"Leif Neland"


A 240/120 Auto transformer is just a 240 volt winding with a tap halfway
up. Very dangerous if you take your 120 off the top half instead of 5the
bottom.

Why should that be dangerous?

Surely you do not rely on the which wire is live and which is neutral, and
have the neutral connected to the cabinet or something?

Or are your insulation so bad it cannot withstand 240 volt to ground?


** Old US made items ( audio, radio TV etc ) have no connection to ground so
the chassis floats at some mid voltage OR is linked to one side of the
incoming AC line with a capacitor. The cap is usually either 0.1uF or 0.05
uF @ 400V DC.

The plug can be reversed so the user is supposed to find the way that links
that cap to neutral and so brings the chassis down to a low voltage. This
will result is less hum and noise in the sound.

If used with a auto tranny from a 240V supply, the cap ( aka " death cap" )
can bring the chassis to 240V or itself experience 240 VAC if the chassis is
grounded by another item. 240VAC is more than such caps can stand and they
often fail short.

With guitar amps, this situation is particularly lethal - hence the title
"death cap"'.

FYI:

An auto tranny will deliver full AC line voltage on BOTH output wires
simply if the neutral is not connected at the supply end.



.... Phil