How To Repair a Power Supply- Bench / Lab Version

How to repair a broken bench power supply (PSU)
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Repairing my bench top / lab power supply. It stopped correctly showing the amperage value but was functionally intact. The problem was intermittent so I had a pretty good idea of what I would find- but I went through the troubleshooting process anyhow for the video. This is the 30V 5 Amp version but others may be the same issue.
Usually my first step is a wiggle/tap/flex test for any intermittent problem. Most often a bad solder joint is the root cause.
At almost zero cost we are back up and running without wasting a perfectly serviceable power supply. I hope this helps you in your repairs.
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Cheers!

[@jp-um2fr]

There are several videos on KZbin with exactly the same fault and like you a successful conclusion. I have noted though that due to this super dooper lead free solder the number of crappy joints seem to be much higher than it once was. I don't know exactly why they use it as here in the UK the only time lead solder is banned is on drinking tap pipes. Maybe the Chinese really are worried about their workers. I hope so. Mind you I only use lead and I'm 71 and just twitch a bit and dribble now and then. Good video, well presented and helpful, Iv'e downloaded it for future reference.

[@mortenrobinson5421]

I have an old broken lab supply too, and i broke it myself. I had some friends over one evening and we were drunk, and for some reason I found it funny to continually short the terminals of the power supply to make sparks... the power supply did not like that in the long run.

[@KirkMcc]

I used to be a bench-technician for power supply makers, and I must say I enjoyed watching your technique. SO great that you kind of poked it with the tool handle, letting people know it's ok to do that. That's exactly how we used to work on them. Also helpful was when you told about how old it is. Others who follow this should recognize that when it's basically new, the problems will tend to be different, like bad solder joints. Most of these are built using flow-soldering. When you see joints that aren't uniform, it's often because a tech caught it and sent it to "re-work" for repair or repaired it himself. So often you can spot where the original had issues before it even left the factory. And sometimes joints work on the test bench, but get cracked after shipping. Oh, and the caps on those things are almost never bad, and usually discharge pretty quickly. I suppose your method is safe, but we never bothered discharging them before poking around. I wouldn't bother with it - it's not like an old TV or something.

[@MkmeOrg]

Kirk M Yeah making videos for KZbin I've learned one has to be a bit careful on what they show and do. I threw in the caps only for some info and a bit of caution for those that may wok on something else and may not be aware of them. My actual troubleshooting took place a few moments before the camera rolled. I was significantly more "invasive" one could say- and the problem presented itself in under 5 seconds :) Before pulling the case off a good "thump" told me what I would find inside :) Great comment and feedback. Cheers!

[@KirkMcc]

Eric William -MKme Tech Anyway, thanks for your videos and for your patience with people (like me). I love your stuff, but sometimes can't catch all of it, and never find time to comment as basically it's all been said. I probably should have kept quiet this time, but what the heck. Keep up the good work. I hope you'll be at the Bay Area Maker's Faire this year.

[@MkmeOrg]

Kirk M I appreciate the comment. Definitely should NOT stay quiet :) Cheers

[@robertmotion]

Hello. I stumbled across your comment that u used to repair power supplies. My son and I received a "free" RD6018 display and 60V 20A module. Unit worked for a few...until I turned it off. Noticed green power button pulsating when I turned it off as well as a blue pulsating light inside on display side of unit as well. Company told me to check fuses...both normal. Told me check if AC/DC module is at least 68V with multimeter with the V+ and V- terminals...only got 2.5 on both V+ and V- But, if the display won't power on, then how can I trust that or know that is AC/DC module and voltage reading is the problem...or the display? Company not really answering so ima figure it out myself. I just need to know where to look. Hope u can help Need help in Brooklyn.

[@StevenKiberton]

Such a simple little thing can affect a lot... Glad to see you got it fixed.. Always gives me a good feeling when I fix something that was broken... Good work Eric

[@MkmeOrg]

Steven Kiberton Thanks Sir

[@wolfdeez]

Thank you so much, after changing so many components in my power supply & spending days trying to repair it, I came across your video, followed you... and found exactly the same problem... This is an example of making a good thing & let it travel and fix others problems, I really appreciate that & Thank you again.

[@MkmeOrg]

You are welcome!

