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STAR*TECH JOURNAL/FEBRUARY 1983
ATARI
"TEMPEST' DISPLAY PROBLEMS/SOLUTIONS AND MONITOR ADJUSTMENTS
SYMPTOM: Some of the rims between the tube rails are missing on
some playfields. For example, the first circular playfield is missing the
top rim. Self test shows an E in the middle of the screen. This indicates
that the EAROM at location C-3 on the Auxiliary PCB is defective.
Replacing the EAROM does not correct the problem.
SOLUTION: The problem lies outside the Auxiliary PCB . Two
probable causes exist. The interboard connector to J-19 on the main
PCB has shorted oropen wires; or, the transceiver IC H-2 (74LS245 or
AM8304B) on the main board has failed.
NOTE: Any individual working on a display should be familiar ' with servicing
procedures and precautions necessary for picture tube and high voltage
equipment Use extreme care when handling the picture tube. Wear safety
goggles and heavy gloves for protection when handling the picture tube.
BRIGHTNESS ADJUSTMENT
"IMPROPER SCREEN (BRIGHTNESS) ADJUSTMENT MAY
CAUSE PHOSPHOR BURN"
The brightness adjustment must not be made using the game or attract
mode.
The brightness is adjusted only to the following procedure:
1. Set game to self test.
2. Activate SLAM Switch until display screen #5 (5 groups of colored
bars) is displayed.
3. Using the center group of bars, adjust the screen control until the fifth
and longest bar is visible. Too much brightness causes the sixth bar to
become visible. Too little brightness causes the fifth bar to disappear.
It is recommended that the brightness be checked on new games and
games which have been moved to a location. Also, a little RTV on the
screen control knob will insure that the control will not inadvertently
move due to vibration, etc.
ZAMPLIFIER
Field Service has received reports of a condition where the picture turns
very bright and the addition of interconnecting lines between objects is
apparent. The cause may be a failure in the video B+ supply due to an
open PCB trace.
If you experience this problem, tum the game off immediately to
prevent phosphor bum.
Proceed to troubleshoot as follows :
1. Disconnect the neck PCB assembly from the picture tube.
2. Disconnect connector on game logic board.
3. Power up game.
4. On the neck PCB, measure the voltage from chassis to the tab
( collector) ofone of the three color amplifier transistors ( Q500, 50 I,
or 502). The correct voltage is 180 volts.
5. If the voltage is considerably less, the video B+ power supply or
associated wiring located in the high voltage unit is defective.
6. Remove the four chassis mounting screws of the high voltage unit
and remove the unit.
I
7. On the circuit side of the PCB, jumper pin 6 of the high voltage
transformer to the anode of diode D90 I.
8. Remove the cage and check the capacitor C901 for a broken lead.
9. Reassemble HV unit and mount to the chassis.
I 0. Again, measure the voltage on the color amplifier transistor tab for
the proper 180 volts.
DEFLECTION PCB
The loss of voltage in either 25-volt power supply has been diagnosed by
some as open filter capacitors C90 I or C902. Before replacing the
capacitors, make sure that the PCB traces near the capacitor terminals
are not cracked. It is recommended that the solder be removed for this
inspection.
INPUT CONNECTOR (Monitor)
With new games, it is always a good practice to inspect the monitor input
jack pins and the harness plug pins. Make certain the pins are fully
inserted and properly seated. Pins making partial contact in high current
lines may eventually corrode due to heat or arcing.
MAIN LOGIC PCB
Sometimes, you may have noticed, a short duration dot in the center of
the screen when switching from self test to play mode. Over a period of
time, phosphor bum may occur. To protect your monitor, perform the
modification below on Rev A, B and C boards.
1. On the circuit side of the PCB, cut the trace which connects pin 9 of
IC/ C-9 to resistor R-32.
2. Jumper pin 9 of A9 to pin IO of B-8.
OUTPUT TRANSISTORS SHORTING
SYMPTOM: Output transistors on Wells-Gardner color X-Y monitor
shorted and fuses FIOO and FI0I blown.
SOLUTION: Perform the following steps:
I. Remove PIO0, IOI, 600, 700.
2. Check DIO0, DIOI , Dl02, DJ03.
3. Check QIO0, QI0I, ZDIOO, ZDI0J, CIOO, CIOI.
Are fuses still popping?
Check for shorted traces.
4. Check JIOO pin #1 = 33.8vdc.
#3 = 28.5vdc.
#6 = -28.5vdc.
#7 = -33 .3vdc.
5. Check Ql02, 103 .
6. Replace PIOO.
7. Check JI()() pin 4 = 27.8vdc.
Check JI()() pin 5 = -27.7vdc.
NOTE: Installing the "IPC Board" will prevent the above problem. Contact your
Atari Distributor for availability and further information.
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BALLY/MIDWAY
"SUPER PAC-MAN" DIFFICULTY SETTINGS
Your "Super Pac-Man" game is set at difficulty level 9 (Switch B:
Position I-On, 2-OfT, 3-Off, 4-On). Bally/Midway's testing has deter-
mined this to be the best setting for the novice player. However, due to
the degree of competence of many Pac-Man type players, you may wish
to monitor the players to see if they become too proficient at this setting.
If, after monitoring the game in your location, you determine that setting
9 is too easy, Bally/Midway recommends you raise the difficulty to the
next higher setting, difficulty Level A (Switch B: Position I-Off, 2-On,
3-OfT, 4-On). Difficulty Level B is higher than Level A and may be
adjusted on dip switch B (Position 1-O·n, 2-On, 3-OfT, 4-On).
Because Level B is the most difficult and aggressive setting, it is
recommended you closely monitor the players reactions to see if they are
becoming too frustrated at this setting.
Star*Tech Journal, Volume 4, Number 12 February 1983. Copyright 1983 by Star*Tech Journal, Inc. All rights reserved. Star*TechJournal is published 12 times a year. Address
inquiries to: P.O. Box 1065, Merchantvil 1
e, New Jersey 08109. Phone: 609/662-3432. Star*Tech Journal verifies the contents of the articles herein as much as possible.
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Contributing Technical Writers: Todd Erickson, Joe Connor, Frank Becker, Mark' BeM' Atteberry.