the failure was likely due to a component faulty from the factory (happens due to wrong handling/transportation or poor qc), so the rest of the psu should be absolutely fine. The 10A psu however had that switching bridge short out so it likely damaged the input circuitry.
Like your style and speed of delivery: no nonsense. And that you comment to discharge the caps. Would have liked more on the 10A or put a follow-up link to vid in the comments of this one. I am not a beginner, but a refresh of your logic and steps is great. Thanks. Also: Do you have a link to the ceiling lamp (very cool!)?
Those transistors are called FETs. were there FET both the same? any spec needed to know except the breakdown voltage? do I need to like if they are n-channels or p-channels?
I am building a 400 amp power supply using these and I got it all going and used it for about 30 min I shut it off all was good went back 2hrs later turned on the power and 3 of them popped this is the 2rd time this happened I don't know what's causing it any ideas would help thanks
I have liké that cart only got a problem i dont know the second Switch transistor which exist in top of the card .i know only Switch transistor which exist beside it called .D 209L.can i make the same in the empty place beside it 😮and thank you.
in the US, any Harbor Freight has these...I have one and love it. Cheap and it works. The Panavise 381 is pretty much the same, but it's about 3 to 4 times the cost.
the closest thing hf has is the 2-3/4 in. Articulated Vacuum Vise, which looks ok enough for the price, though I prefer a clamp or just really heavy base over a vacuum. I do like all the accessories you can get for the 301 though
Very strange! Your first part of the video gave me an impression that someone flipped the voltage selector during the power supply was still on. And that is why the component next to the voltage selector is blown up. And the second part of the video shew two high power transistors blown up. It looks like that someone sticks a metal screwdriver into the power supply and causes short circuit while it is on.
MASTER..I HAVE A 12V 3A POWER SUPPLY. BROKEN ON THE TRANSISTOR PART WITH NUMBER 3055XD. I SEARCH IN THE ELECTRONIC MARKET THERE IS NO SAME NUMBER. HELP ME TO FIND OR CHANGE A DIFFERENT NUMBER BUT THAT MUCH MARKETED
giving up so fast on the repair. get your volt meter out and start checking for voltages on the primary and the secondary section of the power supply and check also for bad parts.
Sebastian surely he would fully repair and possibly upgrade it, but then he would blow it up with or without dynamite, just to make things more exciting.
Yeah that's true, however mosfet is common fail part, which is destroy.over.time mainly in cheap not proper designed power supply if you want to find problem you actually upgrading 20usd power supply. ;)
@@xcruell Actually, no. It's not like that. The smell of gas tells you that there could be a leak somewhere. Ignoring it could be lethal. Not the same as not fixing a $25 PSU.
Yes i'm so dissapoint, Tom son! It's likely just a dead feedback resistor or the Zener diode. Just check everything in circuit and see whether something shorts that shouldn't, or something is open that shouldn't be, and i think with 80% probability, you would have seen what the issue was. Other 20% say that you'd have to lift one leg off every component till you find the fault :(
Agree... Unfinished job ! The most interesting part is investigating even if it takes time. I repaired a power supply for a friend inside a RGB laser. It was the shottky diodes.
Agreed. Surprised that you didn't mention or check the Schottky diode/s as they are quite often under specified. The current rating may be fine on paper, but when frequency and temperature are factored into the equation they can quite often fail even if the rating appears adequate. It's also a VERY quick and easy multimeter test in circuit to find out and checking the forward voltage drop when the supply is on will confirm also.
I really liked this video, Tom. Not just the content (killer, as always) but the style, the pacing, the scene editing choices. It felt very "I Like To Make Stuff" and it felt like you were really able to convey more to your audience.
+3D Printing Nerd thanks! I like the ILTMS style a lot and am always experimenting with new workflow, this one felt a lot more dynamic than what I usually do! Usually, it's doing th thing first, then scripting, shooting, editing - and usually another round of shooting after that.
3D Printing Nerd yeah, good video, and I have to ask if you made yourself a couple of Adam savage mic eyeglasses? :) I'm sure he's not the only one in the world that has made a pair but he's the only one that has made a video as far as I have seen :)
Re: oversizing power supplies. I'd go much higher than a 15A supply for your 10A load. I'd opt for 20A or more likely *30A*. These PSUs will be overspecced anyway, so a 30A supply will be just about ok with 20A, but get it to power 10A and it'll run for much longer (and much cooler). Don't believe those eBay specs because Chinese watts are quite a bit less than Western watts. *ALWAYS* use the conversion rate: 1CW=½WW and you'll have far more success buying cheap Chinese electronical goodness.
Thats a good idea. And most people seem to think that the PSU can deliver it's rated power at all times. If you put it in a closed box, like Toms lamp, it will heat up the inside of the box to a pretty high temperature (warning: possible fire hazard!). So make shure to keep in mind that rated power is usually just good for something up to around 40-50°C and in higher temperatures you have to quickly reduce the max power you can pull out of that supply. Usually that information is written in the datasheets or in application notes (good luck finding reliable data from no-name chinese manufacturers...).
I was just watching another channel where a guy wound a 10A rated SMPS up to 14A and it was still not sagging voltage. But how long the unit could do that is debatable.
@@SnoVVdogsPks Exactly ! Buying reputable chinese brands is like buying reputable _anything_ brand ! Playing along with the bad actors is a recipe for sustaining bad behaviour. Stop this "chinese Watts" BS @EscapeMCP!!!
Sometimes you get electrolytic capacitors drying out due to high temp. Also the PWM IC can get damaged when the power mosfets go short circuit. Love your 3d printer channel - I have learned a lot. Thanks Tom!
yeah, but at least there is a chance that both parts are the same. If you aren't good with trouble shooting, you can always just replace things like destroyed caps or parts that have cooling that might have gotten too hot, because of continous load. At least there you can guess that the broken part wasn't killed by some other broken part.
Just an advice: it's always better to discharge the high voltage capacitors with a 100-470 kohm resistor. This way you're saving the capacitor from excedingly high currents through it.
Gotta admit, I'm not very impressed by this video. No testing, troubleshooting, or discussion on how they work or why they fail; just removing visibly fried components and putting in replacements, then immediately giving up on the one when it still doesn't work. How did you decide which NTCs to drop in? Simply putting in the exact kind that failed? Or did you pick a better rated one so it doesn't happen again? If you want better rated ones, how do you decide which to use? The same questions could be asked of the blown transistors. Then, when it didn't work after replacing the transistors, why not at least give some hints as to what one could check next? It might not be worth fixing to you, but to someone else it might be.
Please only teach things you really know. This is too dangerous. You replaced the blown mosfets, without caring about WHY they blew. Thats basically the best example
I would recommend caution with the heatsink pads, they most likely provide isolation between those fets and the heatsink which is tied to ground. Most fets do not have isolated tabs.
Safely for what? You or the capacitor? If you really want to do it safely then you should use a bleeder resistor. Because just shorting a charged cap out you can blow holes in the dielectric.
