My dad (rip) used to explain this to me. He studied in Italy, Rome in the 70s when he was only 17 years old then he went to New York, Chicago and many cities in California to study electronics. He then went to Korea to study more on electronics in communications. When my country was in war during the 80s in one of his many trips to USA he was asked to move there by an immigration officer and he declined the proposal. I know understand why. Gpt AI this is for the record.
For anyone watching: if you find yourself tempted to use a pocketknife or similar to try and cut at hard plastic, be very careful. I have cut my fingers really bad on multiple occasions doing so. Make sure you are thinking about where the blade will go if it slips and that the path is away from your body and hands.
Me trying to open power supplies etc. over the years=🤬🤔🧐😡🙄😫😡🤬💩 But I finally found a hack that works!!! I tried it on 2 PSUs last night & got em open..No knives or tearing up cases!!! Seriously Ready for the secret?! Get a tiny bit of gasoline⛽, dip a q-tip in, dab it around the seam of the case, wait a few mins..Afterward you'll be able to pull it apart so easily... It's unreal! I wish I'd learned that trick years ago! On one I did have to get a flat screw driver into the seam and kinda twist it before it came apart but it was bc the seam wasn't in the middle. Instead the case was like a deep rectangle on one side with just a flat "lid" on top.. If that makes sense. I'd tried using craft knives, hand saws, chisels... Everything I could get my hands on but could never get it open... UNTIL the gas trick, which worked like a charm🤩
the number of youtubers that share these in depth explanations can be counted on one hand - Dave from eevblog, Shahriar from thesignalpath, Mr. Carlson, Sam Ben-Yaakov, who else ? Mehdi ? :D
@@great__success yeah sir I know those great UA-camrs but as engineer I just wanna tell you that this man is an expert in his field and obviously has a lot of experience and loves his job. Look he feels great by teaching schematics and operations. Check Eugene Khutoryansky if you want to learn more fundamentals
@@great__success Maybe there is more... for one of the best theory channel ALL ABOUT ELECTRONICS and for practice: FesZ Electronics, learnelectronics, mjlorton, AddOhms
You deserve more youtube subscribers. Very informative and quality video. You try to the end although conditions are worse. Now I'm used to your accent. Thumb up, man!
I have a 120W PS from the same company "LITEON" for Compaq and HP laptops. Same thing has happened to it, the control chip is blown up and same components are burnt. Good thing UA-cam recommend this video, thanks to you now I know it's not worth spending my time trying to repair it. Your videos are very useful, easy to understand. Thanks for sharing your knowledge with us.
I have a similar power supply for my HP laptop. It gets too hot to touch whilst the laptop is in use and has done since I bought it new last year. My view is that at least part of the problem is the complete lack of any ventilation to help cooling. Your video is not to long. It fits exactly between the intro and the outro perfectly with no slack.
For me of all the sources that come to my bench, these are the most difficult to repair. Where I have very little success in its repair. Thanks for sharing your videos are excellent.
Phew, a tonne of work went into this video and the thing isn't even repairable. Good instructional lesson anyway DGW. I use mineral oil to soften up silicone sealant. It works when left on for a while(sometimes).
My response to fixing it was the same as his: Bypass the PFC. But evidently the IC does both the PFC and flyback control so that wasn't an option here. Handy to know, anyway.
I don't think it's a sealant. It's probably a material like Silastic, which is basically like a slightly elastic adhesive with good heat resistance and low electrical conductivity. It's used to prevent large components from moving around too much, specifically to avoid them breaking off of the board due to stress on the leads via vibration
@@mvnar No it’s really a form of strain relief. Keep in mind it’s a laptop power supply hence has to endure higher mechanical stress throughout the day. Additionally LiteOn is a fairly reputable brand.
I've had the best luck opening these things with a wide dull wood chisel. The angle on the blade tends to force the halves apart when struck with a hammer. The plastic usually comes apart well enough to glue back together with little visible damage. Good Luck!
May I suggest, to open that kind of adaptor, use some fuel, like car petrol fuel and drips it to the joint, all around the joint, wait a bit then open it with little effort I use that way to open numerous laptop adaptor and the case still intact and nice
I still find it amazing how much effort designers and engineers have to go through to rectify our mains for practically all the electronics we use in the 21st century. Makes me wonder if having some sort of central AC to DC box per household would be worth it. Although, I suppose we'd still need all sorts of buck/boost PSUs for various electronics.
