Simple fix to get rid of most of the switching noise. It's a possible scenario that the power supply was originally designed to use different mosfets with much higher gate capacitance, but then the manufacturer bought a cheap truck load of the Fairchild mosfets and used those instead.

Completely different Power Supply, same problem, same solution. Thanks for pushing me into the right direction. I realy like the way of how you put your videos together. No mocking about, no endless talking about the same thing hundrets of times over... Straight to the point, boom, live with it. Like it.

You went a Longwei to making the power supply almost perfect!

The probe "antenna" along with your surmising the problem was overdriven mosfets and your solution represent an unusually high skill level. Most excellent! Thank you.

I love when you busted out that book of resistors. That was boss!

I've never seen that trick with the loop on the probe before. I'm chasing down some HF noise in a completely different context and that will be really useful, thanks!

With very little load on the power it was jamming my icom 7300 ham transceiver and putting large pulses on some TTL logic signals I was testing. Your corrections fixed the problem. Thank you!!!

Great work, the videos don't get any better than this. You are a very good teacher. I will do this mod to my pwr supply. Thank you. I couldn't read the part number of the cap, you might consider posting a parts list in future. Thanks again.

Just implemented this modification. It works absolutely great. I was really getting annoyed with all the noise of the PS but this solved it. Thanks!

Done. 400mV noise before, 10mV after the mod. Great.

I was considering buying an LW-K3010R then I saw your earlier video showing how noisy the output is so I changed my mind. This video made me change my mind again and I've just ordered one! Thanks for both videos. I've subscribed, liked, and I'll be watching your other videos after this as I like your style and content. Good luck with this channel.

This is so educational and wonderful use of the scope to track down the issues. Thanks

Really helpful videos, thank you for these. I was casting around for a cheap 10A power supply and this convinced me to go for this one.

Thanks, it is a real pleasure to see such intelligent step by step analysis and solution development. I also liked your EMI detection tip. Yes, my degree is from 1972 so I too must learn SMD soldering skills, hope my eyes will be up to the task!

I love the quick and dirt EMC probe. Love it ! Great video !

Cheers! Bought this and did the mod straight outta the box (albeit with 0805 resistors!) LPF with a corner frequency of 102.6KHz.

That's a good tip (ha) on using the ground wire of the scope probe to generate a pickup for pinpointing noise. I always used a few loops of wire but did not think of using the probe wire itself. Nice job rooting out the noise source. Adding the RC filtering helped significantly making the supply a bit higher in output quality. Cheers,

Nice tip on how to use scope probe to pinpoint noise source. Video was way worth viewing just for that. THANX...

Very good investigation of the problem, and explanation of your fix. I have one on order from BG, so will see if I need to do it when it arrives.

Thanks very much for sharing this mod, have just done this to my unit and its made a massive improvement too!

Thank you, good sir! I'd never have found the source of the issue on my own. Now I can get down to fixing it.

Nice mod! And also clever home made probe to scan for EMI 8-)

Great video and something that LongWei should think about doing to improve their product. I can't imagine it would affect the cost all that much and it would bring the rating of their product up over others within the same budget market. Wish I could tag them in this comment... :)

Great Video ... just got hold of the same power supply ... may attempt this fix one day myself ... thanks again ...

I ordered the exact same device. Will try this mod when it arrives. Thank you for the wonderful vide.

Ive recently bought an RS310p 30V 10A PSU. Ive bookmarked this video and will do the same mod to the MOSFETS in mine. I'll also add an inductor between the board and output terminals.

Wow. Great. It shows the in depth knowledge on how SMPS. Thank you.

Very well done, for switching power supply I think it is the best solution.

Wonderful video. As a MSc Electrical Engineering from 1998 I got to 'update' my SMD soldering, but this is gonna work. For reference for others: the components and their respective values you ended up with are at 14:47

Thank you for sharing your opinion of this power supply and especially the noise reducing mods. My PSU arrived today so I'll order the parts as I know I don't have the resistors and I'll have a look through my caps. Great channel, so subbed, thanks.

This was very helpful. Thanks for the great video.

It worked! Fantastic!

