Data Centre 27 Way 3 Phase KWH Meter | Repair Shop Couldn't Fix It - Can I?

[@schleifenbauer_PDU]

Schleifenbauer is now fully focused on producing server rack power distribution units for data centres and has officially discontinued the DPM27 meters. It’s fantastic to see this classic DPM27 brought back to life! This product has served our customers reliably over the years. With the DPM27 now at end-of-life and stocks completely sold out, we are no longer able to offer parts or official support. However, it’s inspiring to see this meter given a second life through your skill and dedication. Much respect for your expertise-keep up the great work, Mick from Buy it Fix it!

[@BuyitFixit]

Thank you very much Schleifenbauer. Really appreciate you commenting and supporting my work 👍 Best wishes Mick.

[@chrisbartlett6022]

Fantastic that a manufacturer takes the time to comment and appreciates you rescuing their product from land fill.

[@Bristoll170]

A quick and dirty test we used to do with suspect cap's was to either heat the solder joints on the board, or rest the iron on top of the cap to heat it up. That would get the cap back into a working state and show the crook one. Easy to do. This is why the cap read OK when removed from the board. De soldering it would have warmed the internals up. If you check them in a couple of days you will find the ESR will have climbed again. Your videos are always a great watch and thanks for sharing 👍 Cheers Pete' New Zealand.

[@BuyitFixit]

Thanks Pete, yes agree heat from the soldering iron. I do remember having faults which cured themselves such as after the "TV warmed up it would work properly" etc, and I've used a hair dryer before on parts of the board to find the fault, so makes sense.

[@Garry1888]

I've seen people using freeze spray to overcome this very issue. As ever, a hugely entertaining and informative video. Thank you, Mick.

[@BuyitFixit]

Cheers 👍

[@Bristoll170]

@@BuyitFixit Yes hot air would do the same thing, but hot air covers a large area. Pin point action with a soldering iron was a bit more precise 😏

[@perkulant4629]

Came to point out the heat, indeed this. Great comment.

[@generaldisarray]

Excellent work Mick. 👏👏👏👏👏 30 seconds in and I'm convinced it's caps. IT'S ALWAYS THE CAPS... Unless it's something else... But IT'S ALWAYS THE CAPS!!! A hungry little processor needs a really, really, stable power supply. Moving and squeezing the caps probably caused the electrolyte, what's left of it, and the plates to shift giving the weird readings. Being slowly baked in a rack for 10 to 20 years won't have helped either. Like you said recap all the electrolytic caps and the other boards will probably be as good as new.

[@BuyitFixit]

Thanks mate 👍😂😂

[@chrisreynolds6331]

The higher ESR on that second capacitor test may be that the cap had cooled down. Just after unsoldering it would have been heated up, possibly giving a false reading

[@quantumleap359]

I tend to agree. One way to troubleshoot audio coupling/decoupling capacitors is to heat them with the tip of an iron. If problem goes away or coupling/decoupling improves, Bob's your uncle.

[@JJ-kr6ky]

Is it also possible that the cap was not fully discharged skewing the reading?

[@BuyitFixit]

I think the heat is correct. The meter discharges the capacitor before measuring (the relay click you can hear when testing).

[@chrisreynolds6331]

@@quantumleap359 Indeed. Shango066 still does this with vintage transistor radios. If the radio is squealing touch the soldering iron to the capacitor. If the squeal fades that's it.

[@MikeyMack303]

Good fix, Mick! I like that the manufacturer even commented!

[@brianwood5220]

When I saw it Boot-Looping, my first thought was Capacitors. Great minds think alike. Nice work, Mick, thanks for sharing.

[@BuyitFixit]

Cheers Brian 👍

[@ninaevans4501]

@brianwood5220 Quite agree Brian, we also thought "capacitors" to. It is also possible that the caps failed under load. This does happen, and is a pain in the a..e to track down. 👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿

[@NeilPho]

Why the heck are people downvoting this? It's pure gold.

[@Snooooozel]

To short, to easy lol 🥳

[@BuyitFixit]

I guess it's just what comes my way.It could be anything from a PS4, to a 27 way data centre 3 phase KWH meter 😂😂and I never know what the fault is going to be or if it's fixable until I get into it.

