Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The capacitor that Apple soldered incorrectly at the factory

downtowndougbrown.com

Post reply on HN
Print view View original

71–80 of 269 posts

Re: The capacitor that Apple soldered incorrectly at the factory

#71

Post by jimnotgym »

rcxdude wrote: post #65
likeabatterycar wrote: post #53

The author seems to misunderstand PCB design flow. This is neither a "factory component placement issue" nor a silkscreen error. The error is in the schematic. The layout CAD is often done by a different team that follows the schematic provided by design engineering. Automated workflows are common. The silk screen is predefined in a QA'd library. It is not their job to double check engineering's schematic. The compon…

>The layout CAD is often done by a different team that follows the schematic provided by design engineering. Just as a note, this is a fairly archaic way of working nowadays. At my place schematic design and layout go hand-in-hand, and we rejected a candidate because he didn't do the latter. The main reason is layout is no longer an afterthought, it's a key part of the electrical design of the system, and there's lit…

And yet it is not at all unusual for a production engineer to spot these faults and pass them back to the design engineers for rework.

Re: The capacitor that Apple soldered incorrectly at the factory

#72

Post by bloak »

tobr wrote: post #16
shiroiushi wrote: post #13

Earlier quoted context omitted.

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.…

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.

My experience of ancient CRT devices is that the display gets gradually dimmer. I once had a TV that was only really usable after dark -- but that's the only time I wanted to use it anyway -- and a huge Sun monitor that was only just about readable in total darkness, but we kept it because we also had a Sun server that we didn't know how to connect to any other monitor and we were worried that one day we wouldn't be able to SSH to it, but in fact the server never once failed.

Re: The capacitor that Apple soldered incorrectly at the factory

#73

Post by rcxdude »

jimnotgym wrote: post #71
rcxdude wrote: post #65

Earlier quoted context omitted.

>The layout CAD is often done by a different team that follows the schematic provided by design engineering. Just as a note, this is a fairly archaic way of working nowadays. At my place schematic design and layout go hand-in-hand, and we rejected a candidate because he didn't do the latter. The main reason is layout is no longer an afterthought, it's a key part of the electrical design of the system, and there's lit…

And yet it is not at all unusual for a production engineer to spot these faults and pass them back to the design engineers for rework.

Also true! Most common when you accidentally screw up a footprint and it doesn't fit the part on the BOM. A backwards part is the kind of thing they're not likely to pick up on (if it's marked on the silkscreen incorrectly, at least), but some do.

Re: The capacitor that Apple soldered incorrectly at the factory

#74

Post by xxs »

verzali wrote: post #46
rvense wrote: post #39

Earlier quoted context omitted.

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

Is that really the case? Because if so, it seems like simply replacing the capacitors would save a lot of waste and unnecessary purchases of new TVs...

Electrolytic capacitors are not solid state and likely #1 failure mode for most electronics. There are options for better (e.g. Al polymer) capacitors that are rather expensive - overall good capacitors are 'expensive', e.g. more than a dollar a piece in some cases.

The 2nd most common failure mode gotta be the mlcc (multi layer ceramic capacitor) cracks/shorts.

Re: The capacitor that Apple soldered incorrectly at the factory

#75

Post by xxs »

Peanuts99 wrote: post #63
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.

A TV used to cost a few weeks pay and now you can get a TV for the equivalent of a few hours pay. There just isn't much of a market for a $3000+ TV.

Few usually means 3-5 or so, a half decent TV would be at least half a grand. That's rather high hourly pay rate.

Re: The capacitor that Apple soldered incorrectly at the factory

#76

Post by bregma »

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…

> The human eye is only capable of so much, so we're seeing diminishing returns.

Or not seeing diminishing returns. Which is the point.

Re: The capacitor that Apple soldered incorrectly at the factory

#77

Post by magic_smoke_ee »

From around 2011-2015, I sometimes talked to an ex-Navy electrical tech who said he was also an early Apple rework tech in the SF Bay Area. He had no shortage of work fixing manufacturing problems, adding rework improvements, and building custom test equipment until they laid him off, outsourced his job to some random country, and then he was homeless until around 2016.

Re: The capacitor that Apple soldered incorrectly at the factory

#78

Post by jdbdbcjd »

yetihehe wrote: post #56
PeterStuer wrote: post #21

In the mid 80's I was the head of the CS student chapter. We ran the computer rooms for the science faculty. We had a room with about 20 Mac 128k. I do not know where Apple sourced their capacitors from, but these were not A-tier. A Mac going up in a puff of white smoke was a weekly occurrence. We had a few in reserve just to cycle them in while they were out to Apple for repair. P.S. still my favorite Mac of all tim…

On the other side, we had intern at our (very small) company and he used his own mac. One time he had to debug a mains-powered device. He decided that he will try connecting it to both mains AND programming dongle without separating transformer. He fried the dongle (it literally exploded, plastic lid banging on desk in sudddenly silent office is the most memorable thing), the company provided monitor and device, but…

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

Re: The capacitor that Apple soldered incorrectly at the factory

#79

Post by magic_smoke_ee »

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.

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 cathode) hopefully without over-pressurizing it to bursting, albeit with much less anticipated lifespan.

PSA: Electrolytic capacitors have a rough lifespan of 10 years. Any much older than that need to be checked out-of-circuit for ESR and then capacitance. Also, tantalums (historically) suck(ed). [0] Quality audio equipment from the 80's like a/d/s/ car amps used only ceramic caps and other over-engineered passives, and have the potential (pun intended) to basically last forever.

0. https://www.eevblog.com/forum/projects/whenwhy-(not)-to-use-...

Re: The capacitor that Apple soldered incorrectly at the factory

#80

Post by yetihehe »

jdbdbcjd wrote: post #78
yetihehe wrote: post #56

Earlier quoted context omitted.

On the other side, we had intern at our (very small) company and he used his own mac. One time he had to debug a mains-powered device. He decided that he will try connecting it to both mains AND programming dongle without separating transformer. He fried the dongle (it literally exploded, plastic lid banging on desk in sudddenly silent office is the most memorable thing), the company provided monitor and device, but…

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 this. But somehow monitor connected to that mac didn't survive it. And several milliseconds of full 220V before circuit breaker reacted, made very thin traces in debugger pretty much vaporise and explode.
Post reply on HN