Previously I have never heard of the "trick" to heat up dry capacitors to get circuits to work temporarily again, very useful!

@DonkeyLearningIT

5 жыл бұрын

It is a highly typical naughty little trick in PSU repair. However, it *should not be done* on bulging capacitors due to the risk of them bursting! Practically the electrochemistry inside the cap will come alive after the electrolyte is heated up, temporarily reducing the equivalent series resistance of the capacitor. Also, the electrolyte will become more fluid, so the capacity will be partially restored until the cap cools down again.

@mrgreenswelding2853

5 жыл бұрын

@@DonkeyLearningIT so tell if this is right, heating up the caps to work again should isolate the problem to the caps?

@DonkeyLearningIT

5 жыл бұрын

Well, if you heat up the caps (take care to use low heat, so you can also use a hair dryer) and the unit works if you plug it back in, that is about 90% of the time dry capacitor. In the 10% of the time it might be a dry solder joint, which after heating up also makes temporarily a connection, since the solder will thermally expand, temporarily fixing a bad joint.

@mrgreenswelding2853

5 жыл бұрын

@@DonkeyLearningIT i first thought dry solder joints. Thanks for the info.

@DonkeyLearningIT

5 жыл бұрын

Just let me know whether hair-drying the board makes it turn on! I am interested in success stories ;)

I have to say that i have great respect for people like you that take their time to teach interesting stuff Thanks for your videos that are always interesting to watch

one of the best SMPS explanations in detail I have seen so far, (although I did not understand everything, being a noob).. way to go !!!

@DonkeyLearningIT

5 жыл бұрын

Thanks for the comment. I tried to explain things as good as I can, and also try to keep the video below 30 minutes. I hope that people will learn from the info presented here.

@parapos

5 жыл бұрын

don't worry, we are learning a LOT from your videos, even if we don't understand every little detail...(yet...lol). I personally like the extra explanation of a component and what their surrounding components do. again, good work!!!

@DonkeyLearningIT

5 жыл бұрын

@@parapos I'm glad that the video was helpful even if it was probably way too detailed for some viewers. In the future I will make more videos so it becomes clear to people who subscribe and watch the videos what is inside an SMPS and how to repair it.

@cwieok

5 жыл бұрын

Agree, it is really great, now i can understand smps. THANK YOU!

@DonkeyLearningIT

5 жыл бұрын

@@cwieok Thanks for watching the video. I am glad if people learn something from the content.

Great video as usual, love the combination of seeing what the parts look like in the real world, coupled with the explanation of how they fit into the overall circuit!

What a wonderful explanation you gave. Great breakdown of each components function and roles they play in the circuit. Thankyou for this!

I love your SMPS repair series!!!

That is a very concise and detailed, component by component walk thru of a SMPS. Your methodical and even tone make following the logic very easy. I like your videos and hope you do keep doing similar ones. Thanks for taking the time.

@DonkeyLearningIT

5 жыл бұрын

Thanks for writing this comment! Also constructive criticism helps, but positive feedback is always welcome ;) Regarding the even tone, I am afraid that for most people it makes the video boring. Those videos are doing good on KZread where people are overacting, like ElectroBoom. I am not that kind of person, so even if my videos might be boring, at least I try to make them informative/educational.

@garybevis8691

5 жыл бұрын

@@DonkeyLearningIT Yes, sadly the youtube audience is awash in simple minded folk seeking only to be entertained. It is the most banal and inane youtubers who mostly have the millions of views. There are some of us who seek knowledge and informative lectures, discussions and tutorials. Sad that everything has to be monetized to supposedly have any value.

Thank you for making these videos. You speak at a really nice speed and tone. Keep up the good work! Greetings from Sweden. =)

@DonkeyLearningIT

5 жыл бұрын

Thanks for the positive feedback! Now I have finished most of the moving to my new apartment, so hopefully I will have time to sit down and make new videos again.

@Kaxlon

5 жыл бұрын

@@DonkeyLearningIT Sounds great! =)

I really appreciate this video of yours.....to reverse engineer this power supply is a very tedious job.... but for your viewers you did it.....i must say although i did not understand fully the working of the power supply still it is very knowledge full.....

@DonkeyLearningIT

5 жыл бұрын

Luckily the PSU is built mostly around the typical circuit suggested by the manufacturer, so it was easy.