[@mickwolf1077]

its the other repair shop thumbs downing 😁

[@orion310591RS]

20:19 - 3 possible reasons, 1. Device it self measured it improperly, 2. You dont use aligator clips for good contact, you push by hand, 3. Capacitors were previously heated for desoldering then you measured them, when they cooled down maybe something changed. But again, a rare video how electrolytic capacitor near MCU can knockout MCU. Looks like many repair shops do not know this or dont care to go that deep into problem solving. Universal rule, if you fix device older than 5-7 years, replace electrolytics. 21:30 - Assuming all 30 units have the same fault, which I believe they do because this device runs 24/7/365, its 815*30=24450 eur worth of equipment. I really hope you get at least 10% of that. Its industrial equipment and repair price is higher for that kind.

[@andymouse]

Yep.

[@BuyitFixit]

I think 3 is the most likely. I've only got the one unit which I'll return to Alex. I think he or his staff are capable of changing the capacitors now they know what the issue is. I think he mentioned that they already replaced a couple of components at the manufactures recommendation.

[@bills6946]

The other repair shop probably only devotes a fixed time for initial troubleshooting and then closes it up. Not a reputable way of running a repair shop. Knowledge and dedication is Mick’s way. Well done sir, as usual.

[@BuyitFixit]

Cheers 👍

[@ghwizz]

To be fair, there aren't that many people who are willing and able to repair basic electrical items, let alone advance electronics troubleshooting and repair. The level of skill, experience and tools that someone like Mick has is very uncommon. You simply can't hire people like him unless you can pay Megabucks. And so a local repair shop is unlikely to be able to fix stuff like this.

[@bills6946]

@@ghwizz The owner first took it to a repair shop. They couldn’t fix it. Did they charge a diagnostic fee or waive the charge? The shop should not attempt a repair they know is beyond their ability. I agree. Not everyone has Micks skill.

[@IANHANDS]

You don't have a clue. . You are also not the reputation police .

[@IANHANDS]

The main reason is . People don't want to pay for it

[@phildegruy9295]

We fixed our own power supplies for a particular industrial robot, about 400 of them. They are a discontinued item, and the electronic repair shop was charging an arm and a leg for repair but not actually fixing them. Repaired units were still failing with the same issues. We started ordering reals of electrolytic capacitors and changing 5 capacitors in each bad supply. This fixed 100% of the supplies that we repaired and we saved about $700. on each supply after our cost for time and materials ($95) was factored in.

[@BuyitFixit]

Very nice 🙂well done 👍

[@f-7670]

I think you are a genius mate. I like electronics and repairing things as a hobby - its very interesting. I like your presentation and style and u have learnt heaps from you, especially programming and EEPROM/BIOS faults. Keep it up.

[@BuyitFixit]

Thank you very much! Really appreciated👍

[@SeanCurran-j5g]

I've been dabbling in capacitor replacement and electronics repair as a hobby for years and capacitor failure is my "go to" when I get a faulty device that won't power up. As others have mentioned, when you've de-soldered the cap, you've warmed it up and brought it somewhat back to working spec. I work in IT and after once replacing a very old, failed Power over Ethernet network switch, a number of IP telephones were dead, after visiting each dead desk phone with a hair dryer, they all sprang into life (and replacement phones recommended). I bought my Peak Atlas ESR70 in *2009* and it's the best ~£90 I ever spent.

[@BuyitFixit]

Cheers for sharing Sean 👍

[@DavoShed]

Great Video. You seemed to go straight to the problem as usual. Glad you work for Biscuits and not Peanuts. 🤠

[@BuyitFixit]

Thanks 👍😂😂😂

[@Jesselovespinball]

Another win for Mick ! I’ve learned a lot by watching your videos which help me troubleshoot pinball machine circuit boards . I learn at least one thing every video I watch , so thank you very much for that ! Well done 👍

[@BuyitFixit]

Nice one Jesse 👍I've worked on a few pinballs back in the 90's - 2000's. I remember changing solenoids and flipper buttons, and replacing bulbs, and the odd fault which required a board changed. I wasn't really repairing things down to component level much at that time, just the odd TV here and there.

[@Unknown1880]

So the Dutch send you Stroopwafels. Very nice of them👌🏼

[@bills6946]

@@Unknown1880Good thing they didn’t send him Schnitzengruben

[@BuyitFixit]

😂😂Yes indeed 👍

[@andyrichardson842]

It's Saturday and there's a new Buy It Fix It video - YAY! 😄

[@BuyitFixit]

Cheers Andy 👍

[@smichels5117]

Brilliant! Yes… leaky electrolytic caps are SO common. I do a lot of “recapping” - great video! Excellent process!