Thanks , fantastic video for people who do not have the practical experience and are not familiar with SMPS ! I have learned the trick of "coiling" the scope's ground wire (making it an Antenna). The manufaturer of this SMPS should take a look at this video :-)

Well done!

Thank you for knowledge about switching power supply, you are great teacher.

A big thanks for the excellent video. I've risked a Topshak (BG's own rebrand) LW-3010EC and hoped that the core is the same (from the LW- type) and yes it is so I did the same mod (actually with 2 of them after seeing the result of the first one and how reasonable the price was) with very similar results (although used 27 Ohm 0805 as that was in my drawer and didn't want to push it too hard as for really low noise I have linear PSU). RMS went down from 12.7 to 3.7mV and Pk-Pk from 281.1 to 83mV in a noisy environment (checked with DSO, tried to avoid noise leaking in as much as possible). One issue though: I guess it's not just about more heat but also reaction time for quick load change that has increased as well. None of my concern, just perhaps something that's also good to be aware of.

Thank you very much for the explanations, impressed by your knowledge. I know that I am a bit abusive in putting it into this topic, since the topic that I am going to indicate to you differs from the one presented. I describe a problem I have with a system based on an ESP32 microcontroller. After many programming tests that I carried out in the house where I live, I got a stable system without resets that works well, but when I moved it to its destination to my country house to control irrigation, boiler, hot water, heating, mains water pressure, temperature... etc. , I discover that the system resets randomly many times a day. The only explanation I can find is that the mains current reaches my house with an unusual noise. I have tried different power supplies for the ESP32 that works at 3.3V and the differences are minimal, and it is independent if I keep the ESP32 disconnected from all the sensors and relays, the problem is always the same. Could you tell me what I could do to eliminate the noise that surely makes my system not work continuously, thank you very much for your help and patience.

Lovely!! I wonder if we can replicate this process on other brands of cheap bench power supplies

absolutely wild!

Very impressed with this video presentation thank you very much.

best modification for 5 yaer of you tube EE univer's ty man

Wow amazing video. I hope I can apply same approach for my meanwell LRS-350

Thank you for you effort. Saved me a lot of time, my thanks

i have a wanptek supply and the noise is insane ! I measured a ripple of over 4v @ 24v output no load. A outputfilter could also help

Very useful video. I will attempt this on the Kungber 30v/10A supply. Am sure they would be somewhat identical.

I just opened my LongWei PS-3010DF to compare it with the K3010D in this video and it's almost identical. When putting everything back together, I was testing the ground connections (front ground banana socket and back AC line connector socket) to verify continuity and noticed that the metal chassis is not grounded. A bit concerning, considering that the incoming live wire is only soldered to the underside of the PCB (the PCB lays flat in this model, not vertical) and close to the chassis bottom.

Nice mod.

Very helpful thanks.

Great video and very nice technique in breaking the tracks to add the resistors. It might have been interesting to see the same test with ferrite beads rather than resistors.

Thank you for the mods. Did you notice that the power switch only turns the power off to the bridge rectifier but not associated mains input filtering circuit , also the metal case is not earthed.

Hi nice video ! but for me it looks risky to tune it without analyzing the pulses on the gates, to see the deadtime and also to evaluate the increase of heat of these transistors ! i'm curious to see the curves of gate signals and how much this rc filter is slowing down it. how about a correct current loop for the transformer, transistor and capacitor with also a shield ?

Thanks for the info.

Nice to know before i buy one of these things what to do

Very good video

Excellent

hello there, Thank you very much. I have 2 of that same PS only one does this the other one is very quiet. BG (big prase here) is sending a replacement, it was so noisy I could not test anything with my scope because of the noise this PS putout the trigger would just not lock. if the replacement does the same thing I will do this. Greate fix.

Yes it will limit the noises because of decreasing dv/dt That means the mosfets switch slower(fall time and rise time increased) So the mosfets will be get hot and ...dead

Hi, thanks for the great video! I got a new Longwei PDS-3010G. I think it's probably quite similar to the LW-K3010D and I'd like to improve the noise/ripple. One difference I see is that the MOSFETs B22 FQPF 10N60C look more like "fakechild". There is no Fairchild logo on them. That should work anyway, right? I'm not very experienced. Thanks a lot!