@annyan904

5 жыл бұрын

Donkey Learning IT hats off you understood this circuit.....its really complicated for me

Keep up the great work on producing your educational and repair videos. A lot of people are starting to watch these sort of videos now. Don't be afraid of the length being longer than 30 mins if it is the same topic, or if it is very long break it into useful parts. Most importantly keep creating more great content like you have been.

@DonkeyLearningIT

5 жыл бұрын

Thanks for the positive feedback. Regarding the video length, if possible I would like to keep them shorter since the time of the people is very finite. However, when it comes to educational content, I just do not see the point to publish 5 minute "daily vlog" videos either. Due to the laws and regulations in the EU (Article 11 and 13), now I will be forced to monetize the channel starting next month. Most likely this will encourage me to create and upload videos more regularly, otherwise I am going down the drain financially. It is sad that even things which should be just a hobby have to be shifted towards monetization and taxes etc.

I didn’t watch the video yet, but I want to thank you first because I know it will be full of knowledge. Thank you from Iraq

@DonkeyLearningIT

5 жыл бұрын

Thanks for the comment. Watch the video and let me know whether it was OK, or you expected more!

Very high quality explaining - loved so much - Thank You, sir

@DonkeyLearningIT

5 жыл бұрын

I tried to cram it all into 30 minutes, so it could have been better. Though, giving too much details might be boring to some people.

@TheJavaSync

5 жыл бұрын

yeahh .. I know, but You explain It whole things - even for replacing output caos - so many thing I learn from You - Thank You :) & still right here waiting for another vids

@DonkeyLearningIT

5 жыл бұрын

@@TheJavaSyncIf all goes right, this weekend I should upload the follow-up video on the error amplifier and feedback loop. Stay tuned!

I really love SMPS series! Tell us more about yourself!

Very good and useful video. Really appreciate this video. Thank you!

A superb video. I’m really looking forward to your video on PFC.

@DonkeyLearningIT

5 жыл бұрын

I had no time to produce videos, and had problems in the family. Hopefully now I will have more time in the future.

You really know your stuff....the way you moved about explaining what each component is doing...

@DonkeyLearningIT

5 жыл бұрын

Many thanks for the positive comment! I try to make good explanations instead of flashy videos with loud techno music. Those videos would get more views, but the informative value would be a lot lower.

Very good video, I love it. Thanks so much. Greetings from Norway.

The copper strip around the transformer is known as a belly band. As you mentioned, it forms a single turn transformer shorting out stray magnetic field and also aids in cooling.

Hello, I recently subscribed here. They are Very helpful and good videos. Thank you very much for sharing your valuable knowledge with others. in good way of speaking : realy clear to understand. Thank you and good Job, dude.

Woah much more of a quality content Very much appreciated Please post the active PFC video soon sir Take care of your health inspite bad weather

I wondered why the heating of electrolytics would make them temporarily work again. However, you explained this in your written notes, the fact that the heat (temporarily) reduces the ESR value of the Electrolytic Cap. Just like many people who watch and learn from your informative vids, it seems almost 'impossible' to follow your teachings - due to the fact that many of us never even went to college / university to study electronics formally. Sometimes, the PCB may indicate a fault, such as a bulging Cap or dry joint, particularly around Electrolytics that seem to expand and contract with use. In many cases of SMPS Power Supplies, the Electrolytic Caps appear to have a limited life - when directly compared to the other components on the SMPS PCB. I have recovered some beautiful Scrap LCD TV's from the Scrapheap, and simply changed-out all of the Electrolytic Caps, and then Bingo, you have a fully-working TV for the cost of a few quality Caps! I always replace these Caps with like-for-like, and try to use quality Caps, like Nichicon, and always 105C rating. Perhaps it would be really good to focus on the Electrolytic Caps - and their Life Expectancy in one of your Vids. I have read that (even the very best quality Electrolytics) may only have a life expectancy of 2000 hours. Cheaper Caps may fail in much less usage. I think that it is important to drive this point home to many of your followers. I am an avid follower of your productions, and you seem to leave no stone unturned. Congratulations and thanks from Australia.