[@matejzeman7765]

Another think to bare in mind : Your solder tip may be grounded ! Check before soldering on live circuits ... :) Thanks for vid, it may help me in future :)

[@njm1971nyc]

When I lived in Italy, in an old apartment with dodgy wiring, the electrical earth had so much stray voltage on it that my grounded soldering iron tip DESTROYED a brand new CD player laser assembly. To add insult to injury, the only reason a soldering iron was even required was to remove a blob of ESD *protection* solder! 😭

[@137bob3d]

i was confused at the start expecting to see that led burn out at 999ma. and later thought that if the led wire had an ammeter added to it ... and read true ma ... this could have had you looking sooner at the display PCB. either way you took us on a good journey. and i will be looking at what else you have posted.

[@jorgewashington2981]

Excellent tips for a newbie like me. Thank you for sharing.

[@MkmeOrg]

+Jorge Washington Welcome. Hope you find other helpful vids on the channel. Cheers

[@MrDinakdakan]

i have the same, replaced the potentiometers still interminent, will look at the secondary board thank you

[@rickygundam]

4:00 You can just gently..... 4:13 "poke poke poke" and here's how we all fix our electronics! especially our occasionally functioning TV remote that have a busted batteries cap. btw Nice video :)

[@MkmeOrg]

Ricky Chau Thanks :)

[@usamamando]

As strange as it is, it works... Thank you!

[@tikabass]

I have the digital version of this PSU. It also died, after a short while. It was missing a resistor.

[@李水-n3k]

I've been having a similar issue except current always reads 0.0. I opened my PS3003U up and sure enough it has some horrible solder joints that need rework. Gonna touch these up and see how things go!

[@mojo5157]

I have the same model at work. I'll use this video if I have an issue.

[@mtrltoolman]

I wonder how does this power supply current adjustment works ? is it have any dummy load resistor?

[@nor4277]

I have one have not use mine yet but I have seen a few videos on these power supplies ,Chinese lack of quality control .

[@MyWillyboi]

@EricWilliam GREAT JOB ERIC!!!! VERY CLEVER FIX, THOSE TIPS WILL CERTAINLY HELP ME WITH TROUBLESHOOTING AND REPAIRS IN THE LEAST. I JUST SALVAGED A PORTABLE DVD PLAYER FROM THE YEARLY DISCARD PILE AT THE CURB, WE DO A TYPE OF CITY WIDE "SPRING CLEAN" NOW I HAVE A LINUX RASPBERRY PI "MONITOR", ALTHOUGH I HAVE ANOTHER FROM ADAFRUIT, THIS WAS EASY AND FREE A/V MONITOR, NOW FULLY FUNCTIONING. QUICK DC POWER JACK REPLACEMENT, AND BINGO!!

[@MkmeOrg]

MyWillyboi Good stuff

[@Shazzkid]

I thought you were AVE, im very disappointed

[@ljprep6250]

Quick and dirty, just like I like my repairs. Ta!

[@SpectreOZ]

I always enjoy DIY electronics repair videos... cheers or sharing :)

[@MkmeOrg]

***** Thanks!

[@SpectreOZ]

Fault finding technique is always educational...

[@andrewverran3498]

Hi mate was in the hi/lo amp push button in the middle , I have the same type of ps but ut does not have this ? Cheers

[@philipecaing1273]

i got voltage but current stays at 0 no matter how i turn the knob. and when i short the probes it hangs up including thr voltage. led light turns to greenish

[@robertmotion]

HELP!! Great video. Hello. I stumbled across your video tryna find help. My son and I received a "free" RD6018 display and 60V 20A module Unit worked for a few...until I turned it off. Noticed green power button pulsating when I turned it off as well as a blue pulsating light inside on display side of unit as well. Company told me to check fuses...both normal. Told me check if AC/DC module is at least 68V with multimeter with the V+ and V- terminals...only got 2.5 on both V+ and V- But, if the display won't power on, then how can I trust that or know that is AC/DC module and voltage reading is the problem...or the display? Company not really answering so ima figure it out myself. I just need to know where to look. Hope u can help Need help in Brooklyn.

[@masonreimert]

Always the simplest thing with electronics!

[@MkmeOrg]

mason reimert Yep :)

[@treadmillrepair754]

Hehehe I have the same power supply, same meter Fluke 289 and same ESR meter. ESR are not the best, I have one 20 years old Dick Smith ESR meter and is too much better. Cheers.