I've got a 15A version of these and from day one it has had issues. Only outputs 10.3V at around 500ma. The adjustment pot does nothing. No parts have any obvious damage. All solder looks good (shockingly). No bridging or breaks. No corrosion or burn marks. I've tested every capacitor, diode, resistor, ntc and transistor...all test out fine. I'm completely stumped as to what the issue could be and see nothing about one of these outputting a voltage lower than should be. I've already spent more than an hour on this thing and for the cost and what I make I could have bought 2 more of them. lol And of course the seller has disappeared so no chance of a refund. Any ideas what else I can check?
A lot of these cheap power supplies don't have continuity between the earth terminal and the metal casing. I've bought a few of them, only one had continuity. Always check and if yours doesn't, just link one up to the side via one of the mounting screw holes.
Replacing Transistors directly is a wrong decision. The Transistors blew because of failure of other components. Always check the repaired power supply with a 100 watt plain bulb in series with the power supply. This will prevent the power supply from further damage in case the repair is unsuccessful. A continuously glowing bulb shows there is still short circuit in the power supply. Without the bulb, the Transistors would blow again. A Series bulb test is the best way to test smps supply. The bulb will glow momentarily and then dim if the smps is ok.
After replacing the switching transistors, on the hot side, it is necessary to check the circuits from the transistor base (resistors, diode and capacitance). To connect the power supply for inspection, it is necessary to use an incandescent lamp of ~ 100 watts instead of a fuse. This will protect the power supply from damage in the event of additional malfunctions. And you can use this lamp for discharging power capacitors.
He does it, but doesn't actually say how he is doing it. you just see him wiggle a screwdriver. I mean, I know what he did, and you know what he did, but not everyone will, and I just don't want to see anyone get a nasty shock.
He used an insulated tool to connect the two sides... that said, it is a huge liability to tell people how to do it. If you are at all uncomfortable or not 100% sure that you have discharged the caps... don't continue.
Oh that I agree with. So just say that - if you don't know how to discharge the caps, just stop now. Or go learn from someone else and sue them if it goes wrong. I just feel like it was a little bit too glossed over for such an important safety step. Then again, this didn't include a step by step tutorial on how to (de)solder things, so I guess some basic knowledge is assumed in the viewer.
In this case, when transistors or mosfets are burnt, the resistor connected to the gate of both mosfets also burn out. That are usually of value 1 ohm. Same case was happen with me on 12v 30amp PSU.
Given the failure modes I would have thought that they failed due to a power surge but the NTC looked like it may have been poor quality given that the bond for the lead had failed. A few more points: 1. The mains capacitors do not always remain charged. It depends on circuit design, bleed resistor failure, and when it was last powered up. 2. A lamp is a handy discharging method. 3. It is very easy to check for charged capacitors with a multimeter. 4. Don't use tools to discharge capacitors. -- It blows holes in the tools. -- You should be using good quality tools and that is not the sort of treatment you would give them. -- The sort of currents that are generated may be bad for the capacitor. 5. Never put the covers back on until you have carried out tests. If you feel unsafe without the covers on you should not be be anywhere near the tools. 6. Your soldering of the bridge rectifier was very poor. Solder joints should have nice fillets and should not be blobs. Obviously the legs were not tinning very well. What you should have done was to clean the legs back to bare copper and then resoldered it back in place. 7. You should have cleaned the thermal paste off the sil pads, especially if it was dry. 8. Whenever the switching FETs have blown there is a huge procedure to go through before applying full mains power. Too long to outline here. 9. The Faston crimp connectors were not needed in this case. All you were doing was a bench test and the terminals on the power supply had a square securing washer designed to clamp directly onto the wire. You wasted three crimps. 10. Invest in a hand operated desoldering pump (at the very least). The method you used for desoldering is tedious and puts unneeded thermal stress on the pcb pads.
soldering pumps are way better than wick. he didn't need to cut the legs if he had one... soldering pumps can last a lifetime. while wick is consumable. The crimped connectors are perfectly fine.... it makes it look neat. sure not necessary but it also helps avoid the chance of a unseen loose wire strand making contact with neighboring terminals. No need to criticize his use of them. highly unprofessional.
Give it to me, i can fix it in minutes. You didn't troubleshoot at all like If the bulk capacitors are getting power or if the ic is getting power to initially start switching , if the ic is functioning at all like it supposed to. Transistors blows up due to some other reasons likely to happen in the driving circuitry. Tons of related video on youtube. For example "Diode gone wild"
Yes, you have to discharge those capacitors before you touch anything on the PCB. I had to learn that the hard way when I repaired an icecream machine. Let's say I was really wide awake after I touched the PCB on the wrong trace. But at least now I can make my own icecream. That's worth it.
Çıkışlardan 12v ölçmeniz çalıştığı anlamına gelmez. Bende aynı özelliklerde güç kaynağı var ve 12v çıkış veriyor. Ancak sadece 1 amper çıkış sağlıyor. Ne yaptıysam arızasını bulamadım.
Would love to see you do more circuitboard troubleshooting videos. I like the way you explain things, and even though you might not be an electronics tech professionally…… It’s always fun for the audience to watch and learn along with you. It’s especially satisfying for guys like me who are professionals and do this full-time, to watch smart and competent folks like yourself learn and grow in their understanding of electronics. PS… Check the zeners and diode‘s on the supply you couldn’t fix. Probably the issue it is very common. Always think UPSTREAM of a failed component as to WHY it failed. Don’t replace a fuse or transistor without figuring out what made it fail. Also a somewhat lengthy load test would guarantee their function for the future. I really enjoyed the video!
Should be re titled...how to possible fix 1 out of 2 power supplies ? Is there a step by step guide to how to repair pcbs...or is it just simply if it looks burnt bulged or damage replace the component until it works ?
My findings so far for such cheap SMPS: (1) PREVENTIVE = Use them for up to 50%~60% of stated current. In that case of a 12V x 3A, drain a maximum of 2A from it. (2) CORRECTIVE = In case they start to “humm” or get lower voltage, change the output electrolytic capacitor for new ones with Double the operating voltage and possibly a larger uF capacity (if it fits inside the available space and height.
Here is mine: DON'T think that setting the soldering-iron hotter than needed by the solder composition is a good idea for desoldering. You just run a higher risk of delaminating the copper traces from the board. Especially on the cheap FR 2 (phenolic) circuit boards you see in all these low cost devices. The only thing that really helps is a higher power soldering iron for desoldering, so you can sink the required thermal energy into the solder joint as quickly as possible.
ExtraBase My main one would be, that the word "solder" has an "L" in it on purpose. I've no idea why people in the US spell it in English, but for some reason say it in French "Souder".
What he didn't do was pull the part out and clean the contamination off the leads. At least one looked like there was some nastiness going on to me. Solder don't stick to dirt. This fact is the leading cause of solder failures too.
Ya, cold solder joint on the bridge, the leads needed cleaned with a wire brush and acetone or something so it will tin. balling solder up to cover it is not a fix.
I just came across his video now. Usually when the 2 switching transistors pop the 2 resistors on the base of the transistors also pop. These are normally 2.2 ohm. This is a quick fix. I also test the power supply before putting it back in the case. Another good practice is to use a 60W or 100W light bulb in series with the mains supply when switching on. This limits the current in the event of a fault still being present. If the light bulb glows brightly you know that there still is a problem. I also do a load test once the repair is complete. Quite often the power supply works under no load conditions, but switches off under load. Anyway keep up the good work!
