Seventh Circle Audio

I completed my C84 and it's working perfectly for a dynamic microphone. When I connect a mic which requires phantom and engage 48V the pre fails to pass signal. The pre will however pass signal from the dynamic mic when phantom is engaged, just not from the condenser. I believe this means that the phantom power supply is not making it to the microphone. What can I do?

As you can see on the schematic, +48v comes into the board at J3, pin 5 and runs through D19, SW2, R70, R71, R3, and R4. Switch phantom power on and measure at all of these points until the voltage disappears. I'd suspect a backwards D19, but it could be a number of things. Let us know what you find.

D19 is correctly installed and I traced the circuit as you suggested finding a +48V reading all the way through R4. Strange. Here's another symptom that may help to trouble shoot:
When I had the dynamic mic connected to the C84 and engaged phantom power the signal disappeared temporarily and gradually faded back in. Then, when i switched phantom off the signal disappeared again only it didn't come back until i turned the gain all the way down and back up again.

Your insights are greatly appreciated!

Thanks!

Do you have the jumper at J1 installed correctly?

hey that was it thanks a lot! This was my first time using headers and jumpers and I guess I didn't understand how to install them correctly. I went back and figured it out, I now have a fully functioning C84!

Thanks Again!