A FEW NOTES: 1. Do NOT try to increase the output voltage above the maximum rating of the output capacitors (probably 16V for a 12V power supply and 10V for a 5V supply) 😜 2. Also as at least two subscribers already mentioned - make sure you CHANGE the voltage markings on the PSU label after you modified it because you quite probably WILL forget that you changed the output voltage after a few months or so. 3. Keep in mind the Wattage - if your load is 12V at 2 Amps that is 12 x 2=24W. If your load uses 14V and it is still drawing 2 Amps that is 28W. Make sure you leave enough enough headroom so as not to overload the PSU 4. Your PSU may have TL431, LM431, KIA431 or some other prefix. They are all equivalent.
My hbp500 generic smps for audio amps is supposed to be 65-0-65 but it's only 38-0-38 I don't think I tested it when it was new but the irs2092 has never had any decent performance at all with it. When I ordered it I selected the 65v option. On the back/bottom of the PCB there is a row of voltage options. Can I modify it to be 65v if they selected the wrong voltage? Edit: also the transformer pins are connected next to each voltage 'option'.
@@Freeknickers24 must be rare that the company includes a transformer with switchable options, due economical reasons (more or less cooper). Its probably that exists different circuit paths for different transformers at installation time. In case that your transformer has such switchable capabilities, you can check the change in the Ohms(resistance) relation (Primary wind Ohms/Secondary wind Ohms) with a decent multimeter for each option (1:1 equal voltage input output, 1:2 doubles voltage and so on)...also, maybe, you need to check the path of protections involved (ie. a rise in voltages, some times, accompanies lowering fuse rates in the same inverse proportion for its amperage, that means 2x voltage, 1/2 fuse amperage and so on...only for fuses but would be other protections involved).
Great video, very informative. About your third point, shouldn't we also consider the current draw? For lower voltages, the current draw might become the limiting factor in terms of safety. Drawing twice the current at half the initial voltage could cause issues, even if the power draw remains the same.
You are an amazing teacher. I really enjoy your explanations and your approach to logical troubleshooting. I truly look forward to the next video and I appreciate you sharing your knowledge with us all. Thank you.
Top Notch Rich, Told ya mate best on youtube. It is a great honor and privilege to pass on your knowledge and experience to the next generations. Very little of us get the chance. Grab it with both hands mate.
I'm really liking your straight forward, even simplistic method of troubleshooting. But, it's the challenge of deciphering your accent that brings me back 😉 👍
2:35 - I have had great success getting into these (without bits coming off from the impact of a blunt object) by using a bench vice as a nut cracker: slowly tighten the vice perpendicular to the seam until it breaks a smile. A slight twist of a flat blade and you’re in! There are no breaks in the shell so it can be glued back together as if nothing ever happened! Although, I must admit your method is a mite faster if there’s no need for aesthetics!
I'm wanting to learn how to fix a wide variety of electronic items from radios to computers GPU etc, in future videos would you contemplate fixing and explaining how radios work?. and how to do signal tracing.
I recently had to modify a smps and your video was a great resource, thanks very much. Something I learned (that may be helpful to others) is how to remove the enclosure in which the smps resides. Taking care not to burn one’s self or melt the enclosure, place the enclosure in a C-clamp or bench vice and warm it evenly til it’s almost to hot to touch. As it begins to cool, start tightening the screw of the clamp until the pad of the screw and jaw starts to compress the walls. May need to reposition the clamp so you’re in the sweet spot near the corners. By squeezing the warmed plastic you’ll be able to get a lever in between the halves of the housing and with a little torque applied to lever( pry bar or flathead screwdriver) the halves should release. If lucky, the clamping force of the CClamp will pop the enclosure apart without need for any other tools. I found this to a better method for myself as I damaged a few PCBs with the hammer technique. Shockingly,(😂) I didn’t realize I’d damaged the board until I plugged into a mains outlet and heard a loud pop and saw a poof of magic smoke release. Thanks for the video and your expertise.
Richard, Wow in just one video their is always a lot to learn from you. Even more to learn and understand when i watch it again and again. Thanks for your time and effort to teach us. Bye for now. 🍻
I very much enjoyed your English accent. I also enjoyed your teaching. It clarified my understanding of the TL 431. And I subscribed to your channel. thanks for sharing.
