Modifying a S-400-12 switchmode power supply for variable output voltage
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- Опубліковано 5 жов 2024
- I've taken a 12V 33A power supply and modified the feedback network to provide a fully adjustable 5-15V. I've also traced out the entire schematic. A full description of operation and details of the modification are available on my website at the link below.
imajeenyus.com/...
The original motivation was to find a means of operating RC brushless motors without relying on lithium batteries.
I'm in the process of repairing a couple of these PSUs and your schematic and explanation helped a great deal, thanks! Mine are a 24V 15A psu but the PCB is exactly the same, just some components were different to make it a 24V supply. I've learned a lot by studying the schematic and datasheet! One PSU is dead and the other drops to 3V under load. It'll be interesting to see how I can fix them. I already replaced one of the output transistors, one of which has failed spectacularly, burning so hot it melted the plastic cover of the 680uF 250V caps! One resistor near the transistor blew as well. But replacing them was not the solution, there's probably more failed components. I'll keep working on them until they are fixed.
Good to hear! Hope you can get them sorted. Don't forget the actual controller IC itself - I once managed to fry the IC in a power supply I was using near high voltage/sparky stuff, probably voltage spikes or noise introduced back into the supply. I took the chip out and put a socket in so I could easily replace it in future.
@@imajeenyus42 Thanks for the suggestion! On psu 1 I missed checking for resistors failing open instead of shorted. I found 4 without any discoloration, probably because base and collector shorted on the bridge transistors.
On psu 2 it's dropping in voltage under load, likely short circuit protection kicking in too early or something keeping dtc pin higher than it should. Some resistors can get quite hot when checking with ir imaging camera, some even 80+ degrees C. And one blue cap too. It still gives 24V withou load. Psu 2 is a newer version with slightly different pcb and component values.
Awesome effort at reverse engineering the schematic. Thanks a ton. I have a 48V 10A adjustable Voltage and Current version and your effort has helped a lot.
Am seeking of making 48v 10 Ampere to 110v 4-5 ampere with replacing o/p capacitor and protection diode and feedback resistor is it possible to double such voltage?
Thanks you so much for the schematic PDF. I suggest putting the links in the description of the video here.
There is already a link in the description. I can't help it if people can't read.
@@imajeenyus42I came here from the website. What I meant was that it could be helpful for CEO purposes to put a direct link to the pdf and sch file here.
Thank you very much, first of all for the schematic. I would like to make just one clarification. I believe the short circuit protection is via pin 15 (I2-) of the IC and not by the circuit around Q5. This should add an extra protection, that of over voltage, by shutting down the IC when this occurs
Mmm....not quite. The feedback from the current sense resistor(s) that goes to pin 15 is used to reduce the PWM duty cycle of the IC if the current drawn exceeds a threshold. However, it does _not_ shut the IC down - it continues operating, simply with a reduced output voltage. The stuff around Q5 deals with an actual short, or more properly, a situation where the load is high enough to cause the output voltage to drop below about 4V, which is where the short-circuit feature is triggered.
@@imajeenyus42 maybe you are rigth, but in my very cheap power supply, using the same pcb, Q5 and related components are not mounted at all, so it seems strange to me to sell a power supply without any short curcuit protection
@@brunodalessio4622 I wouldn't be surprised ;-) I've seen cheap supplies with missing components, or even components fitted but the PCB traces don't connect to anything!
@@imajeenyus42 Chinese people are crazy and we are even more crazy when we expect to buy well-made items for ridiculous prices!
Congratulations, the modification is a success.
I am one of your followers on ultrasonic transducer tuning and now on this video great work thank you
My congratulations. Your project has helped us a lot. Grateful
Dude! Thank you for the back engineered schematic. I wish I had one. You worked hard for hours. Now I have one!
Thanks again for sharing it with the rest of us. Sub'd+1
Others do the work and others just enjoy that. The parasitic life
thank,s for you, sir.... your modification product is excellent and very important....
EYE LADDY GREAT JOB MATE👍👍
Very nice project, i wonder if it would be possible to switch the pot for a digital pot and use a mcu to controlle the feedback and thus output voltage.
