LG TV recall re. bad X-class capacitors

[japlytic]

https://www.productsafety.gov.au/rec...0%9D-smart-tvs
I can't seem to find any infomation about this problem affecting overseas models.

[andrewsawesomr]

Can't be too safe, though, right?
I wonder if it was the design of the circuit board or the quality of / a defect in the capacitors.

[momaka]

Originally Posted by andrewsawesomr

I wonder if it was the design of the circuit board or the quality of / a defect in the capacitors.

Good questions.

I don't think the design of the circuit would be at fault here. At least according to the article, it's the X-caps that fail... and X-caps are only used to filter line RF / EMI to/from the TV. So they are connected to line voltage only. With that said, I'm more inclined to think the X-caps themselves are failing. But why? -Now that's another question. Perhaps LG switched to some other manufacturer if they were short during production. Or maybe the manufacturer of the X-caps had a slip-up in production that somehow went past Q.C.

Would have been nice if these consumer warning sites provided more details. I'm sure an EE or qualified tech (or a team, rather) has already determined the issue. Would be nice if they shared details with the public, though. But I guess that will never happen. Unplug you TV and call tech support. ... (Or if you ask me, just unplug your TV permanently and don't bother with it anymore, as there's nothing worth watching on TV... but that's really only my opinion, of course. )

[stj]

maybe the voltage is underrated or they are before the switch.

[PeteS in CA]

I wonder if the problem is partly not doing well with lower quality power and/or lots of thunder storms, as some parts of Oz might have.

[redwire]

It's an old issue? bad quality X-caps that they already were giving free power board replacements back in 2020 for the issue.
I think it got escalated to recall status because the koreans just keep putting this kind of stuff off. Affected LG TVs are giving a pop-up recall message.

Everything is downstream of the fuse... but... "T12A" MOV, 4 film X-caps 684, 474 275V like on a PSOL-L651B.
So the cap does smoke bad when it breaks down and shorts, before the fuse pops I guess.

"Certain 65” and 77” LG Smart TVs manufactured between February 2016 and September 2019.
"Affected models include those manufactured in
2016:
• 65E6
• 65G6
• 77G6
2017:
• 65B7
• 65C7
• 65E7
• 65G7
• 65W7
• 77W7
2018:
• 65W8
• 77C8
• 77W8
2019:
• 65W9
• 77C9
• 77W9

[stj]

275v caps in a 250v country?
yea, that just screams "long service life"

[PeteS in CA]

IIRC, back when agency-approved X caps were commonly rated for 250 VAC, European mains voltages could range up to 264 VAC. That said, even with a nominal 240 or 250 VAC, a 275 VAC cap is going to experience surges above that rating - due to inductive surges when motors kick in, due to large load changes, due to lightning, etc..

The failure mechanism here is cumulative over time. Surges cause arc-overs that "self heal" (= the metallization is cleared back from the hole) that leave a tiny amount of conductive carbon residue. These small conduction points accumulate until the cap heats into a sort of thermal runaway and sudden unpleasant things happen.

[redwire]

The "275V" marking is part of the Class X2, meaning it's rated for use across mains, up to 275VAC plus transient overvoltages.
X2 is impulse rated to 2.5kV (X1 to 4kV) but there is a MOV first in the LG power supply it looks like to clamp far below that. The parts see mains all the time 24/7.

So the caps are likely failing due to crappy quality. Like a Rifa situation. They are physically quite small for their ratings which is always too good to be true when they are half the size of competing parts.

The recall is for 9,400 sets I think, just part of a production run.

[RJARRRPCGP]

Originally Posted by PeteS in CA

I wonder if the problem is partly not doing well with lower quality power and/or lots of thunder storms

21 years ago, that sure didn't help with my Deer DR-250-ATX!

A thunderstorm also killed the Crotched Mountain campus internet in July, 2001. The internet was down for easily roughly 1 week to possibly 2 weeks!

That was on top of random power outages due to the at least one of the campus generators, along with PSNH (Public Service of New Hampshire) at that time.

But most of the power troubles that were campus-generator-related, was mostly 2000 and maybe 2001, IIRC.

The campus generator setup that they had, is famous for getting us through the ice storm of January, 1998!

[eccerr0r]

Has anyone seen a fire caused by a Rifa?

I suppose the problem is that it causes bad publicity even if it doesn't cause a fire, it sure causes a lot of smoke that may imply fire but it never catches on fire.

I've heard of plenty of old Tek scopes smoke up and keep ticking due to bad Rifas... of course people are scared if they will cause additional damage by running their scope after the Rifa goes up in flames...

[RJARRRPCGP]

Originally Posted by eccerr0r

Has anyone seen a fire caused by a Rifa?

I suppose the problem is that it causes bad publicity even if it doesn't cause a fire, it sure causes a lot of smoke that may imply fire but it never catches on fire.

IIRC, saw them in videos. They are common in Apple IIs! (and Apple IIIs most likely)

[eccerr0r]

Tektronix scopes too. I wonder if the spot welder has them ...