Excellent :) I bet lots of people want to see this same type of vid for computer power supplies. Many people ask how to make one into a variable bench power supply :)
2:09 - whenever I need to crack a wall wart (walnut?) I use a bench vise to slowly add pressure to the longest side until it splits open far enough to get a screwdriver in to pry it further apart. After repair, I can usually glue the case back together to look factory. Only on rare occasions does this method produce fragments (I.e., when I got in a hurry and applied too much vice pressure too fast,)
What a phenomenally useful and clearly-presented video, thanks!! Off the shelf switching supplies have gone from being dark mysteries to useful, versatile gadgets! Thanks again for one of the most useful YT videos in recent memory!
That is such a useful instructional video, we all have many old power supplies lying about a be useful to be able to change their voltage , thankyou for posting :)
Brilliant - I needed this lecture yesterday to test a Samsung LED screen. Used my variable desk PSU, and found that the screen is broken, with zig-zag lines all over and vertical coloured stripes! If it had not been broken, I would have been doing this today, following your very clear exposition 🙂 Thank you very much!
lol, funny how timed that video is, while i'm also working on a small project for my little brother that requires a change in voltage!! he's been gifted a pc and want to be able to use his gpu in it , but it's a hp compaq(small form factor) that uses a non standard power supply(btx instead of atx) with only 240w output.. he already own a 500w atx , so i'm making him an adapter for the 24 pins connector to the two six pins ones that the mobo needs, the color code for the wires is the same on both side, the only problem is the standby one(purple), it requires 12v instead of the standard 5v for atxs... XD but i won't go into the box, i'll just build a step-up into the adapter to keep it usable in a standard atx built!! Anyway, yet another nice and very useful video of yours saved in my "electronics" playlist!!! Keep it up, i can see a bright future for your channel into the repairs and diy communities, the efforts and enthusiasm you put into explaining everything that you do, and why you do it, as clearly as you manage to do it, makes your videos not only useful, but also fun to watch for those into that kind of stuff!!! :p
Great video for learning how to change the output voltage of your smps. But don't forget not to go above the rated working voltage of the output capacitors. If you do then you have to change the change the output capacitors working voltage to match your new output voltage
Fantastic job going through this application and the programmable zener.....even if your accent to rich, your instruction is vastly richer and so are we. Thank You.
Excellent video, I would love to see a similar mod but instead of a fixed voltage, an adjustable voltage output voltage... I would imagine that you would need to have fixed resistors in place to keep the voltage from going too high or too low.... This would be a great mod for a nice high power supply, possibility from a laptop or even those industrial SMPS that are so cheap and usually have some sort of miner adjustment as it is, for all I know, it might only need a fixed resistance change to gain much more voltage adjustment.... Anyway, thanks again for this great video... I have been looking into these power supplies and how to change their output voltage and this video nailed it....
Thanks, mate! Been watching lots of your videos, all VERY useful indeed. Luv it! One could go to varsity for years and [probably] learn very little really useful stuff like this...
You can put few drops of gasoline in the gap . Wait for few seconds, a little twist and pressure , the glue dissolves and that adaptor can be opened without damaging its casing
That schematic in that pdf is a little incorrect, because I don't know if you have noticed, but the bridge rectifier is connected the wrong way round for a start.
Great stuff, A very handy calculator. I just select my required output voltage in the box, and use the calculate R2 Button.Am not sure what the empty box does, to the left of the three buttons.. Happy Days,
Although staying below the voltage rating of capacitors is a good practice, that isn’t necessarily sufficient. The output rectifiers not only have a current rating that should not be exceeded, they also have a reverse voltage that should not be exceeded. Conceivably, one could be below the voltage rating of an output capacitor yet have exceeded the reverse voltage rating of the output rectifier. In order to confirm that the reverse voltage rating of the output rectifiers aren’t being exceeded, some equipment is needed that might not be in the possession of the viewer - an oscilloscope is a must, and a variac is also a good idea to have because the “duty cycle” of the wave shape being fed to the output rectifier can vary with the AC input voltage. And the rectifier reverse voltage rating is not going to be printed onto the device like it would be with a capacitor; the specifications for reverse voltage rating will have to be retrieved from the data sheet for the part.
