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The capacitor that Apple soldered incorrectly at the factory

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Re: The capacitor that Apple soldered incorrectly at the factory

#191

Post by mike50 »

kube-system wrote: post #154
magic_smoke_ee wrote: post #150

Earlier quoted context omitted.

You're making a pretty awkward value judgement about what a "good" engineer is, but you're describing an unethical one with a bizword like "value engineering". I realize ethics are no longer understood by much of Western society because the culture teaches transactionality, worships trickle-down economics and greed, and hyperindividualism. > It isn't that. It's pressure at the shelf that does it. Consumers behavior s…

A good engineer is one that has a job, doesn't put their employer out of business, and produces work that fulfills the requirements they're given. Many people think there's some unethical conspiracy going on, and consumers actually want a product that lasts a long time, but companies are refusing to give it to them. But this is projection of individual preferences on to the market as a whole. Consumers want cheap shi…

Engineers are to consider public safety first. This is not negotiable for real hardware engineering. Poor people could always purchase used appliances.

Re: The capacitor that Apple soldered incorrectly at the factory

#192

Post by bmicraft »

JJMcJ wrote: post #172
Workaccount2 wrote: post #109

Earlier quoted context omitted.

This is also why so many LED bulbs are shit, lots of heat in a small space full of electrolytic caps.

Recently read that if you are going to be using an LED bulb in an enclosed space, buy bulbs designed for the high temperature, otherwise you WILL get premature failures in bulbs that will last for years in ordinary lamps. https://duckduckgo.com/?t=lm&q=led+bulbs+enclosed+fixture+ra...

Alternatively, there are now much more efficient bulbs available. If they're passing A under the new EU Energy Label (from 2021) they'll barely be warm to the touch.

Re: The capacitor that Apple soldered incorrectly at the factory

#193

Post by [deleted] »

shiroiushi wrote: post #26
Throw8394045 wrote: post #15

Earlier quoted context omitted.

They don't do recalls even on modern hardware. But soldering hacks are no longer possible, all parts are serialized. Louis Rossmann made many videos on this.

What are you talking about? Capacitor technology hasn't changed substantially in decades, and it's just as possible to change caps with a soldering iron now as it was 20 years ago. I have no idea what you mean by "serialized".

[deleted]

Re: The capacitor that Apple soldered incorrectly at the factory

#194

Post by mike50 »

chefandy wrote: post #130

What’s the liquid in the old capacitors? PCBs? (as in polychlorinated biphenyls… that abbreviation collision always annoyed me.) I think I know exactly enough about electronics to ask more annoying questions than someone who doesn’t know anything at all.

PCBs were only used in oil capacitors and some transformers. Generally these were used in motor and grid power applications. The only consumer applications are some motor capacitors and florescent light ballasts.

Re: The capacitor that Apple soldered incorrectly at the factory

#195

Post by [deleted] »

analog31 wrote: post #87
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…

Indeed, and this is true in other engineering activities such as mechanical design as well. Possibly with the exception of very large shops, there are no draftsmen any more, and the design engineer also creates the production drawings. And the software lends itself to this. Schematic / layout, and design / drawing, are joined together in the design software. It would be very hard to make a mistake like the one in TFA…

[deleted]

Re: The capacitor that Apple soldered incorrectly at the factory

#196

Post by chefandy »

syncsynchalt wrote: post #177
chefandy wrote: post #130

What’s the liquid in the old capacitors? PCBs? (as in polychlorinated biphenyls… that abbreviation collision always annoyed me.) I think I know exactly enough about electronics to ask more annoying questions than someone who doesn’t know anything at all.

"Wet" capacitors contain any number of liquid electrolytes. Could be something tame like ethylene glycol, boric acid, sulfuric acid, or nastier stuff like organic solvents (DMF or DMA which are poisonous, or GBL which is less lethal). Nothing as bad as PCBs as far as I'm aware.

Cool, thanks. I think I should learn how these components actually work. Individually they seem pretty simple.

Re: The capacitor that Apple soldered incorrectly at the factory

#197

Post by kube-system »

mike50 wrote: post #191
kube-system wrote: post #154

Earlier quoted context omitted.

A good engineer is one that has a job, doesn't put their employer out of business, and produces work that fulfills the requirements they're given. Many people think there's some unethical conspiracy going on, and consumers actually want a product that lasts a long time, but companies are refusing to give it to them. But this is projection of individual preferences on to the market as a whole. Consumers want cheap shi…

Engineers are to consider public safety first. This is not negotiable for real hardware engineering. Poor people could always purchase used appliances.

I agree that products shouldn't be unsafe. And value engineering does not mean making products unsafe.

> Poor people could always purchase used appliances.

The reality in mid 20th century US demonstrates this isn't the case. Most went without the modern appliances that are commonplace today.

Re: The capacitor that Apple soldered incorrectly at the factory

#198

Post by chefandy »

mike50 wrote: post #194
chefandy wrote: post #130

What’s the liquid in the old capacitors? PCBs? (as in polychlorinated biphenyls… that abbreviation collision always annoyed me.) I think I know exactly enough about electronics to ask more annoying questions than someone who doesn’t know anything at all.

PCBs were only used in oil capacitors and some transformers. Generally these were used in motor and grid power applications. The only consumer applications are some motor capacitors and florescent light ballasts.

Yeah I pretty much grew up (unknowingly) playing in an illegal unmarked chemical waste dump so it takes a lot to get my attention, but I opened up an old fluorescent desk lamp from the 60s I had that fried itself to see if it was fixable — and found a small piece of crumbly asbestos shielding about the size of a business card stuck to a big leaky ballast. Pretty solid toxic waste combo. City hazmat got a sweet vintage lamp that day, sadly.

Re: The capacitor that Apple soldered incorrectly at the factory

#199

Post by anon_cow1111 »

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…

Here's a question for EE nerds that happen to be reading this (maybe in the future).

What if I have a stash of big electrolytics that have been out of service for 10+ years? I know that I need to reform them over a few days, but can they even run at spec after so long out of operation?

We're talking BIG stuff, 400v, 200+J each

Re: The capacitor that Apple soldered incorrectly at the factory

#200

Post by amluto »

wbl wrote: post #189
amluto wrote: post #173

Earlier quoted context omitted.

One can build lots of things out of inductors and capacitors. I bet it’s possible and even fairly straightforward to built a little network to allow high frequencies to pass from output to the two line inputs with low impedance but that has extremely high impedance at 50 and 60 Hz (and maybe even at the first few harmonics). It would add components, cost and volume. I bet this could be done at the output side, too. A…

The capacitor has to see the common mode voltage. Where do you put the other end?

Off the top of my head? Make a little gadget that’s an inductor and capacitor, in parallel, tuned to 60 Hz (i.e. a band-stop filter) and, in series with that, a Y capacitor. Wire up this gadget in place of the Y capacitor, so you end up with two of them (line to output negative and other line to output negative, perhaps). Or maybe you just have one, and you connect it between the normal pair of Y caps and the output. It will have very high impedance at 60Hz, enough impedance from DC to a few kHz to avoid conducting problematic amounts of current at DC or various harmonics, and low enough impedance at high frequencies to help with EMI. It might need a couple types of capacitor in parallel in the band-stop part to avoid having the high-frequency impedance of the presumably large-ish capacitor in parallel with the inductor being a problem, and it might be an interesting project to tune it well enough to really remove the annoying touch current, especially if you believe in 50Hz and 60Hz operation. Maybe a higher order design would work better, but the size would start to get silly.
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