Cheers
Hi! How to set current on this power supply? Could you please make a video about this? I'm sure you will have a lot of viewers and likes because there is no such video on the internet.
For everyone looking for it: This supply is sold (produced?) by "ZJIVNV Official Store" on Aliexpress.
Thank u bro for your nice work
But it would be a great help if you put a modified wiring diagram including connection for the volt meter ,i did not know how and where i connect the caps and others diodes you explain ed in the webpage
Please reply and help me with this problem
Hello, I’m not sure what wha you mean - if you take a look down the bottom of the web page, I have described and shown how the auxiliary supply for the meter is connected. Starting at the paragraph “The power supply for the voltmeter module is derived from…”. Please take another look and see if it helps.
Just another question left in my mind.i didn't not fully understand thefeedback circuit without an optocoupler clearly
Please read the webpage, it's explained there.
Do you know if the s-600-12 schematic would be the same? I just bought a bunch from china and plan on building some supplies with a variable pot. Figured I'd have to figure this all out on my own but you explanation was very helpful.
Hello Lindsay
The power supply for the voltmeter module is derived from a couple of extra diodes + 100µF capacitor + 220µH series filter inductor, tacked on to the anodes of D11 & D12 (see photo below). This provides about 20V to the module.Can you show the wiring diagram of the power supply for this voltmeter module? Not exactly seen from the picture.
Well spotted, I forgot to add the photo to the website ;-) If you check the page now (imajeenyus.com/electronics/20151028_smps_variable_voltage/index.shtml), I've added a circuit showing what's used for the extra supply.
Hello! @@imajeenyus42
Thank you for your quick reply.
@@imajeenyus42again thank u for your perfect professional modifying circuit
But the link you suggested for the well spotted hint about the power supply of the voltmeter is no longer exists. Is there any possible way to find what you added in the picture or any explanation that helps
@@imajeenyus42i could not access that link u suggested for the picture
@@amirvafa7344 The link works: imajeenyus.com/electronics/20151028_smps_variable_voltage/index.shtml
Good work sir, i have s-360-12 power supply its a 12 - 30a and i need it modify and take 3v to 30v or 3v to 15v can you please help me to do it thanks in advance
Verry nice project , but I need to ask what would I need change if i want to modify S-300-12 12V 25A psu as I really need to go lower than 10.21V which allow me with onboard potentiometer
Ah! Nice!
Hello Lindsay, very nice video ! i have approx the same SMPS but has no voltage at TL494 VCC capacitor, and then no output. Any idea where to look at ? thanks
Hello! How to adjustable current? Could you please make a video about this? I'm sure you will have a lot of viewers and likes.Because there is no such video online.
good work!
Hey can you please tell me more about or provide schematics for that adjustable ESC controller you were using
Can you modify the current? Like make a variable amp output 1-30amp or whatever the power, 1-16 in my smps
It seems to be possible to at least implement current limiting - see this page, down the bottom, under "Converting a 60V LED switch mode power supply to an 18650 cell charger": github.com/matteljay/ebike
Thats all well and good but what about variable Curent also?
Great video! I went with the easier solution and added a resistor to the trim pot. As my goal is to lower a 24v supply to 17v. I can now get it down to 17v when turning down the pot. BUT it starts to flash on /off when lowering the voltage! It does this even without load. Any ideas?
It's a bit of a guess, but I wonder if it might be the power supply's short-circuit protection circuitry kicking in at lower voltages. It basically looks at the output voltage and if it drops below a certain level, the driver chip is shut off. I've got a section about this on my page. If your supply is the same sort of arrangement, then you should be able to disable this by removing D13 or the equivalent on yours - it's down at the bottom-right of the schematic, in the short-circuit protection section. Try that first and let me know how it goes ;-) Could you also try and see the values of R31 & R38 (or, again, the equivalents)? That's the voltage divider which drives the base of the short-circuit protection transistor.
@@imajeenyus42 Thanks for the fast reply! I have looked into this more now and realized that my power supply uses a different control ic. It has a OB2269AP www.promelec.ru/datasheet/8/e/OB2268-2269.pdf
this does not have appear to have a dtc input?