My power supply is : Jesverty sps-3010n, 30V 10A , with no load make a noise but when put load there’s is not noise how to fix it ?

Great video, thanks! They should just incorporate your fix into the power supply.... one can hope.

what about the improvement of the snobbers instead of slowing down the gate, we could perhaps avoid the loss of thermal efficiency (noob's question), good video thx

So looking at the new version of this powersupply, looks like longwei fixed the noise issue using a very similar method. I was going to do the mod but saw that there was a 10 ohm resistor on the gate of the MOSFETs. No extra capacitors though.

I just order one now. Was looking for a cheap model. Thx

Hi sir, I need your help, In doing the mods I did a mistake in the bottom mosfet for an error indeed of a 22 ohm resistor I put a 22k. During the test at 12V everything seems working but when I push the voltage to 30V I got short and the house protection cut down, after verifying my fault I dismounted the Mosfet and verified that its pins are alla shorted out, I fear can be more component to check, the 22k resistor on the source is ok what else should I have to check other than the mosfet that is broken for sure? Thanks

Hi ! thank you so much for this excellent video I subscribed immediately and i will watch all other video on power supplies, my main interest these days. I am a beginner trying to learn something. I have some questions. 1) in order to understand better the cheracteristics of noise would not be better to check with a spectrum analyzer ? to see the noise vs. frequency ? 2) as i am looking for very low noise voltage sources for some audio preamps i am putting together ... which would it be your first choice for a very low noise voltage source ? linear or switching ? and in case of a linear PSU do you think that IC regulators like the common LM317 can get down ripple to some mV or a more complex design is needed ? In my testing i have been amazed by the difference i can listen from a same preamp using different power supplies. Incredible. With higher noise PSU the sound is confused muffled ... with lower noise one is crystal clear and very nice. I am using a LM317 regulator at the moment bought on ebay. But i am very willing to try something else even less noisy. Thank you very much again. Kind regards, gino

Excellent video. Looks like you used a mica capacitor. What voltage do you think would be appropriate for a 30 volt power supply like this?

Why adding an extra capacitor instead of increasing the gate resistor? It's R x C that counts (where C = Cgate + Cextra), so you could just increase R and leave the extra capacitor, no?

Thank you so much for everything. I live in Viet Nam, longwei power supply is the best deal for me now. How does the bench power supply work in this year after noise mod?

Top draw modification. Great presentation. I was looking to get the LongWei 3010E with the extra pre-set and lock button functionality. Looks great until I read the Ripple and Noise specs; CV≤30mV (effective value) ; CC≤20mA (effective value) - I guess 30mV rms ! and 20mA rms ! Really ? Hoping the circuit is similar to your modified LW-K3010D, as apart from the dreadful noise issue the rest of it looks good value. Do you have any familiarity with the higher spec 3010E please? Keep up the good work.

nice job!

Nice video, I was wondering if a 1/4w or 1/2w through hole resistor instead of a 0603 would achieve the same effect, or if they would be less effective somehow? I don't have any SMD 33Ohm resistors on hand currently. Thanks

Good Day sir, i have same model but the issue is when i increase the output it doesn't increase more than 8.9 volts. Do you have any idea on what could possibly the fault? I already reaplaced the multi turn pot. But the problem stays.

Bravo!

Just have bought one of them, thank you it will be very useful for me in the future! Do you think this could be a problem for working with audio frequency signals? At which frequency does the noise really become a problem?

i have a minleaf 30v 10a power supply i havent got a scope to check it though well i have but its one of those mini DSO138 i dont think its capable of these tests but i could be wrong.

hey brother i need your help, i have this power supply but when i turn it on and turn the current knob the green light does not come on so i can't adjust anything, i can't figure out how to get it working

Hello!! About 1,5 years ago, I bought through Banggood this product LW-K3010D. Since last week, I started having a problem each time I try to raise the voltage from 0-30V on the POTENTIOMETER. It does not exceed 9.2V on the screen, but also at the output of the connectors. Since it does not work properly, I cannot use if for my job. Can you please advise me on how I could fix it? Waiting for your prompt reply. Thank you!