@DonkeyLearningIT

5 жыл бұрын

I have to agree with you that most SMPS failures are caused by capacitors. In fact, even on SMD boards the filter capacitors might often fail, causing similar problems. In the case of the SMD caps there is no indication from the outside that they might have issues, but with time those SMD caps can be gone as well. Sometimes they will just short on some low voltage line (like 1.8V for the CPU or similar). Greetings from Austria, where there are no kangaroos ;)

Love this as it's so detailed as it always is :)

@DonkeyLearningIT

5 жыл бұрын

I try to make some half-decent videos, but even so it is tough to fit something in 30 minutes.

@AliensInc.

5 жыл бұрын

Wonder, is the 30 minutes a rule for you personally?

@DonkeyLearningIT

5 жыл бұрын

@@AliensInc.No, not at all. However, people want entertainment instead of education from KZread. Therefore, they often will not watch a 30 minute video, but instead watch two 15 minute videos where cats are playing the piano.

@AliensInc.

5 жыл бұрын

OK, if I'm interested in something I sure can watch a 2 hour movie and I sure have, but I get your thoughts

Its not boring for us when you repair the psu

@DonkeyLearningIT

5 жыл бұрын

Some people commented that they would prefer short videos with more action, less explanation. It is really hard to guess what type of video to upload to please most people.

Nice and well explained. Thank you very much!

@DonkeyLearningIT

4 жыл бұрын

Thanks for the nice comment!

oh very nice video ,thank you. ,I have seen all your PSU videos but really like this practical repairs with explanation and schematics , It would be great if you can also show the actual measurements with multimeter step by step troubleshooting from main IN-put to output , until you find the actual faulty components and how they were behaving in the closed circuit . (I know the basics of electronics but I always loose track somewhere in the middle of the board..) ..so far I have been successful with only replacement of more obvious failed caps ,fuses,diodes on the more complex switching PSUs

@DonkeyLearningIT

5 жыл бұрын

Thanks for the positive comment! Regarding practical repair, the issue is, that those videos would be awful long, since I would need to film the whole process until I track down the culprit. Of course, one could edit out large portion of it, however than the though process would not be clear. This month I will move to an other apartment, so I will see how much time I will have next month. Who knows, I might produce one of those videos.

wow information packed ! excellent thanks .

@DonkeyLearningIT

5 жыл бұрын

Yep, I tried to put in as much useful info in 30 minutes as I could ;)

Nice explanation 👏

Thank you, thank you, thank you! 🙏🙏🙏

Great explanation. Thanks. Can you please explain the rectifier on the low voltage side? Why do we need two diodes (mbr2545ct)? If it is a half wave rectifier we need only one diode and if it is a full wave rectifier we need four diodes. Right?

Excellent job! "On like Donkey Kong." :-)

@DonkeyLearningIT

5 жыл бұрын

Exactly! I think that most people did not get the reference :-)

Great video, thank you for sharing

@DonkeyLearningIT

5 жыл бұрын

I am glad to be back and making videos again, thanks for the comment!

Very nice video, thank you! The first I watched from you and I've finally learned how pfc works, except that would be even better if signals oscillograms drawn to actually show how pfc injects/recovers energy in phase w/ input AC which would of been lost. Any links you may possibly recommend for pfc details? Also, wanted to ask on how to do diagnostics on properly functioning pfc?

Weather can not stop me this time lol. Wish you good health always sir donkey. Seriusly only health issue stops you from doing video. God speed

@DonkeyLearningIT

5 жыл бұрын

You would not believe it, but it is still snowing and the wind is going crazy outside, so I am glad that I did not wait for better weather. Thanks for the positive wishes, I could definitely use better health as most people. Also wish you good things for this new year!

Love your work. I am having an issue with my 24v 3000w meanwell inverter. Once it turn on it goes directly into overload. I change to input caps then it begin to work then it slowly goes back into overload. Any suggestions?

Best explanation.

@DonkeyLearningIT

5 жыл бұрын

Thanks for the comment. It is a decent video, though I should have probably made it shorter.

Hi, I have a similar SMPS of same make 1100W, -56volt. I want to use it as +54v supply in some project. Do I need to make any changes in the circuit or I just consider GND as positive and -54Volt as GND. Will that work?

Wonderful !!! THANKYOU!

@DonkeyLearningIT

5 жыл бұрын

Thanks for enjoying the video and commenting. See you hopefully in an other video!

