Diagnosing a faulty PSU

A very common PSU fault on a fairly nice power supply from a media player.

Don't be fooled by the cheap SRBP (Synthetic Resin Bonded Paper) style PCB. It's been designed with common sense and safety in mind to comply with UK standards.

The sizing of the diode array is probably mainly for the increased passive thermal dissipation.

This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.

#ElectronicsCreators

[natewillis]

I love these types of videos, helps people get an idea of how legitimate electronics repair goes. Will also help right to repair a teensy bit. Thank you for this Clive!

[Silverfoxwolfen]

It's amazing how quickly you are able to fault trace this problem. Top marks for you and awoo for the fix!

[ScottGrammer]

A long time ago, someone thought, "Let's take the AC mains, rectify it into DC, connect s coil with a DCR of 0.05 ohms to it, and then short it to ground with a fragile mosfet." That man ended up in an asylum, but danged if it didn't work.... It has always been my theory that switching supplies work because of voodoo.

[edwinlipton]

This Clyde could turn children into electronic tech's! He makes the most complicated, easy too understand. GREAT JOB CLYDE! CHEERS!!

[Kwaq]

I consider Mitsumi a quality manufacturer, had lots of 3, 5" floppy drives, never failed. Could be dirty with dust bunnies, still wouldn't misalign heads. This PSU looks to be quite tidy, too.

[bleakrevel]

I’m so glad you covered the charged up input capacitor danger.

[mickdiy]

this kind of repair is the god of all repairs, these days, electronic technicians are not the purest kind.. i remember a friend of mine who works with radar system in middle east, he travels even during wee hours for sometimes 1000 km just to fix a radar. i saw him fix my laptop by cutting some IC connections and jumping it from somewhere with several wires, insulate it and bingo, it works. people like clive and my friend are few among millions who does a work with electronics by just smelling it. salute to you clive. nice video and thank you for sharing it with all walks of life.

[phils]

The choke / capacitor filter at the front end is more to protect the mains from radiated HF interference. Those HF switching PSUs can be pretty electrically "noisy" - and most of the Compliance Authorities (e.g. FCC) now mandate such suppression.

[lp]

Finally, a classic uncut repair video of something other than a LED lamp. ;-)

[joshfriesen]

My favourite videos are the repair videos because they are done by Clive so they are not boring and I learn stuff from them! Thanks for that clive

[foxtrot]

"This is good", I know that feeling when you're expecting a pop or smoke and nothing happens :-)

[hullinstruments]

Would love to see more general troubleshooting and repair videos. They are few and far in between on your channel and you’re a very good teacher and wonderful at explaining things!

[EquinoxPublicAddress]

Thank you Clive! This looks like a fault I had recently in a Peavey mixer. Another chip had visibly blown on the PSU, which I replaced. Now the desk pulses on and off just as you described. I’ll dig it back out and have another go at fixing it now!

[Uncle-Duncan-Shack]

Had the engineering manager where I used to work try to discharge the caps on a 600Kw vsd, with the "Short it out" technique he had heard about.
Luckily he was not injured, but it "Brightened" his day.

[AndrewGillard]

Nippon Chemicon capacitors are generally a sign of someone not cheaping out, so reinforces the "common sense and safety" comment in the description :)

(That big, painful 450V capacitor prominently showed the Nippon Chemicon logo - they only include the company name inside the logo in _really big_ capacitors - and the large capacitor on the secondary side was in the same style, even though the logo was hidden.)

[Casey_Schmidt]

I'm not sure why but I always find PSU's to be some of the more interesting things to watch.

[CasperInkyMagoo]

"Yeah, that's good enough."

No truer words have been spoken.

[Soggstermainia]

If you want to remove a component and need to pull it gently to remove it there is an easy trick I use. Grab a pair of forceps and clip them onto the resistor, mosfet etc and then hold the board so they hang, once you heat the pads up the weight will pull gently for you. An added bonus for exposed metal components is it helps reduce the heat in the parts. Sorta like the opposite to using bluetack to hold parts in place while you solder them in place.

Forceps are an excellent tool for the toolkit for all sorts of little tricks. Very handy and usually a great cheap addition to the toolkit.

[djstraathof]

I love the gigantic primary/secondary labeling. There's no missing that

[daShare]

I use a cable from a dead DVD player as a test mains lead for SMPS boards. The almost all use the same connector for the mains input.