I tried to repair a cheap Chinese one, 12V x 5A, which is smaller than older Chinese ones 12V x 3A. The Mosfet and a power resistor was brownout, but there was also an unmarked IC for main SMPS control that was burned. No IC known/available, no possible repair!
Why do people buy these? They are not that cheap. Just buy a used DELL 1.2kw server PSU, they are about 20 AUD sometimes. And they output 12, 5, and 3.3v; You can also stack them, they are designed for that. *Upsides:* HIGHLY EFFICIENT. High output current. Good selection of taps. Stackable (If you really need 2.5 Kilowatts of power; or... More?! , Or just for the sake of reliability.) Reasonably small. Inexpensive. Stable power. OVERCURRENT trip(s). Isolated. Reliable. When i say aggressive, i mean aggressively cooled. *Downsides:* Well, there isn't many downsides to these units, But ill list a few that come to mind or that i have encountered. Well, this is obvious.. but.. No warranty. They don't have much voltage variation (Most models, i have one that you can push 7v above the limit after replacing output caps) They are REALLY loud, as servers don't really care about noise too much, They seem to have 1:100 scale 747 Jets in them.. You can sometimes trip the OVERCURRENT trip when you plug-in large inductive loads; This doesn't seem to happen when you use 500watt PWM motor or plug-in a bunch of 30 watt LEDS. some of them have "inverter noise" for analog Microphones / Audio stuff (or so people say) I guess Audio noise wasn't in the equation when they were making Server PSU's; i wonder why. And thats all she wrote.
Can you fix mines dc power supply is a QW-MS305D dc power supply.i fix it 2 or 3 times, the problem is,it keeps going to high voltage replacing different mosfets and won't do nothing.first time 0 to 60 mess up mosfet second to 4volts third 50volts I don't know if it's a mosfet has shortened out or I might be able to get the new same one or is it something else.and the problem is i don't have a freaking multimeter.😔
I got a 40 amp 12 volt version to power a 2-way radio repeater and sitting idle (muted receive mode) with less than 2 amps draw the supply failed in about 4 hours. Even when the radio is transmitting at it's 75 watts, 40 amps should be more than overkill.
In Brazil, such psu's are NOT cheap. They cost about U$70,00 for a 250w one and this price is too high considering half of the population earn less than U$300 monthly.
I am up to my neck in broken Electronics stuff all waiting for me to try to fix it. because people know I play with this stuff they bring me their broken Electronics. If it's easy to fix I fix it and give it back if not it goes in the pile. not uncommon to spend hours fixing something that's not worth what my time would be had a mediocre job. It's just too painful to see good stuff get thrown out when all it needs it's a little tweak. I think I have a sickness
No technical expertise, no troubleshooting, just changing obviously burned parts. No explanation of why it failed. Nothing learned here. If these supplies are poorly designed it would help to know how to prevent failure or even if they are worth buying in the first place.
These no name Chinese supplies are garbage. Horrible soldering, cheap components and a fire waiting to happen. You're much better off with a quality brand like Meanwell. It's really not worth your time to 'fix' products of this quality.
I have a $300 solder station with a solder sucker gun, but people like Tom and 8-Bit Guy can desolder better with braided wick than I can with my fancy expensive thing.
This is a single sided board! This is why it cleaned out so easily with the wick. When you have through-plated holes, wick tends to fail, but a bit of flux and it might be good. I personally find solder suckers to be more aptly described as board whackers, but i use them too :( might need to get a better tool.
+Siana Gearz board whacking works. My boss at the board house I used to work at taught me that technique. Just slam the board on the edge of the table while the solder joint is hot, and the solder all flies out of the hole. We called it heat it, and beat it.
But they aren't even good at board whacking. Besides, i think whacking a board with unleaded solder is not the brightest of ideas if you want it to be reliable afterwards. I mean sure, it's likely to be fine, i'm just not comfortable with the idea of whacking brittle joints.
Constructive criticism: Can you add a second or two of "pre roll" on you videos? For some reason some audio setups have a bit of delay before they start (like my surround sound through an nvidia card). This means that I often miss the first few words you say. Thanks!
Thought this was a repair! Swapping the burnt bits hardly constitutes "hope you learned something". Where's the diagnostics to carry on with the 10A one?
Had a cheap Chinese SMPS 12vdc 15 amp go down on me the other day. It's been working for the past three years 24/7, So I looked into repairing it, I found the caps had dried out so I went online E-bay to buy some new ones, 200vdc 220pf ? Lowest price for a pair was approx £6? I looked on line to see how much a new SMPS was of the same build 12vdc but 20 amp instead of 15 amp price£7.20p, so I'm using the old supply for spares and buying a new one, the switching transistors look a bit worn as well so add the price of trans/caps? it's far cheaper to bin and buy new one!
This power supplies has muti-channel output. It has, ++/- -...two positive and two negative. If it says, 20 Ampere for example considering 80% of that....16 Amps,would be the ideal load to be connected...I am confused with this,should it be 8 Amps per Channel so if I have two,that would be 16 Amps? or I Can load the 16 Amp directly on the single channel and don't mind the Ampere distribution per channel. Anyone who has the same problem? If anyone else mind the same problem,or did circuit analysis on the matter please...make an article about it or give me the link for reference. I ussually use this kind of cheap power supply from china too. Thanks Guys! :)
I bought cheap one from Amazon (36v 10A). Is it possible to upgrade or make more reliable it replacing its chunky components with good quality ones? Thanks for your video.
this is the extent of the capability of most so-called repair experts, burnt components are bad , is the fuse ok?, yes, then this is a no fix. and we also charge you for a repair attempt fee. with great power comes great responsibility
Getting 6V instead of 24V, tried adjusting voltage but doesn't see any change. Perhaps, potentiometer has gone wrong? Any input will be helpful Thomas. Thanks for the great video.
great video! Use a little flux will improve both soldering and desoldering and allows you to use lower temperatures. You can also preheat the pcb by putting it on a heated bed at 110 degrees for 10 mins.
One mine it was the 105J 400v capacitor (1mF). Need a capacitor testor for that (I use an LCR component tester). I know its 3 years on; did you ever fix the 2nd one?
Thomas I like you videos very much, both here and in your 3D printing ones; but why do you speak so fast, I have to wind back a few times to catch what you're saying. Sorry to moan but I don't imagine I'm the only one..... :-)
If you want a success repair the spare parts will be purchase from a trusted seller. Counterfeit marketing is a big problem in these days. Most ebay sellers of components are cheaters. Best Regards.
Or just buy a good quality, name-brand PSU that fits in the same location as the original supply in your printer, has a believable output power rating, and has proper safety and EMI certification testing done. A genuine Mean Well LRS-350-12 supply can be had for $32 USD from Mouser, Future, Jameco and a bunch of other electronics suppliers - www.findchips.com/search/lrs-350-12 - this is the supply I recommend to everyone.
they're pretty simple to jump though, you just have to bridge the green and any black wire, you can even buy pre-crimped and ready 24 pin PSU jumpers that you just plug in.