Exceptional explanation of how a switching power supply works, the best I found on the web. One question: you praised Cisco's atention to detail when designing this power supply, could be seen on the PCB that is indeed made by Cisco ? I wouod have expected that Cisco is subcontracting the manufacturing and even the design to a specialized company (KingPower or similar) and they just provide this company with a set of specifications. I find hard to believe is a Cisco design.

@DonkeyLearningIT

5 жыл бұрын

Thanks for the positive feedback! When it comes to the PSU, you are right, it is made by LiteOn. However, considering that it is in most Cisco switches, I still call it Cisco part. Though, most likely it was not designed by Cisco engineers. It is a very decent PSU design, especially considering that it is over 14 years old, and that they had to cram all that into a 1U form factor.

I love the accent. Feels like I'm in college. Great video.

Magnificent!!!

The heat for startup has nothing to do with the NTC/relay design they have going on?

Great work. Thanks...

@DonkeyLearningIT

5 жыл бұрын

Thanks for taking your time and watching the video. Hopefully in the future I will be able to upload at least one educational video a week.

@dricklorenz9340

5 жыл бұрын

@@DonkeyLearningIT - Just subscribed so I'm counting on it!

@DonkeyLearningIT

5 жыл бұрын

@@dricklorenz9340I see! So I better deliver ;) Hopefully my health and time will cooperate...

Fantastic thank you very much.

@DonkeyLearningIT

4 жыл бұрын

Many thanks for the comment! I hope that as a viewer one could learn something from the video.

You are PSU God! :)

I have this one exactly. It has no output voltage. Q171 burns repeatedly. Do you have any L170 boost choke's specification?. You have any idea to fix this failure?. Thanks a lot.

Very interesting

is this a way to roughly check for bad capacitors ? How can you explain the Effekt that they work again when heated ?

@DonkeyLearningIT

5 жыл бұрын

It is a quick and easy way to look for dried out old caps. I have already explained in the comment section what heat does, most likely I should make a separate video about it after I move to my new apartment. What happens practically is that the electrolyte thermally expands, and also it becomes more liquid. Due to the increased volume and lower viscosity the equivalent series resistance value of the cap will partially recover.

I liked learning the new trick with the Caps, however watching you desolder and solder isn't boring, that's why I sat through the whole video! Only to be shocked! (Tee hee, see what I did there?), there was no actual footage of the repair! :(

@DonkeyLearningIT

5 жыл бұрын

Well, the issue is, that most people like short videos up to 10 minutes, and this was even so a long video, so I did not dare to make it longer.

What brand of gloves do you wear. Do they provide protection from low voltage electricity?

What is function of second winding T2C which defacto supplies primary side via D12, C12 together with R27, C26. I have similar circuit but more complicated with small switching power supply at AC input side. BTW nice video, thanks.

@DonkeyLearningIT

5 жыл бұрын

I cannot see the video now on my prepaid mobile phone, but once I get internet at my new place I will check the video and let you know.

@tomasmandys6959

5 жыл бұрын

So the reason is that when U1 is not working (Vcc < limit) then supply voltage is via R27/C26. Power consuption is low (e.g. 1mA) so Vcc rises and when greater than threashold then U1 starts and consumption rises (e.g. 15mA). At this point Vcc start lowering as voltage is not hard. So the T2C/D12/C12 provides sufficient "self generated" voltage till U1 is working which is merged with original one.

Fantastic explanation of an SMPS!! I noticed you use gloves. Are those voltage protection gloves? Are they flexible enough to work with. I usually stay away from SMPS repairs due to the bulk caps as I have been bitten a few times. Is there a good method to safely works with bulk caps, like safely discharge them? Thanks once again!! Keep up the good work.

@DonkeyLearningIT

5 жыл бұрын

The gloves you can see in the videos where I talk about the equipment I use. Practically these are soldering gloves, and trust me, they are *awesome* for protecting your hand. When it comes to voltage protection, this type of gloves provide you almost no protection at all. For voltage protection you would need certified rubber gloves, and it is mandatory to use leather gloves on top of those rubber gloves, so in practice one cannot do soldering work in them. However, *before you even think* about repair, you must first make 100% sure that all caps are safely discharged with a resistor first.

THANK YOU MUCH

@DonkeyLearningIT

5 жыл бұрын

You are all welcome! Hopefully I will able to produce and upload at least one video every week.

