Re: Continuing Problems with 7704A Display

Mark Vincent


The base of the bottom transistor is too far off making the transistor in full conduction. This makes me highly suspect of the 741 IC. See if the output voltage at pin 6 is what the schematic says. If that is not right, replace the IC. A possible bad Q4105 is possible, open B to C. You can check Q4115 if you want to confirm it is good or bad.


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