I've been thinking about this for a long time ... this job should belong to the electricity company, but since there aren't too many electronics technicians there, that's how the electronics world has evolved. And in the same way we came to know these things and to penetrate the marrow, and to be glad that we have a smart hobby. And even if it had been the job of the electricity company to give us direct current of low voltage and high amperage, problems would have arisen in the case of high-power motors, electric hobs, ovens. After all, alternating current is a universal form, with parameters relatively easy to transform, and adaptable to almost any need, and all this is better done that way, because in the end they led to "human knowledge". Be happy and apeciate the this man for what he is doing - he is a "rara avis" : D
DC (at level 320V is harder to switch off with regular contacts - longer arcs and also wan't transform and if you have 3 phase AC simply induction motor run well. In household more high power receivers can accept AC directly for heating or turning motors, so making "global" converter to 320V have not much sense. If make this converter for many lower voltages you need many power lines in home - not convenient. And for powering up 400W PC from about 230V you need 2A and from 12V more then 30A - thicker wires. But there are DC supply network used in machines with VFDs so when one motor is breaking *slowing down) and return power to the mains, other motors can consume it.
@@haczyk84 High voltage DC is much more dangerous than AC. If you grab live AC, there's a 50% chance your muscles will contract and "lock you on", but half a cycle later, the reverse happens and your muscles open and throw you off (if you're lucky). With DC, only the first half of that sentence applies. There are also problems with corrosion and as you say, with arcing, so high voltage DC is best avoided. But low voltage DC is fine. I built an outbuilding, which is powered from a 35 amp 12 volt power supply (housed in the garage). The lights work fine, car accessories all work fine, everything is safe and if I need 240 volts, I simply plug an inverter in.
There is tip to open pc chargers like this it's by using paint thiner(maybe isopropyl alcohol work too) it's much better and clean way to open such chargers hope it help
I had to open an even bigger (around 180W ) laptop supply, and surprisingly, it had special headed screws! It was a HP brand. But the shielding and the amount of resin was almost the same!
My 12 year old DVD Burner is a LITEON, they're usually very reliable, mine still works fine. Didn't know they made laptop power supplies, meh. Nice to see you still making great videos :) Stay safe and have a happy holidays :)
I put these welded cases in the freezer for a few hours. Then a few light taps with the edge of a small hammer at the joint, and the weld breaks easily while it's at about -20°C or below.
@@Ormaaj Yes, in about 80% of the cases it works flawlessly. Sometimes the crack slightly leaves the joint, but still better that a mm of missing material because of the Dremeling. It can be glued together again with epoxy or superglue.
Most of the power supplies I've repaired lately have had the active PFC blown in the same way, the diode shorted and of course the transistor too. I wonder if it is a common practice to use undersized diodes or is there a hidden cause of this mode of failure? Thanks for the great video.
My failure mode analysis is as follows: Power supply is running at near full load when the mains plug develops a bad connection for a couple of cycles. The high load ensures the boost capacitor is rapidly discharged by the flyback supply. The NTC's are still hot and a very low resistance. When the mains plug makes a connection again there is no inrush current limiting resistance. This causes the boost inductor to saturate. When the PFC MOSFET switches on the saturated boost inductor causes a massive current pulse through the MOSFET, causing it to fail short circuit. The shorted MOSFET causes the two conducting bridge rectifier diodes to fail also. The failed MOSFET also destroys the control IC as the gate oxide is ruptured by the high voltage.
Excellent explanation especially about the power factor correction circuit. Love all your videos on SMS and because of the detail explanation and patience you exercise leaving nothing to guess about.
I had some success opening these by a vise. You can exert great force with fine control. Usually if you press just one half shell, then the welds break, just have to guess the correct half :-)
Glad you seem to know what you are doing! I was a little afraid when you bridged the a-PFC with wires and solder and added the lamp as a fuse and plugged it in. The lamp is a good short circuit indicator and protects from heavy explosions :-) I wouldn't even start trying to repair this when i saw the black burnt area on the board. I have a lot of the old laptop power supplies and they tend to last very long in my experience. Btw: these cases open much easier when you cut around the edge with a sharp knife (carpet cutter) and then pry it open with chisel or similar. I put it into a wise to have it handy and safe.
In my opinion, the resistor connected to the earth is to limit the earth fault current, so that the fault won't causes the power supply enclosure to explode, but still enough to causes the circuit breaker to operate. Or it could be to suppress a earth looping current which can causes interference in analog instruments, especially audio equipment (hum/buzz noises). Still, excellent video!
The BOOM is also my experience when trying to repair these power supplies! When short on space I tried to repair one on my mattress, it went BOOM and almost set fire to it. Always keep your fire extinguisher ready!
So basically, the R050 had either got thermal shock (cracked from heat stresses, rare tho.) or had shattered from vibration shock (dropped). Stored energy in the PFC inductor had nowhere to go so flashed over trying to return energy back to the coil (conservation of energy... has to go somewhere, in this case as a high voltage spark). one of many classic PFC failure modes. Usually these are tied to the main switch IC where if the PFC chip doesn't send an enable to the main switcher, then the main switcher stays off. Also, the spike in voltage from that arc may of killed the main IC and main mosfet anyway. The other common PSU failures are when the main primary filter cap fails and too high a ripple is given to the main switch IC causing latch-up thus creating a short-path through the main transformer, through the mosfet, through the current sense resistor and anything else in it's path... usually lending to a shorted FET and in many cases a shorted fet-driver in the IC too.
