmas on Friday, if they have them in stock I can do that, plus work out how to deal with the burnt connector
Yes I would. Otherwise it may not be a fix!
is handy andy from germany ? First I thought it was because he was the handy man fixing random thing, but now we find out he repairs mobiles, and handy is german slang for mobile phones.
What makes an Electronics Repair Pro a Pro? What skills distinguish someone as a Electronics Repair Pro?
Ok
No electronic components shops in the US? I'd blame that on consumerism. Much less people fix stuff over there and a bit less people make custom boards. In the US you just buy new always I guess.
These videos are lots of fun! 🫨🎺 I still do understand almost nothing so I pause a lot and search what different components do. It feels like I am learning programming again from basics.
I did not know that relay and transistor behave so similarly. This was my first time seeing relay. Although it was burnt one.
LER (AKA Comments Below).
Thermocouples doesn't generate any voltage, it change the resistivity. And you learn another how to repair electronics, whit no electronics knowledge. BDW.. You have a beautifully nails.
Why such a complex psu for a simple 12vdc?. In fact the whole thing is overly complex. You can get simple pwm thermocouple based temp controllers for under $30 on a single board up to 2kw.. Or an old school thermostat up to 3kw that would last forever. That bang bang style relay method is doomed to fail. That relay will always burn out when used like that eventually. SSR pwm will last forever.
The build quality of this unit is so bad, that I would tell the customer that with the cost of making fit and safe for use they might as well buy a new one. but this time get one that's CE marked and safe for use in the first place.
Sorry but I will not fix c**P like this and give it back in the dangerous state it would be in.
it needs a lot of work to bring it in line with any safety standards in the EU, but then who ever imported this did not have a clue about the Low voltage Directive to which it should conform to, or what a CE mark should like.
Rant over.
That's some redneck engineering right there. Bit of foam and a cable tie, she'll be right mate.
What do you call the Chinese variant of rednecks anyway? (We call them bogans in Australia.)
@@j.f.christ8421 Yellownecks?
@@j.f.christ8421 ....or Chinecks?