Star Tech Journal

10
-sTAR*TECH JOURNAL/NOVEMBER 1982
A Regular Monthly Feature Technically Outlining a Newly Released Game
NINTENDO'S "DONKEY KONG JUNIOR"
By Joe Connor, Active Amusement Co., Philadelphia, PA
After the great success of Nintendo's first big hit game,
"Donkey Kong" , it's only natural that a sequel to the
original should be released. At one time, it could be said
that remakes always seemed to be disappointing, falling
well short of the players', as well as the operators',
expectations. The recent success of "Ms. Pac-Man",
however, indicates that remakes can be very profitable if
they manage to stay close enough to the original game, yet
(and this is the hard part) provide new and varied
challenges for renewed player interest. Initial response
would seem to indicate that "Donkey Kong Junior" is
generating this kind of interest and is going to be a
successful remake. There have been slight variations to
the original game theme (" Donkey Kong" has been
captured and now Mario is the "heavy") but the same
basic elements of game play still exist - the player starts
at the bottom of the screen and must run, jump, and climb
his way to the top, avoiding a brigade of snapping jaws,
ape-eating birds, and energy pods launched at him. Like
"Donkey Kong", there are four distinctly different screens,
each providing a new challenge with varied sound effects
and outstanding visual imagery.
The electronics package is almost identical to that in
"Donkey Kong" . There are minor changes to the board
set, but the monitor, wire harness, and power supply are
identical in both games. The overall game design is all
Japanese right down to the high quality components,
switching power supply, and non-existent self test.
SYSTEM POWER
The system power (see diagram) is provided by a single
isolation transformer and a switching power supply
mounted on an assembly in the bottom of the cabinet. The
switching power supply negates the need for any additional
transformers since the input for it is I OOvac.
Traneformer - There are two secondary windings
coming off the isolation transformer. One winding supplies
SYSTEM POWER
Power
Supply
(Switching)
10Ovac
Line
Voltage
On/Off
Switch
Isolation
Trans.
JOOvac (1.2 amps) for the monitor and fluorescent tube.
The other winding (JOOvac, 1.6 amps) supplies the input
to the switching power supply. Since most domestic line
voltages are usually between 115 and 120vac, this
transformer is not only isolating the incoming line voltage
but also stepping it down slightly. The transformer is
protected by a 5-amp fuse screwed in next to the line cord.
Switching Power Supply - The power supply, like
those used in some other games (Centuri "Phoenix"), is a
switching power supply. It is capable of delivering + 5 and
-5 volts at 5 amps as well as + 12 and + 24 volts ( using 3-
pin package regulators). By using numerous low power
transformers and an array of inductors, rectifiers, transis-
tors and capacitors, this power supply can operate
extremely efficiently (no heat dissipation), wasting much
Jess power than the standard power supply. The switching
power supply used in "Donkey Kong Junior" is the same
one used in "Donkey Kong" (PP-7B). There is a single 4-
amp fuse located in the power supply, protecting the
lOOvac input voltage. Voltage adjustment pots are also
located inside the power supply, but usually no adjustments
are necessary.
Principle advantages of this power supply are its
reliability (no heat buildup), inexpensive (hard to believe,
but using all these parts is cheaper than purchasing a high-
power multi-tap transformer), and it's lightweight.
Principle disadvantages all involve servicing. Just
opening up this power supply is an accomplishment in
itself. A trained gorilla must tighten the machine screws
holding the power supply together! The fuse usually
doesn't blow, but when it does, it usually means there are
other problems with the supply. After opening the power
supply, you are greeted by two printed circuit boards
interconnected by numerous cables. If you're lucky enough
to isolate the failing parts (NEC type), you probably
won't stock them or be able to find a cross reference on
them. Using the " one handed" method of troubleshooting
10Ovac
A.C.
Outlets
(2)
Clrc ■H
11111
LlcallH
Line-in
(12Ovac)
SA
Screwed in next to
line cord bracket on
bottom right side of game
Power Supply
Input (1 OOvac)
4A
Inside power supply cage
Monitor
Input (1 OOvac)
4A
Monitor
Monitor
B+ voltage
.3A
Monitor
Video
Board
+Svdc------4
-Svdc -----➔
+12vdc---,
+24vdc
10Ovac _ _ _ _ __,
1 OOvac - - - - - - ,
CPU
Board
1
Monitor
1
Fluorescent
Tube
N1t11:
1. On/Off switch located below back door, right side.
2. There are NO interlock switches.
3. A terminal block for varied line voltage is mounted next to
transformer.
4. AC outlets may appear as utility outlets, but are provided for
fluorescent tube and monitor.
*Isolation transformer provides 1 OOvac output for 12Ovac input