Excellent, thanks, I've fixed a couple of SMPSes in the past but still hadn't really got my head around the inner workings, it was more by trial and error - your videos have been super helpful, I guess the only question with this hack is if there are multiple rails and voltage outputs - I think one rail is usually controlled using the reference but I haven't gotten my head around how the other rails are controlled - is it purely by way of zeners on the assumption that only one reference rail controls the HV side and the others just play along?
Simple “fix”! Jst remember that the “total power” should probably be maintained…i.e. if you raise the output dc voltage, the originally rated output current will be LESS in order to maintain the total power spec.
Amazing! Thank you! I certainly did learn something new and will feel more confident if I need to alter any of my PSUs for specific reasons. I have a few spare external hard drive PSUs that could be re-purposed for other things now :D
Thank you for your videos. I learn a lot from them. I wonder how to change SMPS Input voltage (from 110V to 240V). I suppose you have to change the input capacitors, with higher voltage and less capacitance. Am I right?
Yes - usually by replacing the resistor from REF to Cathode (the 20K resistor) - you can see how to add a variable resistor in the 'Shunt Regulator' diagram on the TL431 calculator datasheet at 14:02
Yep great but what happens when someone uses it for something else? You must tell people to change to voltage written on the case. Because what happens is some comes along and breaks my equipment. So now i always change the voltage on the case.😮💨
Yep you are totally correct - it is important to change the label on the PSU - even yourself could forget what you changed the output to in a year or two (or maybe less). I now put your suggestion in a sticky in the comments and highlighted it in the video description. Thank You
I have done this on several power supplies, including those dodgy wall warts. But like Richard points out in his comment, pay close attention not to exceed the output capacitor voltage.
Yes but you are limited to the tolerance of the transformer. Transformers are manufactured with the output voltage and current in mind, the number of windings determines the voltage and the wire gauge determines the current. Say for argument's sake you lower the voltage but pull more amps than the transformer was designed for, the transformer could get very toasty and melt its windings and possibly short to the primary side.
@@snipersquad100 Actually Wattage (which is what causes heat) is volts x amps. So decreasing the voltage and increasing the current proportionally keeps the wattage the same. it's much more likely the output rectifier diode(s) would give up long before the transformer winding as they will have a maximum current rating. 😉 Realistically the limits you are going to face are: The maximum voltage rating of the output capacitor(s) The maximum current rating of the rectifier diode(s) The maximum and minimum duty cycle of the PWM controller (which determines the maximum and minimum output voltage) Personally I would use the technique shown in this video for changing the output voltage of a PSU by a few volts only. The one I modified for the Samsung monitor is working fine by the way after several days and my wife is very happy with her new screen
@@LearnElectronicsRepair If you have a 100watt transformer rated for 12v at 8.3 amps, the manufacturer of that transformer would rate the windings suitable to carry 8.3 amp, probably a little more for head room, say 12AWG. If someone hacked the power supply to put out 5v, that transformer could put out 20 amps, this would fry the windings in the transformer.
Yes you can use a potentiometer (variable resistor) in place of the resistor from REF to Cathode. In theory the lowest output would be 2.5V and the highest output would be dependent on the value of the variable resistor, but bear in mind that you may be limited in voltage range by the maximum and minimum duty cycle of the PWM controller.
since you understand about it, a non related question: can I put white LEDs into the 3,3 V output, just for illuminate de interior of the PC power supply? Just for some modding, asthetic reasons. Or this may affect the motherboard functioning ? thanks!
cheers for that. but if we want to change the voltage alot more than what the power supply is designed for, then what should we do? I suppose the transformer winding turns should be changed too? I need to convert a power supply to 2 volt 40 amp . because I can not find this in the market . help me with this please
Great video, your lucky to not have dust in the monitor, or perhaps your environment is very clean. Would be nice if you took a similar PSU for laptop and showed ripple before/after with removed Y caps that connect to ground. I don't have a scope ant myths of increased ripple are making me crazy. I do not need to have neon light bulb light up when touched to USB ports etc, on laptop with typical crappy PSU design.
Greetings from Ethiopia, my question is I have some Toshiba laptop charger 19 v not sure but 3-5 amps can I do the trick to use it as my Mobile charger USB c or normal Samsung Galaxy phone? I learned that I can reduce or increase the out put volts by changing the value of the voltage divider resistors to the programmable zener Diod TL431, but what about the amps? Thanks
I have tried the same mod on my 24V 6A power supply. I realized that when I changed the output voltage down to 16V and below, it keeps cycling on/off. What could have happened?
