EEVblog

Dave discovers a potential systemic manufacturing issue with Lifud LED light drivers.
A repair of two of Dave's failed Lifud LED studio panel light drivers.
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[@onjofilms]

I believe it is systemic to lead free solder. I work on Motorola products, and that's 75% of the issues. Usually on connectors between boards, then SMD's or even flat pack legs. The rest of the issues are switches, chip/trans failures, pots, knobs and buttons roughly in that order. But, even so, in 1985 I worked on an old box of a 5 watt radio that was outputting less than a watt. I saw a bad solder joint, then just resoldered the whole board and bam, got all of the 5 watts back. That was 6 months into my first electronics job ever and the boss was amazed and I was somewhat proud of that fix.

[@EEVblog]

Tricks of the trade

[@mattb6001]

The micro cracks strike again! My old truck had a faulty ABS module (over $1000+ to replace at the dealership!). After seeing lots of people claim its just faulty solder joints, i took the task to take it out, take it apart, and clean up the joints. Its a big pain since the unit is all sealed up with silicon, but the solder joint touch up did the job. Before the fix, every time i hit a bump, the abs light would come on. Just guessing the vibration + bad joint would cause the fault to trip. Who knows how many people were out $1000+ because of this.

[@joshuanorris5860]

Never saw someone so happy to find a cracked solder joint :P Except maby myself lol Great vid thanks! :)

[@ams718]

2:25 Dave, if you'd allow me an advice: I always solder the end of multi stranded wires before placing them into termination blocks. (1) You never have to worry about oxidation, (2) You need less torque on the bolt for the same result (less mechanical stress for plastic parts) (3) Once the bolt is tightened, it makes a dent on the wire, that provides an extra security for slipping out like what we've just seen. In my lab, all wall sockets, wall plugs, light switches, extension leads are mounted like that.

[@EEVblog]

Or you simply just ensure you screw it up tight enough.

[@LiquidAudio]

I reckon it’s the lead-free solder Dave. I repair a lot of audio gear and the newer stuff with lead-free solder often exhibits these types of faults. Older gear with leaded solder tends to last a lot longer before these sorts of faults appear.

[@simontay4851]

Yeah, same here. Old stuff soldered with leaded solder just keeps working. Lead free is just too brittle. I hate lead free solder.

[@joshuanorris5860]

Liquid Audio deffinetly a big factor. Desoldering lead-free stuff is brutal! Specially when they use tiny amounts!

[@LiquidAudio]

Simon Tay Me too, hate lead-free solder!

[@garbleduser]

Nice bandwagon. Mind if I hop on? Gods bless LEAD!

[@greaser5691]

Interestingly in the old days, in television horizontal stages and switchmode power supplies with high pulse currents, localised heating causes the tin in leaded solder to migrate to the outside, leaving a 'leady' high-resistance joint that eventually fails. Used to be the one of the first thing to check in a dead telly... :)

[@Zeigren]

That's a feature not a problem

[@EEVblog]

Oh, it's the "please buy a new one" flicker feature...

[@stevej420]

"undocumented feature"

[@joshuanorris5860]

Hahaha, "working as intended"? :P

[@devrim-oguz]

No it is disco mode

[@jasonbay13]

i get this flickering problem with a bunch of high bay 250w led fixtures. the problem is that they have poor design. using 12 36v cobs in 6s2p. when one or more led burns out the driver will start flickering the leds.

[@samgab]

MEAN WELL LED Power Supplies!!! Go for them in future. Can't go wrong. I've had good results from all the Mean Well LED power supplies I've used. Many years in with some of them, all still going strong. Great build quality.

[@falkkyburz]

This video helped me find a faulty solder joint on a cheap 12V plug pack. Thanks!

[@Arrviasto]

I repaired similar thing in my LED power supply. Apart from cracked joins I had to add solder to main IC, because half of legs wasn't touched by wave at all. The satisfaction is always there, when you find that thing.

[@gerryjamesedwards1227]

Lead-free solder is too brittle if a bit of thermal cycling between what, 18 degrees and 27, is enough to crack joints. Nice to hear you working the rabbit/herring connection.

