Star Tech Journal

APRIL 1984
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Problem: Shaky video after game warms up.
The problem is most noticeable in the high-
score screen. Fluttering is seen in the words
"Princess Leia's Rebel Forces" and the scores
sometimes move back and forth.
Solution: Replace the 1 0k.n. resistor at loca-
tion R83 on the video board with a 20k.O..
resistor.
STAR WARS DISPLAY
PROBLEMS
Problem: No filament voltage from the high
voltage (HV) PCB.
Solution: Check for a loose connection on
the lugs that hold the HV transformer to the
PCB.
Problem: The voltage is low on the supply
lines on either tHe Deflection PCB or the HV
Problem: The picture shrinks in from the
negative X and Y sides of the screen.
PCB.
Solution: On some deflection boards, R35
and R12 may have a 15.0.. resistoranda30.0..
resistor in parallel to get 1 o.n.. If these come
loose, then some picture shrinkage may occur.
Solution: There are jumpers on the supply
lines of both boards. The Jumpers are marked
with a "W" on the schematic. They look like
resistors on the board and have a single black
band on them. The jumpers should have no
resistance. However, the brown jumpers may
have created some resistance to them. They
should be replaced with a piece of wire. The
white and tan jumper should have no problems.
24V
Problem: Can any other power transistors be
used on the Deflection board?
Solution: Yes, MJ 15003 NPN replaces
2N3716, and MJ 15004 PNP replaces2N3792.
HVPIN4
Problem: What should the output of the 555
IC on the HV PCB be?
I
Solution: The output at pin 3 on the IC should
be a 20-kHz square wave. This is adjusted
with potentiometer R7.
C10
0.1
R19
&BK
sov
DAGGROUND
Problem: There Is no high voltage. The posi-
tive and negative 24 volts are present.
Solution: Check transistor 03. The problem
may be that the transistor tab (collector) may
not be making good contact with the heat
sink.
ORIGINAL
24V
Problem: The schematics for the HV cutoff
circuit do not match the board assembly.
HV PIN4
Solution: There are three board revisions.
You can tell which one you have from the table
here. The schematics for all three boards are
shown.
I
C10
0.1
sov
R19
68K
DISPLAY REVISION INDICATORS
PCB Revision
R16
R18
Original
First rev.
Second rev.
470.n.
Zener
470.0..
27k.!l.
Missing or 27k.n.
33k.fl.
DAG GROUND
FIRST REVISION
Problem: The schematic for the deflection
board shows CR5 as a 1 N714 diode.
Solution: The schematic number is wrong. It
should be labeled a 1 N751 A zener diode. The
rating of 5.1 volts is correct, however.
Problem: On the HV PCB, the output voltage
of the regulator is good when the pin is lifted,
but there is no voltage when the pin is con-
nected back to the board.
Solution: Check for a bad 0.1 uF glass capa-
citor across the voltage regulator. The
decoupling capacitor may be shorted.
as
2N3904
HVPIN4
R18
33K
I
C10
0.1 SOV
R17
20K
Problem: The 24-volt regulator has failed.
DAG GROUND
Solution: Check for cracking around the
regulator leads on the PCB. Also check for
cracking around the leads of C3 and C4.
SECOND REVISION