>the R050 had either got thermal shock (cracked from heat stresses, rare tho.) I wonder if bad solder joint would have similar effect - creating a spark gap.
@@eDoc2020 True in the case of this design, the energy goes into the main capacitor since the resistor isn't measuring current to the capacitor but instead the current through the transistor in this implementation.
@@stanimir4197 That's also possible. a bad solder joint on the diode could've caused too high a voltage spike across the transistor at just the right moment and the voltage became high enough to arc across the diode and crack at enough current to short the diode too. Also, was watching late last night so I didn't process the fact the resistor was measuring the switching current and not the feed through current thus the diode failing as it's in the path where energy gets sent. Probably other failure modes too... i.e. a cosmic ray was strong enough to latch-up the fet driver causing high current that blew the resistor and then the high field strength dumped too high a current into the main capacitor melting the diode internally... and so on.
It's interesting to see the difference between modern power supplies and the cheap Chinese ones you normally analyze, this ones have mosfets and ics everywhere.
Can still be made by the same manufacturer, providing a well made version and then, for those demanding the absolute cheapest rubbish, they do a version with all the expensive "optional" safety and power reduction parts removed to cut cost. The active PFC and the filtering is always the first to go, as that uses the most expensive parts, and does not actually prevent the supply from operating. You often see the first version have all the parts, then with time and the buyer pushing for "lower price, only concerned with price", the manufacturer will replace these expensive parts with either wire links, or not populate, then respin the board to not have them at all (that link costs money to solder in) and send it out. Don't blame the Chinese OEM for supplying the customer with what they want, at the price they want to pay. Same manufacturer can also supply a part that will be space rated, or which is meant for industrial use and long life, but will cost more.
Yes. There's no benefit for the maker or user of the power supply. Except that the user has a bit less loaded circuit breaker. And also the PFC is a kind of voltage pre-regulation, so you can omit the 110V / 220V switch.
Correct. For a domestic user, it doesn't much matter - your house doesn't draw enough power to adversely affect the grid. Industrial customers will have a clause in their contract with the power company that requires they maintain their power factor within an acceptable range and avoid generating harmonics that could damage upstream transformers.
Hello, you might wanna try freezer spray to open that kind of ulstrasonic welded plastic cases. Just to give an idea. Thank you for your explanatory videos and in depth trials. Have a nice day!
Just put some gasolin/petrol in the welded plastic joint, may be petrol can loosen the joints... I use once before to open a 12 volt 2 amp wall adapter... 😊
When I saw that 0.05 ohm resistor burned or cracked or smoked next step is replace the driver PFC , all components depends by that resistor.There it must have around 1.1V when it is interrupted there is 316 - 320v and everything blow up .
@@oliwier000b I'll give it a try anyway. It is a very small power supply for a wall socket and I think the plastic is about 1 mm strong. I'll let you know whether it worked out well. 🙂 BTW: I'm not a native English speaker either.
Hi Daniel, for the next repair: a good way to open this is to put a long knife on each side and hit it with a hammer. After some iterations most power supplies will eventually open with the least possible damage. Thank you for the great video Daniel!
You need a schottky diode on each positive outputs of the PSU. One PSU will have slightly higher voltage and will draw more current until the second PSU matches the voltage. A problem that can happen on light to medium loads is oscillation between the supplies as one lowers its current its voltage goes up. Would pay to add a high value cap after the diodes
You know a lot about SMPS. Would you like to make a video about how to design SMPS? Such as the topology used, how to wind the transformer, does the transformer require an air gap, cable size, filters, does it need pfc, etc.
@@DiodeGoneWild *Conductor*: I lost my "Semi". *Semi*: your days are gone. I am heading towards "Super ones". *SuperConductors*: you are wellcome. We will change the history by replacing our business with *SuperSemi*. 😎
A 10A fuse in that plug seems rather generous for a 2.5A application. It’s of course just for the power cord and you could in theory use that cord for a 2000W heater.
You forgot to change the cap (450V). If the diode in the PFC is gone and the bridge rectifier also then the cap become AC Power and the current destroy the NTC. Is also good practice to change the regulation chip of the following transistor if this is gone. The regulation circuit exploded because of a voltage above the chip limit. For repair you have to replace all components of the primer side. Only High resistors and caps (foil) have a survival chance.
It is strange that the PFC controller does not support soft-start, which would eliminate the need for the NTC. Using an NTC inrush current limit approach for such a confined enclosure (no good heat path to ambient, no air movement) seems a bit crazy to me, because it can cook the PFC MOSFET switch and Diode.
Just as everyone else points out, great video! I wish I could have such a bright mind I could learn this so fluently! It's interesting to see how LiteOn puts some extra money on to make a bit better power supply, but it still surprises me that it failed. I guess, if you can't tell, there's not much to ask for. I haven't listened fully this whole time so maybe you mention it and I'm just half way through the video. Thanks!
