Re: Ampliphone HV-other options?!

Hi Zonn!

Yes, I knew about the inputs to the Cine, I should have said that the
inputs were set to "0" deflection on the screen. I imagine a simple pair
of dip switches could be used to move the beam anywhere one likes for
testing purposes.

I hadn't thought of testing the Cine chassis with BOTH the yoke and
outputs disconnected, I would think that the drivers would not be happy,
but on the other hand, with no load, why would they care? But I don't
know what to think until I study the schematic some more...

 I have accidentally "tested" a Cine with the output transistors
unplugged and the yoke still in, this happened in the early 80's, makes
for a bit of smoke!

John :-#)#

Zonn wrote:
>
> On Sat, 12 Jun 1999 21:16:23 -0700, John Robertson <jrr@flippers.com> wrote:
>
> >One is able to run an XY chassis without a yoke, as the thing is really
> >just an stereo audio amp, and some load resistors would work fine. If
> >you short the inputs to ground, there technically would be no output and
> >thus you could even not have anything hooked up to the yoke socket. The
> >Cinematronics monitor makes a loud statement (a metallic sticker) on
> >their monitor NOT to run them without the output transistors plugged in,
> >however they do talk about running the monitor without the yoke plugged
> >in...the output transistors are then unloaded, and less likely to fry.
> >Your mileage may vary.
>
> The Cinematronics is a bit different. You can't short the inputs since the
> inputs are digital latches. If you plug in a Cinematronics monitor without a
> game hooked up, the vector drawing capacitors will drift and the trace will
> leave the screen, placing a near short on the output transistors, and the
> circuit breaker(s) will blow -- sometimes in time to save the monitor, sometimes
> not.
>
> If you unplug the output transistors and run the monitor, the small pre-driver
> transistor will try to drive the yoke, and they just can't deliver the current.
> They will smoke, or the 47 ohm resistor between them and the yoke will smoke, or
> all of the above.
>
> Removing the yoke is fine. Remove the yoke AND the power transistors is also
> fine, if you just want to go through with a scope looking at signals.
>
> -Zonn

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