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Hello,

On Nov 13, 2007, at 04:27, Schwerzmann, Stephan wrote:

>>   PROBLEM:
>>   my dear old PB G4 Titanium (500MHz, no Gbit, no DVI -
>> the real old one) does not power on any more: whether I
>> leave the battery in place or not,
>
> Allen, Michael,
>
>   thankyou for your information.
>
>   I was not able to pull "ifixit.com" off google, so I'm
> glad I've been pointed to this: I've found and read the
> related article.
>
>   Albeit I know where the PMU reset button is, I did not
> know that it does a "sane discharge": I merely expected it
> to be sort of a 'logic' reset of the PMU and now I better
> understand -and agree upon- keeping it pressed for a long
> time. I'll try harder on this in my spare time.

On my PB3400c it took more than a minute. Just holding it for a  
couple seconds won't do a thing.

>>>   what voltage at which pins are expected?
>> Something between 12v and 16v IIRC, on the two inner rings
>> of the central pin - the tip is unconnected or ground.
>
>   I love to know this.  :-)
>
>   Is the DC voltage unregulated?

Good question.

>   must it be precise within certain limits?

I think so - should be roughly in the same region as whatever the  
battery supplies. A few volt more or less shouldn't make a difference  
- - the laptop has to convert it to 12v, 5v, whatever the CPU's core  
voltage is and so on anyway.

>   I hope to be able to perform trials with my lab
> power supply, therefore also my next question:
>
>   Is the outer "shell" also a ground connection?

I think it's connected to ground but I'm not 100% sure. The connector  
is designed to make it almost impossible to short-circuit it by  
accident.

> (or does it only serve as a protection against shorts when
> the DC cable is danging around?)

Bit of both I think.

have fun
Michael
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