Probably the best repair video ever 🙂thank you Richard for sharing your knowledge. I've seen many techniques for finding short-circuits and I've just come across this one and I would like to share it with you and your viewers, possibly you may know it already. Connect your multimeter to where you found the short-circuit and then using your hot air rework station with the smallest nozzle, go around the circuit board warming individual components and watch your multimeter, if you see a resistance change when warming a particular component then you probably found the short-circuit or are near to where the short-circuit is.Hope this helps everybody.
@@LearnElectronicsRepair I think this technique could be very useful Where the voltage injection method could cause more harm to the circuit for instance on graphics cards. Heating individual ram modules for example cause a resistance to change to identify which ram module is at fault. Be interesting to see if it works.
You wrote " Connect your multimeter to where you found the short-circuit So I ask the question: What if it is not My Multimeter ? Can I still connect it and could it cause a potential problem with the owner of the Multimeter ? Have you undertaken a risk assessment on such an act of using a foreign Multimeter ?
Neither YOU or any'one' can help any'body' because all th ebodies are buried in the cemetery and they do not need help. However you could always help some'one' You ate not yet competent enough in the English language to know the difference between any'one' and any'body' Undertake an extensive reading program to better educate yourself - and write an essay on the importance and significance of 'One' Investigate whether there is another 'One' of you in existence .
@@andrew_koala2974 No I haven't as I own quite a lot of multimeters so don't need to use anyone else's. The only risk assessment I can think of would be to check to make sure the owner isn't bigger than me before taking their multimeter.
Excellent repair and, as always, a great teaching moment. Don't forget to clean out the holes for that thermistor and re-install it before you put the heatsink assembly back in 🙃 Regards, David
*IMPORTANT NOTES* At 00:32:36 I think I can see the 27 ohm resistor connected to the PFC Mosfet gate - there is a small SMD transistor and doide nearby. I did check these for short/open and a couple more near the PFC controller. In circuit, at least, they look OK At 00:59:01 There could be another inductor in series with the Capacitor and Transformer Primary
I brought graph paper for drawing out circuits, when reverse engineering to understand better how the circuit "should" work. This has to be my top tip for making it easier and clearer
At 1:13:38 there's a ball of solder it looks like, hanging off of one end of the capacitor possibly bridging to the adjacent pad. Might be nothing, might be stressing the rectifier. I really appreciate your video's by the way. It's reignited my passion for digital fault finding again. Keep up the great work.
Hi Richard you really need to buy low melt solder ( chip quick) then you wouldn't had so much trouble to remove those components. Nice fault finding. Just look into the low melt solder.
I'm trying to build my abilities & confidence with electronics and these videos are great to watch. I learn so much from each one. Not only in electronic repair, but the internal workings of those devices. This is an Apple iMac, much like the one I'm sitting at watching this with. Probably a 2017 or later based on the case shape. Keep these coming!
Oh you sweet, sweet summer child! Apple does everything it can to either prevent, software lock, or complicate repair of their devices well unless it's two or more of the previously mentioned. Considering the hard drive (instead of a soldered on SSD) this was one of the (more) easily repairable ones.
To clarify: This isn't only Apple doing it they are just the most visible everyday encounter for the average consumer.A couple others (to prove I'm just not picking on Apple): Samsung, John Deere, Tesla, the list goes on and on
@@dlange89 Yeah it was a pain in the butt to work on but I wasn't to be deterred, at least not without a good fight. I've not worked on Apple stuff before, I tend to avoid it, I was playing along a bit in this video (oh you nasty apple people) for the fun of it
How about using Bizmuth low melt solder instead of leaded solder? Love your channel. Thank you for your kind and generous sharing of knowledge. Please keep it up! Cheers to You!!
@@LearnElectronicsRepair Thanks for the reply. I look forward to each and every new video you put out. You have a great talent for teaching and you have a great sense of humor. I also enjoyed the videos you made about where you live and old PC repair. You remind me of Big Clive on the Isle of Man. Both living on an island and both simply Brilliant!
Your BC3 tips might be good Rich, but for this you need one of those carbon contact Scope irons that auto sparkies use. Rarely had something I couldn't unsolder using one of these.
Good evening. Very good Rich, very good indeed. An interesting video and the satisfaction to repair a 'crAPPLE' product even if only to annoying them is let me say... priceless!! Apple I am Sorry for you: this time no PCB swap whose cost Is ten times worth its weight in pure gold!! Shame on you. You Will never get me... Regards from Italy.
One of those channels where I can click on like before I even watch it. Of course I watched it fully and another excellent repair and teaching. Thank you so much for your work.
I've got 4 of these with exactly the same issue in the workshop! It seems a common point of failure by the looks of it. Time to get some components ordered.
