Star Tech Journal

S*TJDECEMBER198115
$26.50
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.: .
Cocktail Tables
Newport
•
Made in the U.S.A. for the
needs of the American Market.
Will replace joysticks in im-
ported and domestic machines.
Interchangeable gateplate for
two, four or eight positions.
Engineered and built to last!
All parts easily replaceable.
FAST SERVICE.
PAC-MAN
Garnes
SATISFACTION
GUARANTEED
Newport Machine Design
P.O. Box 418
Bishop, CA 93514, U.S.A.
(714) 873-4431
BALLY'S
TECH
RAM
-----
* FAILURE * DUE * TO * BLOWN * FUSE
BY HOWARD M. SMITH , ARLINGTON, TX
STRONG,
RELIABLE
JOYSTICKS
Ideal For
"DEFENDER"
- - - - - - - - - - - - --
✓
MODEL 125
CALL TODAY
WILLIAMS
Shorting the coin entry lamp socket
to the front door with power on can
cause a constant Ram Test pattern or
Ram Failure message on Williams
"Defender". The symptoms can be
traced to a loss of-5V due to fuse F4
being blown. If the machine is left on
without the -5V, the 4116 rams may
be degraded to the point of failure.
Replacing the fuse right away will
normally get the machine up and
running. Turning the machine off
before changing these bulbs will avoid
this problem altogether.
* QUIZ * (PART 4)
ANSWERS
QUESTIONS FOR
EVALUATING
NEW TECHNICIANS
BY EDWARD J. SCHMIDT
16. Set function switch: D.C.; range
switch to next highest scale,
example: 500 V; black lead:
common on meter to circuit
ground; red lead: + on meter to
circuit potential. Read voltage on
D.C. 0-50 range.
17. An electronic circuit containing
transistors and perhaps diodes,
resistors and capacitors, along
with interconnecting electrical
conductors-processed and
contained entirely within a single
chip of silicon.
18. A. CE
19. Decoder output active low will
turn Q 1 off causing the + 5 at
R2 120Jt resistor to turn on the
base of Q 2. Q2 turns on.
20. C. High and low logic levels.
THIS CONCLUDES BALLY"S 20 QUESTION TECH QUIZ.
Fuse F4 is a IA slow-blow fuse
that is designed to protect the
transformer from damage in the event
of a short in the -5V regulator
circuit. This fuse failure is very
deceiving because the problem is not in
the -5V circuit.
Close examination of the circuit
diagram shows that if one side of the
lamp socket is grounded, a high
current path will exist through the
transformer, F4, and one leg of BR3.
When changing the bulbs on the coin
door, it is quite easy to bump the
end of the lamp socket to the lip of the
door. If power is on, F4 blows.