Dynan10 Cabinet Ground Noise
Ken Williams
Dynamo Corporation
Richland Hills, Texas
PROBLEM
Let's talk about the noise you are experienc-
ing in your Dynamo cabinets with Wells-
Gardner monitors. The basic problem oc-
curs when you attach a field ground wire to
the frame. Aground loop is created and the
little lost electrons have to make a trip
through the ion guns to see if that's the way
home. Unfortunately, they are a bunch of
litter bugs and leave trash on your screen!
SOLUTION
If you have a Dynamo cabinet with a Wells-
PREFERENCES
I leave the choice to you. Both are safe and
both are effective. My personal choice is to
install the jumper on the power supply. We
will be doing this on all of our universal
cabinets and some dedicated pieces (subject
to customer approval) as of Feb 25, 1989.
Don't hesitate to direct your technical ques-
tions to Ken Williams at Dynamo Corp.
Phone number 800/527-6054 or to Harry
McComb at Wells-Gardner 312/252-8220.
"Power Up" Your
Gardner monitor in an HS-1 through 7 or a
dedicated piece, it is okay to disconnect the
field ground wire from the frame. The reason
it is okay is because every piece of that
monitor is grounded through its signal
ground pin. The frame, the static braid, and
the neck Pcb. Everything.
Doug Hutton
EBSGames
Poway, California
ALTERNATE METHOD
SUBJECT
Another way to solve this problem (which, by
the way, varies from game to game) is to put
a jumper wire from field ground to logic
ground on the power supply. This provides a
more attractive (shorter) way for this current
to get back to earth.
Do you know how to "Power Up" your
Romstar Bubble Bobble? There exists a joys-
tick routine, which when entered by the
player, changes the play of the game.
The basic problem is that the over grounding
is causing a loop to form inside the monitor
from earth ground to logic ground. By put-
ting the jumper on the power supply, you
create a shorter path Ueast resistance) for
the current to travel. Removing the ground
strap from your monitor, you break that
circuit and leave only the path thru the guns
-which leaves its distinctive "foot print."
Bubble Bobble
PROCEDURE
The trick is that you must input the se-
quence during the attract mode when the
large BUBBLE BOBBLE is on the screen and
it must be done with an even rhythm or
nothing will happen. When you do it right,
the word POWER UP appears in the lower
left-hand corner of the screen. Then deposit~
your coin and start the game and Bub and
Bob will move and blow bubbles very
quickly.