[@BuyitFixit]

Thank you 👍

[@johnmolnar2957]

great diagnostic work . my buddy retired from electronics repair always says lot's of times you have to look for the non obvious. You follow that rule all the time too

[@BuyitFixit]

Cheers 👍

[@terrym1065]

Capacitors....why am I not surprised. I wonder if the installation environment is hot? A re-cap of the power supplies is a good idea. Excellent troubleshooting, powering the display separately was smart for sure. Another great fix sir, of all the components on those boards it had to be capacitors... Thanks for the video and work, well done. See ya soon.

[@BuyitFixit]

Cheers Terry 👍

[@TomMannCenturia]

Im nowhere near as knowledgeable as you (or most of the commenters here) and lots of the techncial information goes over my head but I still thoroughly enjoy your videos. I look forward to getting the subscription notification when a new video drops (of whatever weird and wonderful thing you're repairing). Many thanks!

[@BuyitFixit]

Wow, thank you!

[@chrissavage5966]

Having finally accepted my eyesight is beyond hope...I've just ordered a TM4K-AF Flex via your link. Hope it helps a wee bit :) I was looking at a dodgy nightlight this morning and really struggling with the old binocular microscope, holding the tiny PCB, getting the iron in there and the general discomfort of the whole experience, bent over the bench, eyes glued to the cups on the 'scope, trying not to burn myself with the iron. I have no intention of giving up on projects & repairs any time soon, so something had to give. Appreciate the recommendation. I just need to repair a crap-ton of stuff now to justify the expense......

[@BuyitFixit]

Nice one Chris. It's pretty decent to be honest. I've got the MAX which has the 10" screen, I think the flex has the 7 or 8" The image is pretty good, and has a decent working height.

[@chrissavage5966]

@@BuyitFixit I’m a bit tight for space so thought the 8” would be best. There is a 50” Pioneer plasma on the wall for when the eyes get really bad though ;)

[@wisher21uk]

Nice fix Mick, I will echo other’s comments, allow the cap to cool before testing, I have been caught out once testing whilst warm…. Enjoyed the fix thanks keep it up Mick 😊

[@BuyitFixit]

Cheers Gary, yes I'd agree with that, and that's probably the cause of the readings.

[@wisher21uk]

@@BuyitFixit it will be Mick, when the cap is cold is the real reading, I warm caps up to test them in circuit with a hair dryer then freeze spray them to identify the fault!

[@BuyitFixit]

Yes done that myself a few times, although I didn't think a little heat in the legs for a few seconds would have caused much change.

[@wisher21uk]

@@BuyitFixit we learn something everyday Mick, that’s why we all watch your videos 😊

[@IANHANDS]

Are you a parrot

[@kdog3908]

30 of them with the same fault...intriguing. Batch problem? Always a good watch mate. Cheers.

[@Misimpa]

Age problem :)

[@quantumleap359]

@@Misimpa True. These caps have had a long life considering all.

[@gorak9000]

@@quantumleap359 If they had used United Chemicon / Nippon Chemicon / Panasonic caps initially, they wouldn't even be close to failing yet. Use garbage parts, get garbage results - but they usually do that on purpose because if it lasted forever, you'd never buy another one

[@zs1dfr]

Weren't the capacitances of those two caps way out of the 10% tolerance range anyway? Your two in the 195mfd range only just made it. But 165 to 170 was way off, never mind the series resistance. Such a straightforward repair following your gut feeling doesn't say much for the service company Alex sent this unit to.. Well done!

[@BuyitFixit]

Thanks 👍That's what I thought, but on the Dumpster TV video I did there were quite a few comments saying that a tolerance of 20% with capacitors is not unusual..

[@Gazzyb2071]

Excellent fault finding as always, Mick 👌

[@BuyitFixit]

Thanks 👍

[@elsaarmstrong-zp6ng]

Excellent video! Loads of patience here! I hope he remembers it’s mains input here!Fraser😅🛠

[@BuyitFixit]

Thanks 👍😂

[@paolomonai9511]

Great job, as always! As alredy stated by others I think that the first ESR measurement was falsed by desoldering (heating) the caps. To prove this one can resolder the original caps and testing the unit freezing the caps with the spray and heating the caps touching them with the tip of your solder iron for a couple of seconds. You shoud have the unit showing a pulsing or stable display. Anyways, you have magic guts feeling...congratulations!🎉🎉🎉Regards from Italy.

[@BuyitFixit]

Cheers 👍

[@Rustybritjunk]

Good stuff… many thanks for the efforts and content. Caps… as others have said… always the caps!

[@BuyitFixit]

Thanks 👍

[@haakmeer]

great repair, and stroopwafels are yummie

[@BuyitFixit]

@@haakmeer Thanks 👍Yes I agree 🙂

[@ralphj4012]

Well done. The doomsayer (and supposition) in me wonders whether removing C280 & C281 has resulted in all sorts of switching nastiness impacting the electrolytics. Perhaps a cap leakage tester in your letter to Santa.

