Troubleshooting guide

Cinematronics Vector Monitor Repair Guide v.1.0
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converters on the monitor board. These undefined values may (and usually will!) cause the
deflection circuits to drive very hard and burn out components.
• Be careful with the orientation of the ribbon cables used to attach the CCPU board to the
video board. On many games, the connectors are not keyed, and if you install the cable
incorrectly, damage to the video board and/or the CCPU board can result. This is a very
common problem.
• If you know you have a monitor board failure and are actively working on the monitor, you
can disconnect the CRT plug from the neck of the picture tube. This will prevent any
chance of phosphor burns from occurring while you are running tests, etc. You obviously
will not be able to see any of the tests on the monitor screen, but that is ok for most tests.
Never work on the High Voltage unit unless you know what you are doing.
It is dangerous and can kill you.
Cinematronics vector games require a pure +5VDC for the CCPU to function correctly, and you
MUST NOT plug the monitor in until you have proper game sounds when you coin and then start
the game. This requires that you have +5VDC on the CPU board near the eproms/roms. Next (after
checking the monitor for shorted/open transistors and resistors) using your logic probe, check for
activity on the data lines going to the monitor to ensure that there is a changing signal on all data
lines. Now you can plug the monitor in. Listening closely to the yoke of the monitor, turn on the
game for about five seconds. There MUST be a “chattering” noise coming from the yoke area. If
this yoke chatter is not present then turn game off, disconnect the driver transistors and the yoke
from the monitor chassis, and get out your oscilloscope to test for signal flow. If chattering is
present, then move around to front of game to watch for a picture.
Waveforms From Manual
In order to diagnose the monitor board, you can check various spots on the PCB for predetermined
oscilloscope waveforms. All scope waveforms are generated with the game in diagnostic mode
(CCPU dip switch # 7) and with the yoke connector unplugged. For the x and y amplifier sections,
trace through each amplifier with an oscilloscope and narrow down where the problem lies. At that
point you can always do a diode test on the transistor in question and verify if it is good.
Set your scope to trigger at 50% of the peak output voltage (you can usually use the +V side) of
each section of the amplifier or DAC output and look for a ‘decent’ amount of activity (i.e., voltage
swings similar to those pictured below).
The main points of reference you can check are:
1. The collector of Q104/Q204 (although it is easier to look at the diodes)
2. Output of each DAC-80 (pin 15)
3. Input of each TL081 (pin 3)