Hi Thomas my Metal 12v 4 Amp power supply has static current on 12volt output and its showing from tester. So should you please do let me know which parts need to be replaced ? All diodes are OK. Few days back the static currents are not there ..
i have same one .... and I mistakenly put the switch on 110v and connected the power supply to 220v input .... then it stopped ... small burning smell and no obvious burning part ... no 24 DC output ... i dont know how to fix it ... if someone have face similar issue can help pls ?
I had a 24v 10a smps similar to yours, i hear some noise and an output open voltage reading of 19v, and won't adjust even after turning the adjust pot, where could be most likely the culprit?
Today my 12V 30A Chinese Psu blew the glass fuse. There were no damage except for the fuse. I took the psu from the printer and put a new glass fuse to see that will it blow again under no load. The fuse was blown again. So I removed diodes and checked them with multimeter, one diode was faulty. I replaced all of the diodes and now psu is blowing a resistor. I had to buy a new one because even if I repair it by replacing more parts, I will not trust that crap psu.
I have a bad power supply. Im not getting anything off of one of the resistors. The resistor checks out as a 10% silver band resistor. I can't find them anywhere. If I put 2 5% can I create a 10%?
Curious if anyone has used one of these power supplies to power a car audio ( 12v) amplifier inside, trying to find reviews on these little things and how well they hold up. I'm also not talking about a small 200 watt set up, one of the 3 amps I will be running has a peak power of 1800 watts
the capasitors does not charge above to power they are applied to if you put 12VDC to a 400V Cap its stays 12V . but the discharge current (A) can be quite high,,,
Leaded solder may be bad for the environment, a lot of people don't realize that the higher temperature required to solder lead-free actually is worse for the people that do manual soldering. Higher temperatures evaporate the flux more violently, leading to much higher airborne particulate concentrations. This has actually been proven in several tests and studies, so if you have to solder lead-free regularly, you should definately invest in some good air scrubbers.
extrabase, it is proven that its bad its lead afterall!!!! but you should be more worried about flux causing cancer if you dont use a fume extractor. if you ever seen a dirty fume filter then you really have no clue what is going into your lungs if you dont use one lol.
lead free is usually fine on large traces, but try doing repairs on sensitive boards that you need scopes to repair, you would lift and burn the shit out of those traces real quickly.
It is so important to first analyse a fault, then to proceed with an explanation of the fault to your audience - before launching into a soldering lesson! I hope you will view my criticism constructively by taking several steps back, and creating a foundation - before you build the house!
What is with the video picture not being stable? Anything moving or big scene changes is pixellated with big break up. It looked like abstract art. Great content though.
Chinese solder is usually junk. I live in Thailand and that's all I can get without paying a ridiculous postage charge to have it sent from the USA or EU.
RUclips has become the feeding ground for begging(Patreon) and ad revenue(Subscribe to my channel) how can you title a video repairing power supplies when all you did was change the obvious in one and not even attempt to troubleshoot the other?
Good info...just one question: what's an "NTC"? I know transistors, capacitors, even SCRs, but I've never heard of an NTC...and neither has Wikipedia. What are they? -- Mike
To protect power supplies, you usually use a PTC (resistance gets higher if temperature rises). This is to protect the power supply from high currents (self heating of the PTC blocks current flow from getting too high) or just a thermal limiter that protects the supply from overheating itself by reducing the current that can flow into the supply. However, if the element itself is not designed to actually deal with the power it has to handle, the PTC will basically burn out quickly when it should just protect the supply...
That is a different protection. If you plug a PSU into mains, the capacitors will fill and large currents will flow. In some cases, the fuses may even blow. NTCs are used in power supplies to limit these currents. At power on, the NTC is low temperature and has resistance, so limits the currents. It will heat up, lose its resistance, but by then the capacitors will be full.
You are right, +Daniël Mantione Both NTC and PTC can be used in such applications. NTCs are usually the simple and cheap option, while PTC based circuits are more expensive but work quicker and better (more responsive).
This video Is actually very bad. You repair what you see is burned. You also skipped most important part, how to find spare components or/and choose alternatives
Best idea ever... if you post a video asking for help, probably get very few suggestions... post a video where you FAIL and everyone is in a hurry to jump on your failure and show you how good they are by telling you what you did wrong... now you have a bucket full of suggestions to try! Love it!
no telling if the 20a power supply is fixed without at least putting a modest load on it for a while.
Mostly, no telling whether it won’t overheat again.
None of the stuff in a PSU this simple is particularly likely to only half-work, though.
the failure was likely due to a component faulty from the factory (happens due to wrong handling/transportation or poor qc), so the rest of the psu should be absolutely fine.
The 10A psu however had that switching bridge short out so it likely damaged the input circuitry.
"Uh-oh the car doesn't start, tried turned the key twice. Well, the car is broken.. throw it away.."!! ;p
Exactly, this man seems more like a parts changer than a true connoisseur of electronics
You are by far my favorite 3D printing RUclipsr to watch. Thanks Tom.
Like your style and speed of delivery: no nonsense. And that you comment to discharge the caps. Would have liked more on the 10A or put a follow-up link to vid in the comments of this one. I am not a beginner, but a refresh of your logic and steps is great. Thanks. Also: Do you have a link to the ceiling lamp (very cool!)?
I would like to see many more of these power supply repair videos but in real time please.
Great video as always. Keep the good work, sir.You are the best teacher.I have learned a lot from you 😁
man, that lamp! so sick! You don't by any chance have some documentation about your building process there?
+Jocobes it's a project from before I was making RUclips videos. It'll come down soon anyways, maybe that's a good opportunity to document it.
Those transistors are called FETs. were there FET both the same? any spec needed to know except the breakdown voltage? do I need to like if they are n-channels or p-channels?
Crimp connectors rule!
I am building a 400 amp power supply using these and I got it all going and used it for about 30 min I shut it off all was good went back 2hrs later turned on the power and 3 of them popped this is the 2rd time this happened I don't know what's causing it any ideas would help thanks
I have liké that cart only got a problem i dont know the second Switch transistor which exist in top of the card .i know only Switch transistor which exist beside it called .D 209L.can i make the same in the empty place beside it 😮and thank you.
Where did you get the little ball vice from ?
Nick Moxley I own the same model as Thomas. It is called a Precision Vice FMZ by Proxxon. I think it is really good!
PanaVise 301 is a good option for US folk
in the US, any Harbor Freight has these...I have one and love it. Cheap and it works. The Panavise 381 is pretty much the same, but it's about 3 to 4 times the cost.
the closest thing hf has is the 2-3/4 in. Articulated Vacuum Vise, which looks ok enough for the price, though I prefer a clamp or just really heavy base over a vacuum. I do like all the accessories you can get for the 301 though
yea...I modified mine and it's bolted to a board that I can clamp anywhere...
how do you discharge it?
Very strange! Your first part of the video gave me an impression that someone flipped the voltage selector during the power supply was still on. And that is why the component next to the voltage selector is blown up. And the second part of the video shew two high power transistors blown up. It looks like that someone sticks a metal screwdriver into the power supply and causes short circuit while it is on.
Hello Thomas,
What is difference between adaptor and charger
MASTER..I HAVE A 12V 3A POWER SUPPLY. BROKEN ON THE TRANSISTOR PART WITH NUMBER 3055XD. I SEARCH IN THE ELECTRONIC MARKET THERE IS NO SAME NUMBER. HELP ME TO FIND OR CHANGE A DIFFERENT NUMBER BUT THAT MUCH MARKETED
Throw those two fire hazards away and use a mean well psu
My meanwell PS (authentic not counterfeit) died two days under only 1 amp load.. Lol you never know....
