I have designed this circuit to compare the input from a pot in a control console and a feed back pot on a hydraulic pump. The pump is a hydrostatic design and controlled by positioning a swashplate. The swashplates position is changed by energizing and de-energizing two solenoid valves. These valves receive their command signals from the comparator. When a position is selected in the console the comparator sees the difference in the inputs and energizes one of the two solenoids which through the action of the swashplate moves the feed back pot. When the feedback pot inputs the same value the comparator outputs go low de-energizing the solenoids. I put this into a breadboard and it worked perfectly. When the two pot values equaled out both outputs went low. After putting my circuit on a pcb and testing it I found both outputs went high instead of low, which is unacceptable. I recreated the circuit in my breadboard and it is doing the same thing. I can't understand what changed, does anyone have an answer? Also the two trimmers in the schematic are for adjusting the range of output to match the feedback pot. thanks
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