[@amitghosh6966]

Please show circuit diagram of this power supply. Is it Linear regulator one or smps buck converter one?

[@LupusMechanicus]

Thanks so much! I have a similar intermittent problem and had no idea where to start. Well I had an idea it was in the front plate and a diode look suspicious but this helped alot. Edit: Well I guess I am too good of a jiggler as it magically works again, I'll have to go through it with a soldering iron when I get time!

[@MkmeOrg]

+Lupus Mechanicus Nice :)

[@svsv9]

I have same PSU, I replaced the potentiometer, and the psu still float the regulated set voltage I need it to work on, example: it will jump from 5v to 3.4 back to 5.5 and so crazy on, sometimes it get stable. I hear how relays switching while start get unstable. Some help, what could I check?

[@officialmysteriousrider6327]

MKme LAB ive just bought the 1503DD+ model its a 15v 3amp now it works fine for like powering stuff like moters bulbs anything that runs on electric but it doesn't work for like zinc plating it just bleeps & flashes all the time between the anode & the part that i want to plate i dont get why it works or anything else but not for like zinc plating stuff & that's what i mainly bought it for could you help me out please buddy

[@Ricardo-ee2mt]

Hello, I have my source YIHUA PS-3010D, it works ok. How do I adapt the 4-digit ammeter and voltmeter? Do not use the one with 3 digits, please if you can recommend the right model and stores where to buy it. Greetings from Madrid.

[@legominimovieproductions]

On mine (same as yours just other name) the OC protection is screwed, sometimes when the oc kicks in, it randomly starts pushing the voltage up to 80! volts. Dont know whats wrong, do you have an idea?

[@nor4277]

I just bought one of those power supply this video makes me nervous of my purchase, I haven't used mine yet I bought mine to test power some of the chinese kits I buy.but this was a great video

[@ventureelect]

I have had one for 10 years now and use it every day. I have tortured the poor thing. Still works well.

[@rogeronslow1498]

Linear power supplies don't require or use low ESR capacitors.

[@vincentmulwa2792]

I have a lps605d rated 60v 5A, it's showing 99v at output even when measured,opened inside and didn't find anything,any ideas?

[@fatnick2001]

I have one that recently started tripping circuit breakers. Disconnecting the front knobs (voltage potentioneter, and analogue dial) it plugs in and is fine. As soon as i plug in the front plate, it trips circuit breaker. Any ideas?

[@Saidavali.123]

Hi sir , I have one dc power supply beetech 3002. This RPS not running but input supply is perfect.please tell me how to identify what is the problem in rps.

[@DrZipZwan]

I have a Bench Power Supply very similar to this one. When I set it to 12v, after a few second before to be have to add any load voltage gets crazy, it jump to 13 sometime 15v, it does that everytime. So I need to be very carefull when using it, set the voltage , wait a bit and if it doesnt fluctuate, I can add the load. I dont think it is an issue with the pots, because they are fine when turning them to choose voltage. But once I leave them set on specific voltage as said, after a few sec, hope it goes crazy and decide to rise voltage or decrease it. Any idea where to look to resolve the issue?? Thx

[@DrZipZwan]

@@IanApkiewicz nope

[@stewiegriffin6503]

2:35 aren't those jumping numbers on multimeter annoying to you ?

[@MkmeOrg]

Nope

[@NotCaily]

YO YO YO i have a problem with my QW-MS3010D DC power supply with 10a 30v max when it starts up it will go up to 65volts and i can not control the the amps or volts now :(

[@ZeroMass]

did you ever find the fix? I have a 5A version that hits 50V and no response to control of V's or A's... FFS > : (

[@otheruser1541]

hi... i have loadstar LP3005D (30V 5A) dc supply machine.. the problem is Voltage is increasing up to 12V only.. changed potentiometer and relays still same issue.. kindly help

[@shabbirahmed5244]

Thanks bro......

[@MkmeOrg]

Welcome

[@LITTLEEXPERIMENTCHANNEL1]

I have a similar problem with mine, however I think it might be the "pots" I tap the board and it doesn't change but when I spin the pots I get voltage all over the place and the current output does the same? Anyone had that issue, I can still use the unit but I can't trust it will remain on the same voltage.

[@CountParadox]

Thanks! Nice video

[@MkmeOrg]

CountParadox Thanks!

