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What kind of capacitors do Macs use?
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I'd say that the capacitors on your motherboard are very unlikely to be the weakest link in your system and be the cause of you needing to fix it. I'd say you shouldn't lose sleep about this small issue.
I know there's been lots of problems with caps blowing on boards in recent years, but it's probably just isolated cases where batches of caps are badly manufactured. It won't happen to the majority of people.
I know there's been lots of problems with caps blowing on boards in recent years, but it's probably just isolated cases where batches of caps are badly manufactured. It won't happen to the majority of people.
mattjgalloway said:
I cannot give you a link, but I can confirm that the older Palm Pilots that used standard replacable batteries did in fact use a cap. to give the user about 120 seconds of time to replace the batteries without losing memory contents. I know this was specifically the setup for Palm Pilot III and I suspect it was the setup for the earlier models such as the Palm Pilot.
Some people might find the cause of the capacitor problem interesting (see the "Cause of the failing capacitors" section):
http://en.wikipedia.org/wiki/Capacitor_plague
http://en.wikipedia.org/wiki/Capacitor_plague
I cannot believe this thread is gettin ugly like this.
Aside from a couple of people (and I mean about 3), no one here knows the difference in the capacitance of the components in the Macs. And it is really really really not worth bothering about.
Please, lets all go focus on something else.
Aside from a couple of people (and I mean about 3), no one here knows the difference in the capacitance of the components in the Macs. And it is really really really not worth bothering about.
Please, lets all go focus on something else.
I can't say for sure that this is the same with the PowerBooks, but I'd assume it is--don't know what else they'd be using to give you that few seconds of backup juice to keep the RAM live.mrichmon said:
And where I work we've actually used ultracaps (the carbon "foam" or whatever ones) as a small battery replacement. Those suckers hold so much charge that a small bank of them in series is enough to supply the few seconds of current needed to "kickstart" the fan in a fuel cell appliance. I doubt they're using these in any computer applications yet (no reason, really), but it was a nifty alternative to a 9V battery.
They're really amazing from an old-school electronics standpoint--you've got a device the size of a quarter with capacitance equivalent to a cap that would have been the size of a car a few years ago.
Makosuke said:
Powerbooks only keep the RAM alive if you pull the battery out while you are connected to the power adapter. If you just pull out the battery without a connection to power you loose everything. This is true for all Mac laptops that I have had experience with - namely the Powerbook 180, Powerbook 5300, TiBooks, AlBooks, MacBook and MacBook Pro.
There used to be some ruggedized PC laptops that allowed you to remove and replace the battery without loosing the RAM contents if you were fast with the change.
Say what? Sure, if you pull the battery while the computer is ON it dies, but for quite a while PowerBooks (not iBooks) have had a little backup battery that keeps the RAM "live" for about a minute while you swap batteries. Here's the Apple article on the subject:mrichmon said:
http://docs.info.apple.com/article.html?artnum=88059
To quote the paragraph at the bottom:
This article applies to every "Pro" laptop between the PowerBook G4 887MHz 15" and the MacBook Pro (not, apparently, the 12" ones, though I've never tried).
Further, I just did it to the MBP that I'm typing on, and like all the newest Apple laptops it goes a step farther: If I sleep it, disconnect from AC, then pull and re-insert the battery, it actually re-loads the contents of RAM from the drive (displays a grey screen with a progress bar while it does so). Takes about 30 seconds to get up and running, but I assume this would work even if the computer had been off for a while.
I don't know if it caches the RAM during sleep, if it just uses the pagefiles, or what, but it DEFINITELY works. This is a little different from the "RAM backup battery", which according to Apple itself (and personal experience) also works on older G4 PBs.
Makosuke said:
Yes, everything except the 12". And the iBooks (and AFAIK the MacBooks) have never had this feature either.
You will never ever know who makes the capacitors on the motherboards. No, bigger capacitors doesn't necessarily mean better quality. Yes, some Dell Optiplex machines have issues with theirs.
You can tell a blown capacitor on a motherboard by an orangey residue being on the outside of them and a minute bulge in the top. It's usually fairly subtle so you have to know what you're looking for. The Dell Optiplex machines affected tend to blow all their capacitors at once, so that's more likely a failure of the PDU anyway.
That should provide you with all the answers possible to give. This thread may now be closed.
You can tell a blown capacitor on a motherboard by an orangey residue being on the outside of them and a minute bulge in the top. It's usually fairly subtle so you have to know what you're looking for. The Dell Optiplex machines affected tend to blow all their capacitors at once, so that's more likely a failure of the PDU anyway.
That should provide you with all the answers possible to give. This thread may now be closed.
mattjgalloway said:
Too lazy to find a link right now, but they're called supercaps (or is it ultracaps?) and I believe they're made using gold foil. They look like a really big (in diameter) electrolytic cap. I have some in my junkbox that are 0.22 F (yes that's right, 1/5 of a Farad) and those are on the small side. There are multi-Farad ones available. I'm just speculating on their use to backup RAM, but I know they are used in some VCRs to keep the clock from resetting when the power goes out.