[@adambailey1526]

Great video Dave.take care mate...

[@edwardLongman]

Quality repair vid. Thanks Dave

[@XSpImmaLion]

Gah, that's pretty rough. Potential for mass quantities of those getting borked in no time, and Dave might need to open up to fix them multiple times until most components have been resoldered.

[@stevenm.2380]

I love these fix it videos!

[@StreuB1]

Great vid for a Saturday night! Thanks Dave!

[@__dm__]

The first guy had the Line/Neutral backwards!

[@metalpickle]

noticed that as well

[@simontay4851]

Yeah, noticed that too. Even though it makes no difference because the incoming AC gets rectified to DC anyway, its not good practice.

[@joshuanorris5860]

Simon Tay hehe ac trips me out

[@saddle1940]

That as well.

[@iamdarkyoshi]

Simon Tay Only the live is usually fused though.

[@ThaVoodoo1]

Very good repair video Dave!. I had to repair a wine cooler and the amount of dry joints/cracks was remarkable.

[@meowcula]

"we have a bona-fide failure! Beauty!" haha this crowd welcomes them!

[@f.hababorbitz]

Looks like cold solder joints from the higher melting temperature of pure tin is the most likely root cause, and a manufacturing process that didn't get it up to full flow temperature. Looks like these assemblies were hand soldered vs wave or reflow. ROHS is the dumbest idea spawned by politicians of the EU. And is having the opposite effect of more electronics thrown away prematurely. They didn't take into account the amount of toxic chemistry it takes to make integrated circuits, and the printed wiring boards. All they thought about was the lead being tossed into landfills. A better solution would have been a requirement to recycle all electronics. At least the industry I worked in (avionics) was able to get a waiver on pure tin solder. Mainly because of the tin whisker problem.

[@chrisg6597]

I don't think this has anything to do with lead free solder. This problem has been around since well before ROHS was even thought of. This is a typical problem with using cheap single sided, non plated through PCBs. I first saw the problem in portable CRT televisions donkeys years ago. The problem is always with heavier components (typically inductors/transformers) that are 2nd stage (hand inserted) just before the flow soldering process. As you will see in the video, the holes for these components are much larger that you would expect, for ease of component insertion, however this means that the only thing holding the component in is a very thin layer of solder between the lead of the component and the pad due to the reduced meniscus. Thermal cycling and vibration does the rest. If the PCB had PTH's then this wouldn't have been a problem!

[@simontay4851]

Also, large heavy components such as coils, power transistors and caps should always be hand soldered. Wave soldering just doesn't apply enough solder to these because of the higher thermal mass.

[@simontay4851]

17:00 "Is that because of this new fangled lead free rubbish" Yep, that is exactly the reason. Lead free solder is brittle and doesn't flow as well as leaded solder. Also their wave soldering is crap. Wave soldering never properly solders large high thermal mass components like power transistors and coils. Large components should always be hand soldered. Ive lost count of the number of single sided lead free wave soldered boards just like yours that ive repaired just by resoldering cracked joints. On some power supply boards in LCD TVs that I've repaired, ive resoldered every joint with leaded solder because the wave soldering just didn't apply enough solder.

[@danielegger6460]

@Simon Tay > Lead free solder is brittle and doesn't flow as well as leaded solder. Bullshit. If your solder is brittle, then you're using the cheapest China stuff. Modern top shelf lead-free solder has much better properties than the best leaded solder alloys that can be bought nowadays, since vendors stopped producing the above average leaded stuff due to massively dropped demand. > Also their wave soldering is crap. That! Could also have happened with leaded solder but it is much more forgiving to manufacturing problems like that.

[@simontay4851]

I only use leaded solder. I mean the existing lead free solder on the board. It cracks because it is brittle and there not being enough used. Failure rate for lead free solder is definitely higher than leaded solder. Leaded solder doesn't crack as easily.

[@KyleRepinski]

3:00 That tends to happen with stranded wires when they're twisted up and put into bare connectors, or even crimp connections. While it's easier to get them in there because the strands won't bend off as much when you're out of alignment, the issue is the twisted up wire end actually has a larger diameter than if the strands were all straight. Over time it can untwist, get stressed, etc. and then just fall right out!