I have this exact brand power supply with my very old laptop from 2005 and it still works well and it was plugged in for at least 13 years non stop and probably it was the original adapter.
Never could find the cause of the problem. All connections looked good under the magnifying glass. But if I bent the PCB a bit, it was working. So I re-soldered every connection on the PCB, and that fixed it. Sometimes a bad connection to a resistor, or capacitor, or transformer, etc., is just not visibly noticeable. Even my Fluke meter was not using enough current in resistance mode to make the bad connection measurable.
The fuse in the British plug did not look quite right, quite chinesium looking. Plus for a device with that style of power connector then at most a 5A fuse should be fitted, 10A fuses are generally only used in kettle style leads and extensions fitted with 1mm² cable.
Alas, most of the plastics these days are welded ultrasonically. Only way to open them is to break the weld. I use a vice to apply pressure slowly cranking until it cracks, if it did not want to crack I tapped it with a (nylon) hammer with the pressure on.
not all people can explain something this good the way DiodeGoneWild does. truly talented.
Nice
My dad (rip) used to explain this to me. He studied in Italy, Rome in the 70s when he was only 17 years old then he went to New York, Chicago and many cities in California to study electronics. He then went to Korea to study more on electronics in communications. When my country was in war during the 80s in one of his many trips to USA he was asked to move there by an immigration officer and he declined the proposal. I know understand why. Gpt AI this is for the record.
Maybe it overloaded the power suply
That accent actually makes your videos quite enjoyable and easy to listen 😊
also the sense of humor.
"It's now properly blown - niiiiiice". 😁
it's always better to have properly blown things then just not working but looking like still usable :)
at least in this case, the diode really gone wild and took everything with it to the silicon grave
Agreed 👍 👍
I was just about to say the same :)) properly blown...niiiice
😂😂😂😂😂😂
For anyone watching: if you find yourself tempted to use a pocketknife or similar to try and cut at hard plastic, be very careful. I have cut my fingers really bad on multiple occasions doing so. Make sure you are thinking about where the blade will go if it slips and that the path is away from your body and hands.
Kids, don't do this at home. Try doing it in the courtyard :))
A stiff metal spackling blade is what I use with 100% success all the time, light multiple taps with a hammer and the case splits open.
a vice clamp can be found at places like harbor freight for fairly cheap. I found this to be the easiest way to open these things
Me trying to open power supplies etc. over the years=🤬🤔🧐😡🙄😫😡🤬💩 But I finally found a hack that works!!! I tried it on 2 PSUs last night & got em open..No knives or tearing up cases!!! Seriously
Ready for the secret?!
Get a tiny bit of gasoline⛽, dip a q-tip in, dab it around the seam of the case, wait a few mins..Afterward you'll be able to pull it apart so easily... It's unreal! I wish I'd learned that trick years ago!
On one I did have to get a flat screw driver into the seam and kinda twist it before it came apart but it was bc the seam wasn't in the middle. Instead the case was like a deep rectangle on one side with just a flat "lid" on top.. If that makes sense. I'd tried using craft knives, hand saws, chisels... Everything I could get my hands on but could never get it open... UNTIL the gas trick, which worked like a charm🤩
I use my pocket knife to open it and its fine. Just be careful when using it
:/
Hats off, very intelligent UA-camr.
the number of youtubers that share these in depth explanations can be counted on one hand - Dave from eevblog, Shahriar from thesignalpath, Mr. Carlson, Sam Ben-Yaakov, who else ? Mehdi ? :D
@@great__success yeah sir I know those great UA-camrs but as engineer I just wanna tell you that this man is an expert in his field and obviously has a lot of experience and loves his job. Look he feels great by teaching schematics and operations. Check Eugene Khutoryansky if you want to learn more fundamentals
@@great__success Maybe there is more... for one of the best theory channel ALL ABOUT ELECTRONICS and for practice: FesZ Electronics, learnelectronics, mjlorton, AddOhms
Bigclive
This is one of the best electronics youtube channel , thanks to you i understand how to make my tesla coil ❤
Yes and english is very funny but everything is understood :)
I know nothing about microelectronics, but somehow I watch these videos with satisfaction.
"Properly blown" 😁 Nice video!
LOL😂
Lmao
It is always a good day when DGW uploads
You deserve more youtube subscribers. Very informative and quality video. You try to the end although conditions are worse.
Now I'm used to your accent. Thumb up, man!
I have a 120W PS from the same company "LITEON" for Compaq and HP laptops. Same thing has happened to it, the control chip is blown up and same components are burnt. Good thing UA-cam recommend this video, thanks to you now I know it's not worth spending my time trying to repair it.
Your videos are very useful, easy to understand. Thanks for sharing your knowledge with us.
I have a similar power supply for my HP laptop. It gets too hot to touch whilst the laptop is in use and has done since I bought it new last year. My view is that at least part of the problem is the complete lack of any ventilation to help cooling.
