520c: Help Needed

[macosten]

Alright, so here's (the short version of) the deal...

I was playing around with my 520c and it eventually crashed to the point of complete unresponsiveness (not that uncommon of an occurrence with this sort of machine, really). Since I kinda forgot what the force reset combo was, I tried keying it in.

Eventually, I ended up pressing Control, Option, Command, and the Power button all at once, and then the computer shut down all at once. 

...and when I tried to turn it on again, nothing happened.

So I waited 6 minutes with the power disconnected and battery removed and tried again to press Ctrl-Cmd-Opt-Power (that's supposed to reset the power manager or something?). I held the keys down for what I think was around 20 seconds before trying again to boot the machine, to no avail.

Now here I am. What should I do? Currently I have two options that I can think of: remove the Backup Battery then wait a bit before reconnecting it so the computer is forced to load new Power Manager settings (more disassembly than I really want to do right now in my room), or wait an entire day or two before just trying to turn it on again.

Is it possible that I blew the fuse on the Motherboard or something? The speakers did make the sort of "sudden shutdown" noise that happens sometimes when you suddenly cut power to something, so I'm wondering about that as well.

I'm just worried I messed something up permanently by doing something in software, which isn't really an idea I like much.

 

[tjjq44]

First check your power supply, if it is ok then try to find a blown fuse on your logicboard

 

[techknight]

you need to cut all power to the logic board. Main battery, main AC adapter, AND.... the little PMU battery inside the unit which is rechargeable. 

This will allow the little 68HC11 or thereabouts PMU IC to power off, and allow a reset/reboot. 

Everything should work fine after that, 

 

[macosten]

you need to cut all power to the logic board. Main battery, main AC adapter, AND.... the little PMU battery inside the unit which is rechargeable. 

This will allow the little 68HC11 or thereabouts PMU IC to power off, and allow a reset/reboot. 

Everything should work fine after that, 

This was the impression I was under. How long should I keep the PMU battery disconnected for? Ten minutes? A day? 

Either way, because for some reason I need to disassemble the computer from the keyboard down (according to the service manual, anyway) and the battery is part of the bottom case, I guess this means I need to disassemble practically the whole computer. Fooey.

There doesn't happen to be an easier way to get to the battery, right? )

First check your power supply, if it is ok then try to find a blown fuse on your logicboard

I might end up doing this as well, but I feel it's not likely the power supply failed spontaneously like that. Having smelled it when it was plugged in, it's not like it smells fishy (like leaky caps) or anything, so while I'm sure it needs a recap eventually I'm skeptical that it needs a recap right this instant.

 

[macosten]

Alright, the computer has been disassembled; the Backup Battery is out. It's a dinky-looking thing.

Question: how long do I keep it out of the computer for? Should I even put it back yet? It didn't work when it was in the computer so I'm inclined to believe the answer is "no"... but will it work without the battery in there?

 

[techknight]

a minute or so max. The battery is unnecessary unless you want the clock, etc. 

 

[IlikeTech]

Yes it will keep date and time via main battery. You should keep it out.

 

[macosten]

No dice so far. Not sure what's up.

I tried reseating the keyboard a couple of times, too, but the thing just isn't booting. It's as if I'm not doing anything.

Using an external keyboard... well, not like it worked when the machine worked, but it still doesn't work.

What could be up? What could I be missing? I'm getting a bit nervous now. Could I have broken something while I was in there...?

 

[IlikeTech]

Well, if it doesn't work I have one you can possible have as a trade item for something else. It works, but it's missing plastic parts, and it has a working battery.

 

[macosten]

Well, if it doesn't work I have one you can possible have as a trade item for something else. It works, but it's missing plastic parts, and it has a working battery.

Well, I do have the plastic parts for this one. I'll wait to see if there's anything else to be done for this one yet, but if I somehow managed to brick this computer by just a key combination then I suppose I can try buying/trading for yours.

The EHC (where all the electrical testing stuff is) isn't open on weekends so I can't check anything - namely, the fuse, which is the next thing I can think of...

If the fuse is broken, how would I fix that (what fuse would I replace it with)? 

 

[techknight]

And you know for certain the AC adapter is working properly? They are known leakers. 

 

[macosten]

And you know for certain the AC adapter is working properly? They are known leakers. 

It was working before the computer shut down.

I'll just have to test it tomorrow night when I get the chance, I suppose.

 

[macosten]

Are there any generic replacement Power Apaters that would work with this computer, by any chance?

 

[IlikeTech]

Not really, because of its wired PSU Plug. Do you have a multimeter?

 

[macosten]

Not really, because of its wired PSU Plug. Do you have a multimeter?

Won't be able to get ahold of one until tomorrow night; that's why I ask.

Evidently, there are two ground pins and to 16V pins, one at 1.5A and one at 1.0A. I remember seeing this info somewhere else on these forums.

 

[IlikeTech]

Yes, but unless you want to butcher your PSU, then you have no connector.

 

[macosten]

Yes, but unless you want to butcher your PSU, then you have no connector.

Don't want to, but I'm willing to.

I'll poke it with a multimeter tonight, either way.

 

[macosten]

Alright, I've got the multimeter!

...I stuck wires into pins 1, 2, and 3 (not all at the same time - don't wanna cross anything). From 1 to 3, the current is 16.5 V... but from 2 to 3, it's only around 2.1 V.

Something tells me that might be part of (if not most of) my problem, huh?

Well, anything I can do about this one?  Caps to pick up, instructions on how to take the PSU apart?

 

[techknight]

yeap I figured your AC adapter failed. thats why your machine locked up and goofed up. 

common problem. The issue at this point is trying to recap it. the case will shatter like glass when you attempt to snap it apart. Trust me. 

15+ years ago when these adapters first started leaking caps, you could easily pry the case apart without breaking it too much. 

now, its like glass.