Injected a voltage (randomly changed each helicity window from the HAPPEX DAQ timing board dac12 output) into the v2f handling the signal from the dx3 downconverter. Using this, we were able to see that there were periodic double pulses into the cable going to the happex7 scaler.
Found that a copy of this signal was sent to a cable running to the 2nd floor cage. This cable was unterminated. So I unplugged this cable at the Level Translator. Maybe someone was using this signal (at some point) to help commission the GEM detector in the hall.
Signal to HAPPEX daq looks fine now... but we will continue to monitor it.