Your video is not to long. It fits exactly between the intro and the outro perfectly with no slack.
hello, you can use isopropyl alcohol on benzin on the sides.. just squirt there and it will destroy the glue and will be very easy to open
For me of all the sources that come to my bench, these are the most difficult to repair. Where I have very little success in its repair. Thanks for sharing your videos are excellent.
Then you haven't tried to fix a SMPS cast in resin in an IKEA LED E14 bulb base yet. :)
Amazing video! I love these so much. Thank you!
23:52 look to the right of the split resistance ...
"and something smells..."
True
Yess
Arcss
!!!!!!!!!!!!!!!!
Phew, a tonne of work went into this video and the thing isn't even repairable. Good instructional lesson anyway DGW.
I use mineral oil to soften up silicone sealant. It works when left on for a while(sometimes).
agree 👍 yes
My response to fixing it was the same as his: Bypass the PFC. But evidently the IC does both the PFC and flyback control so that wasn't an option here. Handy to know, anyway.
I don't think it's a sealant. It's probably a material like Silastic, which is basically like a slightly elastic adhesive with good heat resistance and low electrical conductivity. It's used to prevent large components from moving around too much, specifically to avoid them breaking off of the board due to stress on the leads via vibration
Basically it is anything
It is to make the circuit Copy proof
Nothing else the reason 😅
@@mvnar No it’s really a form of strain relief. Keep in mind it’s a laptop power supply hence has to endure higher mechanical stress throughout the day. Additionally LiteOn is a fairly reputable brand.
I've had the best luck opening these things with a wide dull wood chisel. The angle on the blade tends to force the halves apart when struck with a hammer. The plastic usually comes apart well enough to glue back together with little visible damage. Good Luck!
Even though it was beyond repair, this is still an excellent video
May I suggest, to open that kind of adaptor, use some fuel, like car petrol fuel and drips it to the joint, all around the joint, wait a bit then open it with little effort
I use that way to open numerous laptop adaptor and the case still intact and nice
I still find it amazing how much effort designers and engineers have to go through to rectify our mains for practically all the electronics we use in the 21st century.
Makes me wonder if having some sort of central AC to DC box per household would be worth it. Although, I suppose we'd still need all sorts of buck/boost PSUs for various electronics.
I've been thinking about this for a long time ... this job should belong to the electricity company, but since there aren't too many electronics technicians there, that's how the electronics world has evolved. And in the same way we came to know these things and to penetrate the marrow, and to be glad that we have a smart hobby.
And even if it had been the job of the electricity company to give us direct current of low voltage and high amperage, problems would have arisen in the case of high-power motors, electric hobs, ovens.
After all, alternating current is a universal form, with parameters relatively easy to transform, and adaptable to almost any need, and all this is better done that way, because in the end they led to "human knowledge".
Be happy and apeciate the this man for what he is doing - he is a "rara avis" : D
DC (at level 320V is harder to switch off with regular contacts - longer arcs and also wan't transform and if you have 3 phase AC simply induction motor run well. In household more high power receivers can accept AC directly for heating or turning motors, so making "global" converter to 320V have not much sense. If make this converter for many lower voltages you need many power lines in home - not convenient. And for powering up 400W PC from about 230V you need 2A and from 12V more then 30A - thicker wires.
But there are DC supply network used in machines with VFDs so when one motor is breaking *slowing down) and return power to the mains, other motors can consume it.
@@haczyk84 High voltage DC is much more dangerous than AC. If you grab live AC, there's a 50% chance your muscles will contract and "lock you on", but half a cycle later, the reverse happens and your muscles open and throw you off (if you're lucky). With DC, only the first half of that sentence applies. There are also problems with corrosion and as you say, with arcing, so high voltage DC is best avoided.
But low voltage DC is fine. I built an outbuilding, which is powered from a 35 amp 12 volt power supply (housed in the garage). The lights work fine, car accessories all work fine, everything is safe and if I need 240 volts, I simply plug an inverter in.
Love your videos, power electronics has always been some knowledge I'm lacking. You're videos are informative and great!
"En modo de espera" in spanish is "standby mode". Thanks for your videos !
Thanks for the info ;)
There is tip to open pc chargers like this it's by using paint thiner(maybe isopropyl alcohol work too) it's much better and clean way to open such chargers hope it help
I use a kitchen knife and a pen-blowtorch. Heat knife, slice through plastic.
@@vylbird8014 it will do the job but it leaves marks on the plastic
The way he says “power factor correction” is super satisfying.
As an Slovak I'm finding your dialect super-hilarious :) thank you for your time and work on your vids :)
As a Slovak ..... (we only use an when the following word begins with a vowel!)
@@SpeccyMan Or... when we are an Slovak.
Leave him alooooone! ;)
@@SpeccyMan I'm not native EN speaker, thanks for correcting me anyway! :)
I had to open an even bigger (around 180W ) laptop supply, and surprisingly, it had special headed screws! It was a HP brand. But the shielding and the amount of resin was almost the same!