The way I remember is by using the alphabet, the electrons travel from Anode to the Cathode. A for Anode comes before C Cathode (or K for that matter) in the alphabet. So knowing which direction the electrons flow the Cathode will be the stripe part of the diode and the flat side of a through-hole LED.
@@snipersquad100 The electrons travel from cathode to anode, if they travelled from anode to cathode a cathode ray tube wouldn’t work. You’re thinking of conventional current.
@@stevebabiak6997 I normally qualify that when I speak, the answer mentions electrons travelling from Anode to Cathode. Clearly they don’t. I would phase the answer something like “ using conventional current flow ( + to - ) the diode symbol looks like an arrow showing the direction, using electron flow ( - to + ) the bar in the diode looks like a negative sign”
Ey up, mentioned this before but not sure if you have come across it, i guess without a board yourself with the issue could be hard to demonstrate - essentially on ASUS motherboards they have fan speed control in the BIOS, when attempting to live plug a fan in - i shorted the pins with a spark, since then the fan will only operate at full speed, all fan control both PWM or DC has gone, there seems to be 3 leg voltage regulators?? near each fan header, is it likely these have gone? i guess they can only be replaced with hot air work station? any info appreciated, cheers
Thanks for the excellent video. I modified a Sony Playstation 8.8V output SMPS with potentiometer but when I tried to set it at 5V, below 5.5V it goes to cutoff mode( output becomes 0V and after putting off it's input, it comes in on mode again). What is wrong? Please explain.
Use a variable resistor to replace the one between REF and Cathode pins on the TL431. Bear in mind in theory the minimum output is 2.5V but you will also be limited in range by the minimum and maximum duty cycle of the PWM controller. The IC (or mosfet it is driving) may also not like running continuously at high duty cycle. I would use this method for changing the output up or down by a few volts, but you can experiment yourself and let us know how you go on.
A FEW NOTES:
1. Do NOT try to increase the output voltage above the maximum rating of the output capacitors (probably 16V for a 12V power supply and 10V for a 5V supply) 😜
2. Also as at least two subscribers already mentioned - make sure you CHANGE the voltage markings on the PSU label after you modified it because you quite probably WILL forget that you changed the output voltage after a few months or so.
3. Keep in mind the Wattage - if your load is 12V at 2 Amps that is 12 x 2=24W. If your load uses 14V and it is still drawing 2 Amps that is 28W. Make sure you leave enough enough headroom so as not to overload the PSU
4. Your PSU may have TL431, LM431, KIA431 or some other prefix. They are all equivalent.
Additionally , check / update over voltage protections, output side, if they are fixed and related to the nominal voltage/current.
My hbp500 generic smps for audio amps is supposed to be 65-0-65 but it's only 38-0-38 I don't think I tested it when it was new but the irs2092 has never had any decent performance at all with it. When I ordered it I selected the 65v option. On the back/bottom of the PCB there is a row of voltage options. Can I modify it to be 65v if they selected the wrong voltage? Edit: also the transformer pins are connected next to each voltage 'option'.
@@Freeknickers24 must be rare that the company includes a transformer with switchable options, due economical reasons (more or less cooper). Its probably that exists different circuit paths for different transformers at installation time. In case that your transformer has such switchable capabilities, you can check the change in the Ohms(resistance) relation (Primary wind Ohms/Secondary wind Ohms) with a decent multimeter for each option (1:1 equal voltage input output, 1:2 doubles voltage and so on)...also, maybe, you need to check the path of protections involved (ie. a rise in voltages, some times, accompanies lowering fuse rates in the same inverse proportion for its amperage, that means 2x voltage, 1/2 fuse amperage and so on...only for fuses but would be other protections involved).
Great video, very informative. About your third point, shouldn't we also consider the current draw? For lower voltages, the current draw might become the limiting factor in terms of safety. Drawing twice the current at half the initial voltage could cause issues, even if the power draw remains the same.
Nice one Richard 🙂
And don't forget to pull the 12V sticker, and stick a new 14V one on it.
Oh yeah.... what this man just said 😁
Good point!
You are an amazing teacher. I really enjoy your explanations and your approach to logical troubleshooting. I truly look forward to the next video and I appreciate you sharing your knowledge with us all. Thank you.
