Re: Mac Quadra 605 & Bad Battery

[et472@FreeNet.Carleton.CA (Michael Black)]

Mike Spurgeon (mike@spurgeon.net) writes:
> The Wizard of Oz wrote:
>> On Sun, 02 May 2004 10:15:51 -0500, Robert J. Stevens wrote:
>> 
>> 
>>>I aquired a Mac Quadra 605 with a bad leaky Battery. I asked a friend to
>>>help me fix it but he drilled out the holes and now I can't find the
>>>Plus side of the Battery on the Mother Board. I have been looking for
>>>Diagrams & manuals on line but to no avail. Does anyone know where the
>>>best place on the Motherboard to patch a Wire to so I can tack in a new
>>>Battery.
>>>Foozed in Wisconsin
>> 
>> 
>> 	Wrong newsgroup. You want a Mac newsgroup not an Apple// group. Same
>> company different line. Follow the same procedure you used to get here and
>> look for "mac" not "apple".
> 
> You would be a bit wrong.  A quadra 605 with a IIe card is what 
> several here would know about.
> 
> If no one else answers, I'll go look at mine...

But plenty of people do post here because they assume Apple=Mac  That
off-topic posting should not be encouraged, so some people routinely
point such people to the right place.

If someone doesn't bother to make an Apple II reference in such posts,
one has to assume they have come here by accident.  Anyone who is
a regular should know better.

Even if the poster is using an Apple II card in there, it's rather a stretch
to believe the post fits here.  This is not related to any Apple II ahrdware
running in there, it is about the Macintosh hardware.

I did not reply to the original post, precisely because it's a Mac question.

But since I'm posting anyway, and this is useful in a general way, then
here are a couple of pointers.

Take a DVM and see if there is an electrolytic capacitor in parallel.
One has to trace circuit board traces, to see if the battery terminal goes
to a an electrolytic.  Since such capacitors are polarized, the battery
lead that goes to the "+" terminal of the capacitor is the positive side
of the battery.

Even simpler is to take that DVM in the ohmmeter function, and see which
leads of the battery go to ground.  This would be the "-" terminal.  Now,
this is slightly risky, since it assumes that whatever the battery connects
to is negative ground.  But it's a pretty safe assumption, since with the
things that would be battery backed up, nothing uses a negative voltage.

Or one wants to verify, first one finds the battery lead that goes to
ground.  Then trace the other lead, until it hits an IC.  Get the pinout
for that IC, and it will tell you what polarity is supposed to be there.

Depending on the circuit, and the battery for that matter, there may
be a diode or diodes used in conjuction with the battery.  One might
extract information from the polarity of the diode, though one
has to know what the circuitry is doing.  


  Michael