TECH: Asteroids picture too big

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hey all. I was playing my Asteroids tonight when the picture suddenly got
much much bigger. The high score numbers seemed fine, the text and saucers
were distorted. Test mode only gave a small horizontal line that didn't even
span the whole width of the tube (about a 2 inch line or so). Spot killer
also came on in test mode with that line. The board was repaired by Alex
Yeckley a while back so I'm hoping it's not the monitor. I also changed out
the HV diode I had thinking that might be the problem. Any tips on where to
start is appreciated. Thanks.

Bill

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hey Alex,

Thanks for the quick reply. I was actually thinking I should try to reseat
the roms real quick just in case. If that doesn't work, I'll be sure to get
the PCB on its way to you this week. I'll email tonight if the rom reseat
doesn't work.
Bill


"Alex Yeckley" <ayeckley@elektronforge.com> wrote in message
news:VKhDe.4215$IG2.1853@newssvr33.news.prodigy.com...
> > Hey all. I was playing my Asteroids tonight when the picture suddenly
got
> > much much bigger. The high score numbers seemed fine, the text and
saucers
> > were distorted. Test mode only gave a small horizontal line that didn't
even
> > span the whole width of the tube (about a 2 inch line or so). Spot
killer
> > also came on in test mode with that line. The board was repaired by Alex
> > Yeckley a while back so I'm hoping it's not the monitor. I also changed
out
> > the HV diode I had thinking that might be the problem. Any tips on where
to
> > start is appreciated. Thanks.
>
> If the picture got larger instantaneously rather than gradually, then it's
a new problem
> with the game PCB. You might get lucky just by reseating the ROMs, but it
sounds
> like it's a DVG problem...
>
> Alex
> ----
> ayeckley@elektronforge.com
> www.elektronforge.com
>
>

Archived from groups: rec.games.video.arcade.collecting (More info?)

It should be easy enough to rule out the scaling circuitry - there's
only about 3 chips involved and the likelihood is that if you piggy
back known good chips in turn on each of them would more than likely
see some change, or a complete fix.

I have my doubts though. I don't think that a scaling issue would cause
the spot killer to come on!

Archived from groups: rec.games.video.arcade.collecting (More info?)

On Wed, 20 Jul 2005 13:28:43 GMT, "Alex Yeckley"
<ayeckley@elektronforge.com> wrote:

>> Download the schematics (say from crazykong.com) and have a look at
>> the scaling circuitry on the Asteroids game board.
>
>The problem is not likely in the scaling circuitry itself.

I think you're right - that'll teach me to reply to messages when I'm
half asleep (as I am now).