Dave Plowman wrote:

In article ,
Old Fart at Play wrote:

A suitable transformer would not be too expensive and would provide
isolation, especially if you add an earth wire just to the
output side.


IMHO that defeats the idea of an isolation transformer.


That depends on where you connect the EARTH wire.
I was thinking of connecting it to EARTH.
What about you? Live? Chassis? Why not be adventurous
and connect it to that thick wire that goes into the side
of the CRT?

Looking in an old RS catalogue I saw a 3W 1:1 speaker isolation
transformer for about 5 quid. Put that before the internal speaker
and you can use a switched 'phone socket.

If you're OK with a separate switch you could use a stepdown
transformer after the internal speaker and do away with the
resistors.

Roger.