[@vasilarsovski9804]

I have the same problem, but i resoldered everything on all the boards, still reading max amps and i cannot regulate them. Just like in the video

[@swansealoaf1999]

I've got voltage on mine but intermittent current any ideas

[@hjcontacts]

very nice video.. i do have a problem and came across your video while searching.. thanks for taking the time to name it.. the problem I'm having that the power supply is at 12 volts and was passing 0.35 amps on electrolysis process.. like you said those are crappy things.. too bad my friend threw out the invoice for the warranty. anyways it was working fine couple of days ago but when i checked it today the current dropped to 0.02 and stayed there. though i could get it to increase if i lower the voltage to 9 volts. if i turn the power supply off wait for a bit.. turn it back on. it goes back to normal for 2 or 3 minutes then it goes back to 0.02, any hint of where i should start trouble shooting? what is the component that leads to such behavior? any idea?.. i would appreciate it so much. thank you

[@MkmeOrg]

Not sure. Sounds like it is just toggling between CV and CC mode. I'd say check it with a known load.

[@hjcontacts]

+MKme Lab thanks bro.. it was working fine with a reasonable load.. for the electrolising it seems that i can't go above 16 volts and 0.50 amps.. so far it's doing good.. I'll check on it after couple of hours =) thanks for the help

[@MkmeOrg]

Hussain Johar I think you might find it will be the resistance/conductivity of your electrolyte. Add something to alter your water perhaps such as more washing soda. Might crank it up a notch.

[@hjcontacts]

+MKme Lab ahhh can't do that if I'm planning to get naoh of ph14. right now it's ph12.2 so that's good.. the reaction is stable so far which is good... thanks for the quick reply bro

[@MkmeOrg]

Hussain Johar No worries. Good luck

[@CHIBA280CRV]

Fantastic thanks

[@MkmeOrg]

Welcome. Hope you find some other videos you like on the channel as well. Cheers

[@stevenA44]

I have power supply that looks identical to yours (on the outside...haven't looked at the inside yet) but a different brand. I am wanting to replace the transformer so I can have a higher current than 5 amps. I'd be happy with 10 amps. Any thoughts on this? I have a few transformers that came out of some other electronics and one is around the same voltage as the one in the supply. Not sure of the amperage yet. I have years of experience with electronics and electricity.

[@MkmeOrg]

You are not going to get it to give you more higher than rated amperage by just changing the transformer...

[@stevenA44]

@@MkmeOrg OK, do you have any idea of how I can get it put out around 10 amps then? Maybe by changing the voltage regulator or something like that? Just curious.

[@guyteigh3375]

@@stevenA44 You will need to uprate the transformer AND uprate the output stage AND possibly modify the current sensing circuit. In reality as a great leaning curve in how to re-design kit, it might be worth doing - from a sensible use of your time (and money for all the new parts), it will be a monstrous experience I think. It really would be easier I think to start with a blank piece of paper and work out your own circuit from scratch - BUT if you want the learning curve - enjoy and have at it!

[@stevenA44]

@@guyteigh3375 Thanks. I love fixing and building things so I would love to learn new things. Any ideas on how to get started?

[@marlonglodo1930]

Hi sir mine is cc not working... can you help please

[@cmvb69]

Why would a 13.8volt power supply be putting out 22volts ?

[@differentname8051]

I have a problem with mine ,it doesn't have such a large transformer yet is capable of 10amp at 30volt. I think it is a switch mode power supply. I switched it on and then it went completely dead within a split second of being powered up with no load attached. I have checked the fuses and all are good and the main caps charge up . The model no is QW-MS3010D any advice would be helpful .

[@diesalweasel]

wayne murphy did you manage to fix the issue regards jay

[@differentname8051]

Hi, no not as yet . The dust is building up!

[@mrsrj87]

In my power supply now getting 50 v instead of 30v and unable to control, I checked the 2N3055 transistor , it is ok

[@guyteigh3375]

I have a similar thing with a 60v 5A version - and I am seeing around 95v. Sounds like the same fault . If it was not the 2N3055, did you ever work out what it was ?

[@Anibal_avila74]

my bench suply baku 1502d+ at first freeze at 5volts..few time later only dots apear in display... not numbers... short... i will love to repair, but i dont know were to start, cheers

[@SilverMoonJoe]

ANIBAL AVILA start checking capacitors...