The topology explanation was useful. After watching a few of your ATX PSU fixing videos, I opened one up and found a topology with a single capacitor which you never showed in videos. I was quite disappointed. Maybe I was unlucky to have the first one with unknown topology, but I'd suggest this should be a part of "all you need to know about ATX PSUs to fix stuff". Or maybe cut the topology part of this video into a standalone video and include it into the PSU fixing playlist?
It's good to see you enjoyed that, and it filled a gap in your knowledge. I guess we all improve as we go along. It is less common in ATX PSU (certainly the ones below about 500W) And yeah, I could do something like that with other types of DC-DC converter too. Thanks for the idea
Be thankful you could order parts for the repair. Sometimes one has to use parts from donor boards for Apple due to restrictions Apple places on the chip manufacturers for some items,
Understand that Lead-free solder is used on the PCB This has a high-temperature melting point - So 1. Always apply some flux to the solder joint FIRST = SUCH AS AMTECH NC-559-V2-TF Flux 2. Solder over the joint with Low-Melt Solder -- This will blend in with the Lead-free solder - making the wires very easy to remove and without stress or damage. 3. Be sure to carefully wick-off the solder pads when the wires are removed, 4. When re-soldering also apply Flux - and use leaded solder. DO NOT use Low-Melt solder for Soldering - It is to be used ONLY for Desoldering
Please make a video about diagnosing AGP graphics cards. I have a stack of them waiting for repair in my personal collection. I was able to fix PCIe GPUs after learning from your vids…now just need to know your tricks of the trade for AGP!
@@LearnElectronicsRepair yes I watched that video already and you did replace caps, but I haven’t seen you perform diagnosis on AGP cards like you have done on PCIe cards. Which pins to check for shorts? What voltages are we looking for? You get the picture…
I hope they don't ban leaded solder. I've only just realised why one uses leaded solder from the higher melting point of modern tin and some silver solder and so forth. I wondered why the other surface mounts didn't get disturbed. Would you solder components back with the higher melting point solder as to the original?
I have tried doing this repair. found the shorted components and replaced them. But after doing so, I found that the coil heats up when applying load, when higher load is applied the same components fails again. I only got it working by effectively removing (bypass) the pfc circuit all together. Looking forward to part 2 of this repair to understand further why it heats up(if you face the same situation) and possibly the final repair :)
A common failure of SMPS coil heating up is that the glue that holds the coil together internally fails, which opens up an air gap, which changes the inductance value as it heats up. It’s a self perpetuating failure in that it gets worse and worse each time it happens. Replacing the surrounding components will allow it to work for a while, but until that coil is replaced, it will always fail at some point later.
@@michaelkeymont501 thanks for the reply , I also do know that from bad soldering(usually cracked solder) of a coil would cause it to heat up as well but in my case I removed the coil that heats up and put it in a known good smps and it doesn’t heat up anymore. So I’m still stuck
you should consider a drill press and 1/8" or so drill bit for those rivets. you really wore out your tools there in my opinion. but you did get it out. eventually.
Fantastic video, learned a lot! I found your channel a while ago wanting to learn about fault finding on PSUs and motherboards, thanks for another great video the information is invaluable!
Hello Richard, thanks for all videos you've been doing, showing and then explaining us with schematics. Regarding this video, could you next time lock the exposure? The picture goes dark then bright, dark, bright, etc. 🍺
I'm just starting out learning so I have been binging on your videos. Amazing channel. One question I do have is that I have noticed people talking about real vs fake Chinese components from sellers on ebay. Are you not concerned that Ali express which is china is risky for buying parts? I have seen transitors for a ham radio that looked almost identical to the genuine and even tested as transitors on a scope but the guy explained the subtle differences to the genuine parts. Just curious to your thoughts on this. Thanks
With Apple products, I always have a plan Z; they were very anti-right-to-repair, especially when replacing a power management chip in an iPad, super videos :-)
I'm only 5 minutes in but Ifixit will have a repair guide to tell you how to take the thing apart so you're not wrestling with it and don't have to remember which screw went where. They certainly won't say how to repair the PSU so this is not to detract from the video, just the battle to get access to the sub-assembly..
Im having a "déjà vu" here. Had exactly same repair last year with exactly same diagnosis. Spoilers, hint-hint, cough-cough, the repair attempt probably fails (you will end up with psu that is turning on, but randomly reboots). Hope you can track fault down that i couldnt... Waiting to see next episode of this PSU! 👍
With the decline of the filamant bulb. What alternatives can be used for the bulb current limiter. I thought about G9 halogen but was reading there would be issues due to the thickness of the filament
Is it wise to purchase components from AliExpress? My experience has been that some of them are fakes or out of spec with the real components...What has been your experience?
When there it also helps to suggest the customer to swap that hard drive for an SSD. Clone 1:1 then the partition can be grown in the disk tool if the SSD is larger than the hdd. These machines get a second life when you do that. The user experience on a mechanical HDD is abysmal on them. Should have never went out the door that way if you ask me.
