265. A circuit card in a RADAR system has just been replaced with a spare card. You notice the voltage level at point E in Fig. 8F12 is negative 4.75 volts when the inputs are all at 5 volts. The problem is:

A negative output voltage of -4.75V with positive 5V inputs indicates an imbalance in the op-amp's gain, likely due to an incorrect resistor value. Replacing a 50kΩ resistor with a 25kΩ resistor doubles the gain of that input, resulting in the observed output voltage and confirming this as the most probable cause.