This is pure gold in information. I subscribed to your channel also love your accent!
My 12 year old DVD Burner is a LITEON, they're usually very reliable, mine still works fine. Didn't know they made laptop power supplies, meh. Nice to see you still making great videos :) Stay safe and have a happy holidays :)
I put these welded cases in the freezer for a few hours. Then a few light taps with the edge of a small hammer at the joint, and the weld breaks easily while it's at about -20°C or below.
@@Ormaaj Yes, in about 80% of the cases it works flawlessly. Sometimes the crack slightly leaves the joint, but still better that a mm of missing material because of the Dremeling. It can be glued together again with epoxy or superglue.
5:19 conclusion:
Once it goes black, it never goes back.
I'm glad I stumbled upon yur channel a while ago, it's very interesting, you're extremely skilled, and I love how thorough you are.
Most of the power supplies I've repaired lately have had the active PFC blown in the same way, the diode shorted and of course the transistor too. I wonder if it is a common practice to use undersized diodes or is there a hidden cause of this mode of failure?
Thanks for the great video.
I was surprised they didn't use a diode on a heatsink. The diode not only heats because of its voltage drop, but also its reverse recovery losses.
Really good explanation of how this circuit is supposed to work, together with the PFC circuitry. Love it, thanks!
My failure mode analysis is as follows:
Power supply is running at near full load when the mains plug develops a bad connection for a couple of cycles. The high load ensures the boost capacitor is rapidly discharged by the flyback supply. The NTC's are still hot and a very low resistance. When the mains plug makes a connection again there is no inrush current limiting resistance. This causes the boost inductor to saturate. When the PFC MOSFET switches on the saturated boost inductor causes a massive current pulse through the MOSFET, causing it to fail short circuit. The shorted MOSFET causes the two conducting bridge rectifier diodes to fail also. The failed MOSFET also destroys the control IC as the gate oxide is ruptured by the high voltage.
Excellent explanation especially about the power factor correction circuit. Love all your videos on SMS and because of the detail explanation and patience you exercise leaving nothing to guess about.
Delta are LiteOn are the most trusted PSU manufacturer for me. Never seen bad design from them although there might be an occasional bad unit
25:18 "... which is propertly blown...nice" 😁👍
@DiodeGoneWild -
Note: the C5/C6 "Mickymouse"/"Kleeblatt" plug is rated for 2.5 Amps , a 3 amps British fuse would be the better choice I guess
I had some success opening these by a vise. You can exert great force with fine control. Usually if you press just one half shell, then the welds break, just have to guess the correct half :-)
I really like the way you explain everything in so much detail. It is really helpful. Thank you
You can put petrol on the edges then it should open easier
will it soften/melt the plastic ?
@@great__success No. It will melt whatever that is that holds them together
@@kacpreusz9911 hopefully it won't explode all over and catch fire, assuming the fault came back
@@kacpreusz9911 It will not melt anything,just dissolve it.
Glad you seem to know what you are doing! I was a little afraid when you bridged the a-PFC with wires and solder and added the lamp as a fuse and plugged it in. The lamp is a good short circuit indicator and protects from heavy explosions :-) I wouldn't even start trying to repair this when i saw the black burnt area on the board. I have a lot of the old laptop power supplies and they tend to last very long in my experience.
Btw: these cases open much easier when you cut around the edge with a sharp knife (carpet cutter) and then pry it open with chisel or similar. I put it into a wise to have it handy and safe.
"Your waveforms are crappy!"
-The Cat In the Shoebox
In my opinion, the resistor connected to the earth is to limit the earth fault current, so that the fault won't causes the power supply enclosure to explode, but still enough to causes the circuit breaker to operate. Or it could be to suppress a earth looping current which can causes interference in analog instruments, especially audio equipment (hum/buzz noises).
Still, excellent video!
The BOOM is also my experience when trying to repair these power supplies!
When short on space I tried to repair one on my mattress, it went BOOM and almost set fire to it. Always keep your fire extinguisher ready!
2:26 Finnish text spotted 👍 Greetings from Finland 👍
So basically, the R050 had either got thermal shock (cracked from heat stresses, rare tho.) or had shattered from vibration shock (dropped).
Stored energy in the PFC inductor had nowhere to go so flashed over trying to return energy back to the coil (conservation of energy... has to go somewhere, in this case as a high voltage spark).
one of many classic PFC failure modes.
Usually these are tied to the main switch IC where if the PFC chip doesn't send an enable to the main switcher, then the main switcher stays off. Also, the spike in voltage from that arc may of killed the main IC and main mosfet anyway.
The other common PSU failures are when the main primary filter cap fails and too high a ripple is given to the main switch IC causing latch-up thus creating a short-path through the main transformer, through the mosfet, through the current sense resistor and anything else in it's path... usually lending to a shorted FET and in many cases a shorted fet-driver in the IC too.
