12V Power Supply Repair
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- Опубликовано: 11 фев 2017
- Fixing a 12 volt power supply that failed after less than a month of powering LED strip.
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I'd like to offer a little tip with that ESR meter you use towards the end. If there are through holes or solder pads for the three contacts, make some leads with alligator clips at one end and solder the other end to the board for connecting to things that are too large or too small to put in the ZIF socket. It makes things tons easier for testing awkwardly shaped components.
Thanks for time you have spent on the video
The 40 amp version I have lasted a whole 4 hours sitting idle before the transistors self destructed. Typical Chinesium branded stuff. I did repair it and upgraded it by replacing those cheap weak transistors with some better spec matched pair of horizontal output transistors for old CRT TV sets, I changed all the caps whether they needed it or not, mounted the thermal sensor for the fan onto the case near the transistors rather than leaving it just flopping about in the case. I dim bulbed it and checked the transistor bias which was fine, then bypassed the bulb and loaded it to 40 amps and let it run for 1 hour and the PSU never even got warm enough to start the fan. Reassembled and added in what appeared to be missing screws and now it is fine doing what it needs to do and not complaining.
hey. im using 30 amp smps and I don't know that my amplifier shorted. i connect the smps to the amplifier and the smps make a noise for a second and die. i try to turn it on again but nothing happen. can you help me ?
Thank you Eman . Please can you tell us what is the switching frequency and what IC driver they us for such frequency.
In operation for a whole 4 weeks, and it was already failing. Your video just appeared on my feed. Subscribed. 👍
You can rebuild it, nah... Get a new one
Nice video, would have been interesting to see the oscilloscope trace after the repair though.
I want to repair a SMPS for a BR/DVD player. The original mosfet bad was SPP11N80C3. If I don t find that can I use an FQA11N90? The ratings are above a little bit so should be good. (900V instead of 800, 11.4 A instead of 11, only the resistance Rds is on original 0.45 on the other one 0.96) But if the power sustained is not so big should it work? Maybe will not get hot so much. I found a protection diode 1N4742 12V 1W bad also, and I would change the controller too, SSC3S111 just to make sure. The thermal paste was drained out from the heatsink and was a big flame on the drain pin which left a mark on the case, also destroying a part of the wiring. The diode tried to protected it so it blew also . The fuse was also blown. I ve replaced the fuse and it powers up, it stays 10 secs or so it says PROTECTION MODE/ OFF and it shuts down. The voltages are not the one who should be. The other mosfet seems right. The other components seems right I ve measured what I could , don t see anything else wrong.I don t have an osciloscope and ESR . I m still doing this like a hobby , I need to get some good tools in the future. The service manual is here : drive.google.com/open?id=1GdO9CzQW9nKLShx4bySaD-AzX-C9Akvp Maybe u take a look when u have time or say an advice on what else to check. It worked for about 10 years without problems standing the test of time. Maybe it worth a try. Thanks!
hello 25v 2200 úf 5 capacitors, the resistance in the middle of how many ohms I wonder
Hi friend, can you share a link or brand model of the Capacitor ESR test board you are using in this video?
Man, great video! I learned a lot! So many negative comments. Screw them.
Thank you! I appreciate the positive comment.
Can I get blueprint for this circuit, the resistances near first gaint capacitor are blown up, and now I can't even measure it, off course because it's blown up, please help me out here
hi friend i have this kind of 12v 20A broken power supply i repaired 12v coming but it wen i put to light its going to power down can you help me plz ?
Great repair
Hey can you help me? I have an esr meter.. My caps are all fine.. But for some reason I cant figure out why dc power supply failed. It won't output any voltage 12V dc is now...reading 0.02v dc Mean well refuses to repair it... and despite being expensive it failed in a day... so I am not sure what is wrong with it.. I would be grateful for your help.. Throwing out seems so wasteful
Nice vid! That was quite bad ESR-value (130 Ohms).
Can you link the two 12 volt outputs in parallel to double the amperage and increase the length of led strip you can use?
There's only one output.
What is a "linthium" source power supply?
What would cause a power supply to put out 22 volts when it should be 13.8v ?
Sir i don't whats a problem with my 12v power supply when I'm im connecting with AC current there tiny sound is comes from that. I'm new to using this.