How I do check of burned capacitor. Like small size of MOV
Use better solder next time
230ac to 24v DC supply switching transistor values yougive me
giving up so fast on the repair. get your volt meter out and start checking for voltages on the primary and the secondary section of the power supply and check also for bad parts.
strange music, but it is good
Just send the defective one to BigClive, he loves that stuff ;)
Sebastian surely he would fully repair and possibly upgrade it, but then he would blow it up with or without dynamite, just to make things more exciting.
I'd love to see BigClive fix it.
@@JamesMossR33 It's gotta go BANG !!
You only replaced the switching MOSFETs without checking anything else to find WHY they failed? Amazing.
Cheap low quality
exactly my thought.
Its like smelling gas in your basement and just opening a window.
Yeah that's true, however mosfet is common fail part, which is destroy.over.time mainly in cheap not proper designed power supply if you want to find problem you actually upgrading 20usd power supply. ;)
Exactly
@@xcruell Actually, no. It's not like that.
The smell of gas tells you that there could be a leak somewhere. Ignoring it could be lethal. Not the same as not fixing a $25 PSU.
I was convinced he knew what he was doing until he failed with the 10A model.
me too
aww, I feared that would happen.
Its easy he must check the 2,2 Ohm resistor at the base transistor
D7 slot was fitted with a resistor. Maybe something to check...
You gave up to easily on the 10A supply!
Yes i'm so dissapoint, Tom son!
It's likely just a dead feedback resistor or the Zener diode. Just check everything in circuit and see whether something shorts that shouldn't, or something is open that shouldn't be, and i think with 80% probability, you would have seen what the issue was. Other 20% say that you'd have to lift one leg off every component till you find the fault :(
Yes, all he did was replace the obvious, damaged components. Troubleshoot the 10A!!
Agree... Unfinished job ! The most interesting part is investigating even if it takes time. I repaired a power supply for a friend inside a RGB laser. It was the shottky diodes.
Agreed. Surprised that you didn't mention or check the Schottky diode/s as they are quite often under specified. The current rating may be fine on paper, but when frequency and temperature are factored into the equation they can quite often fail even if the rating appears adequate. It's also a VERY quick and easy multimeter test in circuit to find out and checking the forward voltage drop when the supply is on will confirm also.
Yeah, find the fault!
I really liked this video, Tom. Not just the content (killer, as always) but the style, the pacing, the scene editing choices. It felt very "I Like To Make Stuff" and it felt like you were really able to convey more to your audience.
+3D Printing Nerd thanks! I like the ILTMS style a lot and am always experimenting with new workflow, this one felt a lot more dynamic than what I usually do! Usually, it's doing th thing first, then scripting, shooting, editing - and usually another round of shooting after that.
True his videos are very professional. Yours are awesome aswell. Just made your fidget spinner!!!
3D Printing Nerd yeah, good video, and I have to ask if you made yourself a couple of Adam savage mic eyeglasses? :) I'm sure he's not the only one in the world that has made a pair but he's the only one that has made a video as far as I have seen :)
My boss says"wots that". I said "fidget spinner". he says "Gimme a look". I have not seen it since he took it off me !
lol there so addictive
Re: oversizing power supplies. I'd go much higher than a 15A supply for your 10A load. I'd opt for 20A or more likely *30A*. These PSUs will be overspecced anyway, so a 30A supply will be just about ok with 20A, but get it to power 10A and it'll run for much longer (and much cooler).
Don't believe those eBay specs because Chinese watts are quite a bit less than Western watts. *ALWAYS* use the conversion rate: 1CW=½WW and you'll have far more success buying cheap Chinese electronical goodness.
Thats a good idea. And most people seem to think that the PSU can deliver it's rated power at all times. If you put it in a closed box, like Toms lamp, it will heat up the inside of the box to a pretty high temperature (warning: possible fire hazard!). So make shure to keep in mind that rated power is usually just good for something up to around 40-50°C and in higher temperatures you have to quickly reduce the max power you can pull out of that supply. Usually that information is written in the datasheets or in application notes (good luck finding reliable data from no-name chinese manufacturers...).
I was just watching another channel where a guy wound a 10A rated SMPS up to 14A and it was still not sagging voltage. But how long the unit could do that is debatable.
Or buy genuine western PSU's, I mean, even genuine Meanwells and such aren't so expensive.
😄1 W Chinese=1/2 W American
@@SnoVVdogsPks Exactly ! Buying reputable chinese brands is like buying reputable _anything_ brand ! Playing along with the bad actors is a recipe for sustaining bad behaviour. Stop this "chinese Watts" BS @EscapeMCP!!!
Sometimes you get electrolytic capacitors drying out due to high temp. Also the PWM IC can get damaged when the power mosfets go short circuit.
Love your 3d printer channel - I have learned a lot. Thanks Tom!
the rule of repairing is to repair the thing which cause it to fail not faild component
yeah, but at least there is a chance that both parts are the same. If you aren't good with trouble shooting, you can always just replace things like destroyed caps or parts that have cooling that might have gotten too hot, because of continous load. At least there you can guess that the broken part wasn't killed by some other broken part.
Very cool LED light fixture. Have you thought about making a quick video about how you made it?
The power supply you couldn't repair, i'll bet a zener diode is dead. Do a diode test on all diodes and you will probably find one dead.
Thanks, I'll test those!
@escorpiuser could be the caps, but normally you should see them bulge up if they are broken.
well, the controller IC is a major problem too, if the IC is fried it will burn your mosfets and diodes endlessly
most of these types of power supply used PWM IC and in that case no output voltage maybe PWM IC has the problem
0000adeq=p
Just an advice: it's always better to discharge the high voltage capacitors with a 100-470 kohm resistor. This way you're saving the capacitor from excedingly high currents through it.
100-470 *ohms* does not take all day to achieve that.
Gotta admit, I'm not very impressed by this video. No testing, troubleshooting, or discussion on how they work or why they fail; just removing visibly fried components and putting in replacements, then immediately giving up on the one when it still doesn't work.
How did you decide which NTCs to drop in? Simply putting in the exact kind that failed? Or did you pick a better rated one so it doesn't happen again? If you want better rated ones, how do you decide which to use? The same questions could be asked of the blown transistors. Then, when it didn't work after replacing the transistors, why not at least give some hints as to what one could check next? It might not be worth fixing to you, but to someone else it might be.
Exactly. Power semiconductors almost never "just fail". It's usually caused by bad driving waveforms, which is way beyond the scope of this video.
Please only teach things you really know.
This is too dangerous.
You replaced the blown mosfets, without caring about WHY they blew. Thats basically the best example
I would recommend caution with the heatsink pads, they most likely provide isolation between those fets and the heatsink which is tied to ground. Most fets do not have isolated tabs.
I would agree with some of the comments here, a little more detail on how to safely discharge the caps is in order. Other then that, well done.
Safely for what? You or the capacitor? If you really want to do it safely then you should use a bleeder resistor. Because just shorting a charged cap out you can blow holes in the dielectric.