@@imajeenyus42 I have measured the inputs of the control ic, and the FB (feedback pin) has 1.5v when power supply is in normal operation. but as son as I lower the trim pot "to far" (about 17v output) the FB goes to 0.5v and its starts to reset.
@@markusgranberg8004 Old post so you may have resolved this but if not the OB2268 datasheet shows an undervoltage lockout (UVLO) function when Vdd on pin 7 falls too low. The relevant voltages are shown on page 5, hard to correct without increasing the number of turns on the transformer winding that generates Vdd.
it is good BUT i suggest you to change elco 3300uF/16v to higher voltage if you want to use output at 15volt or higher (max 24v)...
I mention this on the webpage.
First of all .thank u for a totally perfect explanation and very good job and drawings. Second
I just need help that how can i lower the adjustment pin voltage from 2.5 as reference of tl494 which is normally 5v to 1.25volt.if i could do this so i can lower the output much lower without DTC pin goes high before output reaches under 1.25.again i should thank u becoz of your very neat job.
I'm not clear what you mean. If you mean the reference voltage on pin 2, which is normally 2.5V, then you would change the values of the resistor divider R34 + R30. You would then need to disable the short-circuit protection by removing diode D13. However, I have no idea what effect all this will have on the loop stability, since it will then be operating considerably outside its original specifications. If you really need an adjustable supply that goes that low, then I would seriously consider just getting a bench power supply. Cheap, and designed to adjust right down to 0V.
@@imajeenyus42 you got what i meant
I would think like that i can keep short circuit protection and have such low voltage on pin 2.seems impossible. I well know by grounding pin 4 of tl494.we can bypass all protection and have changes we need.
Thank u for your reply
U R a great help
With best regards
Thank u again bro
How about the cooling fan
How can we keep it on even we use smp on low voltage. I checked the fan is turning a little slower with 7to 8volt
But not turning on 5v.i prefer to have it start cooling all the time the psu is on
@@amirvafa7344 You might try replacing the fan with a 5V version and using a 7805 regulator to power it from the supply's output. However, since the fan supply is derived from the main output, you're never going to be able to run the fan with an output lower than 5V or so.
Hi Lindsay. Great explanation. And thanks for the mod. Can you maybe tell me how to bring voltage of a 5V type DOWN to 3.5V? I need to charge some LiFePo4 with it, and can find out which resistors need to be changed. I know that D13 may be needed to be removed to remove the short circuit protection in this case.
I'm afraid it's difficult to say without seeing the actual schematic and component values. It would probably be easier just to use an additional step-down buck converter instead of modifying the supply. Try looking at the LM2596 or XL4015 modules that are on eBay (e.g. www.ebay.co.uk/itm/293187069736)
@@imajeenyus42 Thanks Lindsay. The layout is exactly the same as the one you got. Traces are the same. I can desolder the resistors and tell you the values, but I'm pretty sure most of the relevant ones are the same. Getting a step down converter is no way, as I need the full 50A of the powersupply. I need to charge 16x 280Ah LifePo4 cells, and every charging amp counts ;) What would you need from me in case you got the time to investigate?
@@izemanevobike I can't promise I can figure it out, but I would need to know the values of all the components in the area marked "Voltage sense" in the schematic on my website, resistors and capacitors.
@@imajeenyus42 WOW. Thanks! I desoldered one leg and measured them: R32 = 1k5 , R39 = 680 , R40= 1k5, R41= 2k6, VR1= 1k type, C31= 35nF, C28 = doesn't exist. I experimented a little with some resistors here and there and could lower voltage to 3.8V, but when I start to go below 4.5V the power supply starts a hissing sound. Don't know where it comes from, but it doesn't sound very healthy. You also get that sound in the unmodified supply if you turn VR1 very quickly from high to low voltage.
@@izemanevobike Try keeping all other components the same, but change R40 from 1k5 to 4k7. That should give you an adjustment range of 3.45V to 3.65V. Alternatively, if you need a bit more adjustment, try R40=3k3 and VR1=5k, which should give adjustment from 3.1V to 4.1V. The hissing sound is strange - that sometimes happens when the supply is unloaded, so it should disappear with a load.