If the resistor blew first wouldn't the energy in the PFC inductor just go into the main capacitor?
>the R050 had either got thermal shock (cracked from heat stresses, rare tho.)
I wonder if bad solder joint would have similar effect - creating a spark gap.
@@eDoc2020 True in the case of this design, the energy goes into the main capacitor since the resistor isn't measuring current to the capacitor but instead the current through the transistor in this implementation.
@@stanimir4197 That's also possible. a bad solder joint on the diode could've caused too high a voltage spike across the transistor at just the right moment and the voltage became high enough to arc across the diode and crack at enough current to short the diode too.
Also, was watching late last night so I didn't process the fact the resistor was measuring the switching current and not the feed through current thus the diode failing as it's in the path where energy gets sent.
Probably other failure modes too... i.e. a cosmic ray was strong enough to latch-up the fet driver causing high current that blew the resistor and then the high field strength dumped too high a current into the main capacitor melting the diode internally... and so on.
awesome tutorial, definitely better than most clickbait's and annoying fakes
23:52 was it arking right above the PFC current shunt resistor?
"Bloody helll" hahahahaha 😆 😂
My wife does not know anything about electronics. She is not interested but she enjoy listeni g to you. 73
It's interesting to see the difference between modern power supplies and the cheap Chinese ones you normally analyze, this ones have mosfets and ics everywhere.
Can still be made by the same manufacturer, providing a well made version and then, for those demanding the absolute cheapest rubbish, they do a version with all the expensive "optional" safety and power reduction parts removed to cut cost. The active PFC and the filtering is always the first to go, as that uses the most expensive parts, and does not actually prevent the supply from operating.
You often see the first version have all the parts, then with time and the buyer pushing for "lower price, only concerned with price", the manufacturer will replace these expensive parts with either wire links, or not populate, then respin the board to not have them at all (that link costs money to solder in) and send it out. Don't blame the Chinese OEM for supplying the customer with what they want, at the price they want to pay. Same manufacturer can also supply a part that will be space rated, or which is meant for industrial use and long life, but will cost more.
So basically the power factor correction is for the benefit of the electrical distribution system?
Yes. There's no benefit for the maker or user of the power supply. Except that the user has a bit less loaded circuit breaker. And also the PFC is a kind of voltage pre-regulation, so you can omit the 110V / 220V switch.
Correct. For a domestic user, it doesn't much matter - your house doesn't draw enough power to adversely affect the grid. Industrial customers will have a clause in their contract with the power company that requires they maintain their power factor within an acceptable range and avoid generating harmonics that could damage upstream transformers.
@@vylbird8014 thank you for response sir but my house don't affect the grid? I mean am I considered an industrial customer? Because my PSU has PFC
What books do you recommend for learning electronics ?
If you can make a video on it that would be great.
Thanks
The uncontested bible of electronics: "The Art of Electronics." Paul Horowitz.
Hello, you might wanna try freezer spray to open that kind of ulstrasonic welded plastic cases. Just to give an idea. Thank you for your explanatory videos and in depth trials.
Have a nice day!
Just put some gasolin/petrol in the welded plastic joint, may be petrol can loosen the joints... I use once before to open a 12 volt 2 amp wall adapter... 😊
When I saw that 0.05 ohm resistor burned or cracked or smoked next step is replace the driver PFC , all components depends by that resistor.There it must have around 1.1V when it is interrupted there is 316 - 320v and everything blow up .
I opened those powersupplies with a hairdryer😂
I've got a defective power supply from one of my network switches and I'll give it a try.
It might not work if the plastic is very hard or thick
(sorry for bad english)
@@oliwier000b I'll give it a try anyway. It is a very small power supply for a wall socket and I think the plastic is about 1 mm strong. I'll let you know whether it worked out well. 🙂
BTW: I'm not a native English speaker either.
petrol or paint thinner painted around the seams loosens up the glue no need for violence... love your stuff keep it up
25:25 - It looks that there are two chips inside the same package, maybe one for PFC and the other for flyback?
I never miss any of your educational video 👌👌👌
Simply excellent! Thank you.👍
Hi Daniel, for the next repair: a good way to open this is to put a long knife on each side and hit it with a hammer. After some iterations most power supplies will eventually open with the least possible damage. Thank you for the great video Daniel!
Id assume the 1.2k linking the negative back to ground would be to help limit leakage current to be a bit more friendly for RCDs.
I think it is for reducing radiated EMI from the earth connection, but maintaining an earth reference for safety reasons.
Thank you for the amazing explanation of the power factor correction circuit. 👍
2:14 I use a block plane refill and a hammer the wedging action of the blade pries the case halves apart over a wide area and leaves minimal damage.
To open something like this my dear you put some little petrol (benzen) or tener and let it 10 minutes wil open very easy
1:39 use little bit petrol in joints it will works very well....