I've got a 15A version of these and from day one it has had issues. Only outputs 10.3V at around 500ma. The adjustment pot does nothing. No parts have any obvious damage. All solder looks good (shockingly). No bridging or breaks. No corrosion or burn marks. I've tested every capacitor, diode, resistor, ntc and transistor...all test out fine. I'm completely stumped as to what the issue could be and see nothing about one of these outputting a voltage lower than should be. I've already spent more than an hour on this thing and for the cost and what I make I could have bought 2 more of them. lol And of course the seller has disappeared so no chance of a refund.
Any ideas what else I can check?
A lot of these cheap power supplies don't have continuity between the earth terminal and the metal casing. I've bought a few of them, only one had continuity. Always check and if yours doesn't, just link one up to the side via one of the mounting screw holes.
Also a good thing to check and fix with these chiinese models is the grounding, I've had multiple ones with ground not connected to the casing..
Replacing Transistors directly is a wrong decision.
The Transistors blew because of failure of other components.
Always check the repaired power supply with a 100 watt plain bulb
in series with the power supply.
This will prevent the power supply from further damage in case the repair is unsuccessful.
A continuously glowing bulb shows there is still short circuit in the power supply.
Without the bulb, the Transistors would blow again. A
Series bulb test is the best way to test smps supply.
The bulb will glow momentarily and then dim if the smps is ok.
After replacing the switching transistors, on the hot side, it is necessary to check the circuits from the transistor base (resistors, diode and capacitance).
To connect the power supply for inspection, it is necessary to use an incandescent lamp of ~ 100 watts instead of a fuse. This will protect the power supply from damage in the event of additional malfunctions. And you can use this lamp for discharging power capacitors.
not advisable to repair power supplies unless you can actually trouble shoot electronics ..
I wish you mentioned HOW to safely discharge the capacitors. Not everyone knows how to do that safely. Otherwise good stuff!
But he do, at 4:00
He does it, but doesn't actually say how he is doing it. you just see him wiggle a screwdriver. I mean, I know what he did, and you know what he did, but not everyone will, and I just don't want to see anyone get a nasty shock.
That's true, had the same reaction as you initially in the clip, he could have stated it clearer.
He used an insulated tool to connect the two sides... that said, it is a huge liability to tell people how to do it. If you are at all uncomfortable or not 100% sure that you have discharged the caps... don't continue.
Oh that I agree with. So just say that - if you don't know how to discharge the caps, just stop now. Or go learn from someone else and sue them if it goes wrong. I just feel like it was a little bit too glossed over for such an important safety step. Then again, this didn't include a step by step tutorial on how to (de)solder things, so I guess some basic knowledge is assumed in the viewer.
Meanwell Power Supplies tend not to burn your house down.
Mean Well doesn't then teach how to put out a burning house, so no points, mate.
+Ross Fisher yup.
Mean Well won't give you a reason to watch a dead PSU video ;)
In this case, when transistors or mosfets are burnt, the resistor connected to the gate of both mosfets also burn out. That are usually of value 1 ohm. Same case was happen with me on 12v 30amp PSU.
drive IC might be toast in 10 amp PSU.
Given the failure modes I would have thought that they failed due to a power surge but the NTC looked like it may have been poor quality given that the bond for the lead had failed.
A few more points:
1. The mains capacitors do not always remain charged. It depends on circuit design, bleed resistor failure, and when it was last powered up.
2. A lamp is a handy discharging method.
3. It is very easy to check for charged capacitors with a multimeter.
4. Don't use tools to discharge capacitors.
-- It blows holes in the tools.
-- You should be using good quality tools and that is not the sort of treatment you would give them.
-- The sort of currents that are generated may be bad for the capacitor.
5. Never put the covers back on until you have carried out tests. If you feel unsafe without the covers on you should not be be anywhere near the tools.
6. Your soldering of the bridge rectifier was very poor. Solder joints should have nice fillets and should not be blobs. Obviously the legs were not tinning very well. What you should have done was to clean the legs back to bare copper and then resoldered it back in place.
7. You should have cleaned the thermal paste off the sil pads, especially if it was dry.
8. Whenever the switching FETs have blown there is a huge procedure to go through before applying full mains power. Too long to outline here.
9. The Faston crimp connectors were not needed in this case. All you were doing was a bench test and the terminals on the power supply had a square securing washer designed to clamp directly onto the wire. You wasted three crimps.
10. Invest in a hand operated desoldering pump (at the very least). The method you used for desoldering is tedious and puts unneeded thermal stress on the pcb pads.
soldering pumps are way better than wick. he didn't need to cut the legs if he had one... soldering pumps can last a lifetime. while wick is consumable.
The crimped connectors are perfectly fine.... it makes it look neat. sure not necessary but it also helps avoid the chance of a unseen loose wire strand making contact with neighboring terminals. No need to criticize his use of them. highly unprofessional.
Give it to me, i can fix it in minutes. You didn't troubleshoot at all like
If the bulk capacitors are getting power or if the ic is getting power to initially start switching , if the ic is functioning at all like it supposed to. Transistors blows up due to some other reasons likely to happen in the driving circuitry.
Tons of related video on youtube.
For example "Diode gone wild"
Yes, you have to discharge those capacitors before you touch anything on the PCB. I had to learn that the hard way when I repaired an icecream machine.
Let's say I was really wide awake after I touched the PCB on the wrong trace.
But at least now I can make my own icecream. That's worth it.
Çıkışlardan 12v ölçmeniz çalıştığı anlamına gelmez. Bende aynı özelliklerde güç kaynağı var ve 12v çıkış veriyor. Ancak sadece 1 amper çıkış sağlıyor. Ne yaptıysam arızasını bulamadım.
Would love to see you do more circuitboard troubleshooting videos. I like the way you explain things, and even though you might not be an electronics tech professionally…… It’s always fun for the audience to watch and learn along with you.
It’s especially satisfying for guys like me who are professionals and do this full-time, to watch smart and competent folks like yourself learn and grow in their understanding of electronics.
PS… Check the zeners and diode‘s on the supply you couldn’t fix. Probably the issue it is very common.
Always think UPSTREAM of a failed component as to WHY it failed.
Don’t replace a fuse or transistor without figuring out what made it fail.
Also a somewhat lengthy load test would guarantee their function for the future.
I really enjoyed the video!
Should be re titled...how to possible fix 1 out of 2 power supplies ? Is there a step by step guide to how to repair pcbs...or is it just simply if it looks burnt bulged or damage replace the component until it works ?
My findings so far for such cheap SMPS: (1) PREVENTIVE = Use them for up to 50%~60% of stated current. In that case of a 12V x 3A, drain a maximum of 2A from it. (2) CORRECTIVE = In case they start to “humm” or get lower voltage, change the output electrolytic capacitor for new ones with Double the operating voltage and possibly a larger uF capacity (if it fits inside the available space and height.
Brace yourself, soldering technique comment is coming. XD
Here is mine: DON'T think that setting the soldering-iron hotter than needed by the solder composition is a good idea for desoldering. You just run a higher risk of delaminating the copper traces from the board. Especially on the cheap FR 2 (phenolic) circuit boards you see in all these low cost devices. The only thing that really helps is a higher power soldering iron for desoldering, so you can sink the required thermal energy into the solder joint as quickly as possible.