I just realised - instead of spending time trying to modify this supply (great if it works, but....!), you do get 3.3V power supplies which would be far better suited. For example, the Mean Well HRP-300-3.3 which has 60A max output current and is adjustable from 2.8-3.8V. They're not exactly cheap, but would be an off-the-shelf solution. One stockist - www.powersuppliesonline.co.uk/power-supplies/enclosed-power-supplies/hrp-series-mean-well/hrp-300-3-3-198w-3-3v-60a-enclosed-power-supply.html
Hello I have a close looking power supply rated for 12v, 240 watts, and has 25v Caps on the DC side, is it possible to make voltage modification for 16.8v? if so how? i don't understand the schematic, I have soldering skills and basic understand of some components. thanks, finding a power supply rated for 6 amps at 16.8v is hard and the ones I did find arm't rated for what they say they are and drop voltage by like 2v and get very hot.
I want to ask you a question, I have a 24v isolated SMPS with an optocoupler and TL431 adjustable zener, i want to modify it to make a constant current source, so can I connect a 0.1 shunt register in series with output, and amplify the shunt register's forward voltage when my desired current flowing through it to 5v, and feed this 5v to feedback circuit by adjusting TL431 to 5v, will it work.
Becoz of almost high amperes delivery of this psu ,i think i can be modified for higher voltage than 15v,but i don't know how much i must change the divider resistance without losing the over voltage protection of course in case this psu has such a protection
Why? Just buy a higher voltage supply. It's not worth the trouble to modify this way. The transformer is designed to output a little over the nominal voltage maximum, so you're never going to get it to produce a significantly higher voltage than its designed to. Additionally, you would need to change the output smoothing capacitors to a higher voltage rating, change the current sense resistor to provide the same power limiting, besides the feedback divider itself.
@@imajeenyus42 thanks for the reply. I have modified an atx psu which is more complicated than this chineese psu ,and i got at least double voltage for every line of it
But i had to ground the dtc pin so losing every protection. But in your job u did lowering the output voltage without losing under voltage protection,i like to do that for O/V protection and change the outputs caps. It's so fun have your psu made specially for yourself.
@@amirvafa7344 If you really must, then make sure that the output smoothing caps are rated at an appropriate voltage.
@@imajeenyus42 of course. Thank u .again u gave a very clear explanation of the modified circuit.but still i think that the fan of the s400 psu must run independent of the main circuit and as soon as the power supply gets on start spinning.
hello, can you tell me if this modification and the same for a 48v power supply? thank you for your help i need 42v thank you
hey Lindsay thank you for this rich and detailed video. My question is this one, i have a qp 200d switching power supply from ebay that should output v1:5vdc adj, v2:+12vdc adj, v3:+24vdc, v4:-12vdc . But after measuring these voltages everything is correct except for the -12vdc. instead of -12vdc i only get -7.1vdc and i am wondering how to get that voltage up to -12vdc. Could you please help me? THANK YOU
Sorry, I really wouldn't know about that - it sounds a much more complex supply, multiple outputs, and active PFC.
im needing a 42v charger for my ebike , was hoping could get up to 10a or so, what would work on this, whats your thoughts?
Why not just buy a charger? www.amazon.co.uk/HalloMotor-Lithium-Polymer-Battery-Charger/dp/B07MZQ8GSN
I made the mod on the exact smps. Variable works down to 5 VDC but I can not exceed 12 vdc. Everything has been triple checked. I want to charge at 14.2 VDC. Can you put some though into what I may have done wrong?
Hi Lindsay, would it be possible to make a broader output control? Something like 10 - 36v? Even with switches from something like 10-20 20-30 30-36? Or the internal transformers or other components can't handle higher voltages (except of course the output caps, easily fixable)? I would love to have something like that to control a CO2 laser! Thank you very much for all the explanations, on the site and on the video! Cheers!
Definitely,, but it would be far more sensible to initially start of with a supply designed for higher output voltage. For example, there are plenty of 36V or 48V supplies available which could probably be modified in a similar fashion to this one. I'm not sure what the undervoltage cutout on these would be - you might need to disable that as well, if you wanted to adjust it really low.