[@BuyitFixit]

Thanks Ralph 👍

[@devttyUSB0]

This was very strange to see. I know this Alex guy and the DC this meter came from quite well. 🙂 Great fix, m8! Enjoy the Stroopwafels! A quick tip: try slightly heating them up over a nice cuppa tea. 😃

[@BuyitFixit]

Nice one 👍and thanks for the tip.. although I'll probably have to get some more as I finished them 😂😂😂

[@IANHANDS]

Wow a claim to fame that don't belong to you. Mate !!!!

[@devttyUSB0]

@@IANHANDS kek~

[@oefzdegoeggl]

Definitely a weird one. Also this 10000uF on the initial in-circuit reading. Would be interesting to see what's the in-circuit value now.

[@manolisgledsodakis873]

Nicely diagnosed. In view of the price of the equipment, I would have replaced ALL of the electrolytics with reliable Panasonic ones (usually brown with a silver or gold stripe).

[@BuyitFixit]

Thanks, yes that's what I've ordered to replace them all 👍

[@frankcarpenetti5776]

LOL! I was right for once. I always change all the electrolytics once I am in there, as long as they are cheap. You may still have an issue with your PEAK? I've never seen that before with mine? You should have a cheap china tester just for back up? Great job once again BRO!

[@BuyitFixit]

Thanks, I've got a cheap tester too T7 I think it is.

[@chrissmith7655]

Hi, what a guy!! Many thanks.

[@BuyitFixit]

Cheers Chris 👍

[@townsend420mt]

Caps sometimes read different with different temperature. Had an amp that wouldn't work right when it was cold but would work right after 30 mins. Needed new caps and worked perfectly after

[@BuyitFixit]

Yes I think that's the case here. I've heated caps up before and the fault has went away, also cooling with freezer spray can bring the fault back. I didn't think the heat de-soldering them would have had much effect.

[@townsend420mt]

@@BuyitFixit yeah sometimes the small parts hold heat better than what think. Great video and knowledge keep them coming

[@LArmor6S]

I'm just wondering, when you initially measured the caps, were they still hot from you desoldering them from the board? I wonder if that was what caused them to read lower when you initially tested them? And I'm glad you said at the end about changing all 6 caps, with those two being faulty, it definitely makes the other 4 questionable, and worth replacing. It always amazes me how many times faults like this can be bad capacitors. It was a long time in hobby electronics before I learned caps can go bad so often, and it was an old TV engineer, who joined our IT repair workshop back in the 90s to fix CRT monitors, who taught me that. It was eye opening, and helped me fix many items since.

[@BuyitFixit]

Thanks 👍Yes a few others mentioned heat from the iron which is very plausible!

[@sdgelectronics]

Not sure if it's the lighting, but the two large capacitors near the switcher ICs looked domed like they're close to failing

[@BuyitFixit]

Cheers Steve, I'll have another look at those when the other capacitors come to replace the output ones. The larger are the mains smoothers, and it might just be the lighting as they didn't appear to be domed when I looked at them.

[@repairchannel]

Great video again. Thank you! But eh... is that the mains connected to the board where your right hand is almost touching?

[@BuyitFixit]

I've had a few "belts" in my time. It would make the video like one of ElectroBooms 😂😂😂You also have a different angle (top down) to me, so it may look worse than it is, as it's also hard to judge depth of field on a TV.

[@ISquishWorms]

Nice fix. I do find it mystifying though as to why a repair shop was not able to test and replace capacitors. Maybe capcitors recover a little bit if they have had power applied to them recently? So after some time you got the true readings, not sure just a guess on my part as it is odd. Ha you heard me, I was saying out loud I would change the other capacitors as well and then I got to the end of the video.

[@BuyitFixit]

Thanks 👍😂😂I think it was the heat from the iron caused the caps to "fix themselves" temporarily until the cooled down.

[@ISquishWorms]

@@BuyitFixit Ah yes good point, I over looked that. I think you are right.

[@canyondan]

well done. Always learn from your videos. Always amazing repairs.

[@BuyitFixit]

Thanks 👍

[@macbilling6410]

Your so clever. Very interesting to watch

[@BuyitFixit]

Thank you! 😊

[@mikecass8306]

Well done Mick 😃

[@BuyitFixit]

Thanks Mike 👍

[@helmargesel3972]

Thanks for sharing your knowledge

[@BuyitFixit]

Thank you 👍

[@AIexanderHartdegen]

Hi sir, despites the control of those capacitor, it doesn't mean than they didn't short circuited the voltage coming from the transformer. Those kind of issue are not visible with any tester. Thanks for sharing.