Can you share the schematic of the smps as you have showed in the video

@DonkeyLearningIT

3 жыл бұрын

I have found it somewhere laying around on the internet from the original IC application datasheet. However, this is not the actual schematic of the SMPS repaired here, it is just similar to it. Sometimes having the original application sheet for the controller IC is good enough.

I noticed that those screws at 8:27 have a dot on them, that means they accept a JIS screwdriver instead of a philips, so if you don't have one, I'd recommend you to buy one so you don't damage them (they actually can accept more torque tan philips with the correct tool), Vessel is a brand that makes good JIS screwdrivers, I work on automotive and I use them on japanese cars, they also fit very well on philips screws.

this is exceptional....

@DonkeyLearningIT

4 жыл бұрын

Thanks for the *exceptional* comment as well ;)

Never seen anyone use a heat gun to check for dry caps .. that is an awesome short-cut for cap testing :)

@DonkeyLearningIT

5 жыл бұрын

I forgot to say in the video, that one can also use a hair dryer set at hot setting. This nice little trick is very helpful when one thinks that the caps might be dried out. The heat will liquefy the old electrolyte, and the cap will temporarily work for a couple minutes. However, one should never do this on bulging caps!

@Tutterzoid

5 жыл бұрын

@@DonkeyLearningIT - :D Was thinking of trying a hair dryer myself :) Thanks for that heads-up :)

@DonkeyLearningIT

5 жыл бұрын

@@TutterzoidWell, if you have a hair dryer, good on you! My hair has mostly fallen out years ago when I was 33, so nowadays I just cut the remainder so short with a machine, that I do barely need hair dryer. Good old days when I still needed a hair dryer and my old pants still did fit me ;)

@Tutterzoid

5 жыл бұрын

@@DonkeyLearningIT - :D Good jokes .. I actually bought a hair dryer back in 1984 for drying out damp tv pcb's of moisture .. and still have it to this day .. and it still works :)

@martinkuliza

2 жыл бұрын

Really ??? that's a very old trick and very well known

adding subtitles helps when viewing the video in a quiet enviroment... . . please include subtitles on all your videos. .. . i am subscribed and like your videos. . .

I got shocked from 400v capacitor with about 329v dc voltage. Just a burn damage like a really hot flame touches my finger. I believe you can't die this way

I get a clock radio, he cannot afford. Great success!

What should cause the big bulk capacitor blow

@DonkeyLearningIT

4 жыл бұрын

These are the three main reasons which can lead to this: 1.) the active-PFC circuit feedback loop has failed, and the PFC circuit has boosted above 400V DC 2.) the diode bridge has at least one diode leaking, feeding the bulk filter cap with AC 3.) the cap just gave up due to old age, or the electrolyte got conductive contamination in it

@Donkey Learning IT I just love your series of videos and the effort you put in them. Its such a hard work from your end. You are the best!! Inspired by your series, I tried to repair one of my Computer PSU, The Silencer 750 EPS12V . It was running fine until it stopped. The problem is it that it starts for a couple of seconds everytime you have discharged the bulk caps and powered up again but then shuts down. I figured that the HY510N monitoring IC is shutting the PSU down for some reason so I replaced the HY510N IC but the problem did not go away. The capacitors are all Nippon Chemicon 105C rated. The power supply is 13 years old though and no capacitor is bulging out. Since its shutting down, I am not sure it is a capacitor problem and I do not know what else to do since I am a novice enthusiast at circuits. Can you please give me some tips what should I try? I really like that PSU and would like to use it some more. Honestly I do not have any1 else but you to ask. I will be grateful if you help :)

@DonkeyLearningIT

5 жыл бұрын

You see it right, thanks for the comment. It takes several hours to produce a half decent video, especially when it comes to editing. Regarding your issue with the PSU, I would say that the problem will be with the overcurrent protection. In any case, I would do the same "hairdryer" trick on it to heat up all caps just for the hack of it and see whether that temporarily solves it. Also, you should look for cold solder joints around the shunt resistors.

@DonkeyLearningIT

5 жыл бұрын

Oh, btw, I assume that when it works after discharging the cap, you have measured the output voltages and they were all totally fine. Otherwise the HY510 chip will shut down the PSU due to under/overvoltage protection.

