Star Tech Journal

STAR*TECH ,Jourr·,al
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a. A. C. input
:i. Fuses
•If blown - check for shorted diodes
(rectifier), voltage regulator, or
horizontal output transistor.
A shorted horizontal output
transistor is the main cause of blowr,
fuses.
c. Voltage regulator input and output
•If the input is too high or too low
check rectifiers and driver
transistors.
* If the input is good and output is
too high, this will enable the
overvoltage protection circuit which
effectively cuts power to the rest of
the circuits - check the voltage
regulator. Check for bad connections to
the flyback transformer. If the
trar,sformer is not conr,ected properly,
it will not draw enough current to
allow the voltage regulator to function
properly. Also check for shorts in the
over voltage protection circuit.
Problem: Hum Bars
Check:
a. Monitor filter capacitor and
b. DC voltages to the game P.C.B.
(See STAR•TECH Journal, Volume 7, 13,
Page 2 under SABLE).
Section 2
"HIGH VOLTAGE (Flybackl SECTION
Problem: No High Voltage (No high
pitched squeal, no heater glow in the
r,eck of the CRT, and no brightness)
Check:
a. Low Voltage Power Supply (Sec ll
b, Horizontal Section (Sec 3)
c, Look for bad solder Points
d. Do not rule out a broken main
monitor PCB or neck board
e. Check for faulty brightness or
focus pots
Section 3
HORIZONTAL SECTION
Proble11: No Horizontal Deflection
(In 110St· cases this also means no
high voltage because the horizontal
section drives the high voltage
section)
Check:
a. Horizontal Output Transistor and
Driver
b. Check horizontal oscillator
circuit (in most cases - the I.C. on
the board)
c. Check for leaky or bad capacitors
Problem: Erratic or Rolled Horizontal
Deflection
Check:
a. Loose or leaky capacitors in
horizontal section. (On Nintendo type
monitors the most common problem is
C407 10uf/160Vl
b. Sync (Section SJ
Section 4
VERTICAL SECTION
Problem: 1/2 or no vertical
deflection
Check:
Vertical deflection transistors.
(These are the 2 transistors on large
heat syncs on the monitor board)
Note: Always check for loose
connect ions or broken "1 egs".
Section S
SYNC
Problem: Rolling or Scrambled Picture
Check:
a. The sync requirements of the board
and make sure they match the sync
abilities of the monitor. Although most
monitors will accept both negative and
positive sync, some do not. In this
case you will need to invert the sync.
Just pick up any Romstar conversion
manual for instructions.
A fe¥1- games use both negative
vertical and positive horizontal. In
this case it will be necessary to
invert only one. Also, most completely
negative syncs are compc,site syncs
(vertical and horizontal on the same
wire).
If your monitor will not accept
COIIIPosite sync it is best to call the
game manufacturer to find where to
split the signals.
b. Be sure you have a good ground or
common from the game PCB to the
rnoni tor.
Section 6
VIDEO Problem: One Color Missing
Check:
a. Connections
b. To find whether the problem is in
the game PCB or the monitor, simply
swap the wire from the missing color
with one of the functional colors. If
you gain the missing color and lose the
"good" color, you are not getting a
signal from the game P.C.B.
If the problem "follows" the wire
-the problem is in the monitor. If your
problem is indeed in the monitor, there
are 2 or 3 transistors from each color
(2 on the main P.C.B. and one on the
neck board l .
Check all of these and be sure to
check continuity in the circuit.
Note: The Nintendo type monitors used
in DONKEY KONG and DONKEY KONG JR. use
negative video inputs. Any conversion
attempted on these mor,i tors wi 11 need a
video inverter board.
For more information on video
inverter boards, please write Dennis
Sable c/o ROMSTAR, INC.
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W l L.L I AIYtS
SHUFFLE ALLEY:
Problems and Tips
September
1'385
(2)
CPU BOARD SWAPPING
Replacing the CPU Board (e.g., System
7 or System 9) from a pinball to a
shuffle alley game requires installatin
of differer,t Jumper wires for proper
game operatior,. (Similarly, going from
shuffle alley to pinball also requires
Jumper changes. l Refer to the manual
about the game you are trying to
utilize the CPU board in, to learn
which J urnpers are necessary.
PIN PANEL TROUBLESHOOTING
Symptom: All pins don't reset.
Solutions:
1. Check cable connector from pin
panel to cabinet for broken wires or
pushed out pins, and repair. Make sure
connectors are securely Mated.
2. Check 2.SA slow blow Solenoid
fuse, F2, on the power supply,
3. Check for shorted or open
solenoid, or shorted diode across the
solenoid.
4. Check wiring in the Pin Reset
Relay circuit for problE!IIIS,
S. Check adJustment and contact
closure of cam switches and other
switches.
6. Check the rollover wireforms (136)
or, the playfield for binding or
sticking; adJust for proper operation.
7. Check CPU Board connectors 1J11
and 1J12 for broken wires or pushed-out
pins; repair as necessary,
Symptom: Pin always actuates -
doesn't reset.
Solutions:
1. Check for open doide.
2. Check for shorted wiring,
3. Check adJustment screws on Pin
Hanger assembly,
4. Check the rollover wireforms (136)
on the playfield for sticking or
binding; adJust for proper operation.
S. Check for damaged or binding
plastic parts on the Pin Hanger
assembly.
6. Check for proper operation of the
assembly's springs,
Symptom: Pin does not trip,
Solutions:
1. Check for shorted or open
solenoid, or shorted diode across the
solenoid.
2. Check for broken wires on
solenoid.
3. Check playfield switch for bad
adJustment or dirty contacts; adJust or
clean as necessary.
4. Check CPU Board connectors lJll
and 1J12 for broken wires or pushed-out
pins; repair as necessary.
PIN RESET MOTOR PROBLEMS
Symptoms/Solutions:
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