[@pauldery7875]

Great video as always, thanks for sharing! Paul, USA!

[@BuyitFixit]

Cheers Paul 👍

[@RambozoClown]

I bet if you had checked for ripple with the scope like you mentioned, you would have been able to see the effect of the new caps.

[@sapperdeflap]

I'm Dutch so i could read modified 9-11- '22(gemodificeerd 9-11- '22) on the back of the lid, that probably explains what you're seeing at 4:04 Enjoy the Dutch stroop wafels! 🙂

[@BuyitFixit]

Nice 👍I wondered what the writing meant. Thanks for that 🙂

[@roy2689]

love your videos on a Saturday night, I always look forward to them, by the way I make my own pizzas on a Saturday night now, you know what I mean 👍👍😋😋

[@BuyitFixit]

Thanks and Nice one! I made pizzas last night as we had friends over 🍕🍕🍕👍

[@shawnphenry]

I had a similar issue with Ubiquiti Security Gateway PSUs. They would flash on and off, just like this, and it also ended up being the main 12v output capacitor. Tested in the picofarad range and a simple replace got it going again! Pesky caps :3

[@BuyitFixit]

Nice 🙂Thanks for sharing 👍

[@joelkist6493]

You sharing those cookies? 🤣Nice fix. Came across that same capacitor readings a few times. I attributed it to F.M. and moved on.

[@BuyitFixit]

Thanks 👍Sorry mate, I ate them already 😂😂

[@jonnyduncan7056]

Top fix.. Well done.

[@BuyitFixit]

Thanks 👍

[@MikeB_UK]

Those caps behaved very odd. I'd have been tempted to put them back afterwards to see if the fault came back and then look at waveforms across them with a scope to see just what had been going on. Maybe something to do with a specific frequency other than what your cap meter tested them with? A very interesting repair.

[@BuyitFixit]

Thanks Mike, a few people mentioned it could have been the heat from the iron caused the caps to "fix" themselves, which I think is correct. I've heated things up with a hair dryer before or sometimes things work when "they warm up" so it's very probable.

[@luckywetland]

Simply brilliant, Mick. The PEAK tester is dope🤩 I hear it clicks when you test a cap, is there some kind of a relay inside?

[@BuyitFixit]

Cheets mate 👍Yes, I think it's the automatic discharge circuit.

[@darrenwardell3079]

Would those Caps read differently after being discharged after you took them off? Great vid too👍👍

[@BuyitFixit]

The meter automatically discharges them, but I probably already did that with the soldering iron when heating both pins together 👍

[@nuckenfutz9983]

It's probably been said, but you must test capacitors when they're at room temperature. The data sheets often give 70F IIRC as a baseline of their specs. Heat will lower their ESR and raise capacitance, and give misleading measurements. It's a total work-flow killer, but I stick electrolytics in front of a fan for a while after desoldering them.

[@BuyitFixit]

Yes, Thanks for sharing 👍

[@andygardiner6526]

Always make sure the caps are discharged before you test them in or out or circuit, unless they are very leaky it can cause spurious readings.

[@BuyitFixit]

Good advice 👍The test meter I was using discharges the capacitors first, that's the click of a relay you hear when it senses the component 🙂

[@mrjsv4935]

Interesting how that capacitor gave different readings, initially looking like it's ok. Funnily enough, this week I had to call service company to change leaking bidet shower in the bathroom. Sure I could've replaced it myself, but this is rented apartment, so everything fixed to this apartment must be done by the service company. Anyway, as the repair guy was present, tried to demonstrate how it leaks, but the darn thing didn't leak initially at all :D I had to really press the handle and release it couple of times before it started showing droplets of water, then the fault was proved, repair was approved and he changed it to a new one. Intermittent faults :P

[@BuyitFixit]

Glad you got the shower sorted 👍 A few mentioned about the heat from the soldering iron "fixing" the capacitor until it cools down, which is quite plausible.

[@dublindave5795]

The dvm showed it had the proper voltage. Would a scope have shown there was a problem in the the voltage to the board?

[@BuyitFixit]

Probably, it could be that the refresh rate of the meter was a lot slower than the ripple of the PSU, so it was just an average and the scope would have shown the power supply dipping and rising.