Top Notch Rich, Told ya mate best on youtube. It is a great honor and privilege to pass on your knowledge and experience to the next generations. Very little of us get the chance. Grab it with both hands mate.
Watching your videos is like gaining a super power. Keep them coming!
This video is solid gold, great tip !...cheers.
I'm really liking your straight forward, even simplistic method of troubleshooting. But, it's the challenge of deciphering your accent that brings me back 😉 👍
2:35 - I have had great success getting into these (without bits coming off from the impact of a blunt object) by using a bench vice as a nut cracker: slowly tighten the vice perpendicular to the seam until it breaks a smile. A slight twist of a flat blade and you’re in! There are no breaks in the shell so it can be glued back together as if nothing ever happened! Although, I must admit your method is a mite faster if there’s no need for aesthetics!
I'm wanting to learn how to fix a wide variety of electronic items from radios to computers GPU etc, in future videos would you contemplate fixing and explaining how radios work?. and how to do signal tracing.
Yes definitely.
I recently had to modify a smps and your video was a great resource, thanks very much.
Something I learned (that may be helpful to others) is how to remove the enclosure in which the smps resides.
Taking care not to burn one’s self or melt the enclosure, place the enclosure in a C-clamp or bench vice and warm it evenly til it’s almost to hot to touch. As it begins to cool, start tightening the screw of the clamp until the pad of the screw and jaw starts to compress the walls. May need to reposition the clamp so you’re in the sweet spot near the corners. By squeezing the warmed plastic you’ll be able to get a lever in between the halves of the housing and with a little torque applied to lever( pry bar or flathead screwdriver) the halves should release. If lucky, the clamping force of the CClamp will pop the enclosure apart without need for any other tools. I found this to a better method for myself as I damaged a few PCBs with the hammer technique. Shockingly,(😂) I didn’t realize I’d damaged the board until I plugged into a mains outlet and heard a loud pop and saw a poof of magic smoke release.
Thanks for the video and your expertise.
Great explanation Sir, thank you for sharing your knowledge & experience. I´ll be looking forward for your upcoming videos
Richard, Wow in just one video their is always a lot to learn from you. Even more to learn and understand when i watch it again and again. Thanks for your time and effort to teach us.
Bye for now. 🍻
After seeing this video I am now more confident to repair a laptop power adapter. Thanks for making this video.
I very much enjoyed your English accent. I also enjoyed your teaching. It clarified my understanding of the TL 431. And I subscribed to your channel. thanks for sharing.
Excellent :)
I bet lots of people want to see this same type of vid for computer power supplies. Many people ask how to make one into a variable bench power supply :)
I absolutely enjoyed this video. Thank you, I always wanted to know how to change the output voltage and you explain things very well.
One of the best electronics channels, you understand the people who are learning and give nice explanations
2:09 - whenever I need to crack a wall wart (walnut?) I use a bench vise to slowly add pressure to the longest side until it splits open far enough to get a screwdriver in to pry it further apart. After repair, I can usually glue the case back together to look factory. Only on rare occasions does this method produce fragments (I.e., when I got in a hurry and applied too much vice pressure too fast,)
What a phenomenally useful and clearly-presented video, thanks!! Off the shelf switching supplies have gone from being dark mysteries to useful, versatile gadgets!
Thanks again for one of the most useful YT videos in recent memory!
Thanks Richard, electronics have been my hobby for many years, and never realized how simply you can modify a smps!. Thanks very much
I wasn't aware of how simple this is. Brilliant.
Just found this channel in love 😍 so much knowledge epic x
That is such a useful instructional video, we all have many old power supplies lying about a be useful to be able to change their voltage , thankyou for posting :)
Brilliant - I needed this lecture yesterday to test a Samsung LED screen. Used my variable desk PSU, and found that the screen is broken, with zig-zag lines all over and vertical coloured stripes! If it had not been broken, I would have been doing this today, following your very clear exposition 🙂 Thank you very much!
lol, funny how timed that video is, while i'm also working on a small project for my little brother that requires a change in voltage!! he's been gifted a pc and want to be able to use his gpu in it , but it's a hp compaq(small form factor) that uses a non standard power supply(btx instead of atx) with only 240w output.. he already own a 500w atx , so i'm making him an adapter for the 24 pins connector to the two six pins ones that the mobo needs, the color code for the wires is the same on both side, the only problem is the standby one(purple), it requires 12v instead of the standard 5v for atxs... XD but i won't go into the box, i'll just build a step-up into the adapter to keep it usable in a standard atx built!! Anyway, yet another nice and very useful video of yours saved in my "electronics" playlist!!! Keep it up, i can see a bright future for your channel into the repairs and diy communities, the efforts and enthusiasm you put into explaining everything that you do, and why you do it, as clearly as you manage to do it, makes your videos not only useful, but also fun to watch for those into that kind of stuff!!! :p
No need to build one. Here it is
www.aliexpress.com/item/1005003523264968.html
Very informative video, thanks for sharing your knowledge.