[@dev639]

Awesome footage. Dodgy solder joints can be quite troubling. I fixed a very old EZflash 3 in 1 by simply removing everything and putting everything back.

[@ElmerFuddGun]

If you suspect a solder joint problem try probing around with an insulated poker on the top components. It often won't take much to make or break the connection and find the faulty part. Then just re-solder all its leads.

[@TonyButchT]

Great video Dave...Thanks!

[@gerryjamesedwards1227]

Wow, there is no way I'd have spotted that with my crappy eyes, probably not even WITH the microscope. Nice work, Dave-O!

[@troppo1751]

Exactly, you would have swapped out the control unit. An hours labour? what is the unit worth.

[@garbleduser]

This is why we love LEADED solder!

[@JoeMuc2008]

Thanks Dave, just had a defective Lifud LED panel light and PSU on the bench where all components measured good but it would still not power on nor generate anything near the specified 55VDC output. You gave me the clue I needed. Despite using a microscope, I could not find any broken joint but it's up and running now that I have redone just all of them. 🤞‍‍ I might have spent around the equivalent of 100 AU-$ on a new power supply, and discarded one where all except the soldering was in best shape, if it wasn't for you. Thank you so much! 👍‍‍

[@Roderick_Legato]

18:00 So, "how ya doin" = bad or dodgy. Right?

[@Huvada]

The most sophisticated method to check all solder joints simultaneously: smack it into the table repeatedly :)

[@EEVblog]

If you cant bang it like that then the age-old technique is to whack each component with the back of screwdriver handle.

[@tocsa120ls]

4:35 that's a very effective way of killing an SMPS...

[@PersonaRandomNumbers]

Dave, you make electronic repairs look easy! I'd never have figured out that problem.

[@Inesophet]

after seeing your ceiling, i feel much much more comfortable with my light installations :D

[@electronic7979]

Useful video

[@TradieTrev]

What?! No bootlaces? The outrage!

[@StuartTaylorEsquire]

Tradie Trev my 1st thought. Bloody amateur elec-chicken.

[@adslf874yti3q7u4hf83]

Every other KZbinr when their LED lights fail: "Well no filming for me until this is fixed". Dave: "Ohh a chance for another repair!"

[@brianangel8201]

I have found that large lead parts need a couple of seconds more in the wave solder machine to prevent a cold solder joint. This was found in failed power supplies for gaming equipment at a manufacture i worked for several years ago,

[@guatagel2454]

I like your way of thinking.

[@jusb1066]

is there some way to buy some various solder alloys and test them for heat stress and mechanical flexibility?

[@thorbennielsen3845]

Great video

[@RaithUK]

I would agree its most likely the solder that's the issue, nicely figured out.

[@leandrolaporta2196]

"u feel lucky....punk....." hahaha LOL! now i'm gonna have to go to my old vcr tapes and watch some of the dirty harry movies! i must have seen them 100 times, still love them!

[@Moonblade042194]

This why you use ferrules on cables.

[@Monkeh616]

Or just suitable screw terminals. No need for a ferrule if the terminal is suited to fine stranded wire.

[@landynhigh]

ferrules also look better. The flair can be a nuisance for closely spaced connectors but in this case would be ideal. IMO opinion it is the better way to terminate a connection.

[@johnfrancisdoe1563]

uptherewhere Ferrules with flairs won't fit mechanically in the space between the cable clamp and the wire clamps. Simple ferrules might fit but are against manufacturer specifications as printed on the lid.

[@JerryDodge]

I hope your next video is addressing the wiring situation in your ceiling...

[@Monkeh616]

Probably wise to go round and check the wiring on all the drivers now you've found that one.. If you can mess it up once you can mess it up twice.

[@johnfrancisdoe1563]

Monkeh Also, make sure to follow the precise cutting lengths specified on the lid, or the wires will tend to come loose!

