4 Mar
2007
4 Mar
'07
8:23 p.m.
Well, yes -
since it would be drawing (to a first approximation)
zero current.
Not so. There will be an out-of-phase current due to the inductance
of the primary winding. IIRC, though, you've got a leak (or short) to
earth from some point
in the HV widning, and another point on that winding (the centre-tap
of the B+ part) is deliberately earthed.
Yes - when it was in-circuit. Not when it's sitting disconnected,
which was the circumstance under which I observed the excessive draw.
That can't be right.
Agreed.
And I'll bet that short-to-reath is not just on
one turn, in other
words you also have shorted turns there.
I agree, especially in view of the "open-circuit" draw. :)
The Z-modulation input is an external brightness
control input, used
for some special applications.
I once built one. :) (It was a 1Kx1 RAM with circuitry to scroll
through all 1K bits, effectively turning it into a 1Kbit shift
register, with the data bit controlling the Z input on the 'scope and
the X sweep generator triggered by the carry-out from the address
counter. Get the clock frequencies about right and hook the input up
to a ham's CW sending key and you get a nice little graphic Morse
display scrolling past.)
(The
unconnected final winding of the transformer is actually the
filament winding for the rectifier whose cathode is shown connected to
^^^^^^^
Don't you mean anode (plate to you) here?