[sci.electronics] Caution: TV Speaker-- possible hot chassis!

wtm@neoucom.UUCP (Bill Mayhew) (10/10/87)

I think it would be a good idea to obtain the schematic diagram for
the television set in question before opening the cabinet and
attaching the speaker leads to your stereo.

Most television sets are paragons of minimalism.  In quite a few
cases I've seen, the speaker is driven from a single transistor
class A amplifier whose Vcc is derived from 170 VDC gotten by
directly rectifying the AC mains!!  Be particularly suspicious if
you peer inside your set and note that the speaker has a 40 ohm or
greater impedance rating.  If in doubt, please contact a qualified
TV repair person for help:  this is much more honorable than frying
your TV, your stereo or especailly yourself!!

Fortunately, ICs are getting to be just as cheap as transistors,
thus such cost-saving measures as above are giving way more often
to low voltage push-pull amps operated from safely isolated power
sources.

Bill
(wtm@neoucom.UUCP)