[@itechflagstaff]

Thanks Dave 👍👍

[@John_Ridley]

Since the advent of lead-free solder, on anything like this, with only maybe 50 or 60 connections, if I suspect soldering issues I just reflow everything on the board with leaded solder. Takes maybe 5 to 10 minutes at most and problems solved. If I try to hunt for individual ones, I've wound up with something that works for another month or two, then I'm right back in there. Not only is the lead-free a problem, but I'm finding that on through-hole stuff they're too skimpy with the solder. They're barely maintaining the physical connection, and vibration easily causes cracks.

[@lasersbee]

5:09... Another problem that I can see is the bare wire strands are not all parallel and twisted together to get a good grip by the Blue Connector clamp.

[@juststeve5542]

I think after the first couple of dodgy joints, I wouldn't have bothered looking for bad ones, I would have just run across all the through holes with proper leaded solder. Damn lead free crap, I swear it's the cause of 90% of failures.

[@CyberlightFG]

It's much easier and faster to reflow everything instead of searching for cracks.

[@Gazz_R]

True! But it's also nice to know what the fault actually was.

[@2009dudeman]

Unless a proper stranded connector is used. In this case, the power supply used a really crappy spring clamp type connector, which is allowed for use with stranded connectors, its just not good at it. You are correct though, when only a screw is present, such as in electrical distribution boxes on the rails or some styles of breaker just use a screw, only solid wire can be used.

[@HighestRank]

Same screw clamps in just about every breaker box that i've come across, designed to be used for solid copper. Maybe they're trying to accomodate solid AL wire with the springs too, but I'd at least try to tin anything stranded, even with leadfree solder, before trusting it under a clamp.

[@KyleRepinski]

These connectors are fine with stranded wire as long as you don't twist it before you put it in. The issue is when you twist up the ends of the wire it has a larger diameter than if you leave the strands all straight. Eventually it can just fall right out, especially if the wire is bending coming right out of the connector into insulation bundling multiple wires together.

[@Arek_R.]

With the first cracked joint we can see that there was not much solder once you heated it, too thin and just cracks. That hole was too big, and because it's single sided PCB, without plated holes, it haven't got filled properly. Could be also because of oxidation on the components(stored for long time).

[@derofromdown-under2832]

Davo, would you recommend soldering the copper on the ends of those mains wires to give the clamps more to squash down and overall conductor density? Once again, another good presentation... 10/10

[@transistorbaluba]

dave, check your "dead" unit pcb again. i wonder if you have a soilder spil over. check at the bottom at 08:56

[@Yes-ng6rf]

Nice wiring neutral in the active terminal and active in the neutral.

[@TheCrustyCupcake]

Had a Sub in a vehicles stock audio system not working, or sometimes working intermittently. A board mounted next to and connecting to the sub was my first spot to check, and after removing it, found the same problem, a cracked joint on a relay. Though, mine was much smaller, but after a quick re-flow of it and a few others just to be safe, popped it back in and it worked, good as new.

[@DoRC]

No way power strips in the drop ceiling is up to code.

[@flapjackboy]

This is Australia. Their building code is literally "She'll be right!"

[@Phantomthecat]

Dan Smith - not at all, Australia has the strictest wiring rules in the world. The wiring in that ceiling space is a dogs breakfast and indeed does not meet the AS3000 wiring rules. A bit more catenery wire and some zip ties would sort it, but obviously the Sparkies who work in this building don't give a shit - a whole different problem. NSW has little to no inspectors who could be asked to look at this after the fact though, In Victoria, a quick phone call to Energy Safe would have a compliance officer on site quick smart and a rectification notice issued.

[@boggisthecat]

Do R/C! It’s fine to do this in Australia and New Zealand (unified standards for most things). You need to have properly installed AC outlets up there, but otherwise this is safe enough. We have a WiFi router and other assorted IT stuff in our much shorter false ceiling space. The reason you go this way is to prevent unqualified people from deciding to save the cost of hiring a sparky, and poking around with permanent wiring. Much safer to have the usual AC outlets available for end-users to plug stuff into.

[@flapjackboy]

+Phantomthecat Bloody hell. Do they do sense of humour removal ops in Australia as well?

[@JWH3]

Yeah, the failure on one line was a loose live wire plugged into the neutral on the driver, she'll be right!

[@arcadeuk]

Does Australia have their wiring opposite? Or did you wire live and neutral back to front?

