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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

#211

Post by raxxorraxor »

jajko wrote: post #165
raxxorraxor wrote: post #83

Earlier quoted context omitted.

I don't. Such mechanisms also disqualify 3rd party replacements. It is just a wasteful solution. Not that any smartphone would qualify as decent here. But as a customer it will overall be more expensive for you.

There are things in life where amount paid is far from top priority, and phone is one these days. With sums we talk about, I just don't care anymore, and Samsung I have now is even more expensive and more wasteful. Re wastefulness - a decent laptop causes 10x more pollution to manufacture than phone. Desktop PC 10x that. TVs. Cars. Clothing. Phones are very much down a very long line of higher priority targets for ec…

I personally don't care much about $ but many probably are. I care that the manufacturers don't work with user orientation in mind and instead take advantage of them. I don't want to be a customer here. Replacement parts are possible and we maybe need regulation on that front to reduce waste. I doesn't matter if other devices are worse.

Other example have a longer shelf life or are at least repairable without being tied to a manufacturer. Notebooks have similar problems and the critique can be transferred here in a similar way. I see synergies in possible rules here of course.

Re: The capacitor that Apple soldered incorrectly at the factory

#212

Post by consp »

kube-system wrote: post #146
magic_smoke_ee wrote: post #142

Earlier quoted context omitted.

I seriously doubt it's ever a deliberate conspiracy in engineering apart from shenanigans like what happened at VW, but it's net effect of product managers, accountants, and contract manufacturers who modify PCBs and BOMs after it's passed off to them to save money on retail products. And so it's likely unintentional with negligence, but it benefits the company. Except for some Samsung appliances made ~ 2010-2014 whi…

> Except for some Samsung appliances made ~ 2010-2014 which seemed to fail just after their warranties expired. And? That just sounds like they have good engineers. If you are designing a machine, you have an target lifetime. You'd obviously want the product to last through the warranty period, because warranty claims are a cost to the company. Every choice of a component affects lifetime. Designers of mass-market pr…

> And? That just sounds like they have good engineers. If you are designing a machine, you have an target lifetime. You'd obviously want the product to last through the warranty period, because warranty claims are a cost to the company.

Product have an expected lifespan longer than the warranty period. This is malicious if given as a target. I'd like to see MTBF numbers on everything so people can lump together and sue the shit out of manufacturers who do this. Would also make it easier to check the 25$ light bulb.

Re: The capacitor that Apple soldered incorrectly at the factory

#213

Post by consp »

kevindamm wrote: post #102
nuancebydefault wrote: post #89

Earlier quoted context omitted.

Once you have experienced blowing up a reversed elcap you will never forget its orientation. I never understood though what makes it leak current and hence heat up.

There's an aluminum oxide layer as a coating on both the anode and cathode inside the (electrolytic) capacitor. Under forward voltage it will gradually thicken but under reverse voltage it dissolves and causes a short. This increases the temperature which causes hydrogen ions to separate and bubble through the material, increasing pressure within the capacitor package until it bursts.

The thickening under forward voltage explains the "recovering cap" phenomenon with some old caps. Didn't know that.

Re: The capacitor that Apple soldered incorrectly at the factory

#214

Post by rvense »

yborg wrote: post #122

I have a Quadra 700 of this vintage that hasn't been powered up in 25+ years. Kind of wanted to fire it up again to experience the glory of A/UX one more time, but sounds like I'd have to replace all the lytics :/

I think the Quadra 700 (and one or two other models) has tantalums on the mainboard from the factory.

Re: The capacitor that Apple soldered incorrectly at the factory

#216

Post by sneak »

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…

IIcx was my first computer! I still have mine.

Re: The capacitor that Apple soldered incorrectly at the factory

#219

Post by upofadown »

johnklos wrote: post #82

It's a good thing that these machines don't even need -5 volts. With just the positive voltages provided, RS-422 still works, including LocalTalk. I think the -5 volts is only there in case an expansion card needs it.

I did a bit of research on this because I was confused about why RS-422 needed -5V. Normally the driver is powered off +5 and 0 Volts for RS-422. By increasing the swing down to -5, the Mac port is compatible with RS-232. So a Mac of this era can connect to a modem with a specially wired cable. No level conversion is required and RS-422 receivers are required to work down to -6V so the Mac is producing completely valid RS-422 at the same time.

Most RS-232 receivers of that era had a fair amount of gain with a transition point close to 0V. So only a little minus voltage would be required in practice, not the entire -5V. So just as long as the reversed capacitor was not entirely shorting out the rail things would have worked.

Re: The capacitor that Apple soldered incorrectly at the factory

#220

Post by [deleted] »

klysm wrote: post #113
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…

That seems like one the least harmful mistakes you could make. Capacitors are sprinkled all over boards in excess’s because it’s probably better than not enough capacitance.

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