@awaisaltaf8876

5 жыл бұрын

@Donkey Learning IT I don't know what your name is Sir, but u r certainly no donkey. I just tried your tips and OMG it worked. Heating the caps with a hair dryer did the trick. The PSU turned and ran for a couple of minutes until the PSU fan started to slow down and eventually the PSU shutdowm. I heated the caps again and the PSU turned on again and kept running for quite a while and even lit up a 100w 12v car bulb as the load. You dont know how much time effort and even some money i spent to learn what was wrong with it. I had assumed that since no cap was bulging they were fine. I took it to my city's repair market even and nobody told me what was wrong. I was interested more in learning than to get it working again and when I had lost hope, you taught me. Salute to you! You must be a very hard working man Sir, making these videos is not easy. Please dont listen to haters. I have seen comments on some of the other videos of your channel. Your videos certainly do not suck so plz never say it again. Watching a video sitting on your couch and criticising is easy, making one with so much editing and effort is difficult and yet you do it. I've learned so much from your videos that my university couldny teach me in my engineering. I respect you very much and pray that u always get success in your life. Keep up the great work Sir. P.S what should be my next step?replacing all the output caps? Thanks.

@DonkeyLearningIT

5 жыл бұрын

I am *really happy that this simple trick was of help* for somebody! In such situations I would replace all caps except the mains bulk filter caps. Namely, not just the output caps will be dried out but also those smaller caps in the range of 1uF to 47uF which are used for the startup of the PSU, and for the feedback loop, etc. Those small caps will cost you anyway less than 0.1Euros per cap to buy, so just replace them. Of course, make sure that you respect the right polarity when you put in the new one, and that you keep the same voltage rating, or eventually you replace with a somewhat higher voltage rating cap.

@DonkeyLearningIT

5 жыл бұрын

@@awaisaltaf8876 If you got too much money, you can also replace the mains bulk filter caps. However, the issue is, that most of the time those caps are really expensive, and in those cases it is no longer worth it to repair a PSU but rather just throw it away.

It's on like Donkey Kong! I love it!

@DonkeyLearningIT

5 жыл бұрын

Yep, it is on. And I hope you were not referring to "I love it" from Lil Pump, since in my opinion that is not a good song. I rather listen to oldschool rap.

@MattyMosArcade

5 жыл бұрын

@@DonkeyLearningIT Oh no, I'm just an old school gamer. I fix arcade and pinball machines for a living.

@DonkeyLearningIT

5 жыл бұрын

@@MattyMosArcade Woow, you are *exactly my type of guy* since I am fixing mostly Data East PCBs for pinball machines ;) It is a small world and now I am getting old, but I am still happy to be raised in the 80-90s.

@MattyMosArcade

5 жыл бұрын

@@DonkeyLearningIT oh that's cool! I'd love to see some videos on the subject!

@DonkeyLearningIT

5 жыл бұрын

@@MattyMosArcade Personally I do not own a pinball machine yet (lack of space and own apartment), but if you think that people would be interested, when I work on a board next time, I will produce a quick video. Btw, there is a guy (ArcadeUK) on KZread who had good pinball repair videos up.

Do you have own group or forum to join ?

I just want to add that a lot of datacenters have a minimum power factor for equipment you plug in, so Cisco probably had this power supply designed to meet those requirements.

@DonkeyLearningIT

4 жыл бұрын

Yes, having a good power factor is a requirement in large data centers. Though, in smaller colos they often do not care.

1. where I can get smps diagram for Cisco 2600 2950 3550 3750

Great

My switch stopped working after a bang. An unpleasant smell came from the power supply. The entire room was also de-energized. Before I disassemble the whole power supply, is there a big chance that it is only the fuse, or that more is going on? Can I carefully pick up the plastic where, among other things, the brand comes up with a hot air gun, or should I really pull it off?

@DonkeyLearningIT

5 жыл бұрын

I can *guarantee you* that more than a fuse is blown. Most likely the diode bridge is gone as well if the whole room was turned off by your main circuit breaker. If you do not have all tools and components already, I would not spend my time on it. Just buy a new Corsair PSU or an other good brand. Also, hopefully your motherboard and the rest of the system is still alive, because in some cases when the PSU does, it takes the motherboard with it...