A small sound? If it's like a small click that is normal. Especially if everything else if fine.
is this power supply can charge the 12v battery?
You should also replace the output caps if they are the same brand or a similar bad brand
Yeah I'm hoping it was just the one bad one but i'm sure its only a matter of time before the output caps fail too. It's doing good so far though.
Eman2000 Good, I really enjoy your videos, I do just about everything you do but a little differently and I'm glad someone likes electronics like I do :)
There is a orange solder sucker that kind like yours on ebay for 7.95,I talked to a few guys that have your model who are happy with it and bought my orange they say and I love mine perfect everytime,just a thought.
Ah the old
just opened one today, ~230v/12DC and it had a beefy 82uF capacitor... and 250v on the prime side... dead as dodo (down to 30nF). Oddly enough survived like a whole year.
I got the
One issue: The top of the new caps are not insulated, and I think they have live voltage on them. And they are real close to the case. Just a little pressure on the case and BANG.
caps aren't made of metal to be conductive ... no way they can shock
I have a meanwell power supply 12volt 350watt which is dameged mosfet is 60R290p original mosfet. do i can replace mosfet to IRF840?
K6a65d
That's a nice looking desktop, it would be a shame to mar it with hot solder blobs. You can easily achieve two improvements in one if you use one of those silicone oven sheets:
1. You'll protect your nice desktop. On mine (approx 0.1 mm thick ONLY!) I can actually solder things directly whilst they lie on it e.g. tinning the ends of wires/cables. Not advisable for long time heating but it works - without damage to the underlying surface - it's amazing stuff and even though SUPPOSEDLY only rated to 230C in an oven appears to have little problem coping with direct heat from a soldering iron set at 340C!. I can even use it to wipe my iron tip!!.
2. if you set the mat up beforehand so that it lies comfortably in front of you for working then set up your camera field of view to keep it central then you have an easy instant visual guide to show you if you are in frame or not (which sadly you were not for much of the time on this - interesting view of the matchbox though! :D )
Here's a link to an example of the silicone oven sheet. It's not necessary to buy the more expensive version that you can also find on eBay with component trays incorporated but they do seem useful.
www.ebay.co.uk/itm/Hot-Silicone-Bakeware-Oven-Mat-Bakeware-Mat-Resist-High-Temperature-Baking-Mat/142346184800?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D2220072%26algo%3DSIM.MBE%26ao%3D2%26asc%3D44293%26meid%3Da6918509315546809d42aa2f74fac056%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D192017922606
This one is a full 1mm thick and even larger. I'm seriously considering getting one of these even though it's around 7 times the price
www.ebay.co.uk/itm/Silicone-Extra-Large-Thick-Baking-Sheet-Work-Mat-Oven-Tray-Liner-Pastry-Pizzas-/381967019811?hash=item58ef022f23:g:fU0AAOSweW5VOQHP
paid links?
@@goku445 if you READ my post properly and examine the link fully you will find there is NO PAID LINK.
The post was a genuine attempt to highlight something useful for readers not to earn income. I also said "as an example". Not sure why the intimation of "paid links?" was even necessary! 🤔🙄
@@boblewis5558 Just a question. Take it easy.
How did it hold up ?
Well... ruclips.net/video/9Hv3nfUGwww/видео.html&lc=UgwA1py6c727IK16gbJ4AaABAg
I have a 10 amp 12 volt power supply thats only doing 4 volts. Can you give me an idea as to where to start looking? Thanks
Capacitors are generally a good start. Make sure you unhook the load form the power supply and test the voltage if you haven't done that already.
Nice video, thanks.
Could have shorted the dead cap and it'd have been a repair as well. They are in series to allow for the 230V switch.
My recommendation is if your going to use a 10 amp load, use a 15 amp supply. If you are going to use a 15 amp load, use a 20 amp load. The most common part to fail in these cheap power supplies is the NTCs. I use these power supplies for very low current load, but pretty high wattage. (Wattage divided by the amperage) usually the load would be about 9 amps for me. So these work fine for me. Also try to find a better quality power supply (like I have) although it might be pretty expensive, it would be worth it.
I measured the amount of current that I'm drawing out of this thing, it's about 8.5 amps and the supply is rated at 12.5. The NTC did fail in this thing by the way. It happened less than a year after I did this repair.
