STAR*TECH JOURNAL/MARCH 1983
6
ATARI
"CENTIPEDE"
* INTERMITTENT TRACKBALL SOLUTION R~VISED * FIRE BUTTON AND COIN SWITCH MOD* PICTURE FLIP MOD
In our January '83 issue (Vol. 4, No. 11) the
modification procedure for the "Centipede" track-
ball circuit was in error. Atari has supplied us
with a revised version of this fix.
Please mark your January "Centipede" article
in error and refer to this updated version.
SYMPTOM: The player loses control of the
shooter with the trackball intermittently.
SOLUTION: Perform the following mod on rev.
A-F boards only. Boards with rev. G-J have these
changes incorporated.
Note: The first half of this mod is for upright
games. Cocktail games will need to do Part 2 as
well.
Part 1.
I) Replace resistors Rl30-133 with 3.3K ohm¼
watt resistors.
2) Clip and lift the following pins. These pins
should be clipped as close to the solder pads on the
board as possible, and the pins lifted only enough
to break connection. On IC FIO-pins I and5; on
IC Fll - pins 5 and 13.
3) Solder a I uf 50v capacitor between the lifted
pins of the IC and the solder pads the pins from
lifted from. The positive (+)side of the cap goes to
the lifted pin.
4) Solder !OK-ohm ¼-watt resistors to the (+)
lead of the capacitors.
5) Solder the free ends of the resistors together.
6) Solder a IK-ohm ¼-watt resistor between IC
Fl I - pins 3 and 4.
7) Solder a !OK-ohm resistor between IC Fl I -
pin 3 and the common end of the !OK-ohm
resistors that are tied together.
8) Solder a I uf 50v cap between the common end
of the I OK resistors and ground. The ( +) lead goes
to the common end of the resistors.
9) Connect a IOOOpf cap between IC Fl I pin 3
and ground.
Part 2. For Cocktail Games Only.
I) Change resistors R83-86 to 3.3K ohm.
2) Clip and lift the following pins as in Part I, item
I, above. IC FIO pins 9 and I I ; Fl I pins 9 and 11.
3) Solder I uf caps across the lifted pins as in part
I , item 3 above. Then solder I OK-ohm resistors to
the cap leads as in Part I, item 4 above, and finally
tie the free ends of the resistors together.
4) Install a IK-ohm resistor between pins 3 and 4
ofICFIO.
5) Connect one end of a IOK ohm resistor to IC
F 10 pin 3 and the other end to the common ends of
the I OK resistors.
6) Connect a I uf 50v cap between the common
end of the !OK-ohm resistors and ground. The ( +)
side of the cap goes to the resistors.
7) Connect a IOOOpf cap between IC FIO pin 3
and ground.
"Centipede" Fire Button & Coin Switch
Switch Mod
SYMPTOM: Intermittent fire buttons and coin
switches.
SOLUTION: For fire buttons, change resistors
Rl15 and 117 from IK-ohm to470-ohm, ¼ watt.
For coin switches, change resistors Rll9, Rl20
and Rl23 from IK-ohm to 470-ohm ¼-watt.
"Centipede" Picture Flip Mod
PROBLEM: Picture flips in an upright game.
SOLUTION: Check to see if pins Zand 15 on the
large 44-pin edge connector ( attached to logic
board) are connected.
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It is recommended that these modifications be
attempted by those who are experienced in trouble-
shooting digital circuits, as well as being
experienced in solid-state circuitry soldering and
rework techniques. Those without this experience
who attempt to do the mods may damage the
board, both physically and electrically. This may
result in extra repair charges by your distributor,
and in extreme cases may render the board
unrepairable.