[@arcadeuk]

Nope, google says Dave wired his lighting back to front

[@raywelshman]

Hi Dave, the first one you removed with the loose wire, is wired the wrong way around according to the markings on the case and on the PCB...

[@EEVblog]

Makes no difference.

[@MazeFrame]

A friend has a broken Philips pc monitor. I wonder if I should give it another day in the lab looking at the solder joints...

[@niyablake]

What no ground wire ??

[@schimbuldenoapte5626]

do you have a bathroom in the studio? I noticed that also the windows are missing, weird.

[@AlexandreJasmin]

Can you put ferrules in these types of screw terminals?

[@wargamingrefugee9065]

@15:01 cracked joint above and to the right of the right hand corner of the iron's tip

[@praestant8]

The tap test, always revealing.

[@marvin19966]

praestant8 tell that to your gf

[@Jamesfo8rf]

As an FYI, If you're based in Australia, those led drivers are missing the RCM mark. Australia national deviation requires a higher glow wire test of 750C on the plastics, EU only require only 650C. Please be careful!

[@jamesdaugherty6952]

Question, is it possible to re flow the entire board?

[@MiggyManMike]

I will never tire of dave referencing LMFAO :D

[@joshuanorris5860]

Ohhhhh hahahaha. Im new to the channel. So this has happened before eh. Haha

[@longdarkrideatnight]

On the cover 4mm lead length from outer insulation to stripped wires. By exceeding this yo are putting the cable outer insulation outside the clamp, or putting a stress on the leads as they 'S' bend between the end of th cable and the clamp.

[@EngineeringVignettes]

Free standing (large mass) components soldered to a one sided PCB with no thru-hole vias using lead-free solder. Throw in some temperature cycling and heating on that nice big copper wire. I'm guessing that copper layer is pretty thin too. Yep. What could possibly go wrong? Good catch on the cold solder joints. I used to have to try and find those buggers without a microscope. Mind you my eyes were only 20 years old. Cheers, - Eddy

[@EEVblog]

It's not the years, it's the mileage...

[@EdwinNoorlander]

Nice repair job. So is SMD better then THT? Because cracks in the solder is always with THT parts.

[@pocoapoco2]

It's Dave's Disco Lab.

[@OneBiOzZ]

I have some test equipment i made my self, the live goes threw a cheap rocker switch and the unit it self is very low power, when turned off the backlight on it flickers every couple of minutes due to capacitive coupling

[@LettuceAttak]

3:20 ... is this wired backward?

[@johnfrancisdoe1563]

For academic history preservation, you should duplicate all those decks to an off-continent similar museum along with photos of any written or printed labeling. Do the same for them.

[@100SteveB]

The joys of lead free solder - now you know why the aviation industry is still allowed to use leaded solder.

[@HDXFH]

Gotta love dry joints, when i repair vintage TVs i always see them

[@FaradayVest]

Disco Mode!

[@JimGriffOne]

He needs multi-coloured ones which flash randomly, and a "magic smoke" machine under the desk with a high power disco laser.

[@joshuanorris5860]

Jim Griffiths LOL Strobes and the works!! The smoke machine was the cherry on top lmao

[@dashcamandy2242]

The Epilepsy Test is not a failure, it's a "feature."

[@doctorazizli]

Hi, Dave. Why didn't you solder AC cable ends or put a proper pins to go under screws? As far as I know cables like yours here should be soldered or used with proper pins. It is interesting what do you think on this?

[@6Diego1Diego9]

this was amazing

[@radoczi94]

Where did the led tubes (installed by Doug) go?

[@EEVblog]

They weren't the same colour temp as the new ones.

[@Tommyinoz1971]

Bad solder joints is the most common problem I have come across in my experience with led lights with separate drivers.

[@gabest4]

The original solder looks to be a hollow cone over the legs. By the way, who cuts them to size?

[@paul66766]

no boot lace ferrules?

[@NebukadV]

You swapped AC_L and and AC_N connection on the screw terminals of the flick-one - no wonder it got loose ;) But where is the AC input filter cap? Is it just that 4,7µF one?