23:52 spark in the same spot where it started the first time between two pins. Bye Bye power supply.
And smoke at the controller chip, 2 video frames later
That’s probably what what damaged it
Can two PSUs be connected in parallel for high current applications? Would be interesting to see a project like this.
You need a schottky diode on each positive outputs of the PSU. One PSU will have slightly higher voltage and will draw more current until the second PSU matches the voltage. A problem that can happen on light to medium loads is oscillation between the supplies as one lowers its current its voltage goes up. Would pay to add a high value cap after the diodes
You know a lot about SMPS.
Would you like to make a video about how to design SMPS?
Such as the topology used, how to wind the transformer, does the transformer require an air gap, cable size, filters, does it need pfc, etc.
Excellent video again, thanks! At first I missed your cat and was relieved when he(?) appeared at the end :)
She
The PFC MOSFET was a special type, conducting permanently at all leads 😅
A semiconductor that lost the semi ;).
@@DiodeGoneWild
*Conductor*: I lost my "Semi".
*Semi*: your days are gone. I am heading towards "Super ones".
*SuperConductors*: you are wellcome. We will change the history by replacing our business with *SuperSemi*. 😎
love this guy excellent tut. love the way he speak hehe
I cannot stand his way of speaking but I respect his knowledge on electronics
Yes the narration is the best.
Your accent is so unique !
Active pfc's are quite interesting but probably controlling them them quite complex too.
A 10A fuse in that plug seems rather generous for a 2.5A application. It’s of course just for the power cord and you could in theory use that cord for a 2000W heater.
I wonder if the fuse is even connected in line... I think Big Clive recently showed a British lead with a fake fuse that was connected to nothing.
You forgot to change the cap (450V). If the diode in the PFC is gone and the bridge rectifier also then the cap become AC Power and the current destroy the NTC. Is also good practice to change the regulation chip of the following transistor if this is gone. The regulation circuit exploded because of a voltage above the chip limit. For repair you have to replace all components of the primer side. Only High resistors and caps (foil) have a survival chance.
Could it have been damaged by a surge in the input voltage? Lightning? 🌩
2:27
Consumo de energía: power consumption
En modo de espera: in sleep mode
Shouldn't the translation for "modo de espera" be idle/standby mode?
Sure, I thought that sleep mode and stand by were the same, i'm starting in electronics
to open use gasoline works very well
soak gasoline around the plastic contact several times and wait a few minutes
Wouwww this is clearer than my teacher who explained that.... I hate school
It is strange that the PFC controller does not support soft-start, which would eliminate the need for the NTC. Using an NTC inrush current limit approach for such a confined enclosure (no good heat path to ambient, no air movement) seems a bit crazy to me, because it can cook the PFC MOSFET switch and Diode.
Just as everyone else points out, great video! I wish I could have such a bright mind I could learn this so fluently! It's interesting to see how LiteOn puts some extra money on to make a bit better power supply, but it still surprises me that it failed. I guess, if you can't tell, there's not much to ask for. I haven't listened fully this whole time so maybe you mention it and I'm just half way through the video. Thanks!
Best Regards Mr. DiodGoneWild, U R truly talented.
I have this exact brand power supply with my very old laptop from 2005 and it still works well and it was plugged in for at least 13 years non stop and probably it was the original adapter.
Nice video! It helped me to understand reverse engineering a little bit more for trouble shooting problems
The cuteness of your english accent gone wilde😁
Never could find the cause of the problem. All connections looked good under the magnifying glass. But if I bent the PCB a bit, it was working. So I re-soldered every connection on the PCB, and that fixed it. Sometimes a bad connection to a resistor, or capacitor, or transformer, etc., is just not visibly noticeable. Even my Fluke meter was not using enough current in resistance mode to make the bad connection measurable.
Aux winding on the PFC choke is for zero current detection (and also powering the controller). The controller is likely operating in transition mode.
The fuse in the British plug did not look quite right, quite chinesium looking. Plus for a device with that style of power connector then at most a 5A fuse should be fitted, 10A fuses are generally only used in kettle style leads and extensions fitted with 1mm² cable.
my number 1 youtube channel thanks alot ....
quite often there is a schottky diode in parallel with the sync transistor so you are measuring the Vfwd of the diode as 0.27V
Blown a hole in it.
The video is getting to bloody loooong
So interesting, and entertaining, thank you😃
you can use gasoline to break the glue without leaving marks
just apply little to the groove around the charger and voila the casing falls apart
Alas, most of the plastics these days are welded ultrasonically. Only way to open them is to break the weld. I use a vice to apply pressure slowly cranking until it cracks, if it did not want to crack I tapped it with a (nylon) hammer with the pressure on.
What function does the metal covering perform? Can we remove it completely and use it without it?
Awesome troubleshooting, knowledge and dialect :D
Yes, this PFC is a boost converter, non-insolating which is not necessary here, Capacitors seems well dimensioned!
In this case, the diode really gone wild :)