Re: Can dust inside an Apple IIgs catch fire?

[Michael J. Mahon <mjmahon@aol.com>]

Riccardo <rigreco.grc@gmail.com> wrote:
>> 
>> 230VAC has peak-to-peak voltage of over 320v, so I can easily imagine
>> 
>> that--particularly for narrow separations. 
> 
> Right,
>  
> 
>> I certainly agree that it's possible--just quite unlikely. Certainly it
>> 
>> would not happen anywhere but the line side of an Apple II. 
>> 
>> 
>> 
>> Opening the power supply and physically inspecting the few places where
>> 
>> line voltage is present would immediately reveal whether it was a factor in
>> 
>> the OP's case. 
>> 
> 
> I agree. I also see possibility of overtemperature circuits, other
> electrical problems like overvoltage of AC power cause only permanently damage, i think.

True, though ironically that "X2" line capacitor is actually
self-healing--it can survive an internal breakdown caused by a line
transient several times. It does this by burning away a tiny part of the
metal foil plates adjacent to a dielectric perforated by the transient. The
dielectric is impregnated with a heavy oil which fills the void, "healing"
the point of breakdown. 

Eventually, the insults are too many in some small region for the oil to
heal it, and increased electrical leakage leads to thermal runaway
punctuated with a "bang" and the pervasive smell of vaporized dielectric
oil. 

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon