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The capacitor that Apple soldered incorrectly at the factory

downtowndougbrown.com

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Re: The capacitor that Apple soldered incorrectly at the factory

#91

Post by nuancebydefault »

yetihehe wrote: post #80
jdbdbcjd wrote: post #78

Earlier quoted context omitted.

That sounds fishy, even if the debugged device directly interfaced mains, the Mac doesn't. And even if it did, how high would the probability be that both machines were on different circuits with phases so much out of sync that it would matter? Unless I misunderstood your story

That device was a cheap wifi power plug, had cheap unisolated power supply, it was never intended to have user accessible electrical parts sticking out, so no need for isolation. In such cases device has common ground with ac voltage. I don't know all specifics, but NEVER connect any single terminal of 220V plug to your computer ground (usb ground in this case). When it's properly grounded, most devices will survive…

If i remember correctly, a lot of power supplies of cheap electronics have AC-coupled the low voltage side with the mains side. There's no physical wire, just a capacitor. You can often feel the AC when touching the 'safe' side of the adaptor.

Re: The capacitor that Apple soldered incorrectly at the factory

#92

Post by nuancebydefault »

shiroiushi wrote: post #13
duskwuff wrote: post #12

Earlier quoted context omitted.

I don't think that's a reasonable expectation in general, and certainly not in this case. The affected TVs were all at least 20 years old - that's well beyond the expected useful lifespan of even a modern TV, let alone an older model like these. Nor is it clear what Sony could reasonably have done to repair them; even by 2010, a lot of the parts used in CRT TVs were out of production and unavailable.

Maybe you're too young to remember, but people used to keep TVs for much longer periods before HDTV and flat panels came out. Also, these TVs are apparently fire hazards. It doesn't matter that they're 20 years old (at the point of the "recall" in 2010). I doubt the parts necessary to fix them were out of production; you can get parts for truly ancient electronics still. Things like capacitors don't become obsolete.…

Suppose they would recall all the old tv's with known faults, can those be fixed to become conform to (today's) quality and safety standards, while being full of old components with characteristics beyond original tolerances?

Re: The capacitor that Apple soldered incorrectly at the factory

#93

Post by cmgbhm »

azinman2 wrote: post #24
kbelder wrote: post #14

Earlier quoted context omitted.

> that's well beyond the expected useful lifespan of even a modern TV, let alone an older model like these A modern TV may have an expected lifespan of five years. TVs from several decades ago had lifespans of... several decades. Quality has plummeted in that market.

5 years? Is that really true? I’m currently using an LG from 2017 and cannot imagine needing to change it. I would be shocked if it stopped working.

I have an LG about that vintage and it’s starting to black out when doing 4K content. All components before it switched out and up to date in firmware. Reatarting works, sometimes all day, sometimes 1 minute.

My other TV about the same vintage is starting to have stuck pixels in the corner.

Modern failure modes aren’t nearly as graceful.

Re: The capacitor that Apple soldered incorrectly at the factory

#94

Post by chrisdhoover »

ethernot wrote: post #35

There are so many cases of this sort of stuff it's unreal. But it gets even stupider. I found one a few years back when I repaired a linear power supply. This required me to reverse engineer it first because there was no service manual. I buzzed the whole thing out and found out that one of the electrolytic capacitors had both legs connected to ground. They must have shipped thousands of power supplies with that erro…

Way back when a co worker was powering up a fire alarm control panel. Poof, capacitor popped and damaged his eye

Re: The capacitor that Apple soldered incorrectly at the factory

#95

Post by nuancebydefault »

rvense wrote: post #39
azinman2 wrote: post #24

Earlier quoted context omitted.

5 years? Is that really true? I’m currently using an LG from 2017 and cannot imagine needing to change it. I would be shocked if it stopped working.

But when it does, it will probably be the capacitors in the power supply that have dried out.

How can I even know which capacitor is faulty?

