4 Jul
2006
4 Jul
'06
1:35 p.m.
I removed the
insulator panel on which these terminals are mounted,
and it is clear that four of the terminals go directly to the
deflection plates (two for each axis), with a resistor (4.7M)
hardwired from there to the deflection-amplifier terminals.
Right. I'd
forgotten about that. Those 4.7M resistors are to
maintain the DC balance of what's normally driving the plates. Using a
voltmeter on the amplifier-output terminals indicates that
one is driving about +100V and the other about +400V (of course,
these may be reading low because of meter impedance, but they
clearly are nowhere near equal).
That's a heck of an imbalance, there. So now
it's just a matter of tracing circuitry back until I find the
problem. (Heh. "Just".) Sorry to bother everyone when the answer
was right there waiting to be discovered all the time.
Probably leaking capacitors
coupling at the amplifier output?