On Jan 26, 2006, at 7:34 PM, Amanda Ward wrote:
I run the maintenance department for a health care facility and work
on a lot of computerized equipment. In almost every maintenance
publication for equipment with external power supplies, the guidance
is to connect the "brick" to the equipment and then to the AC service.
The logic is that plugging an energized connector into the equipment
=could= (=could=, mind you) cause a small arc sending a voltage spike
through the equipment. A small possibility, but not one that I want to
risk.
found this at the MacInTouch site
http://www.macintouch.com/readerreports/powerbookg4/topic2821.html
Mar. 22, 2005
Sterett Prevost
The first time I encountered the Apple recommendation to power the
external AC adapter first before connecting to the Apple laptop was in
the Apple-supplied PowerBook certification training materials prior to
my Prometric certification exam. The topic was addressed in one of the
test questions, so I assumed it was an important issue.
The training materials suggested that the main problem was the onboard
power management unit (PMU) which might eventually get "corrupted" to
the point of no longer correctly managing the recharging of the main
battery (leading to a main battery that "runs flat"). Leaving the power
adapter connected, but removed from the wall socket, was supposed to
lead to PMU confusion as to whether it should keep attempting to charge
or not. Using the PMU reset procedure contained in the appropriate
service manual was supposed to "fix" the situation. The reset procedure
for all Apple laptops is now covered in Apple Support documents 14449
and 58416.
The suggestion about allowing the power adapter to "settle down" before
connecting also makes sense...
Sam Elowitch
I have read with interest the exchanges regarding plugging a laptop's
AC adapter to the wall outlet first, then connecting it to the laptop.
I think I'm satisfied that this is the right way to go; now for the
next logical question:
What about when it's time to turn the laptop off or to begin using
battery power? Should you disconnect the AC from the laptop first and
then the outlet, or from the outlet first and then the laptop?
David Howe
For those still wanting to discuss the AC issue...the following
tutorial on what can go wrong will make you power up before you plug in
to the laptop: Introduction -- Switching-Mode Power Supply Design
the link for the tutorial containing detailed specs
http://www.smpstech.com/tutorial/t01int.htm
Sandra Ragan
www.plumdigital.com
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