[@sacooper802]

mine straight out of the box was junk, like it never went through QC, just kept powering off and on repeatedly and led display flashing off right from the get go

[@MkmeOrg]

That sucks :(

[@BobMellor1954]

Some good tips, thank you. Bob (UK)

[@MkmeOrg]

+Bob Mellor Cheers Bob.

[@letslearnelectronics6208]

nice.

[@Tomtech29]

Thanks to the helpful diagram would be for me if you know where I can download the please let me know (3010D W E P)

[@MkmeOrg]

+Tomtech29 I would just Google around. Cheers

[@scottfirman]

I almost ordered one of those. I guess if I do I best plan on resoldering everything right from the get go. I bought a harbor freight battery charger booster and never even opened the box for two years. when I went to use it... dead. The acid in the flux had corroded the connections. I ended up throwing it out. word to the wize. If you buy these dodgy things, clean the insides well.

[@MkmeOrg]

+scott firman This supply has served me extremely well. Love it.

[@scottfirman]

So you think it would be ok then?

[@MkmeOrg]

scott firman Yepp. Dunno how I lived without it and for the price- one minor repair is nothing. Cheers

[@scottfirman]

Thanks. I always like getting other peoples imput on things before I buy. I am sure those things are mass produced anyways. For the money, if I can get a couple years out of it then it should pay for its self. I was seriously thinking of making one out of a computer power supply but I would still have to add to it. For the money involved and the parts I would have to invest in....I will just get one of these.

[@yurigagarin4974]

good fix, chinese soldering is done with absolute minimum amount possible 😎👍

[@Shazzkid]

Lmao 999A, wtf could even draw that much current haha

[@ljprep6250]

A screwdriver across the mains at the electrical box would have a chance at that arc welding amperage possibility.

[@flyingdutchman6984]

It was showing 999mA. Still not the correct reading, but a big difference between 999mA and 999A.

[@ljprep6250]

@@flyingdutchman6984 Overclocked charger? ;)

[@warrentully5705]

*

[@michaeladam626]

Very informative but I would just google where to buy a new one

[@MkmeOrg]

Then you would have no need for a bench PSU

[@qzorn4440]

Gee, hobby people use cheaper Dig- meters. :-O

[@MkmeOrg]

Nothing better to do than complain? Same type of person who would complain if I was using too cheap of meter. The internet is full of trolls and you=one.

[@qzorn4440]

:)

[@1pcfred]

Some techs just reflow whole boards before they even begin to troubleshoot devices.

[@MkmeOrg]

I prefer to know how and when I have actually fixed something.

[@1pcfred]

MKme Lab If flowing the solder joints fixes it, that's how. When would be when you did it too.

[@MkmeOrg]

Paul Frederick Nope. Once you have done troubleshooting and repair for a living you will find that brute force is a bad idea. Sometimes heating will temporarily bring electrolytic caps to work, movement can temporarily make coil components make connection again...and on and on. It might start working but not stay that way. Test and repair properly...

[@bobhatcher5505]

Wow, bang it with a screwdriver. Why didn't I think of that? Thanks!

[@ljprep6250]

The television bat is too large for his purpose.

[@OffTheBeatenPath_]

yep those power supplies are cheaply made. under numerous "brand" names

[@MkmeOrg]

flahr1 For the price this thing has been amazing. A small repair is no big deal in my book. Still a winner for sure. Cheers

[@OffTheBeatenPath_]

Eric William -MKme Tech Very true

[@AxelWerner]

i have a similar looking, but slightly different model. ( DF1730SB 3A ) with a crackly current pot similar to your fault. JEsus christ! The construction is AWFUL! A rats nets with way too short wires all over the place, NO CONNECTORS AT ALL, No proper nor matching schematics to be found so far, . To fix one pot i'll have to disassamble each and every bit of it. , cut/unsolder wires or make new ones because they all too short to work on it. i really wonder how they put this together in the chinese factory in the first place!! its impossible to work on it. If your time is worth anything, it should go directly to waste and ever ever buy a cheap lab powersupply again that does not come with full schematics and disassenbly manual!!!

[@hitechespresso]

Get what you pay for. JUNQUE!

[@letslearnelectronics6208]

nice.

[@MkmeOrg]

Tks