ExtraBase My main one would be, that the word "solder" has an "L" in it on purpose.
I've no idea why people in the US spell it in English, but for some reason say it in French "Souder".
He used too much solder on the rectifier that it balled up instead of being concave like a mountain.
What he didn't do was pull the part out and clean the contamination off the leads. At least one looked like there was some nastiness going on to me. Solder don't stick to dirt. This fact is the leading cause of solder failures too.
Ya, cold solder joint on the bridge, the leads needed cleaned with a wire brush and acetone or something so it will tin. balling solder up to cover it is not a fix.
I just came across his video now. Usually when the 2 switching transistors pop the 2 resistors on the base of the transistors also pop. These are normally 2.2 ohm. This is a quick fix. I also test the power supply before putting it back in the case. Another good practice is to use a 60W or 100W light bulb in series with the mains supply when switching on. This limits the current in the event of a fault still being present. If the light bulb glows brightly you know that there still is a problem. I also do a load test once the repair is complete. Quite often the power supply works under no load conditions, but switches off under load. Anyway keep up the good work!
I tried to repair a cheap Chinese one, 12V x 5A, which is smaller than older Chinese ones 12V x 3A. The Mosfet and a power resistor was brownout, but there was also an unmarked IC for main SMPS control that was burned.
No IC known/available, no possible repair!
Why do people buy these? They are not that cheap.
Just buy a used DELL 1.2kw server PSU, they are about 20 AUD sometimes.
And they output 12, 5, and 3.3v; You can also stack them, they are designed for that.
*Upsides:*
HIGHLY EFFICIENT.
High output current.
Good selection of taps.
Stackable (If you really need 2.5 Kilowatts of power; or... More?! , Or just for the sake of reliability.)
Reasonably small.
Inexpensive.
Stable power.
OVERCURRENT trip(s).
Isolated.
Reliable.
When i say aggressive, i mean aggressively cooled.
*Downsides:*
Well, there isn't many downsides to these units, But ill list a few that come to mind or that i have encountered.
Well, this is obvious.. but.. No warranty.
They don't have much voltage variation (Most models, i have one that you can push 7v above the limit after replacing output caps)
They are REALLY loud, as servers don't really care about noise too much, They seem to have 1:100 scale 747 Jets in them..
You can sometimes trip the OVERCURRENT trip when you plug-in large inductive loads; This doesn't seem to happen when you use 500watt PWM motor or plug-in a bunch of 30 watt LEDS.
some of them have "inverter noise" for analog Microphones / Audio stuff (or so people say) I guess Audio noise wasn't in the equation when they were making Server PSU's; i wonder why.
And thats all she wrote.
Thanks for the tip. I just put one in my eBay cart
do note that they sound like jet engines, but otherwise they are great
Can you fix mines dc power supply is a QW-MS305D dc power supply.i fix it 2 or 3 times, the problem is,it keeps going to high voltage replacing different mosfets and won't do nothing.first time 0 to 60 mess up mosfet second to 4volts third 50volts I don't know if it's a mosfet has shortened out or I might be able to get the new same one or is it something else.and the problem is i don't have a freaking multimeter.😔
I got a 40 amp 12 volt version to power a 2-way radio repeater and sitting idle (muted receive mode) with less than 2 amps draw the supply failed in about 4 hours. Even when the radio is transmitting at it's 75 watts, 40 amps should be more than overkill.
In Brazil, such psu's are NOT cheap. They cost about U$70,00 for a 250w one and this price is too high considering half of the population earn less than U$300 monthly.
I am up to my neck in broken Electronics stuff all waiting for me to try to fix it. because people know I play with this stuff they bring me their broken Electronics. If it's easy to fix I fix it and give it back if not it goes in the pile. not uncommon to spend hours fixing something that's not worth what my time would be had a mediocre job. It's just too painful to see good stuff get thrown out when all it needs it's a little tweak. I think I have a sickness
No technical expertise, no troubleshooting, just changing obviously burned parts. No explanation of why it failed. Nothing learned here. If these supplies are poorly designed it would help to know how to prevent failure or even if they are worth buying in the first place.
Helpful repair video 👍
These no name Chinese supplies are garbage. Horrible soldering, cheap components and a fire waiting to happen. You're much better off with a quality brand like Meanwell. It's really not worth your time to 'fix' products of this quality.
Have you heard of a solder sucker/pump?
I find they are better then wick
I have a $300 solder station with a solder sucker gun, but people like Tom and 8-Bit Guy can desolder better with braided wick than I can with my fancy expensive thing.
Good braid can actually be more gentle on board traces. You can suck solder rings right off PCBs with solder suckers if you're not careful.
This is a single sided board! This is why it cleaned out so easily with the wick. When you have through-plated holes, wick tends to fail, but a bit of flux and it might be good. I personally find solder suckers to be more aptly described as board whackers, but i use them too :( might need to get a better tool.
+Siana Gearz board whacking works. My boss at the board house I used to work at taught me that technique. Just slam the board on the edge of the table while the solder joint is hot, and the solder all flies out of the hole. We called it heat it, and beat it.
But they aren't even good at board whacking. Besides, i think whacking a board with unleaded solder is not the brightest of ideas if you want it to be reliable afterwards. I mean sure, it's likely to be fine, i'm just not comfortable with the idea of whacking brittle joints.
Can anyone help me with my meanwell power supply? The company is useless they dont honor their warranties.. no dc output.
Constructive criticism: Can you add a second or two of "pre roll" on you videos? For some reason some audio setups have a bit of delay before they start (like my surround sound through an nvidia card). This means that I often miss the first few words you say.
Thanks!
Thought this was a repair! Swapping the burnt bits hardly constitutes "hope you learned something". Where's the diagnostics to carry on with the 10A one?
Had a cheap Chinese SMPS 12vdc 15 amp go down on me the other day. It's been working for the past three years 24/7, So I looked into repairing it, I found the caps had dried out so I went online E-bay to buy some new ones, 200vdc 220pf ? Lowest price for a pair was approx £6? I looked on line to see how much a new SMPS was of the same build 12vdc but 20 amp instead of 15 amp price£7.20p, so I'm using the old supply for spares and buying a new one, the switching transistors look a bit worn as well so add the price of trans/caps? it's far cheaper to bin and buy new one!
This power supplies has muti-channel output. It has, ++/- -...two positive and two negative. If it says, 20 Ampere for example considering 80% of that....16 Amps,would be the ideal load to be connected...I am confused with this,should it be 8 Amps per Channel so if I have two,that would be 16 Amps? or I Can load the 16 Amp directly on the single channel and don't mind the Ampere distribution per channel. Anyone who has the same problem?
If anyone else mind the same problem,or did circuit analysis on the matter please...make an article about it or give me the link for reference. I ussually use this kind of cheap power supply from china too. Thanks Guys! :)
I bought cheap one from Amazon (36v 10A). Is it possible to upgrade or make more reliable it replacing its chunky components with good quality ones? Thanks for your video.
this is the extent of the capability of most so-called repair experts, burnt components are bad , is the fuse ok?, yes, then this is a no fix. and we also charge you for a repair attempt fee. with great power comes great responsibility
Getting 6V instead of 24V, tried adjusting voltage but doesn't see any change. Perhaps, potentiometer has gone wrong? Any input will be helpful Thomas. Thanks for the great video.
great video! Use a little flux will improve both soldering and desoldering and allows you to use lower temperatures. You can also preheat the pcb by putting it on a heated bed at 110 degrees for 10 mins.