[@nixxonnor]

Winner winner chicken dinner! Nice gut feeling and fix :)

[@BuyitFixit]

Cheers 👍

[@dhaggy1980]

Great fix. Could the esr have been skewed a bit from your finger? Or does that matter?

[@BuyitFixit]

Thanks 👍The consensus is heat from the soldering iron, which I'd think is the likely cause.

[@wherami]

Amazing talent

[@BuyitFixit]

Cheers mate 👍

[@theoldbigmoose]

I have had the same experience. Caps check OK on "Peak type" meters, but they are not good. Replacing them brought back a stable microprocessor in industrial type controls. I don't know either why the deficient caps looked OK and tested OK.

[@BuyitFixit]

A few people mentioned it could have been heat from the soldering iron causing the readings (heating caps sometimes makes them spring back into life).

[@mxslick50]

In switch mode power supplies, capacitors are critical. low or high capacitance or low or high ESR WILL make a switching supply malfunction. Remember that in a switching supply, those caps may be filtering frequencies in hundreds or thousands of Hz, not lower frequencies like normal supplies. Bad capacitors affect the stability of switching supplies and can cause a lot of damage in some cases. It's always the caps in any microprocessor (or switching supply) based equipment.

[@BuyitFixit]

Thanks for sharing 👍

[@TimDyb]

Caps breaking down with in-circuit voltage/current. Tester doesn't provide equal voltage or current.

[@ohmbug10]

That's the truth. I had 10,000uF 63V filter caps in a receiver that measured fine. Fortunately I had it on a dim bulb. It would go bright, dim and about 5 seconds later go full bright.

[@BuyitFixit]

Possibly, or heat from de-soldering skewed the readings.

[@catdog726]

Well done

[@BuyitFixit]

Thanks 👍

[@deanstalker7964]

love your channel you have influenced me to try fix my own electronics, some that i have been lucky with like tvs, power banks and some that I've been unlucky with. currently i am working on 2 solar inverters with different faults. one i managed to solve more than one error but is still showing a fault code and another that came faulty from factory and wont accept faulty from customer service. "works but not as efficient as it should" how do i get your help and how much would it cost? thanks, dean

[@BuyitFixit]

Hi Dean, thanks for the support. I tend not to take on too many jobs as I only do this as a hobby pretty much and we also have a farm. I'm not too sure what would cause an efficiency problem unless it's something like two separate inverters and only half of it is working?

[@willemstreutgers1154]

Great fix. Enjoy your "stroopwafels"

[@BuyitFixit]

Thanks, will do!

[@davidquirk8097]

Do you not worry about the influence of your fingers on the esr readings?

[@BuyitFixit]

If you just hold the probes it says no component detected. I'm not sure how much influence it would have on the reading.

[@patrickcraenen5163]

It could be that the electrolytic capacitor was still warm from soldering and therefore gave a good ESR reading. Electrolytic capacitors usually measure better when they are warm.

[@BuyitFixit]

Yes I believe that's the case 👍

[@andyamanda5777]

The reason the esr was higher later in the video is temperature. You tested the caps just after being desoldered, perhaps higher temp? Just a hypothesis

[@BuyitFixit]

Yes, I agree with that hypothesis, a few others mentioned the same 👍

[@stevec5000]

Try testing the caps with different meters. Even the cheap Chinese component testers might turn up a fault.

[@richardtaylor7199]

Great job

[@BuyitFixit]

Cheers 👍

[@Z-Ack]

Lol. Sometimes its hard work and hair pulling headaches of a fix that just defies logic and sometimes its just luck and a gut feeling.. recently i had a car that had an digital display as the dash cluster that indicates speed and all which would only show bits and portions on the screen. Took it out reflowed the display cable and glued it back down, on a whim. And fixed everything. Had another same make model and problem. So i reflowed and same repair but didnt fix it. After a few days of troubleshooting it turned out to be a faulty tipm which is basically a fuse panel on a circuit board that allows for direct voltage and current readings for the ecu or bcm can network..

[@BuyitFixit]

Thanks and nice work 👍

[@phillipsvanderwesthuizen800]

Perhaps a voltage dependent fault on the cap(s) (Start leaking at higher voltage). I have had that on higher voltage caps but not at 16V?

[@julien1997a]

Hi, i think you have fit these capacitors in the wrong polarity position, if you look closely around 16:40 the white band on this pcb indicate the positive and not the negative like should normally be, see the capacitor C14 above rj45 port the negative of this capacitor is inverted compared to the pcb mark, Julien. P.S. Sorry for my bad english😉

[@BuyitFixit]

You are indeed correct, and the only one to spot this mistake! Usually the white donates the negative, but not in this case! I'm really surprised it worked. I've still got the unit here as I was going to change the rest of the capacitors, so I'll replace those two too and fit them all the correct way. Thanks again for commenting and letting me know, and it just goes to show that I'm only human and make mistakes too! Thanks again. Mick.