Hi, I have the same power supply that I use on my 3D printer. The fan on it is quite loud, so I removed it, and 3D printed a cover to mount a silent 12V 120mm fan. I tried to connect the fan in the same output as the old one, but after a few seconds I could smell something, so I stopped the power right away. I think it was the R37 22 ohms (according to your schematic, thank you for that by the way).
I now connected the fan to the 12V output of the power supply, but now it's constant speed regardless of power usage. Do you know what I have to modify to make the fan work like the old one? also do you know where is the thermal switch located? I could not find it on the board. Can the thermal switch handle the new bigger fan? Thanks for any input!
If the new fan was a higher power rating than the old one, the higher current draw might have caused the resistor to overheat, so that's probably the reason. You could always replace the resistor with a higher power rating version. The thermal switch on mine was a small metal-can device glued into the center of the big toroidal output inductor - you can see the two thick black leads on the video. Yours might not actually have a thermal switch - I've seen some variations between supplies - but it should definitely be visible if it's there. It should handle the current no problem - those little metal switches typically handle 1A at 230V or so (even though it's only being used here to switch the 12V fan). Hope that helps!
@@imajeenyus42 Thanks for the quick reply! It looks like my power supply does not have the thermal switch, but the fan does increase the speed as I draw more power. The fan reaction is almost instant, so I think it's based on current instead of temperature. I took a picture of it: postimg.cc/G4qtF3z3 I don't have the skills to reverse engineer the power supply, so I will just leave the fan connected to the 12V output for now. If you are interested to mount a 120mm fan on yours, I uploaded the STL here: www.thingiverse.com/thing:3476492
@@mike36801 Hmm, that's interesting - I didn't realise that some supplies did proportional control of the fan speed, rather than just off/on depending on temperature. I don't see how it manages it, because there's not apparently any extra components visible! The layout is nearly identical to mine (some stuff moved around a little) - is there anything hiding under the transformer?
@@imajeenyus42 Hi, I finally had the chance to open the power supply again. Sorry for the delay. I looked under the transformer and I could only see 2 diodes. The fan (before I made the change) it was not proportional, it had low speed and high full speed, it did not vary in between. But it was turning on at full speed as soon as I was starting to heat the nozzle of my 3D printer. When it reached at required temp (220 degree for example), then I could hear the fan going down in rpm on the power supply, even though the 3D printer is still drawing power because it has to keep the nozzle at 220 degree. The power draw is pulsating to keep it up to temperature.
Hi, just out of curiosity, could you please point out for me, why the output rectifying diodes are arranged this way, I mean why 2 diode packages, connected "in series" with transformer output, it seems to me that only one diode out of each package is doing the rectification, what is the purpose of the other two (1 out of each package). Standard ATX PSU for example uses only one diode package.
Each package contains two diodes, like you say, which share a common cathode. The anodes of each diode are tied together, so you end up with the two diodes (in each package) in parallel. This is quite common in higher-current devices - it's maybe more difficult to make a single high-current diode than it is to make two lower-current diodes and connect them in parallel. An ATX supply might only be using one diode if it's a forward or flyback converter instead.
Thank you for taking your time to answer my question. I've looked at you schematic again and now it all makes sense, for some reason I've completely ignored the fact there was a connection between package diodes anodes, and mistook the line for representing the package itself... I guess I just need to spend more time reading circuit diagrams. Sorry for wasting your time.
Don't worry, I'm happy to help!
Hi,
Great video, reverse engineering is my favorite !
I've read carefully the pertaining article on your web site.
I have one question concerning the 'current' section (the one paragraph thats starts with *_Opamp #2 of the TL494 is used for current limiting_*).
First of all, I'm surprised they did not include an opto-coupler in the TL494 loop-back section, that would have really isolated the output from the mains.
Anyway, I want to use this SMPS as a 4S LifePo4 charger with a 20A charging current.
The initial 'Bulk' section of the charging must be a CC/VV (constant current/variable voltage) that must be followed (as soon as the battery voltage reaches 14.6V) by an 'Absoption' section at CV/VC (constant voltage/variable current).