@DonkeyLearningIT

5 жыл бұрын

Ahh, just saw that you are referring to a switch and not a PC. In any case, that PSU is dead for good based on the things you described. What model of switch is it, so that I can give you some hint whether it is worth fixing it.

@UltimateTBone

5 жыл бұрын

@@DonkeyLearningIT It's a Cisco Catalyst 3560 (WS-C3560-PS24) with PoE. The PSU is the LiteOn pa-2461-1a, the same as your video if I'm correct.

@DonkeyLearningIT

5 жыл бұрын

@@UltimateTBone If you can find a replacement PSU, try to replace the full PSU. I just thrown out couple of these PSUs since I was moving to a smaller apartment, so I do not have one to send you. Plus if you are located in the US the delivery costs could be higher than buying one from the US.

@UltimateTBone

5 жыл бұрын

@@DonkeyLearningIT I'm from the Netherlands. I searched on eBay for a replacement. But the costs to send them are higher than the PSU itself (most from the US). I can search on local market places if I can find an Cisco device with the same PSU. The 3560 I had has the enhanced software, so to keep it legal replacing the PSU or fixing it was the first thing I thought about. Therefore I was hoping it was a good to do job to fix the old one.

Dear respected Sir! I want to build 12 volts 3-4 Smps simple power supply and I hope you will help me

@DonkeyLearningIT

5 жыл бұрын

First of all that is a *beautiful beard* you got there. Mine is not this majestic. I was thinking about giving a try to scented beard-balms. Coming back to the topic of SMPS, if I understood it right, you want to design an SMPS from scratch. Is this correct? Also, what would be the input voltage range?

i would request you to make a video on working of the buck converter with two mosfets.... typically used in step down section of laptops.....

@DonkeyLearningIT

5 жыл бұрын

Thanks for the idea! Though, I had that long ago on my list. On the other hand, considering how common the buck converter circuit is, I am wondering whether people would watch it.

@annyan904

5 жыл бұрын

Donkey Learning IT its the most frequently used circuit in every section of electronic parts....i gues we should clear the basics and then move on to understand this really complicated power supply...

@DonkeyLearningIT

5 жыл бұрын

@@annyan904I fully agree with you. However, when I uploaded some videos on the basics, many people commented that it is not interesting for them, and I should make more advanced video instead :( Thus, it is tough the decide what kind of topic to go for. Personally I would do the basic stuff first, since otherwise the explanation makes no sense for mode advanced stuff.

@annyan904

5 жыл бұрын

Donkey Learning IT yes basics is important but according to mu suggestion basics of just the working of components.....dont go into calculation and minor details.....that would make videos boring....like for eg the rms calculation videos was too much focusing on calculation....but instead if you make videos on repairing point of view you dont need such detailed calculation and would interest many people too....but i know you have deeep knowledge in electronics and you love to share it deeply

@annyan904

5 жыл бұрын

Donkey Learning IT like so for a simple power supply but make sure you explain each section in detail like how the current flows in each section.... the function of each component that would interest many.......specially me....😊

I'm subscribing because you said "on like Donkey Kong"

@DonkeyLearningIT

5 жыл бұрын

Thanks for subbing! Btw, was there any sort of donkey in Donkey Kong (the arcade)? It was a monkey and not a donkey...

@criznach

5 жыл бұрын

Good point. I don't recall a donkey either!

@johnfrank6302

5 жыл бұрын

@@@DonkeyLearningITHere is the naming background from the game designer Miyamoto Shrine. "For Donkey Kong I wanted something to do with 'Kong' which kind of gives the idea of apes in Japanese and I came up with Donkey Kong because I heard that 'donkey' meant 'stupid' so I went with Donkey Kong. Unfortunately when I said that name to Nintendo of America nobody liked it and said that it didn't mean 'Stupid Ape' and they all laughed at me! But we went ahead with that name anyway." and here is a link to the article it came from www.miyamotoshrine.com/theman/interviews/051601.shtml

@DonkeyLearningIT

5 жыл бұрын

@@johnfrank6302 I like his attitude of "But we went ahead with the name anyway..." Is it just me, or people in the 90s had more creative freedom?

Please do a video about PFC

@DonkeyLearningIT

5 жыл бұрын

I will totally do a video both on active and passive PFC in the future.

very good explained .please accept my greetings

@DonkeyLearningIT

5 жыл бұрын

Thanks for watching and commenting!