Minden ilyen videónál többet érne, ha valahol meg lehetne szerezni ezeknek a tápegységeknek a kapcsolási rajzát.
You might want to check the diod bridge to see if it's leaking ac. That tends to cause this.
Good work, I have this power board, but red colour big capacitor damage, I can't find number of it,do you can help , what is it number,?
Just a crazy question, why not run some LED lighting using house mains?
Just to see what it would do? That might be an interesting experiment. It could be possible to use a dropper capacitor or something to limit the current to seriously run them off the mains but that introduces flicker at 60 Hz which wouldn't be good for video.
I replaced the caps and its putting out 13 but not running the fan on the bench and fan works does it have to be on load to work?
You might have a power supply that requires a certain load/temperature in order for the fan to come on.
I have a wfco 8955 converter. I did purchase a new one and will see what it will do but won't give a real trail until camping season.
I have an ATX PSU with a clearly busted TNY176PN, and wondering if replacing just that would fix it..
It might but usually you won't have a controller chip blow unless something else is wrong, like bad capacitors.
Caps all look ok though. Replacing the chip didn't fix it. Yesterday I replaced the whole PST. But I could use the PST as lab power supply if I could get it working.
Vishva Kumara I have a TNY268M that is awaiting repair following what appears to have been a previous repair where a 1A Schottky was used to replace a 3A Schottky (The o/p is supposed to be just 1A) and seems to have been the cause of the problem. With SMPSUs I find it's best to just use the following procedure:
1. Check all active components for shorts in circuit
2. Check all diodes in circuit for shorts AND open circuits
3. Visually check caps for ANY signs of bulging, leakage or anything even a little bit "hinky"
4. If in doubt ... whip it out! Remove dodgy components check/test removed components to try to verify the fault and replace as necessary.
5. Don't forget the Opto isolator/s if fitted.
6. Closely inspect board for dry joints.
After all of that it's power back on, pray and trim for maximum smoke as they say. 😂
You can gently and safely discharge a cap, even the bulk cap (large cap) simply by reading the voltage continuously after power down. Even a good power factor voltage across the bulk cap of 300VDC to 400VDC will bleed off after a few minutes.
In fact, if the output fails on a SMPS supply, you can eliminate the entire PFC stage by verifying that the voltage is present on the bulk cap.
If the voltage across the bulk cap is 160VDC then you’ve lost the power factor and the primary stage is merely rectifying the AC mains input (usually from the DC output of a bridge rectifier).
Short the capacitors with a resistor is the most common way to discharge. For example 1000 ohm 10 watts.
@9:50 please short out with "protective" screwdriver... not with metalic one.
i heard you speaking at begining for some .. saftey :)
I agree wholeheartedly with the safety sentiment, but guys - please use a resistor. Use an appropriate value for the voltage likely and the size of capacitor. Placing a direct short across a capacitor is NOT good for it. They have max dynamic, static and current surge ratings for a reason.
DEFINITELY DO NOT DO THIS ON A SUPER CAPACITOR!!
If you constantly short out capacitors you risk further, more expensive damage later on. If you're doing this kind of a job you should already have the perfect tool - it's EASY to check with a multimeter whether there are lethal voltages present. Plus it's much better practice. If there are, then drain them with a resistor. Once the voltage is down to a "safe" level - say 40 volts it will be fine (unless you're standing barefoot in a puddle of water directly on a concrete floor and have wet hands as well that is :D)
how do you know if a capacitor are in bad shape just looking for the cap?
If you notice that the top of a capacitor is like a dome rather than a flat surface then that is an indication of a faulty capacitor. If you also notice liquids leaking from a cap then that is also an indicator... Etc
According my experience, this kind of failure happens usually beacuse of ballancing resistors for both capacitors are not the same value, therefore one of those caps is overvoltaged. You should have measured volages across both of those caps under no load to PSU in order to check for poor ballancing. Wihout fixing the cause, your cap will probably fail again, especially if the PSU is used with light load.
I might have to open it back up and check that. It is under light load most of the time. However, it has been going strong since I repaired it.
medvídek Krupička Good point, but only true in my experience for series connected caps. These days more and more PSUs use 400v reservoir caps (in parallel) for both 110/120v or 220/250v AC input and there are no balancing resistors required. Any resistors present on, or associated directly with, the caps will be drain resistors or for Inrush control.
