Re: ISA Vector card already done...

From: Al Kossow <aek>
Date: Thu Mar 26 1998 - 13:35:26 EST

A while back, I had talked about putting a watchdog (a couple of
analog compatitors and timer on analog monitors, or a timer
watching the DAC strobe on Cinematronics montitors) which would
detect the fault condition and zero the deflection amplifier
inputs. There are three things that I can think of which would
blow the deflection amps, which are all fixable (actually 1 and
2 are similar problems) 1) overvoltage at the deflection inputs
(which is what the WG clipping circuit tries to prevent) 2)
deflection voltages staying at maximum deflection (max current
dissipation) too long and 3) voltage breakdown of the deflection
transistors due to voltage spikes from the deflection coil
ringing. It looked like there was damping circuitry in at least
the G08 design to limit the bandwidth of the deflection amplifiers
and since I haven't built the test rigs yet for the WG and G08
amplifiers (I actually can SEE my bench again in the garage after
renting a storage space two weeks ago..) to test if case #3 can
actually happen.
Received on Thu Mar 26 10:35:37 1998

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