[@bsmith2053]

To those whinging about it not being up to USA code. Very good as this is in Australia.

[@fouzaialaa7962]

you guys make your homes out of wood and foam ....... your literally living in a fire hazard

[@simontay4851]

Fouzai alaa. Exactly. Houses in europe, Australia and the UK are made properly with solid thick brick walls with caverty insulation, not thin walls made of plywood and plasterboad with no insulation.

[@onemanshow4116]

KeeDx3 Oi mate! Don’t argue with these fine gentlemen! It’s their right as Englishmen to bitch about how shit America is, an’ how great the homeland is! ...and don’t mention the BBC! I hear they go bonkers at the mere mention!

[@Astaldoath]

walls are made by 2x4 or 4x6 depending, im sure if you wanted you could make em thicker. I know id like a brick castle style house if i had the money though

[@onemanshow4116]

Kebabrullerne There, there, lad... let it out. Now tell him how uneducated and uncultured he is! You’ll feel much better!

[@LarryAllenTonar]

In both controllers, diode D2 looks a bit crisped. Run a while and FLIR the board?

[@todesgeber]

wonder is all the hand trimming on that thing may have caused the too little amount of solder to crack. (combined with the repeated heating cooling action on the device in use.)

[@TGLasers]

The reason for the flickering.. You said it was the active/live that had come lose from the terminal block. Well judging from the color then yeah your right. But i can guarantee you the receptacle on the other end of the cable isnt polarized. So the flicering would have been the because the live was feeding voltage into the caps and there is enough ground potential with the return so close to the terminal block. Its just caps charging up and dumping the power.

[@saddle1940]

There doesn't seem to be much strain relief between the pinch jaws and the screw terminals. The grip is a bit dubious, is that enough to pass muster? Could you maybe loop the cable once before the jaws?

[@ppdan]

Some ferrules might help with the screw connectors.

[@4mb127]

I'm just wondering what kind of a fire hazard all of these really dodgy joints are.

[@benbaselet2026]

I don't think it makes much difference in something like this which is relatively low power and electronically controlled. Might be very different if there was a larger battery circuit or something pushing a lot of current through maybe.

[@anlumo1]

Hmm I wonder whether sparks on the joint wouldn't heat up the joint so far that it'd reflow to make a proper connection again before causing a fire.

[@benbaselet2026]

I very much doubt it. Blackening and growing gaps due to displaced metal is more likely?

[@MaxKoschuh]

6:45 he's happy about a broken PSU, that's Dave :-)

[@MVVblog]

3:48 Aishi? Are You kidding me? Throw it in the bin

[@yarik6468]

Запотолочное пространство порадовало меня !))

[@direchannelstream9278]

Hey Dave, proposal: a video about different solder leads and their pros and cons?

[@mcuembedded]

Seems like the HASL surface finish of the PCB somehow did not match up well with the wave soldering? It seems like the tin on the pads did not melt all that well on large components and form a good joint... just made it out good enough to survive for a bit.

[@nonsuch]

Hey quick question about the framerate. I understand why you do 50fps but if most of your viewers are in North America, don't you think you should do 60fps and let everyone else do the conversion? It's better to dumb down then to dumb up.

[@EEVblog]

The camera shoots in 50fps only (Targano does 60fps though)

[@johnnythefixer]

I used to tin wire ends with solder until someone told me it wasn't safe, so I bought a six sided ferrule crimp tool and now whenever I'm wiring anything, I always use ferrules.

[@TonnyCassidy]

3:22 australia have blue wire as live and brown as neutral ? interesting

[@disorganizedorg]

Lead free solder sucks for copper plumbing too. The first time I used it about 10 years back it was some wonky Cu-Se-Bi mix. Took me 4 attempts to sweat a half-inch copper pipe on to a brass valve. Previously I'd had about a 1% failure rate with with 60/40 in. I've since changed solders, and keep my 60/40 for copper drain lines, where it is still legal here.

[@agvulpine]

Huh. I don't see an ROHS stamp. Think it's the solder chemistry or the wave flow, or both?

[@MC-Racing]

Lead free solder just sucks. thank you ROHS for destoying electronics, and therefore creating more junk and more polluting!