What type of component tester is this? Where can I get one of these?
Ebay or Amazon. They are pretty generic. Just search for "component tester" they all have about the same functionally.
Hi Bro, same SMPS but 12v 15A I'm having and same low voltage issue, but it's very new and not used, Just I was playing short circuit testing and suddenly voltage went down to around 5v. My case capacitors are looking fine in appearance and getting some tick tick low noise if you hear closely in center yellow transform, Is there any other checks need to do ? Please support 🙏
Good repair! But you also have to watch out for those metal heads of the caps! As it can become conductive and short circuit with the metal shield if the head of the cap come in contact with it. That is why the original caps where shorter and had a plastic over the metal head!
Thank you. I have actually insulated those caps since this repair by the way.
Eman2000 thanks!
Eman2000 I have lernt it by experience. I had opened the cover of my yamaha stereo amplifier to clean it a bit from the dust that had accumalated inside. there were two power transformers and a discrete power supply with four big elna capacitors along with other components. The amp was unplaged from the main. I could not resist the temptation of touching the metal heads of two of them and i got hit by two of them (120v dc)
Hi. My HP power supply's green light used to light On, now there's not light. It was just plugged in the mains (shut down) and when I woke up there's no more light. What subcomponent should I check first?
God bless, Proverbs 31
Check capacitor ,diodes,transistor
New suscriptor greettings from Jicaral puntarenas costa rica excelent video
Thank you!
You said oscilloscope just as I thought it man hahahahaha
My power supply puts out
26.8 volts instead of 13.8 volts.
Any ideas why? What should I
check? I'm a newbie!!
Turn the lite screw next to the led down.
Thks for sharing..
You should use a isolated screwdriver !!! Especially when discharging capacitors !!! Anyway, interseting video, thanks
Thank you.
nice view of bench but not much else : )
Mine was on for 2 hours, then it started clicking/humming and supplies 4V...
Thanks for the video I was going to get one but will avoid
i have same one .... and I mistakenly put the switch on 110v and connected the power supply to 220v input .... then it stopped ... small burning smell and no obvious burning part ... no 24 DC output ... i dont know how to fix it ... if someone have face similar issue can help pls ?
Nice!
thank you
bro u touchin the capacitor like that man u crazy
Out put voltage 7volt what's reason
"Good", very good video 👍
Would help if you worked in frame. Could see nothing, had to listed while watching the other edge of the board
A Big Clive screw screw driver and an EEV Blog multi meter, I know which RUclips channels you are subscribed to! :)
Yup, you guessed that right!
Working off screen?
Wouldn't it have been safer to use an insulated screwdriver for discharging the capacitors?
my problem is dc voltage is not fixed value. it is very.. ex: 12V coming to same time 11V , 0V , 3V
very nice video sir
Thank you
in the future film the whole pcb, and explain what the tool is called. let's see how you remove the weld and how the part changes
So long as the caps are the nearly same value at or just above the the original value, you shouldn't have any problems. They form part of a voltage doubler seeing that you are on 110 volts and each cap has about 160 volts DC across it. To stop the tracks from lifting, use a 50 watt temperature controlled soldering iron with a fairly large tip, set to 360ºC and solder wick or a solder sucker, if you must. Small irons take so long heat the component legs and melt the solder that the glue holding the copper to the board cooks (oxidizes) and gives up. The judicious used of super glue after your repair can sometimes get you out of the (use whatever word you like). If you use the device in a mobile situation, eg... your car, a little dab of RTV silicone will stop the large component legs from being broken by the vibration. Don't get it on the tracks as it's a bitch to clean up and solder afterwards.
Like your use of the appropriate test equipment. 'Scopes are a really good way to verify the fault and check the repair afterwards.
Peter Dorn thank you, very good advice.
Was an industrial electronic tech for most of my life... recently retired and I don't mind giving good advice to help out. Thanks for "listening".
Shorts caps with metal screwdriver. :)
Not Advisable. At least you checked with multi meter first.
Let me know if any of you can fix my 1500 Watt inverter....
Larger value of cap in a SMPS is quite acceptable. Smaller value should never be done.
Ian Ide 100% agree BUT beware going TOO large as it can cause input problems at switch on with excessive inrush current! This can cause input varistors, NTC Thermistors or Inrush Current Limiter to deteriorate, overload or blow or the input fuse to blow. Easily solved if catered for in the change but can be potentially dangerous for the supply.
