Star Tech Journal

10
STAR*TECH JOURNAL/JULY 1983
CINEMATRONICS
COSMIC CHASM ENGINEERING CHANGES
* MONITOR: JITTER, STRAY LINES, POWER PROBLEM, COOLING* ERRATIC TRACKBALL
* GAME LOCK UP, POWER UP CREDITS * MUFFLED AUDIO
Listed are several engineering fixes for problems that have been
encountered in the field If you have had any of the problems
listed below, you will find the fix under that heading.
PROBLEM
Up and down jitter
Stray long lines
Monitor power problems
Monitor cooling problems
Shaft encoder erratic
Lock-up/credits on power-up
Muffled explosion sound
ECN#
1
2
3
3
4
4
4
N0.1
Assembly: Cosmic Chasm Game Processor - Revision B
Problem: Parts of screen objects are randomly displaced
on the "X" axis ( up and down when the monitor
is mounted vertically). This is caused by insuffi-
cient delay in the assertion of the QAS line
during refresh processor operation.
Sol utlon: One trace cut and one 30-gauge Krynar insulation
wire addition as indicated below. This modifica-
tion will increase the delay of QAS through the
flip-flops of U93.
COMPONENT SIDE
NO. 2
Assembly: Cosmic Chasm Game Processor - Revision B
Problem: Erratic long lines are drawn occasionally.
Solutlon: The two trace cuts and two 30-gauge Krynar
insulation wire additions as indicated on next
page. This modification will improve the noise
immunity of the 6MHz A line.
NO. 3
Assembly: Cosmic Chasm Power Supply Plate/Electro-
home X-Y Monitor
Problem: Short circuit between+ l0vdc and frame ground
on modified Datapower power supply (PSI),
causing Electrohome X-Y monitor failure.
Solution: Measure resistance between case of Ql
(2N6577) power transistor and frame of power
supply. If they are shorted, remove transistor and
insure that nylon insulating shoulder washers are
correctly installed on the transistor mounting
screws.
This problem may damage the Electrohome X-Y
monitor, causing the picture to "swim" off center
on the screen. Check if ground trace on underside
of main circuit board near Q703 is burnt and
replace if necessary with insulated wire between
R735 and W19.
********
Assembly: Cosmic Chasm Cabinet/Electrohome X-Y
Monitor.
Problem: Inadequate ventilation in rear of cabinet, causing
Electrohome X-Y monitor failure.
Solution: Cut two 2", 45 ° notches in the wooden monitor
mounting bezel, one at each corner at the rear of
the cabinet This will allow adequate upward
airflow along the back door of the cabinet.
BACK OF CABINET
N0.4
Assembly: Z80 Audio Board
Problem: Trackball Channel 0 does not work properly.
Ship turns erratically in Cosmic Chasm.
Solution: Add the following wires:
To
From
U6-8
U5-7
U7-8
U6-8
Problem:
Game intermittently "locks up" and credits are
issued on power up. Also audio board does not
reset properly.
Solution:
(a) Insure that U33 is loaded with a Z8430A,
the 4MHz part, and not with a Z8430, the
2.5MHz part
Continued on next page.