EEVblog 1388 - Dumpster Diving 4K TV Murphy's 'Repair'

Dave fixed this Hitachi dumpster diving 4K TV so well that he broke it!

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#DumpsterDiving #Repair #Murphy

[WizardTim]

Pretty confident that 0.3 W was the normal when you had the PFC bypassed as things like energy star require normal standby to be < 0.5 W so 3 W is certainly the fault mode.

Also when you ‘repaired’ it the PFC definitely wasn’t working as you were measuring just under 350 V on the main HV DC cap which is just rectified peak mains, I would expect to see this boosted up to 380 - 400 V if the PFC was running.

I also don’t think I saw you check the PFC voltage/current sense resistors, I would expect in a case where the transistor and diode blow short blowing the fuse for the sense resistor to be damaged which when repaired may have caused the PFC IC to overvolt the actual transformer switcher IC possibly killing it or a support device.

If it’s not that then the only other thing I would suspect is if they share the same VCC logic supply, if the PFC IC died shorting the logic supply it would explain the 3 W and no output.

But I’m glad to see the repair fail! It’s turned a boring common repair into an interesting one.

[LS_NE]

Note to self : don't repair too much, just enough to get it up

[ecaparts]

That $80 replacement board doesn't seem too bad now....

[kevinb]

break out the thermal camera, 3w should be visible lol

[Patrick-plwv]

I love these repair videos Dave regardless of the outcome.

[swilwerth]

Just an hypothesis there.
The PFC controller chip is blown and puts the mosfet always on.
Then either the diode opens, or the fuse blowns.
It draws 3W, so I bet the fast diode got open this time.

[GeorgeWMays]

Wow. This could be a whole month's worth of videos...! I love watching people work. Thanks. It's appreciated.

[PHamster]

Louis Rossmann would be happy that the fuse actually did it's job

[danynolet]

I was "awaiting" you would've done the same error I did, replacing a blown fuse on a 13" CRT TV around 1992: I replaced it, plugged it and boom! The fuse had initially blown because the flyback transistor was dead. Replacing the fuse then blew the transformer. Turned a 5$ repair into a dead TV. Good debug & humility lesson for me. You did much better!

[David-bfpl]

Please do a Part 2 video. I'm learning alot from EEV and all the comments. Thanks for this channel!

[pierQRzt]

beautiful dive in and beautiful recover. More resources should be saved like this, and educate us laymen. This also shows how an intermediate check (the test without power factor correction) is very helpful to know that the thing works.

[TheMadrory]

Steve would be proud: If it isn't broken, we'll fix it until it is 😂

[mikekjellman]

“inspire what? inspire the next repair!” 😂

[vvrooooom]

Love the dumpster gold!!! No matter what you get out of there it's entertaining.

[McTroyd]

So glad to see the FET tried to protect the fuse, as is tradition, but then the diode got in the way. 🤷‍♂️

[PearceYT]

We do this kind of thing at my work all the time. When it ain't broke we will fix it til it is!

[Peter_A]

Tongue at the wrong angle while replacing the mosfet, I'm sure!

[trenvan]

when I had to repair these in peoples homes I used a white sheet over a moving blanket in the middle of the floor right in front of where the TV was stood/mounted and I had a bunch of magnetic parts trays the cheap ones from automotive use.. i would place three per side then I had another 12 for internal screws if I needed them for other internal screws this was module replacement. if you stay organized you can knock one out in 20 minutes.

[HassanHassan-ivlk]

Hitachi Inspire the next repair 😂😂😂 Only Dave can say that

[danmackintosh]

Ohh dear Dave, reminds me of the old saying "if it ain't broke, fix it until it is"... interested to see what occurred, for my 2p Sterling I'm gonna say broken trace or solder bridge from reinstalling the MOSFET. I would also consider unplugging the power supplies from the logic board etc and see if it powers up then, just in case something shorted on there pulling the rails down.