Star Tech Journal

S*TJ JANUARY 1982 4
American
Arcade
Technical
Academy
* tions
In-depth instruc-
on solid state
game equipment.
* Concise
6-day
course, including
*
*
*
*
text books and
technical manuals
Beginners course:
Second Monday
of each month.
Advanced course:
Fourth Monday
of each month.
Videolecture
series home study
program.
Newly expanded
lecture staff
headed by Don
Wright, former
service repre-
sentative
for 2
.
maJor
manufacturers.
4688 Alvarado Canyon Rd.
San Diego, CA 92120
Call now for infonnation:
(714) 287-4263
(in California)
(800) 854-2521
(Nationwide)
Credit cards accepted.
TAITO
"CRAZY CLIMBER"
VIDEO* MOD
SUBJECT:
Mirror Image of Video or Image Upside Down
SOLUTION:
Add Capacitor and Change Chip
PARTS NEEDED:
One 0.luf Capacitor
One 74LS138 Chip
PROCEDURE:
Add 0.luf Capacitor Between Pin 8 and Pin 16 on IC16.
Location 5D; CAREFULLY change IC9 Location 6H
(74LS138).
STERN
"SUPER COBRA"
MPU * MOD
PROBLEM:
"Super Cobra" Randomly Going Into Crosshatch Pattern.
CAUSE:
Timing Error on Address is Causing a Watchdog Reset.
Due to Minor Speed Variations in the Z-80 Processors, a
Timing Error May Develop on A15 of the Z-80 (IA) on the
C.R.T. Board. This Causes the Watchdog to Sense an
Execution Error and Causes the System to Reset.
CURE:
Add a 220 PF Capacitor Between I.C. 3A Pin 4 and Ground.
WILLIAMS
"MAKE TRAX"
COIN* METER* INSTALLATION
BY HOWARD M. SMITH, ARLINGTON. TX
Early versions of the Williams "Make Trax" machine do not
have coin meters. A 6V de coin meter may be installed as follows.
• 1. Connect one side of the meter to +5V at Pin 15 of J2 on the
Power Supply Board. 2. Connect the other side of the coin meter
to the White-Blue wire between the coin door and the edge
connector on the main logic board. This is the normally open side
of the coin switches and is grounded when either coin switch is
closed. 3. Connect a 1 N 4004 or similar diode across the coin
meter with the cathode (banded) end on the +5V lead. This is
necessary to prevent switching transients from destroying the
input devices on the rp.ain logic board. 4. Mount the meter on top
of the cash box enclosure to keep all wires short.