30 Dec
2000
30 Dec
'00
1:56 p.m.
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
Over here, virtually all large-ish screen TVs have
what's called a SCART
socket. This is a 21 pin connector carrying 2 channels of audio in and
out (4 connections), composite video in and out (the input is also used
for composite sync in in RGB mode), RGB input, blanking, etc, and lots
of
grounds.
Never seen one here. This set does take composite video in and audio in
via jack on front (Sharp).
I've never seen a monitor with a hot chassis. I
know the original 110V
version of the TRS80 model 1 monitor was (I have the service manual),
and
had an opto-isolated video input, but surely all more
recent monitors
have isolating PSUs?
Many do, but I was thinking more of TVsets.
About the worst you'll find over here is some
varient of the IPSALO
circuit (IPSALO == Integrated Power Supply And Line Output, Line Output
being what we call the horizontal output stage).
Comon config here in smaller or lowend sets.
With these, the flyback is on the hot side of the PSU,
as is the
horizontal deflection yoke. The horizontal drive signal is
opto-isolated,
the horizontal osciallator, vertical deflection, video
circuitry,
tuner/IF strip, etc are all isolated from the power line, The EHT to the
CRT is isolated as well, by the flyback transformer.
Of course these means that one yoke winding is isolated from the power
line, the other isn't. Adds the 'fun' when servicing these.
Isolation transformer is the only way to live.
Allison