Re: Amplifone jitters

I'm not very good when it comes to technical things like these, but I have a
problem like you mention with my Star Wars where the screen's contrast changes
and everything gets bigger when the Death Star explodes. I think the condition
you mentions happens too. I was wondering if it was suppose to do that, I guess
it isn't. I'd like an answer to this question too!

Thanks for asking it!

-Al-

Joel Rosenzweig wrote:

> Last night I had a few moments so I started to do a little
> troubleshooting. Hooking up the scope proved that the video output is
> clean, therefore it's the monitor that has some problem.
>
> I actually noticed two different problems, the jitter is one, but the
> other is that now all of a sudden, those fireball explosions which are
> bright, cause the screen to expand and contract about an inch. It's
> just like what some people report when the Death Star explodes, however,
> my system has never exhibited this behavior until now, and it happens
> not just on the Death Star explosion, but on any explosion that's
> bright.
>
> Didn't someone say that the expanding and contracting occured because
> the 24 volt regulators couldn't supply enough current at that moment?
> If so, could this effect be eliminated by having a more robust +/-
> 24volt supply replace those regulators? Could the LV2000, for instance
> be used instead to supply a nice regulated +/- 24 volts?
>
> With respect to the loose wire issue, I'll take a look tonight. I did
> check the ground wires on the power supply, and they were still firmly
> in place.
>
> The good news is that I can swap in any component in the game with
> others, so that will at least tell me which assembly is at fault if it
> comes to that.
>
> Anders Knudsen wrote:
> >
> > I seem to remember that Jeff Hendrix had this similar problem with an
> > ampliphone. It turned out that some wire (might have been the HV wire) off
> > the transformer was loose. I am speaking from faded memory here though.
> > Perhaps Jeff can remember. If you could stick a scope in XY mode off the
> > PCB outputs and they are "clean", then your jitter problem is the monitor.
> >
> > -Anders.
> >
>
> Zonn wrote:
>
> >Just out of curiosity, do you still have the metal cage around the HV? Not
> >having the cage will cause the displays to jitter.
>
> I didn't realize there was a metal cage around the Amplifone's HV board?
> Is this a typo?
>
> I guess the absence of mine is not helping things any. However, I do
> own the metal cages for the Wells Gardner monitors, but I don't use
> them, but their absence has not had any negative effect (jitter wise at
> least) on the video quality. The Wells Gardners seem to be rock steady
> as long as the ground wires are solid, and the caps in the LV supply are
> not leaky. At least, that has been my experience with my Tempest which
> once suffered from jitter problems until I checked these two things. I
> actually had the problem in two different Tempests, the ground wires
> fixed one, and the LV cap replacement fixed the other beautifully.
>
> If anyone has any other leads to follow up, that would be great! If
> someone could comment on the utility of replacing those 24v regulators
> with a better supply, that would be good too.
>
> Thanks!
> Joel-
Received on Wed Jun 24 09:53:36 1998