Check resistors R116, R216.
No Brightness Control
Check intensity pot Rill for open wiper or internal short.
Check for open capacitor C17.
Check for bad solder connections to Rill.
Picture on Display Jitters
Replace analog switch IC1.
Check size pots R109 and R209 for wiper noise by turning briskly while observing the screen. Readjust for proper screen size.
Check for bad solder connections on R109 & R209. Check DACIC101 & IC201 for bad solder connections. Insure that all molex connectors are properly seated.
Suspect High Voltage too high/too low
An accurate High Voltage meter will read close to 16KV if high voltage is good. Self-contained HV meters vary widely in accuracy. If +90 and +400 volts out of high voltage supply are good, chances are 16KV is good. If +90 or +400 volts are bad, repair or replace high voltage supply.
Verify proper operation of IC1.
Check for proper +25 and -25 volts DC.
Check operation of DAC's IC101 and IC201.
On logic board, check I 8 pin 2 for pulses. Verify presence at analog switch.
Check for open speaker coil.
Check transistors 2N6292 and 2N6107 and nearby output components on audio board with ohmeter or transistor checker. Check 7815 and 7915 outputs.
Check for open wiper on volume control mounted on inside of coin door. Refer to audio board theory of operation and troubleshooting guide. Replace F2 on logic board.
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