Help with identifying a capacitor on an Asanté MacCon

[Mk.558]

The third-party cards, true, may have a different design philosophy but there's no reason for them to not use a much cheaper electrolytic if it serves the job just fine. A FWB JackHammer, for instance, is a high performance SCSI card with a nice stack of expensive SRAM on board and at least one custom chip, that's different than a generic Ethernet card. A Daystar Turbo 040 has performance in mind, a budget TV tuner card has cost in mind.

Then again, they did use all tantalums in the Quadra 700 and kaBooms are not very common with Q700s, mostly just battery meltdowns. Does that make the Q700 better than the IIci, which did use electrolytics?

@Apollonia, I believe someone mentioned this video somewhere, I think it's relatively decent. It's more focused on power applications, for which electrolytics still hold on. As he says, they do their job where no others can really do it for the cost.

We have to remember that we're dealing with 5V motherboards. They're usually fairly forgiving, compared to chips commonly used these days. 3v3 or 3.3v stuff has been common in the electronics world for over 2 decades, phones and computers these days usually hover around just over 1 volt. Is that better? For performance, yes. For robustness, I'm not so sure, but I'm not an EE major. I can say however, an old-school 555 timer IC with CMOS manufacturing had a voltage range of roughly 4.5v to 16v, which is a huge voltage tolerance in IC terms.

If you're into a bit of a time-trip, check out this site. It's got all the marks of being a late '90s website and the mind of the author could be a interesting topic of discussion. Some of his his ideas are somewhat sketchy in aeroplane circles, but the concept has a foundation.

 

[cheesestraws]

The third-party cards, true, may have a different design philosophy but there's no reason for them to not use a much cheaper electrolytic if it serves the job just fine

The other thing to remember is that every new kind of component you add to the BOM increases cost much more than adding a component of a type you're already using. So it's a benefit to standardise on few kinds of capacitor and just use them as widely as you can.

a high performance SCSI card with a nice stack of expensive SRAM on board and at least one custom chip

There's also a difference between being a high performance system and needing high performance from those passives. A decoupling capacitor on an expensive IC isn't really being driven any harder than a decoupling capacitor on a cheap IC. The same principle holds.

This is not true, of course, for analogue stuff. I wouldn't recommend people indiscriminately muck about with capacitance in, say, high-end sound cards or the analogue side of graphics cards. But digital electronics is usually far more forgiving on passive specifications.

 

[Apollonia]

@Apollonia, I believe someone mentioned this video somewhere, I think it's relatively decent. It's more focused on power applications, for which electrolytics still hold on. As he says, they do their job where no others can really do it for the cost.

Interesting video and helpful. I like his sense of humour: “…well …release the pressure.”