STAR•TECH JOURNAL/SEPTEMBER 1982
11
What this all means is that great care must be taken when measuring
power supply voltages, and that all voltages ( especially-5) must be present
when applying power to the game board. While failures of this type have not
been seen in "Kangaroo", proper maintenance can help keep it that way and
reduce the chances of ever having to change 32 soldered-in 4116 dynamic
RAMs.
To date, the boards in "Kangaroo" have been very reliable. However,
should any problems develop, Atari has included their usual thorough
documentation package which includes block diagrams on each logic board,
a glossary of schematic signal descriptions, timing diagrams, memory maps,
and easily deciphered board schematics (which have to be more accurate
than the early "Dig Dug" schematics).
SYSTEM POWER
There is really nothing new here. The two main components are the
transformer assembly and the audio regulator board (see diagram).
TRANSFORMER - This is the same transformer assembly used in
"Dig Dug". It provides four AC output voltages.
AC Tap
120 vac
12.5vac
6.3vac
36 vac
Destination
Monitor
Bridge Rectifier on T.A.
Coin Door Lamps
Discreet Bridge Rec. on Audio Reg. Board
The transformer assembly also has, as usual, a bridge rectifier and filter cap
mounted on it to supply a high current unregulated DC voltage ( 10.6). This
voltage has 3 destinations and 3 separate functions.
Destination
I. Audio Reg. Board
2. Coin Door
3. Utility Panel
Function
(Input +5 vdc Regulator)
(Left & Right Coin Lockouts)
(Left & Right Coin Counters)
SYSTEM POWER
i----120vac i s o l a t e d - B
Fluorescent
Light
- - - 6.3vac-------
- - - - - - - ~ Utility
Panel
*10.6vdc
36vac
F1
F2
F3
11111
7ASB
4ASB
20ASB
F4
4ASB
FS
4ASB
F6
4ASB
F111
Clrc■H
Line in (AC)
10.6vdc
12.5 vac
(lnputtoMDA3501 BR.)
36vac
(Input Aud. Reg.)
36vac
(Input Aud. Reg.)
6.3vac
(Coin door lamps)
5 v d Logic
c8
+ +
12vdc
Boards
-Svdc
NDm:
1. On/off switch is located on the
back of the cabinet Lower left
side.
2. There are NO interlock switches.
3. *MDA3501 and 27,000MFD @
15v mounted on transformer
assembly.
4. A voltage selection block for
varied line voltaes is present
120vac (yellow wire color).
* All fuses located on transformer assembly
The transformer assembly is extremely reliable, with failures of the
transformer itself virtually non-existent unless overfused or coins drop down
and short out the fuse holders. Any failures that do occur are usually in the
10.6vdc output circuit If the 10.6 volts is bad, the logic board will not
function. A bad voltage could be caused by several things: Occasionally the
solderless connectors on the bridge rectifier overheat and break-down,
sometimes part of the bridge will open and sometimes the 27,000 MFD cap
opens or decreases in value. Since Atari is nice enough to use this same cap
and bridge on almost every game, there is no excuse why any failure of the
transformer assembly cannot be isolated and repaired (with the spare bridge
or cap that you carry in your tool case) immediately.
AUDIO REGULATOR -The audio regulator provides all necessary
regulated DC voltages to drive the logic board. This is the same regulator/
audio Il board used on previous games but is not interchangeable with other
games because the audio amp in "Kangaroo" is mounted on the CPU board.
Therefore, Atari has not bothered to mount the two IDA 2002 audio amps
and associated audio circuitry normally found on the regulator/audio II
board.
Voltage
+ 5
+12
- 5
Destination
Logic Boards (V cc)
Logic Boards ( audio amp, 4116 RAMs)
Video Board (4116 RAMs)
BOARD HARDWARE
+5 Regulator-LM305H
+5 Pass Transistor-2N3055
+12 Regulator-7812
-5 Regulator-7905
-nte only voltage which can be adjusted is the +5 using RS, a lK trimpot
mounted on the audio regulator board.
SELF· TEST /OPTIONS
"Kangaroo" possesses a detailed self-test• feature which can check
numerous game functions. Check the video display and the speaker is all that
is necessary to verify self-test results. These results can be used to verify:
(1) Memory devices on logic board
(4) All game sounds
(2) Dip-switch settings
(5) Color outputs from monitor
(3) Cabinet switch operation
(6)Monitor convergence
-nte self-test switch is located on the utility panel behind the upper coin door.
This utility panel also has a coin switch, volume control and coin counter
mounted on it. The service switch is located on the CPU Board. For detailed
information on self test, see the "Kangaroo" game manual. .
OPTIONS - Options can be set by adjusting the dip-switch located on
the CPU board next to IC42. These options include settings for 3 or 5
kangaroos, various coin/credit combinations, and for bonus kangaroos, if
any. A setting for easy game or hard game difficulty is also available. This
setting in conjunction with the number of lives and bonus kangaroos is the
only present method of cutting down on game play time.
AUDIO 1/0
AUDIO - The audio circuit is slightly different in "Kangaroo" than on
previous Atari games. As mentioned earlier (system power, audio reg. bd.)
the audio amps (TDA2002) have been removed off the audio regulator
board. Instead, the audio amp is located directly on the CPU Board. There
are two volume pots, one on the CPU Board, the other mounted on the utility
panel. The voltage used to drive the audio amp is regulated 12 volts.
Speaker (1)
Audio Amp (1)
Volume Pot (CPU Board)
Volume Pot (Utility Panel)
6" x 9",4ohm, 15w,oval
MB3713
lK Trim Pot
50 ohm wire wound
1/0 - All switch inputs from the coin door and control panel including
the joystick, enter the 44-pin connector (PCN2) on the CPU Board. These
switch inputs can most easily be checked during self test Any problem not
caused by a switch probably can be narrowed down to the resistor/capacitor
network or to the input chips (74LS368) located directly on the CPU Board
(IC43, 44, and 46). Voltages enter this board pins 20, 21, and Yforthe +5
volts and pins 22 and Z for the +12 volts.
The video board has one 10-pin connector (PCN4) which receives 3
input voltages, + 5, + 12, and -5. Additionally, this connector provides the
sync and color outputs to the monitor.
NOTE: The game manual has a helpful section on maintaining and
servicing the 8-way Wico joystick. The one and two player start switches do
not have !eds mounted in them and will not flash indicating a credit
CONCLUSION
"Kangaroo", like "Dig Dug", has been successfully adapted to the Atari
system. Most of the important aspects of game design, ( cabinet and wire
harness) are similar to other Atari games. The only major change is in the
board design and this is of little consequence to the operator. One board or
two, it makes no difference as long as a thorough self test exists. The only
portion of board design that the operator will miss is the absence of the
EAROM. This is the PROM which enables the game to "remember" the
high score table when power was turned off. This feature does not exist in
"Kangaroo"; powering off the game or going into self test erases all scores.
An IC that could possible have been used to cut down on the
aforementioned density and complexity of the video board is the Intel 8202
dynamic RAM controller. This single IC is capable of controlJing 64K of
RAM, connects directly to the buss, and could have eliminated most of the
control signal (RAS, CAS) circuitry as well as a large number of chips in the
address multiplexing circuit Future designs involving dynamic RAMs may
welJ take advantage of this I C's potential use.
At the present time, no major failures or minor problems (i.e. "Dig
Dug"/4 credits-per-coin) have been found in "Kangaroo".