Common approach to repair SMPS generally speaking in my mind; Mosfets, resistors, capacitors, Diodes, controller's. I am sure others will diag them differently. Mostly used is a multimeter.
Good point! I suppose I should have clarified depending on the symptom. But if I have no voltage on the secondary side as in this case, I like to check the controller first because the datasheets for them provide so much information and you can get a lot diagnostics from checking with a scope. And I'm not saying because I think the controller is the issue, but knowing it's operation mode (under voltage lockout, over voltage lockout, hysteresis, etc.) can lead you to finding faults with associated components
@@joelkist6493 ain't that the truth! You're right I probably could have figured this out faster going with your approach. But there have been so many videos done on repairing this power supply that I thought it would be cool to show how it actually worked.
@@fmashockie If the main switching fets are blown then its likely you also have a shorted output pin on the controller IC that drives the gate of said fet. For combination chips that control both pfc & smps you can still have the pfc portion working despite the smps portion blown, which you did.
@@spikester thanks for that input! Interestingly, the DAP053T was still sending gate signals to both HS and LS MOSFETs despite them blowing. I show that in the vid @30:46. I'm not 100% sure what went wrong with the DAP053T, but it seems to be a common failure in this supply from what I've seen
Enjoyed following along but don't know if its a cultural thing but I have never heard 'hysteresis' pronounced that way! in the uk its 'hiss tor ee sis' When I change two blown power devices the first thing I do after power up, if nothing changes, is to check to see if they are still ok because what killed them once can kill them again. Whacky I can't hear anything ! Last thing please be a bit more aggressive with the scope you can get the waveforms so we know what they are as opposed to being off screen or we are looking at the low frequency crap etc ! nice one and the motherboard next !....cheers.
Thanks as always Andy! I really do appreciate your feedback both good and bad. I'll be honest - I wasn't sure if I was pronoucing hysteresis right 😂 I can definitely do a better job with the scope for you guys - make sure I give you a clear shot moving forward and ensure it is triggered properly. And I know the sounds from the inductor didn't sound too bad on video, but man this thing was chirping away in-person - especially at 250W! Thanks as always for taking the time to watch and comment! 🙏🙏
Update: At @31:40 I mention R9 having gone open after I intially tested it (although I'm still not sure if I made a mistake). However, I heard somewhere that this is actually a fuseable resistor. Without a schematic, these can be hard to identify as they can look just like normal resistors. But it explains how it could have easily tested normally at one point, and then later on gone open. Not to say that couldn't have happened with a normal resistor - if you apply enough power to it 😆But still if you plan to do this repair, and you come across R9 open, probably best to replace with a fusable one!
nice job--well explained
Thanks for watching Stan and I appreciate your feedback!
Common approach to repair SMPS generally speaking in my mind; Mosfets, resistors, capacitors, Diodes, controller's. I am sure others will diag them differently. Mostly used is a multimeter.
Good point! I suppose I should have clarified depending on the symptom. But if I have no voltage on the secondary side as in this case, I like to check the controller first because the datasheets for them provide so much information and you can get a lot diagnostics from checking with a scope. And I'm not saying because I think the controller is the issue, but knowing it's operation mode (under voltage lockout, over voltage lockout, hysteresis, etc.) can lead you to finding faults with associated components
@@fmashockie Just remember, time is money. Otherwise I agree.
@@joelkist6493 ain't that the truth! You're right I probably could have figured this out faster going with your approach. But there have been so many videos done on repairing this power supply that I thought it would be cool to show how it actually worked.
@@fmashockie If the main switching fets are blown then its likely you also have a shorted output pin on the controller IC that drives the gate of said fet. For combination chips that control both pfc & smps you can still have the pfc portion working despite the smps portion blown, which you did.
@@spikester thanks for that input! Interestingly, the DAP053T was still sending gate signals to both HS and LS MOSFETs despite them blowing. I show that in the vid @30:46. I'm not 100% sure what went wrong with the DAP053T, but it seems to be a common failure in this supply from what I've seen
Enjoyed following along but don't know if its a cultural thing but I have never heard 'hysteresis' pronounced that way! in the uk its 'hiss tor ee sis' When I change two blown power devices the first thing I do after power up, if nothing changes, is to check to see if they are still ok because what killed them once can kill them again. Whacky I can't hear anything ! Last thing please be a bit more aggressive with the scope you can get the waveforms so we know what they are as opposed to being off screen or we are looking at the low frequency crap etc ! nice one and the motherboard next !....cheers.
Thanks as always Andy! I really do appreciate your feedback both good and bad. I'll be honest - I wasn't sure if I was pronoucing hysteresis right 😂 I can definitely do a better job with the scope for you guys - make sure I give you a clear shot moving forward and ensure it is triggered properly. And I know the sounds from the inductor didn't sound too bad on video, but man this thing was chirping away in-person - especially at 250W! Thanks as always for taking the time to watch and comment! 🙏🙏
@@fmashockie :) probably my age (nearly 60) as to why I can't hear it LOL !! yeah a few little tips there...always interesting to watch !
Update: At @31:40 I mention R9 having gone open after I intially tested it (although I'm still not sure if I made a mistake). However, I heard somewhere that this is actually a fuseable resistor. Without a schematic, these can be hard to identify as they can look just like normal resistors. But it explains how it could have easily tested normally at one point, and then later on gone open. Not to say that couldn't have happened with a normal resistor - if you apply enough power to it 😆But still if you plan to do this repair, and you come across R9 open, probably best to replace with a fusable one!
feynman: the pleasure of finding things out
that is one of the main reasons I do this!