[wynn]

Hey list,

My ac adapter from my gigabook recently died on me. I'm not exactly sure how it happened, but it smells as if something might have shorted inside. I have since replaced it, but was wondering if there was anyone here who knew if it was possible to repair. Can I just crack it open and replace a transistor? (i hope that sentence doesn't reveal how much of an ee noob i am).

Thanks

[Mithras]

120 volts, your lap, and your $2500 computer is perhaps not the best playground for learning electronics?

[neilw]

(a) It's not possible to know from your post exactly what's wrong in your power adapter. It could be as simple as replacing a part.

(b) I'm not sure exactly how easy it is to pry open the adapter and then put it back together.

(c) If you *are* that much of a noob at this stuff, I'd recommend against playing with the insides of the adapter. There's dangerous AC voltages in there.

[wynn]

(a) It's not possible to know from your post exactly what's wrong in your power adapter. It could be as simple as replacing a part.

- I've tried plugging in the ac adapter and it didn't work. I can't imagine there being too many replaceable parts inside of the adapter. If I had said that I had a computer and it wasn't working, well, that I can understand as being too vague.

(b) I'm not sure exactly how easy it is to pry open the adapter and then put it back together.

- Thanks, neither am I

(c) If you *are* that much of a noob at this stuff, I'd recommend against playing with the insides of the adapter. There's dangerous AC voltages in there.

- Could you elaborate on what exactly is the danger? From doing a quick search, apparently there is no danger working with transformer-based adapters if they are unplugged. I did read the switchmode power supplies can be dangerous due to the capicitors storing energy.

So - does anyone know if the apple ac adapter is transformer or switchmode-based?

[icruise]

If you don't know what you are doing, you could create a fire risk by trying to repair your adapter, not to mention that you could damage your computer. Don't be a fool. Throw it away.

[wynn]

Would anyone purposely act foolish?

I do not know what am doing, but I am good at understanding. Why is it, do you think, that people come to the forums? Is the comaraderie? For some, mac-addict, sure it is.

But for many others, it's for finding information. So yes, it's clear from my post that I am not aware of the dangers from opening a power adapter. What I find so surprising is that everyone is simply saying that is dangerous without explaining why.

Perhaps I should have posted in the modding forum instead.

[Raining Down in Texas]

Originally posted by wynn:
Hey list,

My ac adapter from my gigabook recently died on me. I'm not exactly sure how it happened, but it smells as if something might have shorted inside. I have since replaced it, but was wondering if there was anyone here who knew if it was possible to repair. Can I just crack it open and replace a transistor? (i hope that sentence doesn't reveal how much of an ee noob i am).

Thanks

My TiBook power adapter went bad a few weeks ago. I called Apple to file a warranty claim, and they overnighted a new one. I had it about 22 hours later. It's not worth messing with it.

[I Me Mine]

Originally posted by wynn:
What I find so surprising is that everyone is simply saying that is dangerous without explaining why.

Don't mess around with electrical stuff unless you fully understand what you're doing - why risk getting injured/killed ??

[icruise]

Originally posted by wynn:
What I find so surprising is that everyone is simply saying that is dangerous without explaining why.

We're just trying to help you here. There are some things that amateurs (and even semi-pros) should not mess with. Apple did a mass recall of Powerbook G3 adapters a while ago because they could overheat and cause fires. It seems to me that if something designed by professionals and put through all sorts of testing and UA certification could still end up causing these problems, then perhaps someone who admittedly knows nothing about them shouldn't be tinkering with them.

Ask yourself this: is it worth the risk, however small, of burning down your house or electrocuting yourself just to satisfy your curiosity? I've done a fair amount of "modding" but I wouldn't touch that with a ten foot pole.

[Melchizedek]

I bought a Gigabook last November. This last spring (in the middle of school... ) mine did the same thing yours did. The wire got so hot next to the transformer brick that the wire insulation started to burn away. I did get a new one under warrenty...2 WEEKS LATER. Running a TiBook at level 2 brightness can be fun.

[wynn]

Icruise, understood. Thank you for the post.

Melchizedek, did you ever get an explanation of why the ac adapter failed?

[AlbertWu]

What any AC-DC power adapter does:

It takes the AC volatage (which looks like a sinusoid on a Voltage vs Time graph) and rectifies it (so that only the positive or negative remains - runs it through a diode)

the graph would then look like a bunch of humps (only the positive side of a sine graph, for example)

here's the dangerous part: it takes the spikes of power and turns it into a direct current by using a capacitor to store extra voltage from a hump and releases it in a more or less consistant way. Capacitors retain charge for god-knows-how long. Ever been zapped while taking apart a disposable camera with flash? That's the capcitor discharging into you. Now think of 120 volts worth, with hundreds of times more current.

Anyway, I wouldn't recommend it. What PROBABLY happened to the adapter was that a current spike blew out the diode.

Anyway, that's my best guess.

[mousehouse]

hmmmm, i hear the burning AC adapter too many times by now. i've actually had two of them burn up on me in 9 months...

i have the feeling there has been a bad run of productions of these adapters. all of them have the symptom that looks like of of the big capacitors have melted. i wonder if the producer of the adapters for apple (anyone know who?) used a bad batch of these capacitors...

hmmmm

[wynn]

Albert, great explanation - thanks for taking the time to post. That makes sense to me and, as others have mentioned here, it's best not to tinker with it. Would you like my broken power adapter?

[AlbertWu]

nah. We have bottle capacitors in the physics room that we charge up with the van-degraff generator to play with.

what's REALLY cool, is to charge em up, and then throw em at people. People have this sort of instinct to catch things, and if they catch it in the right way... BZZZT