Star Tech Journal

STAR*TECH JOURNAL/FEBRUARY 1984
21
"Mr. Dot's Castle" continued.
screen. After this, the screen will go blank and the
following lines should appear one at a time.
Information in parentheses is not displayed.
CPU 1
(POSITION Sl)
RAM OK
(Hl, El, or Fl)
ROM 1
(Pl)
ROM 2
(Nl)
ROM 3
(Ll)
ROM 4
(Kl)
If a RAM is bad, its board location will be
written out Ifa ROM is bad, itwilldisplay"ROM
X ERROR" The board positions for "X" are
listed above and not in the service manual. Next,
the screen goes blank even if there are errors and
proceeds to the sound 1/0 CPU at L7. The sound
I/0 MPU has one ROM and one RAM (N7 and
P7). It will test its memory and display any errors.
After this, it automatically proceeds to the monitor
test
The intensity test is used to properly set colors
and intensities. The four colors, red, green, blue,
and white will have eight levels of intensities,
including zero intensity. A properly adjusted
monitor should show the dimmest intensity 1 with
no raster lines. There is no blue intensity 1, and
white intensity 1 will appear tan. The brightest
should be 7. By pressing 1st and 2nd player
controls, the switch test is then displayed.
For your convenience, the available switches
are shown below along with the resistors which are
connected to the particular lines. To test the lines
simply pull the edge connector side of the resisto;
low.
Resistor
Switch
2nd Plyr. Down
R37
2nd Plyr. Left
R35
2nd Plyr. Up
R41
2nd Plyr. Right
R39
1st Plyr. Down
R25
1st Plyr. Left
R23
1st Plyr. Up
R29
l st Plyr. Right
R27
2nd Plyr. Start
R33
2nd Plyr. Jump (N/U)
R40
2nd Plyr. Hammer
Rl9
l st Plyr. Start
R21
R28
1st Plyr. Jump (N/U)
l st Plyr. Hammer
R20
R48 (Freezes video)
Pause
R32 (No counter)
Service Credit
R31
Test (N/U)
Tilt (N/U)
R30
R42 (Not displayed)
Real Tilt
Both dip switches are shown and the display
will reflect directly their alterations. Dip switch A
is SWl and dip switch B is SW2. Coin switches
have resistors at RS and R9. These are pulled high
externally through the coin switches. If these coin
inputs are not pulled high externally they will float.
(They are pulled high externally as part of an
anti-stringing circuit.)
The last test displays a pattern of H's for
convergence purposes. Mr. Do! characters are
scrolled left to right in the center.
CONVERSION HINTS
1) Check everything in your kit against the list in
the service manual.
2) The plexiglass panel and the marquee are easily
cut on a router table equipped with a veining bit.
A handsaw can also easily cut the plastic too,
but a jigsaw's up and down motion tends to
break the material unless you cut slowly and
protect the material from excessive vibration. If
you use the control panel plexiglass which
protects the panel from cigarette burns and
vandalism, drill any holes slowly, especially
when the bit is about to break through. Button
holes should be drilled 1 ¼" in diameter or
slightly larger. For metal panels, holes can be
cut easily with a 1 ¼" inch Greenlee punch or
related sheetmetal tool.
3) A light duty paint and varnish remover and a
razor blade easily remove old decals. It is the
responsibility of the converter to determine
whether a painted cabinet may be damaged by
this method.
4) When the proper direction of the wire harness
edge connector plug on the logic board is
found, label the side of the plug "parts side" in
relation to the parts side of the logic board.
5) Hookupthe+5 and+l2first Secondly,hook
up the video plug. If the picture is upside down,
either a) turn the picture tube 180°, b) turn the
yoke 180° and reconverge the picture, or c)
reverse the directions of the yoke terminals
with the help of a monitor schematic. Letter ( c)
procedure is the easiest; just remember that
both the horizontal and vertical yoke wires
must be reversed if the picture is upside down.
6) On an Electrohome G07 color monitor,
separate horizontal and vertical sync are
needed To get separate horizontal and vertical,
follow the schematic diagram on page nine in
the instruction manual. This is not done at the
factory, but the brown and orange wires are
provided in the wiring harness. Early model
Wells Gardner color monitors with the per-
pendicular input boards accept white wire
sync. Caution: When separate sync is used,
cut the trace on the logic board going to pin 6 of
the edge connector. This is the "pause" line
normally.
7) On an upright game, be sure and connect 1st
and 2nd player joystick controls and hammer
buttons together.
8) 6.3V coin door lamps can be run from the +5V
supply. Just connect an extra wire from the
+5V for the coin meter to one side of the lamps
and the other side to logic ground. This also
serves as a good indicator of +5V.
9) Make sure SWl, #6 is off when you set the
game or first power it up.
10) The self-test description of pages 3 and 4 in
the service manual are in error. The first test is
the memory test, second is the monitor test,
third is the switch test, and last is the conver-
gence pattern. There is no "sound off' test.