[@Shineylake]

I have wonder if any boards are made such that the capacitors are pluggable? Seems like you replace a LOT of them.

[@BuyitFixit]

I doubt it, as you would get problems with capacitors dropping out of sockets etc, also it would add a lot more cost to the product if everything were socketed. Most devices these days use surface mount components too.

[@laurencebushby713]

I thought capacitors immediately, but you measured soon after heating with soldering iron, i usually get hair dryer and heat the psu up if it starts working you know it capacitors

[@BuyitFixit]

Yes, heat can indeed affect them. I should have remembered at the time 👍

[@maicod]

Alex must be from my country with his Delicious Stroopwafels (Syrup Waffles)

[@BuyitFixit]

NL 👍

[@michaelthomsen8771]

I wonder if it would have worked if you just disconnected the backlight? (Not as a fix, but instead of powering from you bench psu)

[@BuyitFixit]

Possibly, it might have stopped the PSU resetting.

[@ceemills]

I always wonder why other shops were unable to follow straight forward trouble shooting you perform to fault find such as the main power supply capacitors and yet another the shop obviously hasn't? maybe they did not bother at all?

[@BuyitFixit]

I'm not sure, I've had a few items like this so far where they have been to other places for repair. Perhaps they just "replace boards"? or as you say just don't bother.

[@russellhltn1396]

It looks like the board has a small SMD cap in parallel with the electrolytic cap. That small cap is probably why you were seeing a lower ESR in-circuit.

[@BuyitFixit]

Yes indeed it does. Thanks for sharing 👍

[@ninaevans4501]

@BuyitFixit Another great video Mick. Thanks for sharing with us. It maybe possible that the offending caps were failing under load. A right pain in the a..e to track down 🤨🤨🤨 Thanks once again, nice one. 👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿🫡🫡🫡🫡🫡🫡🫡❤️❤️❤️❤️❤️❤️❤️😊😊😊😊😊😊😊😊😊😊😊😊😊

[@BuyitFixit]

Cheers 👍the consensus is heat from de-soldering caused the odd reading.

[@ninaevans4501]

@@BuyitFixit Yes, Mick, thermaly unstable capacitors are also a big pain in the bum to get to the bottom of (pun unintended) 🫣😏😏 We've all acquired Covid this end, but don't feel too bad to be honest. Cheers Mick Take Care 👍🏿👍🏿👍🏿👍🏿👍🏿❤️❤️❤️❤️❤️😊😊😊🫡🫡🫡😷😷😷😷🤧🤧🤧🤧🥵🥵

[@BuyitFixit]

@ninaevans4501 Sorry to hear. Hope you all get better soon 👍

[@techrestoread]

Wow very interesting think l will learn a thing or to for my channel many thank and keep up the great work 😃

[@BuyitFixit]

Cheers 👍

[@simontay4851]

19:55 That is NOT OK. 165uF and 0.62ohm ESR on a 220uF capacitor is BAD. Even 185.2uF from the previous reading is bad. You should replace all the 220uF caps with 330uF or even 470uF ones for extra headroom.

[@BuyitFixit]

I thought that, but people also mentioned on the Dumpster TV video that it's not unusual for capacitors to have a 20% tolerance, which would mean 185uF would be OK for a 220uF 🤷‍♂️

[@anenglishmaninbrazil3212]

The caps probably had a little charge still in them I have seen weird things before so I tend to short the terminals just to be double double sure

[@BuyitFixit]

The meter auto discharges before testing, the consensus is that the temperature of the capacitor was increased de-soldering it and that caused the odd reading.

[@mikecassap]

Mick the fact that Esr meter is reading 173uf when they should be 220 if that tells me alone that those caps were bad there well out of there tolerance mate

[@BuyitFixit]

That's what I thought but quite a few viewers mentioned on the Dumpster TV video, that capacitors can have a tolerance of 20%, which would be 176uf - on a 260uf on a 220uf?

[@jbrovage]

I'm halfway in, and i've developed a hypothesis: someone attached a 48v POE ethernet cable into the RS-485 ports, and sent 48v where it didn't belong. When something is in a datacenter, any RJ-45 receptacle is ASSUMED to be ethernet. :P

[@BuyitFixit]

Good theory, but they have around 30 of these and quite a few were having similar problems.

