JK Spring 2014

My first project this semester is going to be programming the control boards that regulate the bias voltages for the SiPMs as per the procedures outlined by Alex here.

After some initial issues with the boards, Dr. Jones and Alex discovered that there was a problem with the Vref of the control boards. With the addition of an extra resistor the problem has been fixed and the first and eleventh boards have been programmed. I started on the second board but there was an issue with the first pin that led us to believe that there is a solder bridge underneath the DAC that is sapping voltage from the pin. This is not an issue that we can fix and therefore the board is bad.

As of March 24th I finished calibrating all of the boards that do not have issues. After I finished those I went back and filled in the remaining values for the problematic boards. As soon as I finished that Alex came in to say that the board he had been using to test the fibers in the dark box (board 11) suddenly lost channel 2. When I looked at it the voltage on that channel was steadily dropping to zero, and in addition all of the other channels were higher than what I originally calibrated them to by about 20 mV. I then checked boards 1 and 3 as well to test whether or not it was time that was offsetting the calibrations. Board 3 was in the same area as 11, but 1 seemed fine for the most part. When I come back in I am going to check the first 15 channels on those three boards in rapid succession to see whether or not it is the power supplies that are causing the issues. If board 1 is fine when boards 3 and 11 are not then the issue most likely lies in the circuits themselves.