Re: The capacitor that Apple soldered incorrectly at the factory

#96

Post by jcims »

ethernot wrote: post #35

There are so many cases of this sort of stuff it's unreal. But it gets even stupider. I found one a few years back when I repaired a linear power supply. This required me to reverse engineer it first because there was no service manual. I buzzed the whole thing out and found out that one of the electrolytic capacitors had both legs connected to ground. They must have shipped thousands of power supplies with that erro…

I have a 3D printer where presumably a smoothing cap just fell off the X axis controller section of the mainboard. Didn't make a lick of difference in anything operationally. Still works great.

Re: The capacitor that Apple soldered incorrectly at the factory

#97

Post by Someone »

shiroiushi wrote: post #25
tobr wrote: post #16

Earlier quoted context omitted.

This. I’ve known a TV that was in more or less daily use for over 30 years. Not sure why we stopped expecting that from electronics.

>Not sure why we stopped expecting that from electronics. For TVs specifically, the technology changed a lot. For a long time, everyone was stuck on the NTSC standard, which didn't change much. At first, everyone had B&W TVs, so once you had one, there was no reason to change. Then color TV came out, so suddenly people wanted those. After that, again no reason to change for a long time. Later, they got remote control…

> At first, everyone had B&W TVs, so once you had one, there was no reason to change

Televisions improved over time:

- screens got flatter

- screens got larger

- image quality improved

- image contrast increased (people used to close their curtains to watch tv)

- televisions got preset channels

Re: The capacitor that Apple soldered incorrectly at the factory

#98

Post by canadianfella »

Filligree wrote: post #60
grujicd wrote: post #58

Earlier quoted context omitted.

Well, until today I didn't even know capacitor can have orientation! So more productive Wednesday than yours. In entry level electronics class I had decades ago it was always treated as a component that works the same way no matter in which direction the current flows.

Ceramic capacitors don't have polarity. Electrolytic ones do. Thing is, electrolytic capacitors have far higher capacitance for their size -- though also higher resistance. It's something to check, but the polar ones should be clearly marked as such.

[dead]

Re: The capacitor that Apple soldered incorrectly at the factory

#99

Post by kevindamm »

magic_smoke_ee wrote: post #79
Filligree wrote: post #60

Earlier quoted context omitted.

Ceramic capacitors don't have polarity. Electrolytic ones do. Thing is, electrolytic capacitors have far higher capacitance for their size -- though also higher resistance. It's something to check, but the polar ones should be clearly marked as such.

Electrolytic capacitors are kinda like lead-acid batteries in that they are polarized through manufacturing processes. A voltage is applied in the factory to anodize the anode with a thin oxide layer. For fun, I think it would be possible to buy a quality low voltage cap and reverse the polarity of it in-situ which would remove the anodization from the new cathode and deposit a new layer on the new anode (former cath…

Or much shorter, around two years, if it was part of the Capacitor Plague.

https://en.wikipedia.org/wiki/Capacitor_plague#Premature_fai...

   The normal lifespan of a non-solid electrolytic capacitor of consumer quality, typically rated at 2000 h/85 °C and operating at 40 °C, is roughly 6 years. It can be more than 10 years for a 1000 h/105 °C capacitor operating at 40 °C. Electrolytic capacitors that operate at a lower temperature can have a considerably longer lifespan. ... The life of an electrolytic capacitor with defective electrolyte can be as little as two years.

Re: The capacitor that Apple soldered incorrectly at the factory

#100

Post by robomartin »

jcims wrote: post #96
ethernot wrote: post #35

There are so many cases of this sort of stuff it's unreal. But it gets even stupider. I found one a few years back when I repaired a linear power supply. This required me to reverse engineer it first because there was no service manual. I buzzed the whole thing out and found out that one of the electrolytic capacitors had both legs connected to ground. They must have shipped thousands of power supplies with that erro…

I have a 3D printer where presumably a smoothing cap just fell off the X axis controller section of the mainboard. Didn't make a lick of difference in anything operationally. Still works great.

It could be there to control emissions. You’d need to analyze the circuit to determine its purpose.
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