[Ti] Grounding Problem? (was: another Battery Question)

[Jess Girard]

Try changing the position of the AC plug 180º in the wall outlet.  There is 
a high probability that will fix the problem. There is a "hot" versus a 
"ground" side to AC outlets. If the AC adapters for the new 17" Powerbooks 
actually has a direct connection to one side of the AC circuit from the AC 
socket to the Powerbook (which is possible but would really surprise me!) 
and you have it in the "wrong" way you can have 117 (or 220) volts of AC on 
the case. And if that's true you really don't want to be holding the 
Powerbook and touching anything grounded. You then become a part of a 
high-voltage circuit, which can be painful to say the least.

Many household appliances come with polarized 2-blade plugs (one blade 
wider than the other) to make sure you never put them in the "wrong" way, 
but of course that assumes that the person who installed the wall socket 
wired it correctly.

Devices like laptops should be electrically isolated from wall current 
because they use transformers to step down the AC voltage from 117/240 to 
the nominal 24 volts the Powerbook eats. The M8482 battery charger/AC 
adapter for my 15" PB certainly feels heavy enough to have a transformer in 
it, and the plug isn't polarized which implies it's isolated. But it is 
possible that a worker mistakenly connected one side of the input to one 
side of the output. You can test that with any VOM (Volt Ohm Meter). A few 
models back (Lombard? The one with bronze-color keys) there was a recall of 
the older rectangular black adapters; they were replaced by Apple for free 
with saucer-shaped units.

These are inexpensive devices, made by the lowest bidder. Problems with 
them would not be surprising.

At 05:45 PM 7/2/2003 -0400, you wrote:
>What I discovered on my 17" Powerbook raises an electrical question 
>related to the AC adaptor which in turn could be health related.  After 
>the battery is charged to 100% I have noticed a mild electrical buzz can 
>be felt all over the aluminum case.  It is a tactile vibration, meaning to 
>feel it you should lightly rub your fingers over the surface.  It only 
>happens after the battery reads 90+% charge.
>
>I have not looked at schematics for the 17". With that said, a power build 
>up seems to be creating a ground problem that is leaking a charge onto the 
>case itself.
>
>I believe this to be true because when I unplug the AC the electrical 
>ground buzz on the case stops.  Plug it back in and it starts again.  I 
>haven't tried to meter the aluminum case yet but was curious to hear if 
>anyone else experienced this AC related effect on their 17 or Ti.
>
>MBurke

Best Regards
Jess Girard
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