Great video for learning how to change the output voltage of your smps. But don't forget not to go above the rated working voltage of the output capacitors. If you do then you have to change the change the output capacitors working voltage to match your new output voltage
Absolutely awesome...well done on helping people. May your business exponentially prosper...
Fantastic job going through this application and the programmable zener.....even if your accent to rich, your instruction is vastly richer and so are we.
Thank You.
Very useful video Richard - thanks for posting
Thank you Richard that was very interesting. Keep up the good work. Always a pleasure
Excellent video, I would love to see a similar mod but instead of a fixed voltage, an adjustable voltage output voltage... I would imagine that you would need to have fixed resistors in place to keep the voltage from going too high or too low.... This would be a great mod for a nice high power supply, possibility from a laptop or even those industrial SMPS that are so cheap and usually have some sort of miner adjustment as it is, for all I know, it might only need a fixed resistance change to gain much more voltage adjustment....
Anyway, thanks again for this great video... I have been looking into these power supplies and how to change their output voltage and this video nailed it....
Thanks, mate! Been watching lots of your videos, all VERY useful indeed. Luv it! One could go to varsity for years and [probably] learn very little really useful stuff like this...
You can put few drops of gasoline in the gap . Wait for few seconds, a little twist and pressure , the glue dissolves and that adaptor can be opened without damaging its casing
Great video,Did you make a video on your current limiting light bulbs that you used at the end of this video?
I'm working on it - I want to do something a little special with that 😉
Like so many others have said, Awesome! Thank you! I need to mod a small Chinesium module supply to a exact voltage as none come with adjustments.
That schematic in that pdf is a little incorrect, because I don't know if you have noticed, but the bridge rectifier is connected the wrong way round for a start.
The one in the video is Rev 11 and they have fixed the bridge by the Rev 16 that I have.
awesome - I'm learning stuff I could not grasp before - thanks to YOU sharing your knowledge - it's just the way you teach.
Very nice video. Thank you very much M.Richard !
Great stuff, A very handy calculator. I just select my required output voltage in the box, and use the calculate R2 Button.Am not sure what the empty box does, to the left of the three buttons.. Happy Days,
Thanks for sharing your knowledge ... Greatings from Portugal 🇵🇹 🌟
Awesome Video ! 👍 learned heaps
Although staying below the voltage rating of capacitors is a good practice, that isn’t necessarily sufficient. The output rectifiers not only have a current rating that should not be exceeded, they also have a reverse voltage that should not be exceeded. Conceivably, one could be below the voltage rating of an output capacitor yet have exceeded the reverse voltage rating of the output rectifier.
In order to confirm that the reverse voltage rating of the output rectifiers aren’t being exceeded, some equipment is needed that might not be in the possession of the viewer - an oscilloscope is a must, and a variac is also a good idea to have because the “duty cycle” of the wave shape being fed to the output rectifier can vary with the AC input voltage.
And the rectifier reverse voltage rating is not going to be printed onto the device like it would be with a capacitor; the specifications for reverse voltage rating will have to be retrieved from the data sheet for the part.
To help open a case like this a sharp wood chisel and a smal mallet can be very useful
Excellent, thanks, I've fixed a couple of SMPSes in the past but still hadn't really got my head around the inner workings, it was more by trial and error - your videos have been super helpful, I guess the only question with this hack is if there are multiple rails and voltage outputs - I think one rail is usually controlled using the reference but I haven't gotten my head around how the other rails are controlled - is it purely by way of zeners on the assumption that only one reference rail controls the HV side and the others just play along?
You can try putting the power supply in a clamp and slowly squeeze it to crack the glue...
That sounds like an interesting idea. Thanks.