Do you think that if I would make a mod to R21/R35 and make them variable instead of fixed values that woud help to control the intial output current to 20A with an increasing output voltage and *THEN* as soon as the battery will have reached the set voltage (14.6V), the current will go decreasing ?
To make a long story short, I am not quite sure how output current and voltage are intricated in this SMPS ...
Can you share experience and give me clues on that ?
Thanks for commenting. I'm afraid I don't really know how that would behave - while adjusting the R21/R35 combination would allow the threshold to be changed, I'm not sure if that would then function as an actual constant-current regulated supply. That being said, someone has apparently converted a supply into a constant-current charger for an e-bike, so it would be worth taking a look at their info. There's a github page here, and there's info about the constant-current modification at the bottom of it: github.com/matteljay/ebike#converting-a-60v-led-switch-mode-power-supply-to-an-18650-cell-charger
@@imajeenyus42 thanks alot !
Hello, I am doing the same thing with the same type of 24 V - 15 A switching field
I did it, but the voltage changed only from 9.6V to 16V.
Among them, the transistors Q1 and Q4 were broken, especially from Q4, the fire came out.
It is very disappointing. Please tell me what to do and what are some good ideas.
You are a very smart person.
A bad head like me has a hard time.
I'm sorry in poor English.
Thank you.
Sounds pretty terminal - Q1/Q4 are the main bridge transistors. Assuming you can get a working supply again, either by replacing the transistors or just getting a new supply, you could try just increasing the the existing trimmer pot (VR1), rather than replacing the entire feedback network. The response won't be linear, but it's a simpler modification and less risky. A larger value for the pot will let you adjust the voltage lower. Hope that helps!
Hello, thanks for the reply. I am happy that I could interact with foreign people. It is good to replace the transistor Q1Q4 and increase the resistance of the part of the volume. Thanks to you I'm sure I will not lose 35 dollars. I will do my best and try. I thank you.
Just by mistake I conected the same power supply to 220V with the switch in 110V, the only thing i've seen it's broken is Q4, is there anything else that could suffer damage?
C3 may need replacement since you have applied approx. 220 x 1.4 volts into a capacitor rated at 250V
After days of frustration, my low voltage output was due to the mains voltage selector switch was in the 220 vac position DOUGH!!!
Thanks for sharing the idea
I have a Question
How i can make it work to be 4.2volt with the same current Amp ?
Can you help me about this
Iwill be so grateful your kind help
It wouldn't make any sense trying to modify a 12V supply to give a 4.2V output. Get a 5V supply instead, then see how much adjustment you can get from the existing potentiometer.
@@imajeenyus42 not available in my country 😔
@@ezaztyco2434 There's plenty on eBay, AliExpress, Uxcell etc.
Mr Wilson
I have a way to make the cooling fan running regardless of the output voltage. In my modification the voltage for the digital voltmeter ranges from 12 to 18volt of the power supply circuit for the meter. If i take power for the fan from meter power and using lm7812 regulator.
Do you think this method is ok and no harm to the power supply and its output?
Thank u
Yes, that should work - remember that the LM7812 has a dropout voltage of around 2V, so your fan will run at a slightly reduced voltage until the power supply reaches 14V.
@@imajeenyus42thanks
How about the lowering the output voltage a little bit more to 4 volts,mine the lowest reach to the 5.9 volt
Which resistors in the divider network i should change to get the 4 volts at the lowest
@@amirvafa7344 You would want to increase the value of R4 - this will decrease the lower voltage limit. However, you may then run in to problems with the short-circuit protection circuit kicking in, in which case you would have to remove D13 as described on my page.
Thank u bro
As soon as l added a load to the output ,the lowest voltage came to 4.8.and every thing was perfect
No need for any changes
You were a great help for me
Your description and analysis of the circuit was perfect. I learned very much
..im not professional in electronics
Im just an aircraft electrical technician
Which mostly our jobs is troubleshooting for wires and generators which rarely involved in electronics
Take care and bye
plese can i modify it to output 3000 v pulse not dc or dc no problem please
Uhh....please stay away from anything electronic, if that's how you think power supplies work....
Yes ,it is good to do that
will be a exelent product if you make a lion litihum cc cv charger modifiin a power supply....