It's nothing to do with modesty or the lack of. It's called click bait 😂 Hope you enjoyed the video though. Now try the followup Probably NOT the best repair video on RU-vid ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Vhi9Kf4YgDs.html See, modesty works both ways with me 😉 Hmm note to self... 'Possibly the best' video title got 31K views. 'Probably NOT the best' video title got 8.7K views. Seems I was right the first time. Where's that window to throw modesty out of? Apparently modesty is useless.
I did have to smile when you said .."how difficult could they make this..." .........................It's an Apple!!!!! ...........Nuff said! I'm sure they're working on it. In fact you also mentioned about making the HDD more easily user removable. I'm surprised they didn't design it to read the disk hadware data into othe BIOS on first power up, so if you try to replace it, the computer detects the change and totally bricks itself. Not that Apple go in for shady restrictive practices or anything. Sorry, rant over. Excellent vid btw!
I have worked on older Imacs and they are all a pain. Built like tanks but a pain to work on. Why the engineers designed the holder for the FETs with the mounting screws facing down was cruel. I guess they want you to buy a new PS instead of repair in the field. Makes me wonder if the rubbery black insulation was specially designed to go conductive after the end of the warranty. No lead solder should be banned along with the officials that required it !
Philosophy behind the Macs is that you don’t change anything like the graphic card or something. You buy a new one and transfer the data and then sell the old one. There are always people like students who are happy to get a cheaper Mac for themselves. You sell it to a company that is specialized to these and they check that everything works and gives one year warranty for them. Everyone is happy. If you change graphics card then the old one is electronic waste also the old parts might not be up to date with the graphics card so there could be bottlenecks. Apple likes to have everything as compact as possible.
More I was just playing along really, but yeah they are nasty. I haven't worked on Apple equipment before, I tend to avoid it. I tried to avoid this one too, like 'sorry but I don't have the tools to remove the screen safely' but Handy Andy took it out himself then brought it to my workshop so then I had no excuse! 😆
@@LearnElectronicsRepair What a relentless customer ;) I'm sure you watch Louis Rossmann's channel and his struggle with Apple. Anyway, I love to watch your videos. Keep up excellent work!
@@Piasecznik72 Yeah I have. This channel exists mainly due to the influence of two other RU-vidrs who I never chatted with (yet) but both made me think 'I can do that too'. Those two guys are Louis Rossman and Sorin at Electronics Repair School. My early videos were very much based on Sorin's method of video production.
@@mariolemerise7732 Actually no, I wasn't really aware of Alex' channel when I launched LER. I had watched Elitech and Tech Cemetary so that was another influence
I wish I could do this stuff. My iMac PowerBook is only a couple years old and the entire motherboard blew up. Luckily I had the apple care so they had to fix it for me or it would have been a $2000 tragedy. They still charged me over $300. Said it had “water damage.” NEVER seen a single drop of water ever for 100% sure, so that’s a lie. They even got rid of all the buttons for the volume/brightness/etc for a “Touch Bar” that just decides whenever it wants to work or not. Horrible. Not to mention they probably have more personal data on us and our movements/interests/finances/HEALTH than the CIA…
It's an Apple product that is why there is Lous Rossman around to repair. They don't want you repairing their stuff. Louis is an advocate and has lobbied legislatures for Right to Repair. I have shipped my MacBook Pro to him twice for reapir. I am just afraid to attempt to repair them.. He is an expert at reapiring Apple products.
6:42 - Why is the question; Apple is the only reason. The PITA is designed into all their products - a concept that has pushed the "Right to Repair" movement squarely into the limelight in the US.
The trouble taking this unit apart is one of the reasons why I "avoid" working on these brand name products. It even got you cussin'. The idea is to replace the board - not troubleshoot.
@@verttikoo2052 It wasn't so much difficult, just more difficult than it needed to be. How hard would it be to put a connector on the PSU mains in? Likewise why mount the heat sink on the output devices the way they did? Sure solder it to the board to help heat transfer, but bolt the transistors to it from the top like everyone else does, to make it easier to work on. It would not take any more space to do that.
Dude!!!! what is the matter with you? Torturing that board and wasting your time for over an hour. Hakko makes larger nozzles of all sizes for their vacuum desoldering guns. May be it's time to get yourself an assortment of those (they are all less than $20 a piece). They would desolder the heatsink like a breeze. I have done that a countless number of times. and if you need to use a hot air gun without wiping out all the adjacent little components, use "Kapton" tape (or however it's pronounced). Other than that, awesome as always. Can't thank you enough for all your effort making the videos.
You can charge the customer more money because repairing an Apple computer or a Windows Computer is not the same. Just go to an Apple repair service check their prices and you will know what I mean
ok I apologize. what you lack in apple knowledge, you have 10x in power supply knowledge. but that second cable from the power supply pulls up from the inside of the iMac. you didn't have to unsolder it.