11) Use the switch test to aid in the final connections
.of the panel assembly.
". . . when the original
Mr. Do! was caught by a
monster, his head
exploded. Yuk!"
LOGIC BOARD
This is a knockout of a logic board! It uses three
Z80As! The main program CPU is at Sl, the
sound 1/ 0 MPU at L 7, and the video MPU at Al .
To make this a unity board, two P ALs are used in
the video section as well as a forty-pin custom
function (F5) chip which aids in addressing the
video RAM. To condense the input section, two
forty-pin chips (TMsl025's) are used at locations
D8 and F8 on the logic board, as well as a 6845
CRT controller (S5-6) for video. There is 128K
bytes of screen RAM, the most I have seen yet
dedicated purely to video. Four programmable
sound generators, 76489s, are at P9-R9. To give
you an idea of how versatile a 76489 is, only one is
used to create sound for all games in a Colleco Vision
home video game system! (It is a 16-pin chip.)
To specify further, the program(32K) is located
at Kl-Pl in four 2764s (8Kx8 bytes). 6K of main
program RAM resides in 8128 type RAMs ( 2Kx8
bytes) at El-Hl. CharacterROMs are four 2764s
at H4-M4 and one 27128 (l6Kx8 bytes) at A3.
The sound 1/0 MPU (L7) operates from the
27128 EPROMatN7 andan8128 atP7. Service
hint: The 2Kx8 RAMs (8128s) are identical in
pinoiit to a 2716 EPROM. They have become
very popular because of their byte size and cost.
There are many replacements for these RAMs.
just observe access time. Some substitutes are
2128s, TMS2016s, and 6116Ps. Five of these
RAMs are used. The RAM at DE4 needs a
lOOnsec access time an!i the five at Cl, El, Fl,
Hl, and P7 have 150nsec access times.
••
The MPU s are reset simultaneously by the 5 56
dual oscillator wired as a one shot at J9. The 556 is
triggered by a semi-sleepy watchdog pulse inverted
from P3 and originating from P2, a 74LS139
which is controlled by the main program (Sl)
CPU. Sometimes the watchdog doesn't work.
(The designers hope that if S 1 gets lost, it will
accidently pulse the watchdog line!)
All three MPUs as well as the four sound
generator chips are clocked simultaneously by the
undivided but buffered four Mhz crystal XL2.
Two ALS type TTL chips are used on this board,
both in the clock sections. ALS stands for Advanced
Low Power Schottky, a design which provides
50% less power consumption, yet has improved
circuit performance over a standard "LS" chip of
the same type.
A 9.828 Mhz crystal, XLl, is divided by a
74L2161 (P3-4) to provide sync signals for the
video section as well as the RAS and CAS lines for
the video RAMs.
The signal frequencies should be approximately:
P3-4
Pin 14
QO
4.914 Mhz
P3-4
Pin 13
Ql
2.457 Mhz
P3-4
Pin 12
Q2
1.228 Mhz
P3-4
Pin 11
Q3
0.614 Mhz
Some other signals of interest
~ for MPUs
4.0 Mhz
RAS for 4164s ~ 2.445 Mhz
CAS for 4164s ::::::;: 2.445 Mhz
H Pin 39 of S5-6 ;:c:::: 15,760 hz
V Pin 40 of S5-6 ~ 60 hz
The self test provided checks only the main
program memory at Pl-El and the sound 1/ 0
memory at N7 and P7 . Nothing, I repeat, nothing
in the video section, including the A 1 MPU nor the
4164 RAMs is checked.
Any failure other than the most minor in the
main program or sound 1/0 section will crash the
system. The video section won't likely crash the
main program if part of it is defective, however.
(Don't be misled; if any main program ROM or
RAM or sound 1/0 ROM or RAM has just one
bad byte in essential program step areas or RAM
areas the board will keep resetting if S 1 is lucky
enough to pulse the watchdog line.)
If it is a video problem, the remainder of the
article should help you locate a bad character
ROM or video RAM. Also, I shall write some
troubleshooting hints for the 76489 sound
generators.
This troubleshooting section consists of a
description of what certain chips do during the
attract mode. The attract mode with its four
separate subset screens; l) Mr. Do!'s Castle
(MDC). 2) High Score Table(HST). 3) Instruction
Screen (I), and 4) Scene l (SCI).
The following information of what the video
chips contain will be listed according to subset
screens.
EPROM H4-HST-None; MDC the word
"castle"; I - all of the blocks; SC I - key blocks,
skull blocks, and moveable ladders, Mr. Do! ' s
hammer, some of Mr. Do' ' s movement segments,
and the extra flags.
EPROM J4 - SCI - Shield, fruit blocks, the
monsters with the letters of EXTRA on them;
MDC- The scrolled pattern behind "Mr. Do!'s";
HST - none; I - none.
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Continued on next page.