Same value are the best choice, ever. Higher values cause excessive inrush current, smaller values cause excessive ripple.
Did I just see him discharge those switcher caps with a metal handle screwdriver?
Very hard to make affordable repair on these cheap import supplies their mosfet transistors and decent cap replacement prices are worth more than the total price of the supply itself the only people who can make a money worth repair are the people who stock pyle of them old supplies in their basement who can steal parts from the other dead ones ! I hate these switching supplies their in everything we own now in our dishwasher control panel in our fridges , some of them are truly dangerous set themselves on fire when faulty ! The old linear power supplies pre 1990 where the best with a transformer and bridge rectifiers who would last 50 plus years safely all you had to do to maintain them was changing the electrolytic capacitors every 30 years or so or a few diodes !
As long as you are not in the US, those capacitors must be rated 400V (√2 × 230 = 325V). If you are, 250V is much enough (√2 × 120 = 170V). You've posted this video some two years ago. How long your 250V capacitors lasted?
If I remember the circuit in this thing correctly, the 2 caps were in series giving a voltage rating of 500 instead of 250. As of right now the power supply is still functioning.
I had to laugh at your shorting out the caps with your finger on the metal !! PTFE tips on solder suckers are best. Obviously you make a complete balls up of removing the two caps as you didn't show the finished job! As there was no evidence of fan activity (no dust), I would have replaced ALL the caps and made sure that they were 105 degrees C!
Oh, by the way, I have been fixing PSU's for over 40 years.
Big Clive shorts out caps like that it must be fine! The finished product wasn't too bad (with solder on it you couldn't even tell that I slightly damaged the pads. I can never seem to desolder stuff right no matter what I do. I guess I need more practice! I agree with replacing all of the caps. I pretty much just did this to get back up and running as fast as possible as I needed this power supply, and I don't think I would have all the required caps laying around. I think if it goes out again I will just buy a decent quality power supply instead of trying to repair this cheap one again. The good news is it's still holding up good!
eevblog multimeter !! LoL!!
Have to agree with @bigatom...its as if the hands cannnot function without the mouth moving. Can I recommend the gift of silence instead of talking cr@p non-stop?
I don't know why people use solder suckers, I just heat it up and braided wire or any of the metal wick used for this.
I really never had good results with either. I guess I just need more practice.
Soldier sucker is faster
Send it back under warranty. This cost the supplier more for the repair and it is the hope that the quality will rise.
Get a couple Maxwell Capacitors
The ones I put in there were Rubycon capacitors. No worries about quality there, except for the fact I pulled them off of a different power supply.
👍
Hello!
I've two capacitor in series with nominal value of 250v 470uf into a power supply, after having problem with this last i noticed that the same capacitors have a value of 356 and 395 different of the nominal are this maybe the problem?
ruclips.net/video/AwUDncGaDKg/видео.html
Note the white past is normal?
Thank you
Those capacitors seem pretty low for 470uf. Could definitely be a problem.
Surely this would have been under warranty in such a short time? Save some effort and get a brand new one!
IMO it would be more effort to deal with the warranty.
Where is clear?
camera work needs improvement
Greetings: Good example of Chinese junk. U wanted cheap. U got it. Personally I stay away from SMPSs. Unreliable, destructive when they fail and 2 much PIA and expense 2 repair. I will use a boat anchor NE day.
Looks like a scoundrel
Why do you pronounce solder with a silent "L" ?
Cause 'Merica
this 12.5A board has thicker traces THAN 20 dafuq
Boy those power supply is a real joke yes...I had a Nippon America power supply for 17years and it now fail
Everybody please click on the Bernie ads. The cominazi has to pay RUclips every click. Help him understand how a free capitalistic society works.
U took 20 mins for a 5 minute video
cheap onehunglo caps...typical problem on ps failures.
I know exactly what the problem is...It's fucked!
much better if we could see something
buy a cheap atx powersupply even a old free one
They don't give enough voltage for my application. The ATX supplies are fixed at 12V, these you can adjust a little bit. I have this one set at around 14V.
sir eiska ful ripayering in hindi me do sir
How NOT to repair a power source.
Fixing cheap Chinese psu's is sooo old now.
Most of what you're doing is off camera.