Star Tech Journal

Issue: 1991-July - Vol 13 Issue 5

Rowe R-89 Juke
Backwards Play
Data East TMNT
Ball Shooter Fix
Don Frederick
Blackwell Music, Inc.
Greenville, South Carolina
Todd Tuckey
TNT Amusements
Southhampton, Pennsylvania
SYMPTOM
SYMPTOM
Here's another good one for the old 45 rpm units
likeaR-89. You walkintoajolntand thewaitress
tells you the jukebox has been playing the
records backwards.
My new out of the crate 'Turtles pin, using the
ball shooter, couldn't quite make it up the first
ramp. The ball would come back to the shooter
lane and the automatic shooter arm would hit
the ball again, this time making the shot.
CAUSE
Before you send her to a mental ward, check out
the main power supply. Take a look at the red
wire going to one of the main power transistors.
Chances are you have a bad solder joint (or no
solder at all as in my case).
PROBLEM
Usually when your shooter on any pinball ma-
chine doesn't hit the ball squarely, you can
loosen the assembly screws and adjust the
whole mechanism.
SOLUTION
SOLUTION
Resolder red wire and no more backwards
records. I never did see it play backwards, but I
did see it make the turntable start and stop
during play. I did have several different people at
different locations describe the problem as back-
wards playing sound before I saw it happen
(start and stop) on the first occurrence.
I didn't want to start doing this as the auto
assembly was involved, so I solved the problem
by removing the rubber shooter tip and placing
a small mini post rubber inside it, flat, with a
needle nose pliers.
Willianis Pinball
Display Count Off
RandyTeny
Alpine Amusement
Connersville, Indiana
Now the tip extends that slight extra amount to
hit the automatic assembly and the ball makes
it every trip.
This quick fix might fix other pinballs for you tool
* * *
PROBLEM
Displays appear to "count off' left to right: alter-
nating between players 1 & 3, then 2 & 4.
CAUSE
In the power supply (Part #D-7999) capacitor C7
or Cl 1 (l00ufd @ 150v) ls baked open and not
properly regulating the + 100 or -100 vdc.
SOLUTION
Replace capacitor with equal or better rating.
MURPHY'S LAW
# 1305
H
Atari Centipede
Distorted Audio
\STAR*1ECHJoumal
s
Beckman
A
DM25XL
L
RandyTeny
Alpine Amusement
Connersville. Indiana
E
SYMPTOM
'
Multimeter
EASY
ro UsE,
LARGE DISPLAY, Low Cosr!

Distorted Audio ( especially after the first screen).
• 29
20
• BUILT-IN
SYMPTOM
At first. I would adjust RB (1 Kohm potentiom-
eter) but after a few more months on location, the
same thing would occur so I investigated further.
RANGES
MHZ LOGIC PROBE
20 MFD
MEASUREMENT To 2000
• CAPACITANCE MEASUREMENT To
• RESISTANCE
MEGOHM•
1 O AMP
RANGE Ac AND
De
• TRANSISTOR GAIN MEASUREMENT
CAUSE
Asit turned out R6 (2.9 kohm, l/4w) and R7 (7.5
kohm, 1 / 4w) on the regulator audio II PCB (AO-
35435) were baked off value.
SOLUTION
Replace R6 and R7 with exact replacements at
1/2 w (5% tolerance).
$89
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