Utilizing the High Speed Multi-Channel Data Recorder (HSMCDR) developed at Sandia National Laboratories, we have measured the erection pattern of a 3.2 MV PBFA I Marx. This has allowed us to study variations of the erection pattern caused by changing resistors within the Marx. The effect of each resistor change was determined by monitoring the optical signal associated with switch closure using fiber optic links and the HSMCDR. Using this photonic technique, we have carried out modifications that have reduced the Marx jitter by a factor of two.