Thanks. You have give me a more information how smps work
Thanks for your videos im subscribed
Simple “fix”! Jst remember that the “total power” should probably be maintained…i.e. if you raise the output dc voltage, the originally rated output current will be LESS in order to maintain the total power spec.
Quite correct. I take it you read the pinned comment I made here called 'A few notes:'?
Amazing! Thank you! I certainly did learn something new and will feel more confident if I need to alter any of my PSUs for specific reasons. I have a few spare external hard drive PSUs that could be re-purposed for other things now :D
Excellent.Next time do the same with a zener diode PSU instead .If you don't have one,a theoretical pen and paper video would do.
What a brilliant helpful hack!!
Awesome tip Richard, was it just me or did anyone sing the splash screen "danger danger high voltage" when it popped up? 🤣🤣
Not just you. I was singing it as well 😁
Excellent video
Thank you for your videos. I learn a lot from them.
I wonder how to change SMPS Input voltage (from 110V to 240V). I suppose you have to change the input capacitors, with higher voltage and less capacitance. Am I right?
This is really useful, and well explained.....thank you!
Ty this was very cool. This could come in handy in the future.
Could you put a trimer or a potenciometer instead of fixed value resistor ?
Yes - usually by replacing the resistor from REF to Cathode (the 20K resistor) - you can see how to add a variable resistor in the 'Shunt Regulator' diagram on the TL431 calculator datasheet at 14:02
Very informative, thanks
Needed this solution so many times 😏 now I'm looking for an excuses to try it out 😂 thanks for the education!
Yeah this video and all other ones are great, thanks for sharing.
Thank you Sir. All my best. Oh and greetings from Tennessee.
Yep great but what happens when someone
uses it for something else? You must tell people to change to voltage written on the case. Because what happens is some comes along and breaks my equipment. So now i always change the voltage on the case.😮💨
Yep you are totally correct - it is important to change the label on the PSU - even yourself could forget what you changed the output to in a year or two (or maybe less). I now put your suggestion in a sticky in the comments and highlighted it in the video description. Thank You
Thank you for sharing. Great content!
Great tutorial but i will decrease voltage instead from 12v to 6v for my tubeamp, hope it works.
could you potentially make this into a variable power supply by using a potentiometer instead of a fixed resistor?
Yes, correct.
I have done this on several power supplies, including those dodgy wall warts. But like Richard points out in his comment, pay close attention not to exceed the output capacitor voltage.
Yes but you are limited to the tolerance of the transformer. Transformers are manufactured with the output voltage and current in mind, the number of windings determines the voltage and the wire gauge determines the current. Say for argument's sake you lower the voltage but pull more amps than the transformer was designed for, the transformer could get very toasty and melt its windings and possibly short to the primary side.
@@snipersquad100 Actually Wattage (which is what causes heat) is volts x amps. So decreasing the voltage and increasing the current proportionally keeps the wattage the same. it's much more likely the output rectifier diode(s) would give up long before the transformer winding as they will have a maximum current rating. 😉
Realistically the limits you are going to face are:
The maximum voltage rating of the output capacitor(s)
The maximum current rating of the rectifier diode(s)
The maximum and minimum duty cycle of the PWM controller (which determines the maximum and minimum output voltage)
Personally I would use the technique shown in this video for changing the output voltage of a PSU by a few volts only. The one I modified for the Samsung monitor is working fine by the way after several days and my wife is very happy with her new screen
@@LearnElectronicsRepair If you have a 100watt transformer rated for 12v at 8.3 amps, the manufacturer of that transformer would rate the windings suitable to carry 8.3 amp, probably a little more for head room, say 12AWG. If someone hacked the power supply to put out 5v, that transformer could put out 20 amps, this would fry the windings in the transformer.
As always brill
Can you make a video on how to convert a server power supply to a variable power supply? Preferably 48v 40a supplies. Thanks
hello Richard, why not using a potentiometer in place of a fix resistance, so you obtain a variable power pack ?
Top stuff could be handy for dropping output voltage to 5v when you only have 12v units
That was brilliant. Would using a pot in place of one of the resistors give a variable output power supply, or would it impact the performance?
Yes you can use a potentiometer (variable resistor) in place of the resistor from REF to Cathode. In theory the lowest output would be 2.5V and the highest output would be dependent on the value of the variable resistor, but bear in mind that you may be limited in voltage range by the maximum and minimum duty cycle of the PWM controller.
Spot on.
