I have a circuit where I am replacing what I believe was a SMD Zener diode. The points for connection are ground and a voltage source of 4.9 volts with the diode not installed. I believe the 4.9 volts needs to come down to 3.3 volts with a half watt 3.3volt zener installed. Is this possible or am I barking up the wrong tree? I installed a 3.3 volt zener but the voltage remained 4.9 volts?