[@karlfell3768]

The internal heating from desoldering the caps will affect your readings

[@BuyitFixit]

Agree, totally forgot about that, but a few people have mentioned the same 👍

[@zentechnician]

Make sure the caps are drained before you test them. Low voltage is still voltage. Those ESR meters all vary so much, you want one you can select what frequency you are testing at.

[@Tekwyzard]

The tester he's using has the ability to automatically discharge the DUT, but you're correct otherwise, other commonly available ESR meters can very easily be damaged by connecting capacitors with any residual charge left in them.

[@zentechnician]

@@Tekwyzard Weird note in the manual about it removing a charge of a few tens of volts. Obviously they are indemnifying themselves against soneone discharging a higher voltage cap in the unit but that same statement kind of indicates the lower end may be ignored. At 16v you aren't even going to discharge that with your fingers without quite a bit of effort. It's a cooked off capacitor, the heat assessment seems really logical. You never know what's going on inside the layers of these things when they are a quart low on fluid. Seems like letting the caps sit and stew a while was the key to getting a good bad reading so something changed. Doing 2 tests in a row might reveal whether it was residual voltage that skewed the results. Makes me curious, maybe I'll go blow something up now.

[@MC-Racing]

when i saw that restarting, i would have jumped directly to replacing caps :-)

[@BuyitFixit]

Yes, it's what I pretty much thought at first. But it seemed that the MCU was getting 3v3 and it was only the backlight voltage that was jumping a bit.

[@MC-Racing]

@@BuyitFixit yeah I agree, but if it's the same supply generating both rails,, there might be enough ripple on the other rails to reset mcu. Anyways as another guy posted, it's always the caps 😁👍

[@frankcarpenetti5776]

Right in the first couple of minutes, I am calling a cap. Had an epensive coffee maker with similar problems? We shall see!!

[@BuyitFixit]

I thought caps too at first and then had my doubts...

[@tasmedic]

Capacitors are weird things. They behave differently depending on the frequency they are working at. and some go intermittent short (which is what I think might be happening here) at one voltage but are fine at lower voltage due theit toilet roll costruction (in the case of electrolytics. as here) When I see flashing on and off like that, it makes me think of a switch mode with a faulty bootstrap circuit. I think using a seperate power supply to the display was a master stroke. That immediately identified which board was the likely culprit.

[@BuyitFixit]

Thanks, yes I was expecting a bootstrap cap too, as you say it's often the symptom you get. Although a short on the output of a PSU can also give similar symptoms.

[@jumboegg5845]

Dont write-off measuring capacitors in circuit so quickly, its a good easy check and often works, but not always, depends on the circuit. You got weirdly high reading on the dodgy capacitors in circuit, which may have been an indication. Would have been good test to see if you got the same weirdly high capacitance readings on the new capacitors in circuit. If they read around 200uF in circuit, and not the weirdly high readings (11, 220uF), then it says it was not the circuit, it was the dodgy capacitors giving the weird reading on your meter.

[@BuyitFixit]

I'll give it a go in the future, I'm going to try to get a set of probes for the meter.

[@snik2pl]

Hot caps have lower esr. That why when they fail in tv you cant switch on at first and when you wait plugin they will swich. Then it get worse and heating will not help. I would also change caps in other power supply.

[@BuyitFixit]

Thanks yes, planning on changing them all 👍

[@Dutch_off_grid_homesteading]

Heya,nice repair from some industial tools

[@BuyitFixit]

Hey, thanks

[@josephcote6120]

At first I suspected a bad cap, but I 99% expected it to be one of the tantalums.

[@BuyitFixit]

Nice avatar 👍

[@josephcote6120]

@@BuyitFixit Thanks. My own repair work is limited to point-to-point and through hole. My old eyes can't deal with SMDs.

[@BuyitFixit]

Me either, that's why I have to use a microscope! 😂😂👍

[@GearHeadGeeks]

What I do if I suspect a cap going out is just put my meter on AC and measure the AC voltage where DC should be coming out. It will be high if the caps are going away. Just a thought.

[@BuyitFixit]

Great idea, I hadn't though of that. Thanks for sharing 👍

[@jackbauer2698]

Maybe it measured differently first time because it was still warm from desoldering it from the board?

[@BuyitFixit]

Yes, I think that's the general consensus 👍

[@fredwooding599]

Why do you not wear an Anti-Static wrist band?

[@BuyitFixit]

I haven't got one 😂😂I think possibly on one occasion over the last 35-40 years I might have had something fail which possibly might have been due to static, but I've worked on PCs, built PCs etc etc and never had a problem...