Hi,
In your picture, the sense pin of the voltmeter module is connected to the jumper named J9 in the pcb diagram. My power supply is not fully compatible with your source. Please explain what other circuit elements the jumper named J9 is connected with?
I'm not sure what you mean - there isn't a J9 in my circuit diagram. The sense connection of the voltmeter module is connected to the output of the power supply.
@@imajeenyus42 I'm talking about the J9 jump shown in the red circle in the picture. Which circuit elements this jumper is connected to. i.resimyukle.xyz/R8OHW0.jpg
@@technology520 Ah sorry, I see now. J9 is weird - both ends are connected to the positive output, so it doesn't actually do anything! I don't know why it was added, possibly just to increase the current-carrying capacity of the PCB trace and reduce heating. I used it as a convenient connection point for the output voltage sense.
@@imajeenyus42 Thank you for your answer.
@@imajeenyus42 Hi,There are two UF4004 diodes that connect to the voltmeter module. Can I use a 1N4004 diode instead of these diodes?
Hi. I have a question for you.
When the 12V is applied, is the output 30A?
Not sure what you mean - the load will draw whatever current it requires, according to Ohm's law.
it can be (max) 35A in short time...before overheated and melting...
προσθετω επισεις οτι η τροποποιηση ειναι παρα πολυ απλη και ευκολη με μικρη πτωση τασης στα 20 αμπερ
I did the schematics many years ago, and ever keep looking for the web without any of that until today that your post appear despite you say you post it in 2015.
Some details in your schematics i found and are fail, first C5 is in conection with C10 in one side and the 3 resistors in the other and not as you put in your schematic and the second is that R26 connect to anode of DB1. I didn't see in that day that jumpers were shunt and put the coil connected to ground and thanks for your measure (i have not a miliohmeter) i'll fix that.
Here my schematic i did in 2014
i.imgur.com/pJII94G.jpg
These differences are electrically identical - they won't affect the operation of the circuit any.
@@imajeenyus42 Yeah, you and I both know that electrically won't affect but when is about a reverse engineering and documentating anything it must be 1:1, the most exact as possible to get it. Don't take it as a destructive critic but rather as a other eye that look that you skipped. I also skipped the shunt resistors in that moment and didn't care about it, so, i must admit you open that part i was blind (due a lack of instruments). Best regards.
Cud not see the circuit.need to add variable voltage and variable current to my 24v,10amp smps.alao add a voltmeter and ammeter.nees this for electrolysis.
Please visit the link in the video description.
I need to add a variable voltage and variable current potentiometer.
@@natarajvenkatadri921 These supplies can't do current regulation. You'd be far better using a separate module to do that. Search eBay for "constant current step down converter" or similar.
@@imajeenyus42 tried a few,they keep blowing.i need to control output current,not very particular ABT regulation.like I said,need this for electrolysis.have found a source for such a Chinese smps.shud be getting it soon.
Si anche la modifica per fare da 12v a 24v?
No
Hey Bro nice work i am going to buy vigen 500W U.P.S power supply from [made in China.com]
It is a 24Volt Power supply
Will your components will fit as it is in it?
Plz reply Yes or No !
Sorry, I've no idea. If it's a UPS, it's probably an entirely different circuit.
@@imajeenyus42 It is not a ups consider it as a usual 500w psu
It is a ups+psu
But psu will be same
Is this power save to powering motor DC?
I don't understand what you mean.
@@imajeenyus42 - nothing, I have answer in this video
γεια σας απο το ιδιο τροφοδοτικο των 12 βολτ εχω παρει ρυθμιση 4.7 βολτ εως 22.7 βολτ ευχαριστω
Ευχαριστώ πολύ! Χαίρομαι που το θεωρήσατε χρήσιμο. Σημείωση - ελέγξτε την ονομαστική τάση των πυκνωτών εξόδου αν την χρησιμοποιείτε πάνω από την αρχική τάση.
www.szeverreliable.com
Hello, very nice work, I was wondering why you could not just remove the trim pot for v-adjustment and wire a 10k pot in it's original place? Thanks in advance for the reply
Thanks - you could, but you'll then still have the problem of a nonlinear adjustment, plus the possibility of instability since the frequency response of the feedback loop will have changed.