I have the same exact scope as yours. I wonder if there is a firmware update available for it? Nice video, I liked the probe loop technique to detect noise. Thanks.

I have the same model. It just died on me. Zero amp on the display and it doesn't charge anything. I've opened it up and I don't see any components that are blown. Do you know what it might be the problem?

keen

Good video bro. I have this power supply brought from aliexpress, but cant work, because protect led always on. :(

Nice video. I am curious when adding the caps to the Gate, I would think if the Gate is not 'discharged fast enough then you can have MOSFET's on at the same time in this half-bridge setup unless the dead time is long enough and not causing the issue. I also do not see they put on any ferrite beads on the MOSFET's legs to reduce switching noise.

Thanks for the video, very informative, I would like to ask a question, do not understand the capacity of the capacitors used? thank you.

I have 22R and 47R 0805 250mW resistors but no 33R. Based on your previous testing, do you think it would be better to go with the 22 or the 47? Sorry, I know this was 3 years ago already and you may not recall all the details!

Hi sir, i have the same power supply and the problem is that cannot keep Amps stable, up - down. Could you tell me sir where to look or what to replace?

What if you put just the capacitors without the resistor on the gate

good vid. I'm new to this.. Why not just leave it as i, why do you try to reduce noise what is the benefit?? Thanks

I cannot find a schematic for this power supply. I need to help a friend of mine with the current adjust pot, I wish to order a multi turn pot to replace the 3/4 turn current pot, it is too "touchy" Can someone advise the pot value, I do not have the power supply on hand, thanks

would capacitor polarity (shielding) in this case matter? Thank you for putting these great videos out here

R-SPS3010 or longwei(K3010D) . what is the best ?

Brilliant work. My PSU died when I was using it to drive an arcing spark generator (don't ask), but I found the circuit diagram for the same PSU but with a less max ampage. So the area that you worked on failed. One of the large MOSFET's went short, 2 of the surface mount transistors that you pointed to went short, and so did ones of the schotky diodes next to those surface mount transistors - I've replaced all those . The PSU currently pulses the display showing 000 when switched on. Now I'm wondering if the switching controller you pointed to has died? I think this is the circuit diagram I had (thought you might find it interesting or useful) = www.eevblog.com/forum/repair/permanent-cc-and-no-output-(longwei-k3010d)/

30 ohm resistors and 47nF caps. 2 of each. I bought a larger power supply (link in reply below), 120VDC and 3amp, 360W. The 47nF caps shown are only rated for 100V, is this mod going to work for me I think I need higher voltage caps? Can I directly replace the ones in the video with 630V Polypropylene Safety Plastic Film 630V 47nF?

Hi, I just bought this power supply and did the noise mod to it. I have a few issues that I would love to have answers/fixes to. 1. When I touched the transistor heatsinks, I felt the 230VAC go into my finger. It was probably not the full 230VAC, but I definitely felt it. Is that normal? Correct me if I'm wrong, but I don't think it is. 2. A high pitched whining noise is coming out of my unit. When you'd look at the supply on 6:20 that's the approximate location the noise is coming from. Is it the big transformer? The coil right above it? Caps? please advise. Love your vid

does this mod work the same at high power? I also noticed in your old review video on this bench PS that it ha difficulty in regulating in the 20V range. did this mod solve that problem too?

I have a source of this LongWei LW-K3010D it is falling unregulated voltage does not let it go over 9V then turn on the sera fan q can be the mosfet???

The question for me is why can't the Chinese spend the 30 cents extra to add these cheap parts to the circuit and charge one dollar more for a low noise power supply?

what is the reason for removing the noise? i am thinking of powering a radio transceiver that requires "12v", i have not done this yet, but would this noise come through the radio some how?

if I replace 10N60 transistor for 20N60 transistor will have any problem to circuit? I will need change something else ?

is the switching noise as dangeorous as ripple for electronics? Thank you :)

In my opinion, the worst feature of this PS is the current spike when used as constant current supply at low levels. The behaviour reminds that of a line output with a relevant capacitor in parallel. Did you check if your mod do not worsen the already bad spike?