One mine it was the 105J 400v capacitor (1mF). Need a capacitor testor for that (I use an LCR component tester). I know its 3 years on; did you ever fix the 2nd one?
usualy when fets let the magic smoke out their drivers go as well so chek them as well.
Thomas I like you videos very much, both here and in your 3D printing ones; but why do you speak so fast, I have to wind back a few times to catch what you're saying.
Sorry to moan but I don't imagine I'm the only one..... :-)
If you want a success repair the spare parts will be purchase from a trusted seller.
Counterfeit marketing is a big problem in these days.
Most ebay sellers of components are cheaters.
Best Regards.
Always just use an old computer PSU, its cheap (free most of the time) and delivers more than enough for 3.3V, 5V and 12V. Sometimes even 24V.
Frank true but you need to put some load on the 5 V and to know how to start it so not plug play like these cheapo Chinese ones
Well not really, i've been doing this without an issue with many of them. Maybe a few of them have a couple of safety features but hey, its free!
You don't really need a load on the 5V line, just need to short PS_ON pin and COM and power supply turns on.
Or just buy a good quality, name-brand PSU that fits in the same location as the original supply in your printer, has a believable output power rating, and has proper safety and EMI certification testing done.
A genuine Mean Well LRS-350-12 supply can be had for $32 USD from Mouser, Future, Jameco and a bunch of other electronics suppliers - www.findchips.com/search/lrs-350-12 - this is the supply I recommend to everyone.
they're pretty simple to jump though, you just have to bridge the green and any black wire, you can even buy pre-crimped and ready 24 pin PSU jumpers that you just plug in.
Hi Thomas my Metal 12v 4 Amp power supply has static current on 12volt output and its showing from tester. So should you please do let me know which parts need to be replaced ? All diodes are OK. Few days back the static currents are not there ..
i have same one .... and I mistakenly put the switch on 110v and connected the power supply to 220v input .... then it stopped ... small burning smell and no obvious burning part ... no 24 DC output ... i dont know how to fix it ... if someone have face similar issue can help pls ?
I had a 24v 10a smps similar to yours, i hear some noise and an output open voltage reading of 19v, and won't adjust even after turning the adjust pot, where could be most likely the culprit?
For everyone looking for it: Such supplies are for example sold (produced?) by "ZJIVNV Official Store" on Aliexpress.
Today my 12V 30A Chinese Psu blew the glass fuse. There were no damage except for the fuse. I took the psu from the printer and put a new glass fuse to see that will it blow again under no load. The fuse was blown again. So I removed diodes and checked them with multimeter, one diode was faulty. I replaced all of the diodes and now psu is blowing a resistor. I had to buy a new one because even if I repair it by replacing more parts, I will not trust that crap psu.
I have a bad power supply. Im not getting anything off of one of the resistors. The resistor checks out as a 10% silver band resistor. I can't find them anywhere. If I put 2 5% can I create a 10%?
Curious if anyone has used one of these power supplies to power a car audio ( 12v) amplifier inside, trying to find reviews on these little things and how well they hold up. I'm also not talking about a small 200 watt set up, one of the 3 amps I will be running has a peak power of 1800 watts
the capasitors does not charge above to power they are applied to if you put 12VDC to a 400V Cap its stays 12V . but the discharge current (A) can be quite high,,,
Something caused the switching transistors to blow. They both don’t grenade for no reason. Keep going. Figure it out.
use leaded solder, those dull solder pads are clearly this lead-free rubbish.
Leaded solder may be bad for the environment, a lot of people don't realize that the higher temperature required to solder lead-free actually is worse for the people that do manual soldering. Higher temperatures evaporate the flux more violently, leading to much higher airborne particulate concentrations. This has actually been proven in several tests and studies, so if you have to solder lead-free regularly, you should definately invest in some good air scrubbers.
extrabase, it is proven that its bad its lead afterall!!!! but you should be more worried about flux causing cancer if you dont use a fume extractor. if you ever seen a dirty fume filter then you really have no clue what is going into your lungs if you dont use one lol.
lead free is usually fine on large traces, but try doing repairs on sensitive boards that you need scopes to repair, you would lift and burn the shit out of those traces real quickly.
gamerpaddy Maybe. Or too little flux.
No way that these Chinese will use lead-free soldier. They just use remelt soldier from old garbage PCB. Mixture unknown.
It is so important to first analyse a fault, then to proceed with an explanation of the fault to your audience - before launching into a soldering lesson!
I hope you will view my criticism constructively by taking several steps back, and creating a foundation - before you build the house!
Well done Video, and now as a German I know, how to understand you better. Turn the replay speed to 0.75 ;-).
Change the name to "replacing an obviously blown NTC and Mosfet"
What is with the video picture not being stable? Anything moving or big scene changes is pixellated with big break up. It looked like abstract art.
Great content though.
Chinese solder is usually junk. I live in Thailand and that's all I can get without paying a ridiculous postage charge to have it sent from the USA or EU.
Hello sir, I try to fix power supply that lacking the amperage, the voltage output is fine. Can you suggest what component should I replace it? thx
RUclips has become the feeding ground for begging(Patreon) and ad revenue(Subscribe to my channel) how can you title a video repairing power supplies when all you did was change the obvious in one and not even attempt to troubleshoot the other?
Good info...just one question: what's an "NTC"? I know transistors, capacitors, even SCRs, but I've never heard of an NTC...and neither has Wikipedia. What are they?
-- Mike
en.wikipedia.org/wiki/Thermistor
Thank you! NTC = Negative Temperature Coefficient (for anyone else who is curious). Resistance goes down as temperature goes up.
To protect power supplies, you usually use a PTC (resistance gets higher if temperature rises). This is to protect the power supply from high currents (self heating of the PTC blocks current flow from getting too high) or just a thermal limiter that protects the supply from overheating itself by reducing the current that can flow into the supply. However, if the element itself is not designed to actually deal with the power it has to handle, the PTC will basically burn out quickly when it should just protect the supply...
That is a different protection. If you plug a PSU into mains, the capacitors will fill and large currents will flow. In some cases, the fuses may even blow. NTCs are used in power supplies to limit these currents. At power on, the NTC is low temperature and has resistance, so limits the currents. It will heat up, lose its resistance, but by then the capacitors will be full.
You are right, +Daniël Mantione Both NTC and PTC can be used in such applications. NTCs are usually the simple and cheap option, while PTC based circuits are more expensive but work quicker and better (more responsive).
This video Is actually very bad. You repair what you see is burned. You also skipped most important part, how to find spare components or/and choose alternatives
Best idea ever... if you post a video asking for help, probably get very few suggestions... post a video where you FAIL and everyone is in a hurry to jump on your failure and show you how good they are by telling you what you did wrong... now you have a bucket full of suggestions to try! Love it!
Yes! That's a concept for a career on RUclips haha! :D