Guide
How To Repair A Switch Mode Power Supply Without Blowing
How To Repair A Switch Mode Power Supply Without Blowing It Up!
#Repair #Switch #Mode #Power #Supply #Blowing
“Learn Electronics Repair”
Sometimes you can replace the faulty components in a switch mode PSU only to plug it in and watch your shiny new parts self destruct. I recently have this problem with a power supply that blew up even though it was connected to a current limiter (light bulb). Find out why this happens and how…
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looking forward to the next vid on this .
26:56: Instead of cutting traces to insert the light bulb, couldn't you also desolder one of the big filter caps and reattach it with a pair of wires and then a bulb in series? If the "blow-up current" comes from the caps, it should suffice to limit their output, no? You'd probably still need the limiter on the input for other faults (e.g. the bridge rectifier suddenly going short) but you don't have to damage the PCB or bend mosfet legs or stuff like that.
Amazing content!
I was never able to confidently fix PSUs. Unless it was something pretty simple, like replacing capacitors, they've always shorted again just after powering them up. I've change every component in the PSU (but the transformer) once, and it still shorted again right after powering it up 😅🤷♂
To me, people like Haseeb are magicians.
Just my opinion but if I am repairing something for a paying customer I will never trust mosfets purchased from aliexpress or ebay go with a reputable seller like Mouser and DigiKey. Yea you pay more but they are not fake.
Brilliant thank you, Looking forward to the next one.
Maybe bring it up on a Variac and look for hotspots or find the short on the board, But it will be interesting to see the bulb inserted in like this as I haven't seen it before ! I look forward to part 2…..cheers.
Interesting video. Always HATED working on those PSU's. These days i send them to someone else to repiar. Cant be bothered.
but why should we insert the bulb into the mosfet circuit, to see that they are burnt…
isn't it easier to check them and all the connections with the surrounding resistors and so on?
Hi Rich,
Decades ago my old dad who was a 'sparky' for the SWS which became the Midland Electricity Board if you remember them. He showed be a way of using a lamp holder on flying clip leads to help diagnose this sort of problem and to this day, I keep a 15W or 25W, 240V pigmy bulb set up like this in my tool collection. Most of his job involved transmission @11kV and above so I guess he did not wave his trusty test lamp about too often at work 🤣 but it came in handy on domestic duties. I found through my teenage years that this can be a useful technique for finding automotive issues, too!
Incidentally, for many years I could not figure out how I got a nasty 'belt' from my (12VDC) car horn on one occasion, having had one or two from ignition coils and the like it was a bit of a shock (pun intended)! Far more recently, through programs like yours and others, I discovered the mystery of back EMF as the horn operated when shorted to earth through a relay as there is quite high current through a horn circuit!! We live and learn, as 'tis said!🤯
Could also use a variac to reduce the input voltage.
Great as always Rich.. Looking to set up a permanent isolation transformer on my bench. Will appreciate your thoughts on the alternate solutions you spoke about …Thanks
Thanks again Rick. But are we positive that the aliexpress replace components are good for the job?
Heya, love the trouble shooting thought. as with a accident I sorted my Mppsolar inverter the MPPT pcb probbebly gone try to repair it my self already openend the inverter (wouw what a lot of wires in there took foto so I later can see hohw everything is connected thinking of filming it ut don't know jet ( don't want to look as a fool if I can't repair it) also looking at youtubers who already did some repair work on these imverters
Fantastic! Is there a "current limiting lightbulb" explanation somewhere on your channel. Very interested in putting one together. Thank you for your patience, Richard and thank you for your channel!!
Is the power supply going through the isolation transformer and oscilloscope
It would be nice if you show us the all of the different methodes as you suggested. We could see the pros and cons. Thanks Ritchie.
Nice explanation thanks for that.
It will be interesting (probably, just to me) to see whether the lamp reacts faster than any dodgy mosfets and if it withstands the 320V DC (albeit for a very short period).
Takes me back to the days of the earley PACE set top boxes chopper transitor shorts change it and anything that looked burnt turn on and bang .thank god somone bought out a repaire kit .
i learning a lot from you