Aren't those logic level fets? 13 years is not long ago!

LMFAO...... it's on like donkey kong LMFAO My coffee went up my nose LMFAO

@DonkeyLearningIT

2 жыл бұрын

I am happy for creating a good moment. I am sorry about the coffee though ...

@martinkuliza

2 жыл бұрын

@@DonkeyLearningIT So you should be LOL You should give people some warning if you are going to mention Donkey Kong or any arcade character but it's ok, i'll forgive you this time :P

बताव ये गोरी हमरा गन्ना के .........👌👌👌👌

👍👍👍👍

WOW NO EXPENSE. Nice PSU to keep after the equipemnt is decomised or put our of service.

@DonkeyLearningIT

5 жыл бұрын

I was thinking the same. I have a couple of these units, and I might keep them for LED drivers or for a home-made power supply or such. Since it is using the TL431, it should be easy to make the output be adjustable by playing around with the outer voltage feedback loop. The fast current loop should not even need to be modified.

i have one power supply unit i need that drwing static system group power supply unit model no:75039 for nursing call system

@DonkeyLearningIT

5 жыл бұрын

OK, now the question is how can we help you. Do you need help for troubleshooting, or you want to buy a replacement part? Personally I do not sell anything, but when it comes to repair/troubleshooting I might be able to help you out.

Get a patron PayPal account where subscribers can donate money to encourage you to continue making these fine videos!!!!! You love your profession and you love to teach. You do a fine job and if your subscribers can afford an occasional donation, so it should be.....every little bit adds ups where you won't mind buying those expensive bulk capacitors. I wish you all the joys in life along with good health and long life!

You changed the way you pronounce, "circuit". :)

@DonkeyLearningIT

5 жыл бұрын

I know, I know. So many people were complaining that I had to check what is the right pronunciation, so now I try to say it right, or at least close to it.

@Franklinveterinarycenter1of4

4 жыл бұрын

@@DonkeyLearningIT too kind and considerate of you.

hello sir i have one smps it is not getting dc output voltage i need detail information about the smps it is using for nursing call system 28volt dc output static system group if you want picture of smps i will send your email id

@DonkeyLearningIT

5 жыл бұрын

Hi there. Do you eventually have a link to this PSU, or a link to the datasheet/manual/electronic diagram? Without any info I cannot really help you.

The only thing I don't understand in this video is why it has 18 dislikes.

The minimum equilibrium temperature of that heat gun is 750 F. One hell of a diagnostic tool. Do people pay you for this work? It is absolutely sickening to see the technology race to the bottom happening today. We need to make major changes in our regulatory environment.

I've noticed you tend to use the term "so called". In english this is shorthand for 'or so it's called'. It is generally accepted that a name generally describes a thing. However, sometimes names are for whatever reason misleading. Let use for example take an element called a heater whose actual function was to cool something down. The name 'Heater' is known by people in a particular field to have this function but the name is counter intuitive. You might in this case you might say 'The so called heater is used to cool the flux initiator until it reaches the transient state of -40 degrees where negative tachion flow is possible. Perhaps the term heater is a sort of inside joke. Or maybe at some time it did heat something but now it needs to cool something but the name was never changed because of convention.

@DonkeyLearningIT

5 жыл бұрын

Thanks for taking your time and explaining this. I am not a native speaker, and in German the "sogenannt" does not have a negative overtone, it is more like to point out that a name or a short definition will follow. If I understood your explanation right, I should not use "so called" but instead just say what it is.

@JayHova4x4

5 жыл бұрын

@@DonkeyLearningIT "So called" might for instance be used to explain current flow. Since the electrons flow in the opposite direction one might expect. You might say the guy that always borrows money from you and never shows up when you need help is your "so called" friend. It's not necessarily negative it's just used when a name might be misleading or counter intuitive.

Ltec caps are really low tier capacitors and not of high quality. You can read here, Tom has put them in the fourth tier: www.tomshardware.com/reviews/power-supplies-101,4193-5.html

@DonkeyLearningIT

5 жыл бұрын

Well, I was also not very enthusiastic about the Ltech caps. They could have probably chosen something better, but these PSUs still work for over 12 years 24/7 operation without problems.