Re: One last monitor problem

To quote from Jed Margolin's Secret Life of Vector Generators:

"In order to have the Death Star explode the way we wanted it to, it wasn't
enough to draw lots of concentric circles. We wanted to defocus the beam to fill
it in. We briefly considered adding a vacuum tube to the monitor to control the
Focus Voltage. Fortunately, the lead time for the part was too long. So what I
did was to give the Vector Generator the ability to overdrive the monitor's
color inputs. Overdriving the inputs causes the CRT to draw more current than it
normally uses and drags down the High Voltage., which changes the normal ratio
of Focus Grid voltage to Anode voltage, which defocuses the beam. This
relationship is explained in The Secret Life of XY Monitors."

So your high voltage is really being sucked down during the explosion, you won't
see this on a scope.

There was a hack added to the amplifone deflection boards where to power
resistors (50ohms I think, but I could be wrong) were added across the voltage
regulators. Make sure you have those resistors and that they are not fried.
They allow more current to pass to the HV section when the regulators have
reached their max current output levels.

Other than that I don't know what to tell you except that it really sounds like
a high voltage problem.

-Zonn

On Tue, 05 Feb 2002 21:41:53 -0800, Matt Rossiter <rossiter@ni.net> wrote:

>Ok. This one is difficult to pin down, so I hope that maybe someone has
>seen this before and has fixed it.
>
>My Star Wars is working great now. I can focus and everything. The
>only thing is, when the screen gets really bright - for example when you
>get hit or especially when the death star blows up - the screen
>stretches. At the last, white explosion of the Death Star - It
>stretches REALLY BIG. It didn't do that before.
>
>So.... In trying to isolate the problem here's the steps I have
>taken.....
>
>1) Swapped the amplifone HV board with another one that works fine.
>Hmmm... same problem
>2) Swapped the amplifone deflection board with another one that works
>fine. Hmmm same problem
>3) Hooked up the X and Y outputs to an oscilloscope - Screen Doesn't
>scretch. It's fine - so it can't be the AVG board
>4) Hooked up a WG K6100 - Screen doesn't stretch. -- Hmmmmm. the yoke
>maybe?
>5) Swapped the WG k6100 yoke with the Star Wars yoke. Hmmm. Not the
>yoke.
>
>I really can't figure this problem out. It can't be the tube. It's new
>- but I'll run it through the tube tester anyway.
>
>What could it be? My Star Wars started doing this after the HV went
>dead.
>
>My two choices seem to be 1) Something weird with the tube, which I
>doubt. 2) Or both Amplifone HV boards have the same problem.
>
>Ideas anyone? I think I've seen this problem before on another star
>wars game, but I never found out what it was.
>
>Thanks!
>
>Matt
>
>---------------------------------------------------------------------------
>** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
>** message body to vectorlist-request@synthcom.com. Please direct other
>** questions, comments, or problems to neil@synthcom.com.

---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
Received on Tue Feb 5 23:04:04 2002