Lindsay Wilson one other question please, I want to make my 36v 16.5a supply variable so I take it my values would be 3 times higher than you used in this for components in the conversion except with possibility of the 10k pot?? Thanks again for any help
I bought a couple of these PSU 24v 20a but have 24v AC ripple across the DC output, any ideas anyone. Thanks
Jeff Cole 24 ripple ?!? Yikes. Something sounds seriously wrong with them - are the output filter caps good?
Checked the caps and looked ok 0.6 ohm and close to the spec. I overloaded the units and replaced some resistors and MOSFETs. Perhaps I'll change the filter caps as well sometimes you forget the routine. Everything else reads OK and looks fine. Thanks for the fast response.
0.6 ohms is not that good !
Came across your website/video from doing a google search on this model of power supply.
I have one of these Power Supplies for my 3D printer, which is in the next room, the only problem I have is it causes me hash/rfi on 160m, it's worse when the current draw is high on this power supply, i.e heating the bed/hot end.
I wonder if there anything I can do to this to stop the hash/rfi it's putting out on 160m (1-2mhz)
Great website by the way :)
Hi, I would try adding an extra line input filter before the power supply to try and block any RF that it's putting back on to the mains input, and I'd also try adding another stage of output filtering (DC inductor + more smoothing caps) to do the same thing at the output. Also maybe use shielded cables going to your heated bed, in case that's acting as a bit of an antenna?
επισεις εχω προσθεση και ενα ποτενσιομετρο 1κ και κανω ρυθμιση ρευματος απο 500ma εως 30 αμπερ το τροφοδοτικο ειναι στα 33.7 αμπερ
Hi
In my PSU board C31 is 33 nF.
Could i replace it with 47nF?
Why would you want to change the value? That'll change the frequency response of the feedback loop.
@@imajeenyus42 In new divider you replace C31=100nF With 47nF.
Should i change it too to get higher frequency response?
@@mohammadrezasafari102 All the component values in the new feedback network, including C31, were chosen to result in a roughly similar frequency response to the original feedback network. If the other component values in your supply are different, then you'll need to change the values in the new network as well.
@@imajeenyus42 Only C31 is different, other components are same as yours.
Should i change them all or just C31?
@@mohammadrezasafari102 What exactly are you trying to do with the power supply? I don't understand.
Price
What do you mean, "Price"? I don't know what you're asking. The price I paid for it? The price I'm willing to sell it for? Which I'm not, because nowhere have I said that this power supply is for sale - I don't even have it any more. Why do you automatically assume that it is for sale? A one-word question isn't going to get you far.
εχω αντικαταστισει τους πυκνωτες των 16 βολτ με 35 βολτ στην ιδια χωρητικοτητα
Εξοχος!
@@imajeenyus42 can i replace two big electrolytic capacitor? default electrolytic capacitor like cheap capacitor?
@@SIAgarage Sure - just make sure the voltage rating is suitable.
@@imajeenyus42 Thanks dude, i will replace that. I want to do what you do. Make large range voltage. But in my case the mode switch is 48 volt 10 A. do i have to change some resistor? I dont know to measure sense voltage to ic.
@@SIAgarage You will need to change the feedback divider. Please see my webpage (link in description) for information on this. You will need to determine suitable values for your supply to give the desired range.
This Video Is 1.2v - 15v : ua-cam.com/video/cVfdtUZ2eWk/v-deo.html
Things a pos. Horribly noisy circuit. Junk
I don't understand what you're talking about.
Hi buddy. Thank u for your efforts to help those who are interested in modification in electronic field
May i have your email address
Since i cannot send pictures and my questions via the comments . No item to send u some diagram of my own smps.
lindsay@imajeenyus.com
@@imajeenyus42 Hi
First thank u for your very useful explanation of the modification in UA-cam.
Im a technician from iran. I sent u comments on your video for a help on a subject. Please in case u got free time
Think for my problem on smps s-360-12 30A
Chinese made model
@@imajeenyus42 i will mail u the problem with pictures and diagram later
Thank u very much