Oh thanks that great
Much appreciated sir
@ 6:16 the bridge rectifier don't look correct to me
great video!
Very Nice. 👍
A tutaj się Pana nie spodziewałem ;) kupiłem ostatnio zasilacz 12V 106A i zastanawiam się jak by go zmodyfikować tak żeby nadawał się do ridena 6024..
since you understand about it, a non related question: can I put white LEDs into the 3,3 V output, just for illuminate de interior of the PC power supply? Just for some modding, asthetic reasons. Or this may affect the motherboard functioning ? thanks!
I enjoy this video tks so much......
Hi friend thanks for the informative video
Your a great teacher. ty 👍
Good work
many thank s sir keep it up
Awesome !!!
cheers for that. but if we want to change the voltage alot more than what the power supply is designed for, then what should we do? I suppose the transformer winding turns should be changed too? I need to convert a power supply to 2 volt 40 amp . because I can not find this in the market . help me with this please
Great video, your lucky to not have dust in the monitor, or perhaps your environment is very clean. Would be nice if you took a similar PSU for laptop and showed ripple before/after with removed Y caps that connect to ground. I don't have a scope ant myths of increased ripple are making me crazy. I do not need to have neon light bulb light up when touched to USB ports etc, on laptop with typical crappy PSU design.
Can i use a potentiometer to alter the voltage rather than a resistor?
Good explanation thanks. Bob's ya uncle, for sure.
Greetings from Ethiopia, my question is I have some Toshiba laptop charger 19 v not sure but 3-5 amps can I do the trick to use it as my Mobile charger USB c or normal Samsung Galaxy phone? I learned that I can reduce or increase the out put volts by changing the value of the voltage divider resistors to the programmable zener Diod TL431, but what about the amps?
Thanks
good job
Useful to know - thanks
Thanks
I have tried the same mod on my 24V 6A power supply. I realized that when I changed the output voltage down to 16V and below, it keeps cycling on/off. What could have happened?
very usefull video
do you have a memory trick to remember which end is cathode or anode in wiring diagrams?
The way I remember is by using the alphabet, the electrons travel from Anode to the Cathode. A for Anode comes before C Cathode (or K for that matter) in the alphabet. So knowing which direction the electrons flow the Cathode will be the stripe part of the diode and the flat side of a through-hole LED.
@@snipersquad100 The electrons travel from cathode to anode, if they travelled from anode to cathode a cathode ray tube wouldn’t work. You’re thinking of conventional current.
@@ozriblit - you are correct on electron flow, and that which was described by the other comment is actually covering conventional current flow.
@@stevebabiak6997 I normally qualify that when I speak, the answer mentions electrons travelling from Anode to Cathode. Clearly they don’t. I would phase the answer something like “ using conventional current flow ( + to - ) the diode symbol looks like an arrow showing the direction, using electron flow ( - to + ) the bar in the diode looks like a negative sign”
Heya oh wouw yeah that was eye opening for me thanks
Ey up, mentioned this before but not sure if you have come across it, i guess without a board yourself with the issue could be hard to demonstrate - essentially on ASUS motherboards they have fan speed control in the BIOS, when attempting to live plug a fan in - i shorted the pins with a spark, since then the fan will only operate at full speed, all fan control both PWM or DC has gone, there seems to be 3 leg voltage regulators?? near each fan header, is it likely these have gone? i guess they can only be replaced with hot air work station? any info appreciated, cheers
What if the output will desired to be less than 2.5 volt such as 1.8 volt or 0.5 volt,how can i achieve this.thanks at all
Thanks for the excellent video.
I modified a Sony Playstation 8.8V output SMPS with potentiometer but when I tried to set it at 5V, below 5.5V it goes to cutoff mode( output becomes 0V and after putting off it's input, it comes in on mode again). What is wrong?
Please explain.
If this is due to duty cycle limitations, then how to tackle it?
I have a hard time soldering those tiny resistors.
we make variable power supply if we use 5k pot for r2 and change caps?
Use a variable resistor to replace the one between REF and Cathode pins on the TL431. Bear in mind in theory the minimum output is 2.5V but you will also be limited in range by the minimum and maximum duty cycle of the PWM controller. The IC (or mosfet it is driving) may also not like running continuously at high duty cycle. I would use this method for changing the output up or down by a few volts, but you can experiment yourself and let us know how you go on.